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ACNS 2004American Conference on Neutron Scattering

S P O N S O R E D BY T H E N E U T R O N S C AT T E R I N G S O C I E T Y O F A M E R I C A

H O S T E D BY T H E N I S T C E N T E R F O R N E U T R O N R E S E A RC H

College Park, Maryland June 6–10, 2004

General InformationThe Second American Conference on Neutron Scattering is hosted by the NISTCenter for Neutron Research, and will be held in the Inn and Conference Centerfor the University of Maryland University College in College Park, MD June 6-10,2004. The conference is being organized under the auspices of the NeutronScattering Society of America (NSSA) and is sponsored by the North Americanneutron centers. It is planned to be hosted by one of the centers every otheryear, in years that do not coincide with either the International Conference onNeutron Scattering or the European Conferences on Neutron Scattering. Thefirst conference was a resounding success, being hosted by the SpallationNeutron Source-High Flux Isotope Reactor User Group at Oak Ridge NationalLaboratory in Knoxville, Tennessee, in June 2002.

The conference is intended to showcase recent scientific results in neutronscience in a wide range of fields, including soft and hard condensed matter,biology, engineering materials and applications, chemistry and materials,fundamental physics, and developments in neutron instrumentation. This willbe accomplished through a combination of invited talks (30 minutes), contrib-uted talks (15 minutes), and poster sessions. The conference will feature thepresentation of the first Cliff Shull Prize for Neutron Science to Dr. J. MichaelRowe of NIST.

The conference is also intended to fulfill many of the objectives of facility“users’ meetings” but on a national scale. Presentations will be featured thathighlight the present and planned capabilities of the instrumentation for usersat the major neutron centers in North America and will provide a forum forusers to ask questions and raise issues that relate to using these facilities.

The conference particularly encourages the participation of graduate students,postdocs, and new faculty, as well as established researchers in neutronscattering and allied disciplines. For the former groups, funds will be available tohelp defray travel expenses.

Additional information about the conference is available on the ACNS website atwww.ncnr.nist.gov/acns/

NSSA InformationThe Neutron Scattering Society of America (NSSA) was formed in 1992 and is anorganization of persons who have an interest in neutron scattering research in awide spectrum of disciplines. Membership in the society is open to individualsin academia, industry, and government. Graduate students and recent Ph.D.sare especially encouraged to join. There is no cost to be a member, and allmembers receive a complementary copy of Neutron News. The NSSA website ishttp://www. neutronscattering.org. We encourage all conference attendees tostop by the NSSA booth in the Main Concourse during the ACNS meeting.

NSSA Executive CommitteePresident Robert M. Briber, University of Maryland

Vice President James D. Jorgensen, Argonne National LaboratorySecretary Simon Billinge, Michigan State UniversityTreasurer David Belanger, University of California—Santa Cruz

Membership Secretary Gregory Smith, Oak Ridge National LaboratoryMembers at Large Shenda Baker, Harvey Mudd College

Susan Krueger, NISTFranz Trouw, Los Alamos National Laboratory

WelcomeWelcome to the second American Conference on Neutron Scatter-ing! Your enthusiastic response reflects the strength of theneutron scattering community in the U.S. and Canada. A total of389 abstracts were received, a 40% increase over the very

successful first ACNS held two years ago in Knoxville, TN. Many of theseabstracts represent the research work of young scientists, including over50 abstracts from graduate students who are competing for the firstNeutron Scattering Society of America Prize for Outstanding StudentResearch, foretelling a very bright future for the field.

The papers presented in this conference show the diversity in sciencethat is directly impacted by the use of neutron scattering including:biology, chemistry and materials, engineering/applications, instrumenta-tion, soft matter, condensed matter physics and fundamental physics.

At this meeting, the first Clifford G. Shull Prize in Neutron Science will beawarded to Dr. J. Michael Rowe “for his seminal vision, leadership, andcontributions to the field of neutron scattering.” The NSSA is extremelypleased be able to honor achievements in neutron scattering with boththe Shull Prize and the NSSA Student Research Prize at the 2004 ACNSand we hope to continue this tradition in the future.

Organizing a meeting like this takes an enormous amount of work. Weespecially wish to express appreciation to the NIST Center for NeutronResearch for hosting the conference. Jeff Lynn and Shenda Baker havedone an outstanding job in organizing the program, Dave Belanger hashandled all of the finances, and Julie Borchers has acted as the localcontact for the conference. They have contributed countless hours to themyriad of details that must be gotten right to make a successful meeting.We also express appreciation to the Intense Pulsed Neutron Source atArgonne National Laboratory, the High Flux Isotope Reactor and theSpallation Neutron Source Project at Oak Ridge National Laboratory, theManuel Lujan Center at Los Alamos National Laboratory, the NeutronScattering Group at Brookhaven National Laboratory, the Department ofEnergy - Basic Energy Sciences, the Canadian National Research Counciland Institute for Neutron Scattering, the University of Maryland and theNational Science Foundation for generous financial support.

Most importantly, we express our appreciation to all of you for contribut-ing such a large number of abstracts for oral presentations and posters.The presentation of great science is what makes a great meeting. Therewill certainly be a lot of good science presented at ACNS-2004. Enjoy themeeting!

Robert M. BriberPresidentNeutron Scattering Society of America

Jim JorgensenVice PresidentNeutron Scattering Society of America2004 ACNS General Chair

American Conference on Neutron Scattering

Contents 1 Conference Organization

2 Transportation

2 Satellite Meetings

4 Lodging

5 Registration

5 Travel Reimbursements

5 Internet Café

6 Breakfast, Lunch and Breaks

6 Receptions and Conference Banquet

7 Neutron Scattering Tutorials

9 Awards

10 User Group Meetings

11 Breakout Sessions

11 Tour of the NIST Center for Neutron Research

11 Neutron Scattering Facilities Displays

12 Conference Exhibitors

13 Information for Presenters

14 Invited Speakers

15 Conference Overview

16 Room Layout

17 Epitome

21 Program

147 Author Index

168 Advertisements

College Park, Maryland, June 6–10, 2004 1

SponsorsThe ACNS has received generous support from the following sponsors:

National Science FoundationDepartment of EnergyArgonne Intense Pulsed Neutron SourceBrookhaven National LaboratoryLos Alamos Manuel Lujan Neutron Scattering CenterNIST Center for Neutron ResearchOak Ridge High Flux Isotope ReactorOak Ridge Spallation Neutron SourceUniversity of Maryland

Organizing CommitteeGeneral Chair

James Jorgensen, Argonne National LaboratoryCo-Program Chairs

Jeffrey Lynn, National Institute of Standards and TechnologyShenda Baker, Harvey Mudd College

NSSA PresidentRobert Briber, University of Maryland

NSSA TreasurerDavid Belanger, University of California—Santa Cruz

Local Contacts:Julie Borchers, National Institute of Standards and TechnologyRobert Briber, University of Maryland

Program SubcommitteesBiology

Joanna Krueger, University of North CarolinaDean Myles, Oak Ridge National Laboratory

Chemistry and MaterialsJohn Larese, University of TennesseeMike Crawford, DupontThomas Proffen, Los Alamos National Laboratory

Engineering/ApplicationsAaron Krawitz, University of MissouriCam Hubbard, Oak Ridge National Laboratory

InstrumentationRoger Pynn, Los Alamos National LaboratoryKent Crawford, Oak Ridge National LaboratoryDan Neumann, National Institute of Standards and Technology

Soft MatterMike Kent, Oak Ridge National LaboratoryLee Magid, University of TennesseeJyotsana Lal, Argonne National Laboratory

Condensed Matter PhysicsSteve Nagler, Oak Ridge National LaboratoryJohn Tranquada, Brookhaven National LaboratoryPeter Gehring, National Institute of Standards and Technology

Fundamental PhysicsJohn Doyle, Harvard University

ConferenceOrganization

American Conference on Neutron Scattering2

The program committee, and in particular the program co-chairs, thankAlan Munter and Ronald Cappelletti for their invaluable assistance in theelectronic organization of the program—abstract submission, electronicscheduling, and converting and editing the abstracts (much of which wasdone by suitably written macros), and editing the final program. We aregrateful to Kristina Nixon for aesthetically organizing the ACNS websiteand keeping it up-to-date. We appreciate the prompt assistance of JillWessner and Tim Altenberg from the Inn and Conference Center, and wealso thank Lisa Press and Sue Warren from the University of MarylandConference Planning Office.

Conference on Polarized Neutrons in Condensed MatterInvestigations (PNCMI 2004)http://www.sns.gov/pncmi2004/June 1 - 4, 2004 at the Renaissance Hotel in Washington, DCThis workshop is being organized by Frank Klose (SNS) with programchairs Hal Lee (SNS) and Georg Ehlers (SNS).

Workshop on Applications of Neutron Scattering toEnergy Production and Storagehttp://www.sns.gov/jins/nmi3/June 4-5, 2004 at the Renaissance Hotel in Washington, DCThis workshop is jointly organized by the UT/ORNL Joint Institute forNeutron Sciences and the European NMI3 program, with an internationalscientific organizing committee coordinated by Lee Magid (University ofTennessee), Al Ekkebus (SNS) and Flavio Carsughi (University of Ancona).

The ACNS conference is served by three major airports, BWI, DCA andIAD. The Supershuttle (http://www.supershuttle.com) provides transporta-tion to and from all major airports. Call 1-800-BLUE VAN (258-3826) forfares and to schedule pick-up and departure times.

Following are specific suggestions for travel to campus from these airportlocations:

Baltimore-Washington International Airport (BWI) is located approxi-mately 25 miles north of the university. Driving time is approximately 35minutes. Ground transportation to College Park is available by van ortaxi.

Airport Connection provides van service for about $18.00 (discounts formore than one person traveling together). Call 1-800-284-6066 or stop attheir location at the airport. Taxi service costs approximately $35.00.Alternately, Metrobus express route B30 runs between the Greenbeltstation of the Metrorail and BWI Airport. (See B30 timetable.)

Reagan National Airport (DCA) is located in Arlington, Virginia andabout 15 miles from College Park. Travel can be slow through downtown

SatelliteMeetings

Transportation

Special Thanks


Washington, D.C. during rush hours; approximate driving time is 40minutes.

You can take the Metrorail from Reagan airport to College Park. Taxiservice directly from the airport is approximately $40.00 one way.

Dulles International Airport (IAD) is located near Herndon, Virginia andis about 35 miles from College Park. Driving time is approximately onehour.

Taxi service costs approximately $55.00 one way. Washington FlyerTaxicabs serve Dulles International Airport exclusively with 24-hourservice to and from the airport. Taxicab Dispatchers are on duty 24 hoursa day at the East and West ramps on the lower level of the Main Termi-nal. For information or to arrange transportation for your return trip, call703-661-6655.

Washington Flyer Coach service is available to take you to the West FallsChurch Metrorail station.


Inn and Conference CenterAll technical sessions will be held in the Inn and Conference Center forthe University of Maryland University College in College Park, Maryland.The Center has spacious meeting facilities located in a campus setting,and includes The Garden Restaurant, Oracle Lounge, and StarbucksCoffee Shop in the Facility. A room rate of $119/night for single or doubleis available at the Inn for conference attendees. All rooms are equippedwith high speed internet access and other amenities. Parking is free inthe garage for all conference attendees. Please tell the parking attendantthat you are with the ACNS conference upon leaving the garage.

To book your stay online, follow the Hotel Accommodations link on themain webpage, click on the Lodging at the Inn and Conference Centerwebpage at www.ncnr.nist.gov/acns/, and then click on the preferredroom type and select the dates of stay. To make reservations by phone,please call 1-800-228-9290 and ask for the special rate for the AmericanConference on Neutron Scattering (group code “ACNACNA”) at theUniversity of Maryland University College Marriott Conference Hotel.

On-Campus Lodging for Students onlyLocated in a residence hall on-campus at the University of Maryland.Walking distance to Inn and Conference Center of 15 minutes or greater.Room occupancy ranges from 1-4 people (of the same gender) in singleand double rooms and 4-8 people in suites. Roommate requests andadditional nights are available upon request. Maximum of 50 students.(For additional information regarding on-campus lodging, view theSummer Guest Guide on-line at www.umd.edu/cvs/guestguide.)

Options include:

Package A: Includes 5 nights lodging (check-in Saturday, June 5th,check-out Thursday, June 10th ) Single bedroom: $236.00, Shareddouble bedroom: $200.00

Package B: (Includes 4 nights lodging (check-in Sunday, June 6th,check-out Thursday, June 10th) Single bedroom: $189.00, Shareddouble bedroom: $160.00

Campus Meal Plan: Dinner in the on-campus diner on Sunday, Mon-day and Wednesday. The diner is a 15-20 minute walk from resi-dence halls. Total cost of $33.00.

Register for On-Campus lodging by using the On-Campus On-lineregistration or by filling out the On Campus Lodging Form (PDF) mailingor faxing it to Conferences and Visitor Services - ACNS, University ofMaryland

Lodging


Registration is available on-line at the conference website(www.ncnr.nist.gov/acns/). On-site registration is also available. Allconference attendees must register and wear their badges during themeeting. The conference registration desk is located in the Main Con-course of the Inn and Conference Center. The registration desk will beopen on Sunday, June 6 from 12:00 – 19:00. On Monday throughWednesday, June 7 – 9, the desk will be open from 7:30 – 17:00. On-lineregistration fees are:

Registration

*On-line Registration ends May 31, 2004. After 5/31 you must register on-site – $25 additional fee will apply.

Cancellations received on or before May 14, 2004 are fully refundable,less a $50.00 processing fee.

No refunds after May 14, 2004. All cancellations must be in writing.

All registrants will receive a badge, a copy of the program book, acomplimentary copy of Neutron News, a list of participants, a bag with theACNS logo, continental breakfast on Monday through Thursday, lunch onMonday through Wednesday and continuous daily refreshments.

The ACNS anticipates being able to partially support the travel expensesof some conference participants. Preference will be given to graduatestudents, postdocs, and junior faculty in the U.S, but others will beconsidered as funding permits. If you wish to request travel support,please fill out an application on the webpage. Support decisions forregistrants applying by April 30 will be conveyed to applicants by May14. Later applications will be considered as time and funds permit.

Reimbursement checks will be available during the conference at theNSSA booth in the Main Concourse. Please note that the registration feemust be paid in advance; support requests may include the registrationfee.

Questions concerning travel support may be directed to Professor DavidBelanger at [email protected]

TravelReimbursements

Full Registration

Student

On or before April 25, 2004

$250.00

$100.00

After April 25, 2004*

$300.00

$150.00


Several computers and internet connections will be available in the MainConcourse for attendees to use. In addition, wireless access (802.11b) tothe internet will also be available in the main concourse.

High speed internet connections are also available in each room, andwireless access is available in Starbucks and the Oracle Lounge.

A continental breakfast will be available in the Main Concourse each day(Monday-Thursday) of the conference starting at 7:30. Lunch will beavailable in the Grand Ballroom on Monday at 12:30 and in the FortMcHenry/Founders rooms on Tuesday and Wednesday at 12:30. Refresh-ments and snacks will be available continuously all day outside of thesession rooms during the scientific sessions (Monday-Wednesday).

Sunday Evening (June 6)An Evening Welcome Reception will be held Sunday evening from 19:00–20:30 in the Founders room.

Monday Evening (June 7)A reception will be held Monday evening starting at 19:00 in the FortMcHenry/Chesapeake rooms, in tandem with the Facilities User Meetings,and will extend into the NSSA Student Research Award Poster Session.The reception will end at 21:00.

Tuesday Evening (June 8)The conference banquet will be held at the College Park Aviation Mu-seum, an affiliate of the Smithsonian Institution, starting at 19:00. Themuseum is located on the grounds of the world’s oldest continuouslyoperating airport, in College Park, Maryland. Additional informationabout this historic site can be found at http://www.pgparks.com/places/historic/cpam/

The banquet will feature several food stations with Caesar salad, pennepasta, grilled tenderloin of beef, petite pastries and other fare. Wine andbeer will be served. The ticket price for the banquet is $50.00. Ticketscan be purchased online at the ACNS website or at the Registration Deskon Sunday and Monday. Buses will be available for transportation to andfrom the banquet. Buses will depart from the main lobby of the Inn andConference Center beginning at 18:30.

The Museum is located at 1985 Corporal Frank Scott Drive in CollegePark, Maryland near the University of Maryland, between US Route 1 &Kenilworth Avenue (Route 201). To drive from the Inn and ConferenceCenter to the Museum:

1.Start out going East on MD-193 E/UNIVERSITY BLVD E towardADELPHI RD –1.8 miles

2.Take the US-1 S ramp toward COLLEGE PK. – 0.1 miles3. Turn SLIGHT RIGHT onto BALTIMORE AVE/US-1 – 0.8 miles

Breakfast,Lunch and

Breaks

Receptions andConference

Banquet

Internet Café


4. Turn LEFT onto PAINT BRANCH PKWY – 1.0 miles5. Turn LEFT onto CORPORAL FRANK SCOTT DR.

The conference has organized three different tutorials on neutronscattering, the NCNR Summer School Lectures, a tutorial on Residual Stressand Mechanical Behavior, and a tutorial on Pair Distribution Function (PDF)Analysis of Diffraction Data. These sessions will start at 13:00 Sundayafternoon (June 6) and will run in parallel. The NCNR Summer SchoolLectures will be held in Room 2101/3/5, the tutorial on Residual Stresswill be held in Room 2110 and the tutorial on Pair Distribution FunctionAnalysis will be held in Room 2129. There is no charge for attendance,but please indicate your interest on the registration form if you want toattend one so that we will know how many people to expect. Please alsonote that the NCNR Summer School Lectures are required for people whoare accepted into the hands-on part of the training that immediatelyfollows the conference.

Conference registration is mandatory to attend the tutorials.

NCNR Summer School LecturesA series of introductory lectures in neutron scattering techniques andapplications will be presented as part of the NIST 10th annual SummerSchool on Neutron Scattering. These lectures will cover fundamentalconcepts underlying the theory and practice of neutron scattering andare intended for those with little or no experience with the technique.They are open to anyone attending the ACNS meeting.

Topics to be covered in the Sunday tutorial lectures include: Fundamentals of Small-Angle Neutron Scattering

Charles Glinka, NIST Neutron Reflectometry: Theory and Practice

Chuck Majkrzak, NIST Methods and Applications of Neutron Spectroscopy

Dan Neumann, NIST Membrane Diffraction

David Worcester, University of Missouri

In addition to the Sunday lectures, there will be reserved space forapproximately 32 participants who will continue with the hands-on partof the NCNR summer school in Gaithersburg on June 10-12, which will

NeutronScatteringTutorials


focus this year on SANS and Reflectometry. The summer school isorganized by the Center for High Resolution Neutron Scattering that isjointly funded by the NIST Center for Neutron Research and the NationalScience Foundation. Travel and subsistence support is available for thoseattending the full summer school.

Introduction to Neutron Diffraction Studies of ResidualStress and Mechanical BehaviorsMechanical behavior and residual strain mapping have become majorfields of study at nearly every neutron source. Dedicated instruments areavailable or under construction at most facilities. Mechanical behaviorstudies incorporate use of load frames and optionally furnaces on theneutron diffractometer to study the grain to grain interactions of materi-als as a function of load and temperature. These studies have expandedrapidly in recent years with the establishment of 2nd generation facilitiessuch as SMARTS at Los Alamos. Engineering studies based on strainmapping are becoming more widely used by industry and academicengineers and will likely expand as international standards for suchmeasurements are established. The tutorial aims to provide the essentialinformation for an interested scientist or engineer to use these tech-niques and to understand the interrelationship between them.

Topics to be covered include: Introduction to the study of residual strains and mechanical behav-

ior by neutron diffraction Data analysis approaches and demonstrations for handling data

from reactor and spallation sources Role of modeling in interpreting the experimental data

Audience:The tutorial is intended for students, faculty, and industrial scientists whoare considering using neutron scattering for residual strain mapping andmechanical behavior studies. The tutorial is sponsored by the Universityof Tennessee’s International Materials Institute (IMI) program . AdvancedNeutron Scattering netWorking Education and Research (IMI-ANSWER)sponsored by NSF. Students from US institutions who need travel assis-tance to attend can request support by contacting Dr. Hahn Choo([email protected]).

Local Atomic Structure Using Neutron Pair DistributionFunction (PDF) AnalysisThis tutorial will cover theory and practice of the study of disorder incrystals and the study of nanocrystalline materials using real-spaceatomic pair distribution function (PDF) techniques, with the emphasisbeing on PDFs obtained from neutron diffraction data. Lectures willinclude overview and fundamentals, experimental methods, methods ofdata analysis and modeling. We intend that the latter lectures will includea “walk-through” of a typical data analysis and modeling. CD’s of thesoftware and examples will be given to participants who can follow thewalk-through on a laptop if available.

The tutorial will be at a level appropriate for a research-active graduatestudent or more senior researcher new to the subject. Please contactSimon Billinge ([email protected]) or Thomas Proffen([email protected]) for more information.


NSSA Clifford G. Shull Prize in Neutron ScienceThe NSSA established the Clifford G. Shull Prize in Neutron Science torecognize outstanding research in neutron science and leadershippromoting the North American neutron scattering community. The prizeis named in honor of Professor Clifford G. Shull, who received the 1994Nobel Prize in Physics with Professor Bertram Brockhouse for theirseminal developments in the field of neutron science. The establishmentof the prize was announced at the inaugural American Conference onNeutron Scattering in 2002.

Purpose: To recognize outstanding research in neutron science andleadership promoting the North American neutron scattering community.

Nature: The prize will consist of a plaque and an honorarium of $5,000to be presented at the American Conference on Neutron Scatteringtypically held every two years. The recipient is expected to present anaddress at the conference. A stipend towards travel expenses to theconference will be paid in addition to the honorarium.

Establishment and Support: The prize was established in 2002 and willbe administered by the Neutron Scattering Society of America (NSSA.)The NSSA is currently soliciting funds from members and industrialsources toward the endowment of the prize. Individuals or organizationswishing to contribute to the prize endowment fund should contact Prof. DaveBelanger. NSSA Treasurer. Physics Dept.. University of California, Santa Cruz,CA 95064 (e-mail: [email protected])

The 2004 Clifford G. Shull Prize will beawarded to Dr. J. Michael Rowe at thebanquet Tuesday evening, and his Lecturewill be in the Monday morning plenarysession in the Auditorium. He is cited ”Forhis seminal vision, leadership, and contribu-tions to the field of neutron scattering.”

Early in his career, Mike Rowe was at theforefront of research on the dynamics,structure and fundamental properties ofmaterials, including influential work onhydrogen in metals, orientationally disor-

dered solids andmonatomic liquids. Inaddition, he has madesignificant contribu-tions to the develop-ment of inelasticspectrometers andother instruments thatutilize cold neutronsand is a leader in thedesign of the latestgeneration coldneutron sources,including the mostefficient hydrogen cold

Awards

Dr. J. Michael Rowe

Mike Rowe (left) and Cliff Shull in 1995.


source currently operating in the world at the NCNR. Dr. Rowe’s talentsand his profound impact on American neutron science go far beyond hisindividual contributions to research and instrumentation. Through hisleadership and engineering creativity over the past 15 years, the NCNRhas become the most important and widely used neutron facility thus fardeveloped in the United States. Dr. Rowe received his PhD in 1966 fromMcMaster University where he worked with Nobel Laureate B.N.Brockhouse. From 1966-72 he worked at Argonne National Lab beforejoining the National Bureau of Standards (now NIST) in 1973.

NSSA Prize for Outstanding Student ResearchAn NSSA Prize for Outstanding Student Research has been established bya generous private donation, and will be awarded at each ACNS meetingstarting with the 2004 meeting in College Park. To qualify for the award,the student presenting their work at the ACNS must be no later than twoyears past their graduation date, and the work submitted for consider-ation must come from their thesis research. The student does not have tobe a graduate.

The work must be presented in poster format at the meeting. Studentsshould indicate during the abstract submission to the conference thatthey are requesting that their poster presentation be considered for theaward. This will allow the student posters to be grouped together duringthe same poster session (scheduled for Monday Evening, June 7, in theMain Concourse).

The candidate will be asked to certify that they performed the majority ofthe actual neutron scattering work, and will be asked to provide contactinformation for their advisor. A subcommittee of the overall conferenceprogramming committee will judge the work and decide the winner. Thewinner will be announced during the conference banquet.

The award consists of a certificate, plaque, and $500 cash.

The user groups from Chalk River, LANSCE, HFIR, IPNS, NCNR, and SNSwill host a combined meeting in the Fort McHenry/Chesapeake rooms onMonday evening (June 7) beginning at 19:00. The user group meetingswill coincide with the beginning of the Monday evening reception, whichwill continue into the NSSA Student Research Award Poster Session.

The goals of the user reception are to obtain feedback from neutronusers on issues regarding the neutron sources and to inform users of thecapabilities of various sources and actions they can take to help thesesources in carrying out their mission. The reception format has beenchosen to provide a more informal forum for discussions and to promoteparticipation of the users.

The meeting will be divided into four separate groups in different areasof the Fort McHenry/Chesapeake rooms. Each group will have a differentfocus area for discussion:

1. Facilities – description of facilities and planned upgrades2. Instruments – description of new and upgraded instruments

User GroupMeetings


3. User Support – covering issues such as sample environment, dataacquisition and analysis.

4. Administrative Issues – lobbying and user support for sources. Thefirst three areas will be staffed by members of the participatingsources while the final area will be staffed by members of the usergroups.

The afternoon of Wednesday, June 9 is being set aside to accommodateBreakout Sessions requested and organized by groups that want to plan,organize and discuss specific projects such as the development of aspecific neutron instrument, data collection or analysis systems, etc. Thetopics of the Breakout Sessions are listed in the program, and the agen-das will be distributed by the session organizers. All Breakout sessionswill run in parallel beginning at 15:45 in the designated rooms.

A tour of the neutron facilities of the NCNR is being organized for Thurs-day morning, June 10. Buses will leave the Inn and Conference Center at8:30, after breakfast. It is about a 30 minute drive to NIST. Transportationreturning to the Inn and Conference Center will be available aroundnoon.

If you wish to visit the NCNR, please fill out the form on the ACNSwebpage, as visitor clearance must be accomplished in advance of yourvisit. The transportation to the NCNR can also be used for those who areparticipating in the NCNR summer school, and if you wish to ride the busto NIST you should sign up for the tour.

Displays from each of the neutron scattering facilities in North Americawill be located in the Main Concourse and available Monday-Wednesday.These facilities are the Oak Ridge National Laboratory Spallation NeutronSource and High Flux Isotope Reactor, the NIST Center for Neutron

BreakoutSessions

Tour of the NISTCenter forNeutronResearch

NeutronScatteringFacilitiesDisplays


Research, Los Alamos Manuel Lujan Neutron Scattering Center, NeutronProgram for Materials Research at Chalk River Laboratories, and theArgonne Intense Pulsed Neutron Source.

ConferenceExhibitors

The ACNS will feature elevenexhibitors in the Main Concourse.Hours for the exhibits will beMonday – Wednesday (June 7–9)from 8:00 to 17:30.

Exhibitors are:

LND, Inc.3230 Lawson Blvd.1 Oceanside, New York 11572http://www.lndinc.com

Advanced Research Systems, Inc.905 Harrison St.Allentown PA 18103http://www.arscryo.com

Ordela, Inc.Oak Ridge Detector Laboratory1009 Alvin Weinberg DriveOak Ridge, TN 37830http://www.ordela.com

GE Quartz and GE AdvancedCeramics22557 W. Lunn RoadStrongsville, OH 44149http://www.gequartz.comhttp://www.advceramics.com

CAEN and WIENERWIENER, Plein and Baus, Ltd.300 E. Auburn AvenueSpringfield, OH 45505937-324-2420http://www.wiener-us.com

Kurt J. Lesker Co.1515 Worthington AvenueClairton, PA 150251-800-245-1656e-mail: [email protected]://www.lesker.com

SwissNeutronicsNeutron Optical ComponentsOberes Zelgli 6CH-5313 KlingnauSwitzerlandphone: 41 56 245 0202fax: 41 56 245 0204e-mail: [email protected]://www.swissneutronics.ch

Oxford Instruments130A Baker Avenue Ext.Concord, MA 01742Direct: 978-369-7407 ext. 103Fax: 978-369-6616e-mail: [email protected]://www.oxford-instruments.com

CILAS / GMI8 avenue BuffonBP 631945063 Orlans CedexFRANCEhttp://www.cilas.com

Del Mar Ventures4119 Twilight RidgeSan Diego, CA 92130http://www.sciner.com/


Oral PresentationsContributed oral presentations are 12 minutes with 3 minutes for ques-tions. Invited presentations are 25 minutes with 5 minutes for questions.

Overhead projectors and LCD projectors with a switch box will beavailable in each room. We encourage speakers to use the LCD projec-tors. Speakers should bring their own laptop if possible. Each room willbe equipped with a laptop with a CD-ROM and USB port and the follow-ing software installed:

Windows 2000 Microsoft Office 2000 Adobe Acrobat Reader Windows Media Player

We prefer that all computer-based presentations be in MicrosoftPowerPoint 2000 format. During the question-and-answer period of eachtalk, the next speaker should hook the laptop with their presentation upto the LCD switch box in preparation to begin speaking immediately.Speakers that choose to use the laptop provided by the ACNS should loadtheir presentation onto the computer prior to the beginning of thesession.

If presenters have additional technical requests, they should contact JeffLynn ([email protected]) or Shenda Baker ([email protected])before the conference. The laptop computers available on the PC Cart inthe Main Concourse will have similar software to those in the Conferenceareas, and will be available for speakers to check compatibility of thespeaker’s presentation with the available software.

PostersPoster sessions will be in the Main Concourse, and poster spaces will beidentified by number. Posters should be available for viewing in themorning prior to the start of the oral sessions so that they are availablefor viewing during the entire day. The presenter should stand by theposter throughout the Poster session. Posters should be attached withpush pins, which will be provided. Dimensions of the usable posterdisplay area are about 46 inches high by 94 inches wide.

Set-up times for the posters.

Monday evening session: Set up no later than lunchtime on MondayTuesday morning session: Set up during breakfast time on TuesdayWednesday morning session: Set up during breakfast time on

Wednesday

Posters should be taken down in the evening so that poster boards areavailable before the first session of the following morning.

Information forPresenters


Plenary Speakers:

Michael Rowe, NISTRobert Briber, University of MarylandJoel Mesot, PSIThomas Mason, SNS

Invited Speakers:

Kent Blasie, University of PennsylvaniaSusan Krueger, NISTJuergen Eckert, LANLRaul Lobo, University of DelawareSimon Moss, University of HoustonJorge Iniguez, University of Maryland/NISTJim Martin, North Carolina State UniversityAlexander Kolesnikov, ANLPatrick Woodward, Ohio State UniversityJohn Root, Chalk RiverErsan Ustundag, California Institute of TechnologyRuss Hemley, Geophysical LaboratoryBarbara Wyslouzil, Ohio State UniversityRay Osborn, ANLNitash Balsara, University of California—BerkeleyWilliam Hamilton, ORNLVivek Prabbu, NISTDobrin Bossev, University of Maryland/NISTJanna Maranas, Pennsylvania State UniversityMichel Kenzelmann, Johns Hopkins University/NISTIgor Zaliznyak, BNLGeorg Ehlers, ORNLYumi Ijiri, Oberlin CollegeBrooks Harris, University of PennsylvaniaYing Chen, LANLYoung Lee, Massachusetts Institute of TechnologyRobert McQueeney, Iowa State University/Ames LabBrian Maple, University of California—San DiegoJack Carpenter, ANLHerb Mook, ORNLKazu Yamada, Tohoku UniversityChristopher Stock, University of TorontoSergei Dzhosyuk, Harvard UniversityWilliam Hersman, University of New HampshirePaul Langan, LANL

InvitedSpeakers


ConferenceOverview

TUESDAY

Continental Breakfast

Parallel ScientificSessions

Break

Poster Session

LUNCH


BREAK


Conference Banquet

WEDNESDAY


Neutron PlenarySession

Break

Poster Session

LUNCH


BREAK

Breakout Sessions

Open

MONDAY


Welcome andIntroductions

Clifford Shull PrizeLecture

Break

Parallel ScientificSession

LUNCH


BREAK


User Facility Meetingsand Reception

Student ResearchAward

Poster Session

MORNINGS

AFTERNOONS

EVENINGS

THURSDAY

ContinentalBreakfast

Tour of theNIST Centerfor NeutronResearch

Buses Returnto ConferenceCenter

SUNDAY

Neutron ScatteringTutorials

ConferenceRegistration

Welcome Reception


Room Layout


Sunday, June 612:00 – 19:00 Registration (Main Concourse)

13:00 Neutron Scattering TutorialsNCNR Summer School Lectures (Room 2101/3/5 Green)Residual Stress and Mechanical Behavior (Room 2110)Pair Distribution Function (PDF) Analysis (Room 2129)

19:00 – 20:30 Evening Welcome Reception (Founders Room)

Monday, June 78:30 M1-B, Opening Session, Chair: Robert Briber

(Auditorium)WelcomesShull Prize Lecture, J. M. Rowe

10:30 M2-A, Thin Film Magnetism, Chair: Charles Majkrzak,NIST (Room 2101/3/5 Green)

Ijiri, Lee, Soriano, Kepa, O’Donovan10:30 M2-B, Polymers and Surfactants, Chair: Kent Blasie, U.

Pennsylvania (Room 2100/2/4 Red)Balsara, Hjelm, Mehta, Wang, Hu, Tirumala

10:30 M2-C, Instrumentation, Chair: Kent Crawford, ORNL(Auditorium)

Osborn, Glinka, Bleuel, Barker, Ankner10:30 M2-D, Zeolites and Clathrates, Chair: Thomas Proffen,

LANL (Room 1123 Blue)Lobo, Nair, Hemley, Jones, Lokshin

12:30 Lunch (Grand Ballroom)

13:30 M3-A, Alloys, Chair: Stephen Shapiro, BNL (Auditorium)Moss, Zarestky, Delaire, Wagner, Benson

13:30 M3-B, Proteins and Membranes, Chair: Joanna Krueger,U. North Carolina (Room 2100/2/4 Red)

Krueger, Holt, Mihailescu, Caliskan, Bossev13:30 M3-C, Ferroelectrics, Chair: Takeshi Egami, U.

Tennessee/ORNL (Room 2101/3/5 Green)Stock, Ratcliff, Gehring, Vajk, Xu, Yong, Jeong

13:30 M3-D, Dynamics in Chemical Systems, Chair: DanNeumann, NIST (Room 1123 Blue)

Eckert, Reiter, Yildirim, Hartl, Ramirez-Cuesta, Iniguez15:45 M4-A, Cuprate Superconductors, Chair: Young Lee, MIT

(Auditorium)Mook, Tranquada, Mesot, Chen, Yethiraj, Yamada

15:45 M4-B, Neutron Properties and Interactions, Chair:Mohammed Arif, NIST (Room 2101/3/5 Green)

Hersman, Fisher, Black, Gudkov, Dzhosyuk15:45 M4-C, Confinement, Chair: Paul Sokol, Penn State

(Room 1123 Blue)Chen, Melnichenko, Kolesnikov, Georgiev, Narehood,Kintzel

15:45 M4-D, Polymers and Colloids, Chair: Michael Kent,Sandia (Room 2100/2/4 Red)

Prabhu, Kamath, Krishnamurthy, Wang, Gopalakrishnan19:00 MU, User Meetings and Reception (McHenry/

Chesapeake Rooms)

Epitome


20:00 MP, Poster Session: Student Research Award (MainConcourse) (Reception Continues)

Tuesday, June 88:30 T1-A, Chemical Applications of SANS, Chair: Charles

Glinka, NIST (Room 2101/3/5 Green)Wyslouzil, Prud’homme, Krishnamurthy, Kramer

8:30 T1-B, Thin Films and Membranes, Chair: Lee Magid, U.Tennessee (Room 2100/2/4 Red)

Blasie, Pencer, Smith, Kent8:30 T1-C, Magnetic Structures, Chair: Taner Yildirim, NIST

(Room 1123 Blue)Harris, Vaknin, Garlea, Arrott

8:30 T1-D, Neutron Sources, Chair: Roger Pynn, LANL(Auditorium)

Baxter, Robinson, Greene, Russina, Carpenter10:30 TP, Poster Session II (Main Concourse)

12:30 Lunch (Fort McHenry/Founders)

13:30 T2-A, Proteins: Structure and Hydration, Chair: DeanMyles, ORNL (Room 2100/2/4 Red)

Langan, Gregurick, Pivovar, Russo13:30 T2-B, Materials Chemistry, Chair: John Larese, U.

Tennessee (Room 1123 Blue)Livingston, Allen, Hartman, Martin, Williams, Schultz

13:30 T2-C, Instrumentation, Chair: Kenneth Herwig, ORNL(Auditorium)

Chen, Gibson, Krist, Kampmann, Weber, Kim, Peters13:30 T2-D, Heavy Fermion Systems, Chair: Raymond Osborn,

ANL (Room 2101/3/5 Green)Maple, Llobet, Christianson, Nakotte, McQueeney

15:45 T3-A, Charge, Orbital, and Spin Ordering in Oxides,Chair: Michael Crawford, Dupont (Auditorium)

Woodward, Greedan, Ye, Chatterji, James, Rosenkranz15:45 T3-B, Polymer Dynamics, Chair: Jyotsana Lal, ANL

(Room 2100/2/4 Red)Maranas, Soles, Sung, Taub, Yardimci

15:45 T3-C, Mechanical Behavior and Residual Stress, Chair:Camden Hubbard, ORNL (Room 1123 Blue)

Ustundag, Saleh, Gnaeupel-Herold, Wang, Kulkarni,McDaniel

19:00 TB, Banquet at College Park Aviation Museum (Busesdepart Inn starting at 18:30)

Wednesday, June 98:30 W1-A, Neutron Sources (Plenary), Chair: Michael Rowe,

NIST (Auditorium)Briber, Mesot, Mason

10:30 WP, Poster Session III (Main Concourse)

12:30 Lunch (Fort McHenry/Founders)


13:30 W2-A, Mechanical Behavior and Residual Stress, Chair:Henry Prask, NIST (Room 1123 Blue)

Root, Brown, Ruiz-Hervias, Wagner13:30 W2-B, Lipids and Micelles, Chair: Shenda Baker, Harvey

Mudd (Room 2100/2/4 Red)Hamilton, Gerber, Doshi, Prud’homme

13:30 W2-C, Cobaltates, Chair: James Jorgensen, ANL(Auditorium)

Lee, Huang, Avdeev, Zaliznyak13:30 W2-D, Low Dimensional Magnetism, Chair: Stephen

Nagler, ORNL (Room 2101/3/5 Green)Ehlers, Matan, Zhang, Masuda, Zheludev, Kenzelmann

15:45 W3-A, Breakout Sessions, Chair: Shenda Baker, HarveyMuddW3-A1, Perspectives for Neutron Scattering ofBiomembrane Systems (Auditorium)

Organizers: Loesche, White, Tobias, BlaiseW3-A2, Use of Depleted U Targets at Low and MediumPower Spallation Source (Auditorium)

Organizers: Rhyne, TellerW3-A3, SNS Magnetism Reflectometer (Room 2100Red)

Organizer: Klose (SNS)W3-A4, Portable Software for Neutron Scattering(Room 1123 Blue)

Organizers: Worlton, Mikkelson, PetersonW3-A5, Doing Science with Neutron Scattering Data(Room 1123 Blue)

Organizers: Fultz, WangW3-A6, Sample Environment at Neutron ScatteringFacilities (Room 2102 Red)

Organizers: Volin, Dender, J. S. Fieramosca, SantodonatoW3-A7, Fermi Chopper spectrometers for the SNS(Room 2104 Red)

Organizers: Abernathy, Fultz, Granroth, NaglerW3-A8, VISION, A Neutron Vibrational Spectrometerfor SNS (Room 2101 Green)

Organizers: Larese, Hudson, DaemenW3-A9, Detectors and SCD for SNS (Room 2103 Green)

Organizers: Hoffmann, Bau, Koetzle, SchultzW3-A10, HYSPEC: A Novel Direct Geometry PolarizedBeam Inealstic Instrument for the SNS (Room 2105Green)

Organizers: Hagen, Shapiro, Zaliznyak

Thursday, June 10Morning Visit to the NIST Center for Neutron Research(Buses depart the Inn at 8:30)

Program


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Sunday12:00 – 19:00, Registration (Main Concourse)

13:00, Neutron Scattering TutorialsNCNR Summer School Lectures (Room2101/3/5)Residual Stress and Mechanical Behavior(Room 2110)Pair Distribution Function (PDF) Analysis(Room 2129)

19:00 – 20:30, Evening Welcome Reception(Founders Room)

MondayM1-B, Shull Prize Lecture, Chair: Robert Briber(U. Maryland), Auditorium

M1-B1 (08:30) WelcomeTBA

M1-B2 (09:00) Forty Years of Neutron Scattering –a Personal View (Plenary)

J. M. Rowe (NIST Center for Neutron Research;Clifford G. Shull Prize Lecture)

This talk will present a personal view of the trends inneutron research over the past 40 years, illustratedby examples from the author’s own research inter-ests and management activities. It will include a briefhistory of neutron source development in the USA, asseen by an inveterate committee member. Thedevelopment of the NIST Center for Neutron Re-search will be discussed in some detail, particularlyas it relates to new science opportunities and useractivity.

M2-A, Thin Film Magnetism, Chair: CharlesMajkrzak (NIST), Room 2101/3/5 Green

M2-A1 (10:30) Neutron scattering studies ofexchange bias in Fe3O4/CoO epitaxial thin films(Invited)

Y. Ijiri (Department of Physics and Astronomy,Oberlin College, Oberlin, OH 44074)

In recent years, there has been much interest inunderstanding and manipulating two-componentmagnetic systems that exhibit the phenomenon ofexchange biasing. First discovered in the 1950s, theeffect typically refers to the biasing or shift of thehysteresis loop of a ferromagnetic (F) material due toexchange interactions with an antiferromagnetic (AF)

material. Despite extensive work and its technologi-cal importance in data storage, many questionsremain concerning the microscopic mechanisms, andas a result, there is a significant need for experimentsdesigned to characterize the nature of the interfacialspins (F and AF) in buried interfaces.

Neutron scattering work in this area has providedimportant insights into exchange bias. In particular,in this talk, I will describe our results in investigatingthe spin structures in a series of exchange-biasedFe3O4/CoO epitaxial thin films. Focusing on the AFCoO spins, we have observed new easy axes distinctfrom bulk behavior and in addition, an increase inthe effective ordering temperature (~ TN) for de-creasing CoO thickness. At the same time, we havealso found an unusual perpendicular coupling of theAF and F spins in this system. The field and tempera-ture dependencies of the spin structures exhibitstrong correlations to the macroscopic biasingphenomenon. In particular, the perpendicularcoupling arrangement of the AF and F spins freezes inat the blocking temperature (TB) below which ex-change biasing is observed. These results are inter-preted with a model for biasing that highlights therole of anisotropic exchange, as first proposed byDzyaloshinsky and Moriya.

This work has been done in collaboration with J.A.Borchers and R.W. Erwin (NIST), P.J. van der Zaag(Philips), and T.C. Schulthess (Oak Ridge NationalLaboratory).

M2-A2 (11:00) Magnetic coupling across antiferro-magnetic layer in exchange-bias Co/FeMn/Pytrilayer

W.T. Lee (Spallation Neutron Source, Oak RidgeNational Laboratory), G.P. Felcher (MaterialsScience Division, Argonne National Laboratory), F.Y.Yang (Department of Physics, Ohio StateUniversity), F. Zhu, C.L. Chien (Department ofPhysics & Astronomy, Johns Hopkins University)

Polarized neutron reflectometry (PNR) and magneti-zation measurements were used to study an unusualmagnetic behavior found in trilayers of Co/FeMn/Py,where the soft ferromagnet permalloy and the hardmagnet Co were separated by an antiferromagnet(AF) FeMn layer of thickness t. Each sample wasstudied for the effects of two different field-coolingprocedures: The trilayer was initially subjected to amagnetic history at 425K, which is above the FeMnNeel temperature TN, such that the Co and Py magne-tization were either (1) parallel or (2) opposite to eachother in the field-cooling field. After field-cooled thesample below TN to room temperature, the measure-


ment field was applied along the field-cooling axis.We found the hysteresis loop for a film depended onits field-cooling history. In films with t > 90 Å, PNRstudies showed that the Py and Co were magnetizedcollinearly to H as two independent films. Theexchange-bias induced hysteresis loop shifts of the Pyand Co can be individually identified. In contrast, infilms with t < 90 Å, the Py and Co magnetic vectorsformed an angle that depended on both t and H.Such angular dependence was found regardless ofthe field-cooling history of the trilayer. We thereforeconcluded that the angular dependence arose not asa result of the field-cooling procedure, or a “freezingin” of the magnetic configuration below TN, butrather from a magnetic coupling of the Py and Co.

M2-A3 (11:15) Magnetic behavior of epitaxialEuropium thin films

S. Soriano, K. Dumesnil, C. Dufour, T. Gourieux(L.P.M. (UMR-CNRS 7556) Universite H. Poincare,BP 239, 54506 Vandoeuvre Cedex, France), A.Stunault (Institut Laue Langevin), M. Hennion(Laboratoire Léon Brillouin, C.E.A Saclay, 91191 Gif-sur-Yvette Cedex), J. Borchers (NIST Center forNeutron Research), Ph. Mangin (L.P.M. (UMR-CNRS7556) Universite H. Poincare, BP 239, 54506Vandoeuvre Cedex, France; NIST Center for NeutronResearch)

We present the magnetic behavior of thin films of avery atypical rare earth, Europium, which has onlyrecently been grown by molecular beam epitaxyalong the [110] direction to form a bcc single-domaincrystal[1]. In these (110) Eu films, the [001] axis liesin the growth plane, whereas the two others cubicaxes ([100] and [010]) are out of the plane at 45°from the growth direction. Below a temperature Tcl,the sample is clamped to the (sapphire + niobium)substrate, which gives rise to strains eps(T). Tcl

decreases and eps(T) lowers as the europium thick-ness is increased. The magnetic structures have beendetermined using Resonant x-ray Magnetic Scatteringat ESRF and neutron scattering at LLB and at theNIST Center for Neutron Research. As in bulk eu-ropium the thin films exhibit a helical magneticordering at TN = 90 K with magnetic propagationvectors along the cubic axes [100], [010] (out of theplane of the sample) and [001] (in the plane of thesample), which gives rise to three kinds of magneticdomains D1, D2 and D3 respectively. However, as thetemperature is lowered two phenomena are ob-served:i) The wave vectors of the D1 and D2 domains leave

the cubic directions and move closer to the [110]growth direction. They rotate of an angle β(T).

ii)The D3 domains vanish at a temperature T1 and

are only restored (and even, as in the bulk, fill thenthe whole sample) if a critical field Hc(T) is appliedalong [001]. β (T), T1 and Hc(T) are shown to becorrelated to the strain components eps(T), them-selves related to the thicknesses of the samples.The role of the shear deformations is shown to beof prime importance. In addition, unlike in the bulk[2], it seems the magnetic transition is no longer offirst order. To explain these evolutions, severalmechanisms are discussed. They are based onsurface dipolar effects, exchange anisotropyinduced by the deformations and onmagnetoelastic contributions.

[1] S. Soriano, K. Dumesnil, C. Dufour, D. Pierre (inpress) Crystal Growth (2004)[2] A.H. Milhouse, and K.A. McEwen, Solid StateCom., 13, 339-345 (1973)

M2-A4 (11:30) Neutron scattering studies of thespin structure and magnetic domains in semicon-ductor superlattices

H. Kepa (Department of Physics, Oregon StateUniversity, Corvallis, OR 97331, USA; Institute ofExperimental Physics, Warsaw University, ul. Hoza69, Warsaw, Poland), A.Yu. Sipatov (Kharkov StatePolytechnic University, 21 Frunze St., Kharkov310002, Ukraine), P. Sankowski, P. Kacman(Institute of Physics PA S and ERATO SpintronicsProject, Al. Lotnikow 32/46, 02-668 Warsaw,Poland), C. F. Majkrzak (NIST Center for NeutronResearch), T. M. Giebultowicz (Department ofPhysics, Oregon State University, Corvallis, OR97331, USA)

Neutron diffraction and reflectivity experimentsperformed on a number of magnetic semiconductorsuperlattices (SL), in search for interlayer coupling(IC), are reported. Antiferromagnetic (AFM) EuTe/PbTe SL and ferromagnetic (FM) EuS-basedmultilayers, with narrow-gap semiconductor (PbS) aswell as insulating (YbSe) diamagnetic spacers, werestudied. Pronounced interlayer magnetic correlationshave been revealed in EuTe/PbTe by neutron diffrac-tion, the only tool which enables such observation inAFM systems. In the FM multilayers it was proven byneutron reflectivity experiments that consecutive EuSlayers are antiferromagnetically coupled. In order todetermine the strength of the AFM IC in EuS-basedsystems, the intensity of the first magnetic SL Braggpeak vs. applied external magnetic field was mea-sured. Finally, the in-plane anisotropy and thedomain structure were studied by polarized neutronreflectivity. Despite the fourfold symmetry of thegrowth plane, a preferred orientation of domainmagnetization directions along one of the two


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possible in-plane axes ([210] and [110] for EuS/PbSand EuS/YbSe, respectively) was found.

The IC strength J and the anisotropy constant K wereobtained by least-square fitting of the peak intensityvs. magnetic field experimental data to model data.The model is based on minimizing the total magneticenergy of the SL as a function of the magnetizationdirections. To obtain a good fit, it was necessary totake into account the interfacial roughness by assum-ing a Gaussian spread of J. For both EuS/PbS andEuS/YbSe SL, the best fit was obtained for thedirections of the in-plane easy axes, which agree withthose determined by polarized neutron reflectivity. Atight-binding theoretical model was proposed, whichexplains the IC phenomena in both, AFM and FM, IV-VI semiconductor SLs in terms of electronic bandstructure effects. This is the only model whichpredicts the AFM IC between EuS layers, as seen inthe experiment. The model also predicts smallerstrength and shorter range of IC when the EuS layersare separated by YbSe instead of PbS, in qualitativeagreement with the fitted J values.

M2-A5 (11:45) Polarized neutron reflectivity onCoFeOx exchange springs for spin valve applica-tions

K. V. O’Donovan (NIST Center for Neutron Research;University of Maryland, College Park and Universityof California, Irvine), J. A. Borchers (NIST Center forNeutron Research), S. Maat, M. J. Carey, B. A.Gurney (Hitachi Global Storage Technologies)

Modern hard disk reading heads employ spin valves,which are multicomponent magnetic films with twoindependent ferromagnetic layers. Most spin valvesuse a metallic antiferromagnet, such as PtMn, to pinone of the ferromagnetic layers. Use of an insulatingbiasing layer can be advantageous because it pinswithout shunting the current, which leads to highergiant magnetoresistance (GMR) values, thus providinggreater readback sensitivity to the recorded data.One promising candidate is ferrimagnetic cobaltferrite (CoFe2O4), which pins the neighboring ferro-magnetic layer through an exchange-spring mecha-nism.1 Recently, we grew a CoFe2O4/Co/Cu/Co/NiFespin valve that shows high GMR, excellent pinningand good free-layer properties. To optimize theperformance of this structure, we have examined thefield-dependent switching of the individual layersusing polarized neutron reflectometry (PNR). Mea-surements of the reflectivity from the front and backof these films can be used to discern noncollinearmagnetism, in which the direction of magnetizationchanges by several degrees over a depth of a fewnanometers. Our measurements on a CoFe2O4(50.0

nm)/CoFe10(6.0 nm)/Ta(10.0 nm) sample confirm thatthe hard ferrimagnetic CoFe2O4 layer and the softferromagnetic CoFe layer are coupled together inapplied fields ranging from 0 to 900 mT. In interme-diate field ranges near 54 mT, fits to the data indicatethat a twist is evident in the exchange-spring asexpected and it is confined mostly to the CoFe2O4

layer. This surprising result contrasts with the usualexpectation that the magnetic twist reside in the hardlayer in the field region of reversibility. Fits suggestthat the twist gradually collapses as the field isincreased.

1 E.F. Kneller and R. Hawig, IEEE Trans. Magn., 27,3588 (1991).

M2-B, Polymers and Surfactants, Chair: KentBlasie (U. Pennsylvania), Room 2100/2/4 Red

M2-B1 (10:30) Searching for the Critical Nucleus inPhase Separating Polymer Blends (Invited)

N.P. Balsara (University of California, Berkeley;Lawrence Berkeley National Laboratory), T.J. Rappl(University of California, Berkeley)

The initial stage of liquid-liquid phase separation inmetastable blends of high molecular weight polymerswas studied by time-resolved small angle neutronscattering. The large size of the polymer moleculesused in this study causes chain entanglement tooccur, leading to extremely slow dynamics. Thisenables direct examination of the initial clustering ofmolecules prior to macroscopic phase separation. Wefind that the scattering profiles are time-independentfor scattering vectors (q) larger than a critical scatter-ing vector (qc). We demonstrate the relationshipbetween the critical nucleus size (Rc) and the criticalscattering vector. The dependence of Rc on quenchdepth is in qualitative disagreement with all availabletheories on phase separation kinetics.

M2-B2 (11:00) Volume transition and internalstructures of small poly(N-isopropylacrylamide)microgels

R. P. Hjelm (Los Alamos Neutron Science Center, LosAlamos National Laboratory), X. Xia (Departmentof Physics, University of North Texas, Denton, TX),L. Arleth (Los Alamos Neutron Science Center, LosAlamos National Laboratory), J. Wu (Department ofChemical and Environmental Engineering,University of California, Riverside, CA), Z. Hu(Department of Physics, University of North Texas,Denton, TX)

Monodispersed poly(N-isopropylacrylamide)(PNIPAM) nanoparticles, with the hydrodynamicradius Rh less than 50 nm at room temperature(about two orders of magnitude smaller than those


reported previously), have been synthesized in thepresence of a large amount of emulsifiers. Thesemicrogel particles undergo a swollen-collapsedvolume transition in an aqueous solution when thetemperature is raised to around 34°C. The volumetransition and structure changes of the microgelparticles as a function of temperature are probedusing laser light scattering and small angle neutronscattering (SANS) with the objective of determiningthe small particle internal structure, particle-particleand particle-solvent interactions. We find that, withinthe resolution of the experiments, these particleshave a uniform radial cross-linker density on eitherside of the transition temperature, in contrast toprevious reports on the heterogeneous structures oflarger PNIPAM microgel particles, but in good agree-ment with recent reports based on computer simula-tions of smaller microgels. Furthermore, the particleinteractions change across the transition tempera-ture: at temperatures below the transition, theinteractions appear to be described by a hard spherecontact potential, although there is evidence for astrong hard-sphere-like repulsive particle interaction;above the volume transition temperature, the poten-tial is best described by an attractive interaction.

M2-B3 (11:15) The Impact of the Molecular Struc-ture of a Compatibilizer on the Interfacial Struc-ture of Compatibilized Polymeric Interfaces

R. Mehta, S. Kamath, C.P. O Brien, M. Lay, M.D.Dadmun (University of Tennessee)

This talk will discuss results by our group that hascentered on understanding the optimal modificationof polymeric biphasic interfaces to improve theirstrength. Monte Carlo simulation and experimentalstudies indicate that copolymeric interfacial modifiersthat are blocky copolymers improve the strength ofpolymer/polymer interfaces most effectively. Thisresult is interpreted to indicate that these copolymersmost effectively entangle with the homopolymers bythe formation of doubly bound loops at the softinterface.

Additionally, neutron reflectivity has been completedto correlate this mechanical data to the structure ofthe copolymer/homopolymer interfaces. Morespecifically, the depth profiles of trilayer thin filmsthat consist of a layer of deuterated poly(methylmethacrylate), a layer of a protonated styrene/methylmethacrylate copolymer, and a top layer of deuter-ated polystyrene were determined using neutronreflectivity for various copolymer architectures,ranging from alternating to random to diblockcopolymers. The depth profile and interfacial charac-teristics of this trilayer indicate that the specific

sequence distribution of the copolymer dramaticallyimpacts the ability of that copolymer to extend intothe polymer and entangle. The data demonstratethat, for a given molecular weight and copolymercomposition, the pentablock and triblock copolymerscreate the broadest interfaces between the copoly-mer and homopolymer, while random and alternat-ing copolymers produce the narrowest. This trendagrees with the mechanical testing data and will bediscussed.

M2-B4 (11:30) Dispersing Single-Walled CarbonNanotubes with Surfactants

H. Wang (Department of Materials Science andEngineering, Michigan Technological University,Houghton, MI 49931), W. Zhou, K. I. Winey, J. E.Fischer (Department of Materials Science andEngineering, University of Pennsylvania,Philadelphia PA 19104), D. L. Ho, E. K. Hobbie, C.Glinka (National Institute of Standards andTechnology)

We have investigated the dispersion of single walledcarbon nanotubes (SWNTs) in heavy water with thesurfactant Triton X-100 using primarily small angleneutron scattering. The data show that the SWNTs inthis study have a large incoherent scattering cross-section, implying that they may be heavily hydroge-nated due to acid treatment. The hydrogenation ofSWNTs may play an important role in their dispersionwith amphiphilic surfactants. The data also suggestan optimal surfactant concentration for dispersion,which we suggest results from competition betweenmaximization of surfactant adsorption onto SWNTsurfaces and a depletion interaction between SWNTbundles due to surfactant micelles. The latter effectdrives SWNT reaggregation above a critical micellarvolume fraction, leading to the general conclusionthat the amount of surfactant, rather than its SWNTmass ratio, is the more relevant parameter in control-ling dispersion. At optimal dispersion, the surfactantadsorption ratio is ca. 0.004 mol/g, comparable toprevious findings.

M2-B5 (11:45) Photoacid reaction-diffusion path ina chemically amplified photoresist

Tengjiao Hu, Ronald Jones, Eric Lin, Wen-li Wu,Dario Goldfarb, Marie Angelopoulos (NIST PolymerDivision)

Photo-generated acid molecules act as a catalyst inthe deprotection of chemically amplified photoresists.The initial locations of the acid molecules providereaction centers and the subsequent movement ofthese small acid molecules during a heating stepdefines the physical reaction paths. The spatialevolution of the reaction paths is closely related to


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the overall shape of the latent image. Acid reaction-diffusion paths near the imaging edges play animportant role in the line-edge roughness control,which is approaching to only a couple of nanometersin patterns created from photoresist. A few prelimi-nary works have focused on measuring the aciddiffusion coefficient in photoresists. The movementof the interface between acid feeding layer andphotoresist layer has been used to indirectly infer theacid diffusion because the results are coupled with afurther development process. Ion conductivitymeasurement overcomes this complication but stillassumes a Fickian model for acid diffusion. However,there is no such a proof yet. Identifying the relation-ship between the evolution of microscopic reaction-diffusion paths to a macroscopic latent image iscritical information for industrial applications.

A model photoresist polymer with only side groupsdeuterated was used in our experiment. Deprotectioncleaves the deuterated parts and causes a largecontrast change in neutron scattering, which can befollowed in a standard small angle neutron scatteringexperiment. At extremely low acid concentration, thescattering provides the form factor of the diffusionpath of a single acid molecule in the photoresist. Ourresults indicate that the acid molecules diffuserandomly in the photoresist. The overlapping andmerging of several deprotection paths was studied byvarying reaction time at a constant acid concentra-tion. Our result shows a gradual merging of differentdeprotection paths as determined from the effectivefractal dimensions of the observed deprotectionvolume. The fractal growth of the deprotectionvolume is closely related to the distribution of thedeprotected monomer units and the subsequent finalpattern formation after development.

M2-B6 (12:00) USANS Investigation of Poly (N-isopropylacrylamide) Gels Prepared from Synchro-tron-Radiation-Induced Polymerization in aRetrograde-Precipitation Environment

V. R. Tirumala (Advanced Photon Source, ArgonneNational Laboratory, Argonne, IL), L. Guo (IntensePulsed Neutron Source, Argonne National Lab), G. T.Caneba (Department of Chemical Engineering,Michigan Technological University, Houghton MI49931), D. C. Mancini (Advanced Photon Source,Argonne National Laboratory, Argonne, IL), P.Thiyagarajan (Intense Pulsed Neutron Source,Argonne National Lab), J. G. Barker (NationalInstitute of Standards and Technology)

Poly (N-isopropylacrylamide) belongs to the class ofthermoreversible hydrogels that can respond to achange in ambient temperature with a change in

their physical characteristics. Due to their reversibleresponse and hydrophilic behavior, hydrogels basedon poly (N-isopropylacrylamide) are widely re-searched for applications ranging from controlleddrug delivery to microfluidic valves and actuators.The stimuli-response behavior of these gels, whichdepends on their synthesis route, is therefore, ofutmost importance. Conventional synthesis ofhydrogels results in a nanoporous morphology thatdecreases the permeability of water and, therefore,their response rates. Gel response can thus beimproved by introducing macropores into the poly-mer network. The morphology of the gel networkscan be characterized by neutron scattering in thepresence of a deuterated solvent.

We have recently prepared poly (N-isopropylacryla-mide) hydrogels by a novel synchrotron-radiation-induced polymerization. The monomers weresolution polymerized by exposing to x-rays from 2-BM-B bending magnet, at the Advanced PhotonSource. The time of exposure affects the crosslinkingdensity, since monomer crosslinking and polymerchain scission occur simultaneously during irradia-tion. The gels were also prepared above their lowercritical solution temperature in water, which results ina microporous morphology that is evident only whenthe gels are swollen. Such unique morphology ofthese gels should enable them to be ultrafast in theirstimuli-response. The inherent pore structure of thegels was characterized below and above their phasetransition temperature by ultra-small-angle neutronscattering. The correlation length of the gel networkwas observed to be power-law dependent on theabsorbed dose. The average pore size of the gels wasalso found to reversibly change by ~ 200 Å, depend-ing on the monomer concentration and the absorbeddose.

Acknowledgments: Work at the Advanced PhotonSource was supported by the Department of Energy,Office of Science, BES, under contract No. W-31-109-ENG-38. The U.S. Government retains for itself, andothers acting on its behalf, a paid-up, nonexclusive,irrevocable worldwide license in said article toreproduce, prepare derivative works, distribute copiesto the public, and perform publicly and displaypublicly, by or on behalf of the Government.

M2-C, Instrumentation, Chair: Kent Crawford(ORNL), Auditorium

M2-C1 (10:30) Prospects for Single Crystal DiffuseScattering with Elastic Discrimination (Invited)

R. Osborn, S. Rosenkranz (Materials ScienceDivision, Argonne National Laboratory)


There is growing interest in understanding complexmaterials in which disorder, and the nanoscale self-organization associated with it, plays an importantrole in their bulk properties. Examples of disorder incrystalline matrices include polaronic disorder inmagnetoresistive oxides, stripe disorder in supercon-ducting cuprates, nanodomains in ferroelectricrelaxors, defect correlations in fast-ion conductors,rotational disorder in molecular solids and intercala-tion compounds, adsorption in microporous frame-works, and quasicrystals. Coherent diffuse scatteringfrom single crystals, using either neutrons or x-rays,is the most powerful probe of such complex disorder.It is the only technique that can be used to determineboth the local distortions around a point defect andthe length scale and morphology of defect-defectcorrelations, i.e., the tendency for defects to clusteror self-assemble into nanoscale structures. Neverthe-less, there are formidable technical difficulties both inobtaining reliable diffuse scattering data and in usingit to construct models of defect structures. White-beam pulsed neutron instruments provide efficientaccess to the large volumes of reciprocal space thatare required to model disorder accurately. However,they accomplish this without energy analysis so thatstatic diffuse scattering is contaminated by inelasticscattering from vibrational and other dynamicprocesses in the sample. At present, there is no wayto eliminate this inelastic signal withoutmonochromating the incident or scattered beams,which results in a substantial loss of intensity. Aproposed instrument, named Corelli, solves thisproblem by combining the high-efficiency of white-beam Laue diffraction with energy discriminationproduced by the use of statistical choppers. Thelimitations of the cross–correlation method, by whichthe intrinsic scattering law is reconstructed from themodulated data, and the reasons for its effectivenessin this context will be discussed.

This work was performed under the support of theUS Department of Energy,Office of Science, undercontract no. W-31-109-ENG-38.

M2-C2 (11:00) Sub-Millisecond Time-ResolvedSmall-Angle Neutron Scattering

Charles J. Glinka (NIST Center for NeutronResearch), Stephan Polachowski, J. Raebiger (FZ-Juelich)

A time-of-flight (TOF) technique at a steady statesource proposed by Roland Gähler for time-resolvedSANS measurements with sub-millisecond timeresolution is currently being implemented on one ofthe 30-m SANS instruments at NIST’s Center forNeutron Research. The technique, labeled TISANE by

Gähler, requires a high-speed disk chopper, precedingthe instrument’s pinhole collimation, to pulse thebeam at a frequency that is linearly related to thefrequency (10 to 1000 Hz) of an applied field at thesample. In TOF terminology, the instrument operatesin the far frame-overlap regime such that neutronsfrom several successive pulses arrive at the detectorat a particular time corresponding to a definite (sub-millisecond) time interval within the period of theapplied field at the sample.

The plan for implementing TISANE on the NIST/NSF30-m SANS instrument on guide NG-3 at the NCNRand its current status will be described along withestimates of the attainable time-resolution (~ 50µsec). Possible applications for the technique inmacromolecular systems and structured fluids will bediscussed.

M2-C3 (11:15) Modulated Intensity Small AngleNeutron Scattering - MISANS

M. Bleuel, J. Lal, K. C. Littrell (Intense PulsedNeutron Source, Argonne National Lab), R. Gaehler(Institut Laue Langevin)

We present MISANS, a new design of an instrument,which combines the properties of an existing SmallAngle Neutron Scattering (SANS)-spectrometer at apulsed source (SAD@IPNS) with a MIEZE-typeneutron resonance spin echo (NRSE)-spectrometer.Thus the new instrument features the high NSEenergy resolution for quasi-elastic measurementswith a SANS q-resolution. Furthermore the MIEZE-technique allows the measurement of magnetic andspin-incoherent scattering samples as well as the useof an area detector.

The spectrometer will also take full advantage ofusing a pulsed source, both the spatial and the timedomain will be completely scanned within one pulse,without moving parts inside the instrument. In orderto archive all provided information, the planned areadetector consists of time resolving scintillation photomutlipliers.

M2-C4 (11:30) Performance of a Thermal-NeutronDouble-Crystal Diffractometer for USANS at NIST

J. G. Barker, C. J. Glinka, J. Moyer, M-H. Kim (NISTCenter for Neutron Research), A. R. Drews (FordMotor Company, Dearborn, MI), M. Agamalian(Spallation Neutron Source, Oak Ridge NationalLaboratory)

An ultra-high-resolution, small-angle neutron-scatter-ing (USANS) double crystal diffractometer (DCD) hasbeen constructed at the NIST Center for NeutronResearch (NCNR). The instrument uses multiplereflections from perfect single crystal silicon (220),


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before and after the sample, to produce a lowinstrument background suitable for small anglescattering measurements. The minimum detectorbackground to beam intensity ratio is 5x10-7. Theinstrument is located on a dedicated thermal neutronbeam port, utilizing 2.38 Å wavelength neutrons,producing a 17,000 cm-2s-1 peak neutron flux at thesample. The measurement range of the instrumentextends from 3x10-4 nm-1 to 0.2 nm-1 in scatteringwavevector (q), corresponding to structure sizeinformation in materials ranging from 30 nm to20,000 nm. If the capability of the DCD is combinedwith the NCNR’s 30 m long pinhole type instrumentscovering 0.01 nm-1 to 6.0 nm-1 in q, structure inmaterials from 1.0 nm to 20,000 nm can be mea-sured. The design and characteristics of the instru-ment, and the mode of operation, are described, anddata are presented which demonstrate the instru-ment performance.

M2-C5 (11:45) Instrument Design via EnvelopeBack and Spreadsheet

J.F. Ankner, Ch. Rehm (Spallation Neutron Source,Oak Ridge National Laboratory)

All too often, the first recourse of the neutron instru-ment designer is to some sort of stochastic or MonteCarlo (MC) simulation. While very efficient at gener-ating results, MC simulation can suffer from adeficiency of insight, failing to provide clear criteriato direct instrument design choices. This state ofaffairs is as unnecessary as it is unfortunate, since themodules used in MC simulation must, by definition,contain analytical descriptions of the componentssimulated. By abstracting out the analytical formal-ism, thinking a bit about the relevant phase space,and developing common-sense metrics, one canprovide a framework for understanding simulationresults. Further, since these computations generallyconsume far less time than full-blown MC, one canmodel phenomena, such as background scattering,that simply cannot practically be addressed via MC.We will describe our application of acceptance-diagram techniques to primary neutron opticaldesign (including disk choppers) and present a set ofphase-space simulation metrics for evaluating results.In addition, we will consider the optical characteris-tics of neutron scattering/emission from interiorbeamline surfaces, a type of secondary-sourceproblem difficult to treat using MC. Ultimately, thesurest designs arise from judicious use of bothanalytical and stochastic methods, the formerproviding a framework for understanding the latter,as well as the means for circumventing their compu-tational limitations.

M2-D, Zeolites and Clathrates, Chair: ThomasProffen (LANL), Room 1123 Blue

M2-D1 (10:30) Structural Refinement of DisorderedZeolites Using the Pair-Distribution FunctionMethod (Invited)

I. Peral (Department of Chemical Engineering,University of Delaware, Newark, DE 19716; NISTCenter for Neutron Research), M.M. Martínez-Iñesta, R.F. Lobo (Department of ChemicalEngineering, University of Delaware, Newark, DE19716), T. Proffen (Los Alamos Neutron ScienceCenter, Los Alamos National Laboratory)

Structural disorder is a common fact in zeolitematerials and the methods commonly used for therefinement of zeolite structures (Rietveld refinementsand single crystal structures) are unsuitable to obtaindetailed atomic information of the disorderedcounterparts. To address this need, we have appliedthe Pair Distribution Function Method (PDF), anexperimental function that describes the distributionof the atomic distances of a material, to zeolite beta,an important zeolite catalyst in the petrochemicalindustry. Zeolite beta is a high-silica 12-ring porezeolite containing a three-dimensional pore system.The structure of beta was conceived as anintergrowth of two crystalline (hypothetical)polytypes A and B. The pores in polytype A arearranged in an ABABAB… type configuration and inpolytype B they are arranged in an ABCABC… typeconfiguration. We were able to refine the structure ofboth polytypes of zeolite beta by combining refine-ments with the neutron and synchrotron pair distri-bution functions. Comparing the calculated neutronPDFs, we observe a large general improvement in thefit of the experimental neutron-PDF from the ac-cepted structural model to our refined model as seenin the difference curves. It is, however, necessary torefine both neutron and x-ray PDFs sequentially toobtain reasonable models of the zeolite structures.

M2-D2 (11:00) Methyl Rotational Tunneling Dy-namics of p-xylene confined in a crystalline zeolitehost

S. Nair (School of Chemical & BiomolecularEngineering, Georgia Tech), R. M. Dimeo, D. A.Neumann (NIST Center for Neutron Research), A. J.Horsewill (Department of Physics & Astronomy,University of Nottingham)

The rotational tunneling of molecules, functionalgroups or ions is known to be a sensitive and quanti-tative probe of the local energetics and structure of amaterial. Crystalline nanoporous aluminosilicates(zeolites) are used in organic separations owing totheir shape- and size-selectivity for various types of


organic sorbate molecules. This behavior is influ-enced by the framework-sorbate and sorbate-sorbateinteractions, which determine the molecular adsorp-tion and transport processes in the porousmaterial.The methyl rotational tunneling spectrum ofp-xylene confined in nanoporous zeolite crystals hasbeen measured by inelastic neutron scattering (INS)and proton nuclear magnetic resonance (NMR), andanalyzed to extract the rotational potential energysurfaces characteristic of the methyl groups in thehost-guest complex. The number and relative intensi-ties of the tunneling peaks observed by INS indicatethe presence of methyl-methyl coupling interactionsin addition to the methyl-zeolite interactions. The INStunneling spectra from the crystals (space groupP212121 with four crystallographically inequivalentmethyl rotors) are quantitatively interpreted as acombination of transitions involving two coupledmethyl rotors as well as a transition involving single-particle tunneling of a third inequivalent rotor, in amanner consistent with the observed tunnelingenergies and relative intensities. Together, the crystalstructure and the absence of additional peaks in theINS spectra suggest that the tunneling of the fourthinequivalent rotor is strongly hindered and inacces-sible to INS measurements. This is verified by protonNMR measurements of the spin-lattice relaxationtime which reveal the tunneling characteristics of thefourth inequivalent rotor.

M2-D3 (11:15) High-Pressure Neutron Scatteringand the SNAP Instrument at the SNS (Invited)

R. J. Hemley (Geophysical Laboratory, CarnegieInstitution of Washington, Washington, DC 20015,USA), John Parise (Departments of Geosciences andChemistry, State University of New York, StonyBrook, NY 11794) Chris Tulk (Spallation NeutronSource and Chemical Sciences Division, Oak RidgeNational Laboratory, Oak Ridge, TN 37831) and Ho-Kwang Mao (Geophysical Laboratory)

Research on materials under pressure is experiencingimpressive growth in a number of new areas. TheSNAP (Spallation Neutrons And Pressure) facility, thehigh-pressure instrument at the Spallation NeutronSource (SNS), is poised to capitalize on the manyrecent developments in the study of materials underpressure. The project involves the creation of aunique instrument that will utilize the high neutronflux of the SNS together with state-of-the-art high-pressure devices and advance the current pressurerange of neutron studies well beyond present limits(tens of GPa), making possible many new classes ofexperiments. The facility will enable studies of a widevariety of new scientific problems involving matterunder a broad range of pressures and spanning

physics, chemistry, geoscience, planetary science,materials science, and bioscience. The instrumentwill be designed for single-crystal and powderdiffraction measurements, with a flexible detectorsystem and space for focusing optics, ancillary on-line measurements, and sufficient area downstreamfor a second station. An important recent advance isthe development of new K-B focusing optics forneutrons that can now produce beam sizes down to100 x 100 µm. Moreover, the creation of the SNS istaking place just at a time when radically newpressure cell designs will vastly broaden the numberof techniques available for routine studies of materi-als over a broad P-T range, to well above megabar(> 100 GPa) pressures, while allowing unprecedentedresolution, accuracy, and sensitivity at all conditions.A new generation of large volume gem-anvil devicesbased on moissanite (SiC) and single crystal dia-mond, including new single crystal diamonds pro-duced by chemical vapor deposition, is becomingavailable. In the intermediate pressure range(< 30 GPa), devices such as the Paris-Edinburgh andZAP cells will be used, and high-precision measure-ments at lower pressures (~ 1 GPa range) will bedone with gas apparatus. These high-pressure deviceswill be coupled with the high-pressure instrument togive maximum performance, with the high-pressurefacility also providing core support for high-pressureactivities at other instruments at the SNS.

M2-D4 (11:45) Structural Distortions and GuestDynamics of Clathrate Hydrates

C. Y. Jones (NIST Center for Neutron Research), I.Peral (NIST Center for Neutron Research;Department of Materials Science and Engineering,University of Maryland)

Gas hydrates are water-based, natural gas-containinginclusion compounds that occur in nature in vastdeposits under the ocean floor and in the arcticpermafrost.(1) They belong to a larger family ofinclusion compounds known as clathrate hydrates.The structure of a clathrate hydrate (CH) compriseswater molecules held together by hydrogen bonds ina three-dimensional “host” network of sphericalpolyhedra, or cages, which contain a small “guest”molecules. Neutron powder diffraction studies of aCH (C4H8O·17D2O) with the guest tetrahydrofuran(THF) in the range (7-165) K have shown that distor-tions occur in the host as a function of temperature(T).(2) In particular, distortions at low T brings Datoms closer than the O atoms to the center of thecage, and indicate that changes in the specificconfiguration of O and D may be important in thedetermination of the guest-host interactions and theresulting CH properties. An explanation for the


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distortions is suggested in the findings fromquasielastic neutron scattering studies (QENS) oftrimethylene oxide (TMO) CH, chemical formulaC3H6O·17D2O.(3) The QENS results show distinctregions of high-T and low-T rotational dynamics, andan activation energy for guest rotation which ishigher in the high-T regime than at low T. Thispresentation describes recent neutron diffraction andQENS results in the range (5-260) K on the CHs of thecyclic ethers THF, TMO, and propylene oxide. Arelationship between the host structural distortionsand the changes in the guest dynamics is proposed.

[1] Makagon, Y. F.; Trebin, F. A.; Trofimuk, A. A.;Tsarev, V. P.; Chersky, N. V.; Dokl. Acad. Sci. USSR —Earch Sci. Sect. 1972, 196, 197-200.[2] Jones, C. Y.; Marshall, S. L.; Chakoumakos, B. C.;Rawn, C. J.; Ishii, Y. “Structure and ThermalExpansivity of Tetrahydrofuran Deuterate Deter-mined by Neutron Powder Diffraction.” J. Phys.Chem. B 2003, 107(25), 6026-6031.[3] Jones, C. Y.; Peral, I. “Dynamics of TrimethyleneOxide in a Structure II Clathrate Hydrate.” Submittedto The American Mineralogist.

M2-D5 (12:00) Crystal structure of hydrogenclathrate hydrate by in situ high-pressure neutrondiffraction

K. A. Lokshin, Y. Zhao, D. He (Los Alamos NeutronScience Center, Los Alamos National Laboratory),W. L. Mao (Department of the Geophysical Sciences,University of Chicago, Chicago, IL 60637, USA;Geophysical Laboratory, Carnegie Institution ofWashington, Washington, DC 20015, USA), H.-K.Mao, R. J. Hemley (Geophysical Laboratory,Carnegie Institution of Washington, Washington,DC 20015, USA), M. V. Lobanov, M. Greenblatt(Department of Chemistry and Chemical Biology,Rutgers University, Piscataway, NJ 08854, USA)

New experimental setup for neutron diffraction athigh hydrostatic pressure (up to 10 kbar) and in the10-300 K temperature range was developed atLANSCE, LANL. The detailed crystal structure informa-tion was determined for hydrogen clathrate hydrateas a function of temperature and pressure for the firsttime. We found that hydrogen occupancy in the(32+x)H2*136H2O, x = 0-12 clathrate can be revers-ibly varied by changing the large (hexakaidecahedral)cage occupancy between 2 and 4 molecules, butkeeping single occupancy of the small (dodecahedral)cage. Above 130-160 K the guest hydrogen moleculeswere found in the delocalized state, rotating aroundthe centres of the cages. Decrease of temperatureresults in the rotation freezing followed by a completelocalization below 50 K.

M3-A, Alloys, Chair: Stephen Shapiro (BNL),Auditorium

M3-A1 (13:30) NIST-DCS Neutron Measurements ofLattice Disorder in a dilute Ge-Si Crystal and in aNull-matrix Ni(62)-Pt Alloy Crystal (Invited)

J.A. Rodriguez, S.C. Moss (Physics Department,University of Houston), J.L. Robertson (Oak RidgeNational Laboratory), J.R.D. Copley, D.A. Neumann(NIST Center for Neutron Research), J. Major, V.Bugaev, H. Reichert, H. Dosch (Max Planck Institutefuer Metallforschung, Stuttgart)

Using the disk chopper spectometer (DCS) at NIST inan elastic scattering mode, we have investigated twoalloy crystals: 1) a dilute alloy of Ge in Si (~10%) and2) a null-matrix crystal of O.5262Ni-0.48Pt, so chosen(62Ni has a negative scattering length) that all effectsdepending on the average lattice scattering (Braggpeaks and Huang diffuse scattering (HDS—due todisplacement-displacement correlations) vanisheswhile the short-range order (SRO) and cross correla-tion between concentration and displacements, oftencalled the size effect scattering (SE), are now given bythe sum of the absolute values of the scatteringlengths of the two components.

The Si-Ge crystal was initially studied in the (-110)plane in reciprocal space. After removing the canscattering and normalizing the data, the planar plotfrom this (previously determined) random alloyshowed pronounced fans of diffuse scattering ema-nating strongly on the low angle side of the Braggpeaks. Selected asymmetric line scans confirmed ourearlier SE and HDS scan (1) along <110>, a suresign that the size of Ge is larger than Si and itsdisplacement field extends to distant neighbors. Thisdata is currently being analysed in Stuttgart by Prof.Bugaev and his students and additional scans in the(001) plane are underway.

The null-matrix data are truly extraordinary. Thereare only tiny specks of Bragg peaks (useful foralignment) and absolutely no HDS about the Braggpositions. The SRO and SE scattering are quiteprominent and are being analysed in real space byRodriguez and Robertson to extract both SRO andindividual species-dependent displacements for eachcoordination shell, and in k-space by Prof. Bugaevand his colleagues.

The results as they come out will be discussed in thecontext of the electronic theory of alloy phasestability, determined from data above Tc, the firstorder phase transition temperature.

[1] D. LeBolloc’h et al., Phys. Rev. B 63, 035204 (2001)


Research supported in Houston by the NSF on DMR-0099573

M3-A2 (14:00) Compositional variation of thephonon dispersion curves of bcc Fe-Ga alloys

J.L. Zarestky, O. Garlea (Ames Laboratory andDepartment of Physics and Astronomy, Iowa StateUniversity, Ames, Iowa 50011), T.A. Lograsso (AmesLaboratory, Metal and Ceramic Sciences, Iowa StateUniversity, Ames, IA 50011), C. Stassis (AmesLaboratory and Department of Physics andAstronomy, Iowa State University, Ames, Iowa50011)

The Fe-Ga system is of considerable scientific andtechnological importance(1) because it is a uniqueexample of a ductile polycrystalline magnetostrictivealloy. Motivated by elastic constant measurements(1)

which indicate that the shear elastic constant 1/2(C11-C12) decreases with increasing Gallium concentrationand extrapolates to zero at approximately 26 at. %Ga, we began a systematic study of the phonondispersion curves of these alloys as a function ofconcentration. The TA2[110] transverse phonons, withpolarization in the [1-10] direction, show consider-able softening as the composition is varied from 10.8to 22.5 at. % Ga. This softening occurs not only atlow wave vectors (q’s) (elastic wave region) but at q’sextending to the zone boundary and is greater thanexpected from the difference in Fe and Ga masses. Itis correlated with the large increase in magnetostric-tion observed in this range of compositions. Thesoftening of the dispersion curves in other symmetrydirections will also be discussed.

[1] M. Wuttig et al. - Applied Physics Letters, Vol. 80,No. 7, 1135, 2002

M3-A3 (14:15) Vibrational Entropy of DiluteAlloying in Vanadium Studied by Inelastic NeutronScattering

O. Delaire, T. L. Swan-Wood, M. G. Kresch, B. T.Fultz (California Institute of Technology)

Inelastic neutron scattering spectra were measured atroom temperature on the LRMECS spectrometer forthe dilute random substitutional alloys V(X) withX=Ni, Pd, Pt and Co, at impurity concentrations of6 % to 7 %, and compared to that of pure vanadium.These spectra show a large stiffening of the phononDOS when these impurities are introduced into the Vhost, even at these low concentrations. The experi-mental neutron-weighted DOS curves were invertedusing a supercell Born-von Karman model coupled toan algorithm for optimizing the force-constants. Fromthese calculations we obtained inter-atomic force-constants and DOS curves de-weighted from the

different neutron cross-sections of V and impurities.The vibrational entropy of substitutional alloying invanadium was calculated using these inverted DOScurves. We estimate the phonon entropy of alloyingin vanadium for 6.25 % Ni, Pd, or Pt, and 7 % Corespectively to be: -0.093 ± 0.001 kB/atom, -0.136 ±0.001 kB/atom, -0.188 ± 0.001 kB/atom, and -0.305± 0.003 kB/atom. The large negative vibrationalentropy of alloying observed for the V-Pt and V-Cosystems is comparable to or larger than the gain inconfigurational entropy for a 6 % to 7 % soluteconcentration. The source of this stiffening is prima-rily an increase in the 1NN longitudinal force-con-stants between the impurities and the host atoms.We show that the magnitude of this effect is in goodagreement with the Rose universal equation of stateand elastic relaxation theories. We expect to presentadditional results on V(Fe,Ti, Zr) alloys of similarcompositions.

M3-A4 (14:30) SANS Investigation and ModelDescription of Micromagnetism in a nano-precipi-tated two-phase Alloy

W. Wagner, J. Kohlbrecher (Paul Scherrer Institut,5232 Villigen-PSI, Switzerland)

Small-Angle Neutron Scattering (SANS) was applied toinvestigate the micromagnetic properties of an alloywith nanometer sized ferromagnetic clusters embed-ded in a nonmagnetic (or paramagnetic) crystallinebulk matrix. Such kind of structure establishes in thetwo-phase alloy of composition Cu-24at.%Ni-8at%Fe,upon annealing segregating precipitates of a ferro-magnetic Fe/Ni-rich phase embedded in a paramag-netic Cu-rich matrix. The precipitate array is gov-erned by a pronounced 100<110> rolling texturein combination with a preferential pile-up along the<100> directions, resulting in a fourfold peak-structure in the two-dimensional, nuclear andmagnetic SANS pattern.

For a detailed interpretation of the magnetic SANSpattern and their response to an external field, acomputer-assisted model reconstruction was per-formed, considering a regular three-dimensionalarray of magnetic clusters with variable orientation ofthe magnetic alignment in a thermally activatedenvironment. These simulations prove that themagnetic moments of the precipitates are tightlybound to the easy directions, i.e. to <100>. At zerofield, they are randomly distributed to all possibleeasy axes, whereas an external field of intermediatestrength switches them into the easy axes with fieldparallel component, before they are forced into field-parallel alignment by a very strong field. The data areinterpreted in terms of a model balancing the


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magnetic anisotropy, magnetic coupling across theinterfacial matrix, potential energy in an externalfield and thermal activation.

M3-A5 (14:45) Fatigue-Induced Martensitic PhaseFormation and Its Deformation Behavior in aCobalt-Based Superalloy

M. L. Benson, T. A. Saleh, P. K. Liaw, H. Choo(Department of Materials Science and Engineering,The University of Tennessee, Knoxville, TN 37996,USA.), M. R. Daymond (ISIS, Rutherford AppletonLaboratory), D. W. Brown (Spallation NeutronSource, Oak Ridge National Laboratory), X.-L.Wang, A. D. Stoica (Los Alamos Neutron ScienceCenter, Los Alamos National Laboratory), R. A.Buchanan (Department of Materials Science andEngineering, The University of Tennessee,Knoxville, TN 37996, USA.), D. L. Klarstrom(Haynes International, Inc., Kokomo, IN 46904,USA.)

ULTIMET®, a cobalt-based superalloy, is known to gothrough a martensitic phase transformation from ametastable face centered cubic (fcc) phase to a stablehexagonal close packed (hcp) phase during deforma-tion at ambient temperature. In situ neutron diffrac-tion measurements were performed to study thedeformation behavior of ULTIMET® alloys during twotypes of cyclic loading tests, i.e. stress-controlledtension/tension and strain-controlled tension/com-pression fatigue tests. The relationship between themagnitude and sign of the applied stress (or strain),development of intergranular strains, and the evolu-tion of deformation-induced hcp phase fractionsduring the fatigue testing will be discussed. Further-more, differences in mechanical behavior betweenthe two different types of fatigue experiments will bepresented. The data obtained from these experi-ments will be used to explain the evolution of latticestrain in the two crystallographic orientations and indifferent phases during fatigue. A goal of this work isto use the information obtained to improve lifetimemodeling techniques of this alloy.

Acknowledgements: The author acknowledges thefinancial support of the National Science Foundation,the Combined Research-Curriculum Development(CRCD) Programs, under EEC-9527527 and EEC-0203415, the Integrative Graduate Education andResearch Training (IGERT) Program, under DGE-9987548, and the International Materials Institutes(IMI), under DMR-0231320, to the University ofTennessee, Knoxville, with Ms. M. Poats, Dr. W.Jennings, Dr. L. Goldberg, and Dr. C. Huber ascontract monitors, respectively. In addition, thefinancial support of the Tennessee Advanced Materi-

als Laboratory (TAML), with Prof. E. W. Plummer asdirector, is recognized.

M3-B, Proteins and Membranes, Chair: JoannaKrueger (U. North Carolina), Room 2100/2/4Red

M3-B1 (13:30) SANS Characterization of StandardVirus Particles for Clinical Diagnostic Assays(Invited)

S. Krueger (NIST Center for Neutron Research), I.Elashvili, C. Wick (Edgewood Chemical BiologicalCenter, 5183 Blackhawk Road, Aberdeen ProvingGround, MD 21010-5424), C. O’Connell(Biotechnology Division, NIST, 100 Bureau Drive,Stop 8311, Gaithersburg, MD 20899-8311), D.A.Kuzmanovic (Biotechnology Division, NIST, 100Bureau Drive, Stop 8311, Gaithersburg, MD 20899-8311; Geo-Centers, Inc, P.O. Box 68, AberdeenProving Ground, MD 21010-5242)

Small angle neutron scattering (SANS) has been usedto characterize the structure of wild-type and geneti-cally modified MS2 bacterial virus (phage) by examin-ing its physical characteristics in solution. Thisresearch was initiated in response to scientific needsfrom the biomedical community. Technical advancesin molecular biology have made the synthesis ofproteins for basic or biomedical research routine.Although artificially produced, many of these proteinsare enzymatically active. In the case of some virusproteins, they also retain the ability to self-assembleinto complete virus-like particles (VLPs). The inabilityof modern molecular biological techniques alone toidentify or physically characterize these VLPs hashampered their use in vaccine development and asstandards in commercially available clinical diagnos-tic assays.

Presently, noninfectious, genetically modified formsof the MS2 phage are commercially available for usein basic research diagnostic assays for the HIV, Ebola,Borna, Hepatitis A, C, and G, Dengue, Enterovirus,West Nile, and Norwalk viruses, among others.However these standard virus particles are notcommercially available for human biomedicaldiagnostic assays because their physical characteris-tics in solution have not been measured. In this work,SANS has been coupled with a novel virus countinginstrument, the Integrated Virus Detection System(IVDS) to address the scientific analytical challengesassociated with this new generation of biologicalstandards and potential vaccine carrying agents.Specifically, IVDS and the SANS contrast variationtechnique were employed to determine the molecu-lar weight of the individual components of the MS2


virion (protein shell and genomic RNA) and thespatial relationship of the genomic RNA to its proteinshell. Results will be shown for wild-type MS2particles, recombinant MS2 particles containing RNAof different sizes and from different sources, and forRNA-free reconstituted MS2 capsids.

M3-B2 (14:00) Self Assembly of Membrane ProteinArrays

Stephen A. Holt (ISIS, Rutherford AppletonLaboratory), Jeremy H. Lakey, Neil Keegan (Schoolof Cell and Molecular Biosciences, The MedicalSchool, The University of Newcastle-upon-Tyne, NE24HH, United Kingdom), Sofian M. Daud (Institutefor Nanoscale Science and Technology, TheUniversity of Newcastle-upon-Tyne, NE2 4HH,United Kingdom)

High density protein arrays on solid surfaces arebecoming an increasingly important component ofpost-genomic technologies where there is a need forprotein recognition interfaces in physical devices.Uses for these layers range from protein arraytechnology for screening of the proteome throughdiagnostic “point of care” devices aimed at specificprotein or metabolite targets to biocompatiblesurfaces for nanoscale design of implant surfaces orcell culture environments. DNA arrays have becomewell established in the marketplace, however DNArecognition is only a one-dimensional interaction.Protein-protein recognition usually relies upon thethree-dimensional fold of both components. Themaintenance of tertiary structure with the correctorientation relative to the substrate is essential for awell defined protein array. The outer membrane poreforming protein OmpF from Escherichia coli hasbeen used to produce protein arrays on silicon blocksthat have been coated with titanium and gold. Theprotein has been mutated by the addition of a singlecysteine residue which enables it to chemisorb to thegold substrate with the required orientation. Athiolipid is then added to the sample cell to completethe self assembling membrane mimetic at theinterface. We have applied neutron reflectometry tothis system to validate our models which incorporatethe relative distribution of the lipids and proteins, theexclusion of water from regions of the bilayer and theoverall thickness of the lipid layers and the protein.Initial modelling of the data demonstrates that theprotein array has self assembled with the expectedphysical dimensions. Further detailed analysis of thedata is currently underway.

M3-B3 (14:15) Determining lipid structure byneutron reflection

M. Mihailescu, S. White (University of California at

Irvine), N. Berk, C. Majkrzak (NIST Center forNeutron Research)

Multilamellar lipid membranes from the Glycero-Phosphocholine category, deposited on solid sub-strate were analyzed in reflection geometry, underlow hydration conditions, i.e. 0 to 95% relativehumidity. The new Advanced Neutron Diffractometer/Reflectometer built and operated since September2003, under the “Cold Neutrons for Biology andTechnology” project, was employed for these investi-gations. The high quality of the data permittedreconstruction of the scattering length density profileof the lipid along the normal to the multi-bilayerplane, and allowed for a direct comparison withmodels published previously [King & White 1986].Contrast variation by replacing H2O vapor with D2O,in the sample ambiental chamber, allows for thedetermination of the water distribution around thelipid head-group [Wiener & White 1991]. Moreover,the degree of lipid packing order is explored, byvarying number of double bonds per lipid acyl chain.The position and extensions of the double bonds areassessed. Functional data analysis methods can beused to asses statistical uncertainties of the measuredprofiles.

[1] G. I. King and S. H. White, Biophys. J. 49 : 1047(1986)[2] M. C. Wiener, G. I. King and S. H. White, Biophys.J. 60 : 568 (1991)

Acknowledgments: Research supported through GrantNo.NIH-RR14812 from the National Center forResearch and Resources, and the University ofCalifornia at Irvine

M3-B4 (14:30) Dominant effect of solvent onprotein dynamics

G. H. Caliskan (The University of Akron, PolymerScience Department), M. T. Cicerone (NIST PolymerDivision), M. Gangoda, R. B. Gregory (Kent StateUniversity, Department of Chemistry), A. Kisliuk(The University of Akron, Polymer ScienceDepartment), I. Peral (University of Maryland,College Park), J. H. Roh, A. P. Sokolov (TheUniversity of Akron, Polymer Science Department)

Dynamic transition in proteins and DNA is observedas a sharp increase in mean-squared displacement(MSD) of atoms at the transition temperature (TD).This transition is closely related to the activation ofprotein’s functions. However, due to MSD being anintegrated quantity, the origin of this transition is stillnot clear. Analysis of energy resolved spectra wouldshed light on to the origin of the dynamic transitionin biological macromolecules.


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We measured dynamics of protein lysozyme invarious solvents, (water, glycerol, trehalose and drystate) in a broad temperature (150K to 320K) range.High Flux Back-Scattering Spectrometer, in combina-tion with the Time-of-Flight Spectrometer at theNational Institute of Standards and TechnologyCenter for Neutron Research have been used formeasurements of the spectra in a broad energy rangefrom ~1 µeV up to ~65 meV. Our measurementsrevealed two different relaxation processes in theaccessible energy window. The fast process with thewidth ~2 meV and is rather independent of tem-perature, except for the amplitude. The slow processis strongly temperature dependent, and is observedbelow ~0.5 meV. Our results unambiguously showthat the dynamic transition is caused by the slowrelaxation process that moves in to µeV energywindow. This leads to a sharp increase in the mea-sured MSD. The slow process of the protein isstrongly affected by the solvent, and it is possible toshift the TD, by changing the solvent. Moreover, TD

observed for lysozyme in water and in glycerolappears to be close to the dynamic crossover tem-peratures of bulk water and bulk glycerol, respec-tively. No dynamic transition is observed for proteinin trehalose, at least below the glass transition oftrehalose. This proves the earlier idea formulated inthe field that the solvents control the protein dynam-ics and activity. It opens a new perspective to controlthe bioactivity of proteins.

M3-B5 (14:45) Bending Rigidity of Bio-MembranesStudied by Neutron Spin-Echo Technique (Invited)

D. Bossev (University of Maryland, College Park;National Institute of Standards and Technology), N.Rosov (National Institute of Standards andTechnology)

The dynamics of multilamellar vesicles made of1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine (DMPC),is studied in the presence of cholesterol, addition ofelectrolyte, and as a function of temperature usingNeutron Spin Echo (NSE) technique. NSE is the mostdirect method to monitor the thermal undulations ofthe lipid bilayers in solution because it is a uniquescattering technique that covers the time scale of0.01 ns to 100 ns, characteristic of these motions. Wehave used the Zilman-Granek approach to interpretthe decay of the intermediate scattering function andto evaluate the bending modulus of elasticity, κ, ofthe lipid bilayers. To elucidate temperature effect onκ we have done measurements in a crystalline stateof the bilayers (T < Tc, Tc = 24 ºC for DMPC) and inthe liquid state (T > Tc). The bending modulus ofelasticity in a crystalline state is one order of magni-tude higher than that in the liquid state whereas in a

liquid state κ is found to be independent of tempera-ture. The presence of 30 % to 50 % cholesterolincreases the bending modulus of elasticity of DMPCbilayers in a liquid state by a factor of 4 to 7. Pres-ence of electrolyte (NaCl at 0.05 mol L-1) also stiffensthe DMPC bilayers by a factor of 1.5 in a liquid state.Both, cholesterol and NaCl electrolyte, have a negli-gible effect on κ in a crystalline state. The results arecompared to those obtained by other methods. Thepossible mechanisms of these effects are alsodiscussed in the scope of DMPC bilayers structure.

M3-C, Ferroelectrics, Chair: Takeshi Egami (U.Tennessee/ORNL), Room 2101/3/5 Green

M3-C1 (13:30) Dynamic Properties of the RelaxorsPb(Mg1/3Nb2/3)O3 and Pb(Zn1/3Nb2/3)O3 (Invited)

C. Stock, R. J. Birgeneau, S. Wakimoto (PhysicsDepartment, University of Toronto, Toronto,Ontario, Canada), G. Shirane (Physics Department,Brookhaven National Laboratory)

The relaxors Pb(Mg1/3Nb2/3)O3 (PMN) andPb(Zn1/3Nb2/3)O3 (PZN) both exhibit a very similardielectric response around the critical temperature Tc.Recent neutron inelastic scattering results have founda recovery of the transverse optic mode below Tc inboth materials, indicating that a ferroelectric distor-tion exists in the unpoled state. It was widely be-lieved that these two materials were very differentbased on x-ray diffraction results, which pointed toPZN as being rhombohedral at low temperatureswhile PMN remained cubic. Recent high-energy x-rayexperiments have suggested, however, that the bulklow-temperature unit cells in both PMN and PZN arenearly cubic, and have found that the near-surfaceunit cell in PZN is rhombohedral. Because of thisoutcome, a detailed comparison of the dynamic andstatic properties of PMN and PZN is required in orderreveal their similarities and differences.

We present a review of neutron scattering resultsshowing that the static and dynamic properties ofPMN and PZN are very similar. We define the similar-ity through a comparison of the low-frequencyphonons and the diffuse scattering observed in bothsystems. Based on these similarities we propose thatthese materials belong to the same universality class.We argue that the three-dimensional Heisenbergmodel, with cubic anisotropy, in a random field mayexplain many of the unusual properties observed inPMN and PZN and compare the static and dynamicproperties to those of Mn0.5Zn0.5F2. We also discussresults suggesting that the diffuse scattering and theanomalous damping of the optic mode can beconsistently understood, and are not simply artifactsof coupling between the acoustic and optic modes.


M3-C2 (14:00) Elucidation of a MagnetoelectricSwitch

W. Ratcliff II, S.-H Lee (NIST Center for NeutronResearch), V. Kiryukhin (Department of Physics andAstronomy, Rutgers University, Piscataway, NewJersey 08854, USA), R. Erwin (NIST Center forNeutron Research), N. Hur, S.Y. Park, S.-W. Cheong(Department of Physics and Astronomy, RutgersUniversity, Piscataway, New Jersey 08854, USA)

It has been recently found that a Mn based magneto-electric material develops a spontaneous electricpolarization below the Neel ordering temperature.Furthermore, this spontaneous polarization can beswitched through the application of a magnetic field.Several anomalies were also observed in the dielec-tric constant. We have performed neutron diffractionmeasurements on a single crystal, and have foundthat anomalies in the dielectric constant and thepolarization are correlated with magnetic transitionsinduced by field or temperature. During this talk, Iwill present the magnetic phase diagram of thissystem and show how it corresponds to the sponta-neous polarization and anomalies in the dielectricconstant.

M3-C3 (14:15) Neutron Diffuse Scattering fromRelaxor Ferroelectrics

P. M. Gehring (National Institute of Standards andTechnology), K. Ohwada (Japan Atomic EnergyResearch Institute, Synchrotron Radiation ResearchCenter (at SPring 8)), H. Hiraka (Tohoku University,Institute for Materials Research; PhysicsDepartment, Brookhaven National Laboratory), G. Y.Xu (Physics Department, Brookhaven NationalLaboratory), S. H. Lee (National Institute ofStandards and Technology), G. Shirane (PhysicsDepartment, Brookhaven National Laboratory)

We report measurements of the neutron diffusescattering from a single crystal of the relaxor ferro-electric PbZn1/3Nb2/3O3 doped with 8% PbTiO3

(PZN-8%PT) for temperatures 100 K < T < 530 Kand electric fields 0 kV/cm < E < 10 kV/cm. Thediffuse scattering transverse to the (003) Bragg peakis strongly suppressed in the tetragonal phase at400K for E = 2 kV/cm applied along the [001]direction. Surprisingly, no change is observed in thediffuse scattering measured transverse to (300), evenfor field strengths up to 10 kV/cm. Thus the applica-tion of an external electric field in the tetragonal(ferroelectric) phase of PZN-8%PT does not producea uniformly polarized state. This result can be under-stood within the context of the Hirota model ofdisplaced or phase-shifted polar nanoregions. We alsoreport cold neutron measurements of the diffusescattering in PbMg1/3Nb2/3O3 the small-q region near

the (110) Brillouin zone center between 100 K andthe Burns temperature Td (~ 620 K). A strongquasielastic component of the diffuse scattering crosssection is seen near 400 K. The reciprocal spacegeometry of the diffuse scattering cross sectionmeasured near (100) and (110) at 100 K changesdramatically at higher temperatures, which webelieve reflects the underlying chemical short rangeorder present above Td.

M3-C4 (14:30) Magnetic Excitations in HexagonalFerroelectric HoMnO3

O. P. Vajk, J. W. Lynn (NIST Center for NeutronResearch), S.-W. Cheong (Department of Physicsand Astronomy, Rutgers University, Piscataway,New Jersey 08854, USA), S.B. Kim (RutgersUniversity), C. Broholm (Department of Physics &Astronomy, Johns Hopkins University), M.Kenzelmann (NIST Center for Neutron Research)

Materials with both magnetic and ferroelectric orderare of great interest because of their potentialapplications as well as the novel physics that mayresult from the interplay of these two phenomena.Hexagonal HoMnO3 is a frustrated antiferromagnetwith a complex magnetic phase diagram as well asstrong ferroelectric order. Anomalies in the dielectricconstant at magnetic phase transitions have shown acoupling of the ferroelectricity to the magnetic order.We have performed neutron scattering experimentson single-crystal HoMnO3. Order parameter measure-ments are used to measure the multiple magneticphase transitions, and inelastic measurements reveala mostly two-dimensional excitation spectrum.Details of the magnetic field, electric field, andtemperature dependence of the magnetic propertieswill be discussed.

M3-C5 (14:45) Decoupling of lattice distortion andferroelectric polarization in the relaxor systemPMN-xPT

Guangyong Xu (Physics Department, BrookhavenNational Laboratory), D. Viehland, J. F. Li(Department of Materials Science and Engineering,Virginia Tech., Blacksburg, VA), C. Stock(Department of Physics, University of Toronto,Toronto, Ontario, Canada), P.M. Gehring (NISTCenter for Neutron Research), Z. Zhong (NationalSynchrotron Light Source, Brookhaven NationalLaboratory, Upton, NY), G. Shirane (PhysicsDepartment, Brookhaven National Laboratory)

We present neutron and x-ray scattering measure-ments on the structures of lead oxide perovskiterelaxor system PMN-xPT (Pb(MgNb)O3-xPbTiO3),which has extraordinary piezoelectric properties. Thecurrent zero field phase diagrams of PMN-xPT, and its


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close analog, PZN_xPT, share many common fea-tures. The system is in a cubic phase for T above theCurie temperature Tc. When the temperature goesbelow Tc, it was long believed that a structural phasetransition occurs to a rhombohedral phase for smallx, and tetragonal phase for large x, separated by anarrow region of monoclinic phase.

Several recent studies have now uncovered evidenceof a new phase located on the rhombohedral side ofthe phase diagram. High energy x-ray (~67 keV)diffraction work by Xu et al. on pure PZN singlecrystals show that the (111) Bragg peak does not splitbelow Tc = 410 K, and the inside of the crystal doesnot have any measurable (rhombohedral) latticedistortion, providing conclusive evidence of a newphase (X). While phase X has an undistorted unit cellshape the true symmetry of the phase is still un-known. Similar behavior has also been observed inPMN-xPT series. High q-resolution neutron scatteringwork by Gehring et al. and Xu et al. show thatPMN-10 %PT and PMN-20 %PT also transforms intophase X instead of R below Tc. However, in PMN-27%PT, the low temperature phase was found to berhombohedral instead of X. These results indicatethat the ground state for the inside of PMN-xPT issimilar to that of PZN-xPT system, i.e., phase X forsmall x values, and with increasing x, rhombohedraldistortions develop and the system changes into atrue rhombohedral phase.

Another important finding during the x-ray diffrac-tion work on pure PZN was the existence of an“outer-layer” with different structures than the insideof the crystal. Lower energy x-rays (~10.2 keV) wereused to study the PZN single crystal, and a rhombo-hedral distortion was found to exist below Tc for theouter most 10 to 50 µm of the crystal. This naturallyexplains the discrepancies between earlier x-raypowder diffraction and the recent neutron and high-energy x-ray scattering results. And the fact that x-raystudies of pure PMN have not observed a rhombohe-dral phase could be understood if PMN represents thelimiting case of phase X with a very thin outer-layer.

Despite the absence of a rhombohedral distortion inphase X, ferroelectric polar order is still present inthe system. Recently, neutron inelastic scatteringmeasurements by Wakimoto et al. of the ferroelectricsoft TO phonon in pure PMN revealed that the softmode recovers at temperatures below Tc ~ 213 K.Similar measurements on PZN were later performedby Stock et al., where Tc ~ 410 K. The linear relation-ship between the soft TO phonon energy squaredand T is a clear signature of an ordered ferroelectric

phase below Tc. Phase X is a very unusual phasewhere ferroelectric spontaneous polarization and anundistorted lattice coexist in a free-standing crystal.

An important question concerns the origin of phaseX and its relationship with the polar nanoregions(PNR). We believe that the uniform phase shift of thePNR plays an essential role in stabilizing this phase(X), by creating an energy barrier thus preventing thePNR from melting into the surrounding ferroelectricphase. The balance between this energy barrier andthe coupling between the polar nanoregions and thesurrounding environment determines the stablephase of the system below Tc. With higher PT concen-trations, the coupling becomes stronger and eventu-ally phase X develops into the rhombohedral phase.

[1] G. Xu, Z. Zhong, Y. Bing, Z.-G. Ye, C. Stock, and G.Shirane, Phys. Rev. B 67, 104102 (2003).[2] G. Xu, D. Viehland, J. F. Li, P. M. Gehring, and G.Shirane, Phys. Rev. B 68, 212410 (2003).

M3-C6 (15:00) Structure of Nano-Polar Domains inFerroelectric KTa1-xNbxO3

G. Yong (Lafayette College), R. Erwin (NIST Centerfor Neutron Research), O. Svitelskiy (LehighUniversity), L. A. Boatner (Oak Ridge NationalLaboratory), B. Hennion (Laboratoire LéonBrillouin, C.E.A Saclay, 91191 Gif-sur-Yvette Cedex),J. Toulouse (Lehigh University), S. M. Shapiro(Brookhaven National Laboratory)

The temperature-dependent diffuse neutron scatter-ing (DS) associated with the cubic-to-tetragonal (CT)transition in single crystals of ferroelectricKTa1-xNbxO3 (KTN) has been characterized for x =0.16 and 0.19. The features of the DS are similar tothose found in relaxor-ferroelectric transitions. TheDS is consistent with domain wall crossings in adirection perpindicular to the domain polarization.The DS intensity and measureable domain size aremaximal near the temperature where macroscopicstrains and relief of extinction appear. The measuredDS does not overlap the inelastic scattering from softoptic phonons. An accomodation of the sublatticestrain across domain walls is able to bring theobserved and calculated DS structure factors intoagreement.

M3-C7 (15:15) Direct observation of the formationof polar nano region in Pb(Mg1/3Nb2/3)O3 usingneutron pair distribution function

I.-K. Jeong, T. Darling, J.-K. Lee, T. Proffen, R. H.Heffner (Los Alamos National Laboratory), J. S.Park, K. S. Hong (Seoul National Univ.), W.Dmowksi (University of Tennessee), T. Egami


(University of Tennessee; Oak Ridge NationalLaboratory)

We studied atomistic nature of Burns temperatureand formation of polar nano region (PNR) inPb(Mg1/3Nb2/3)O3 using neutron pair distributionfunction (PDF) over wide temperature range between15 K to 1000 K. Temperature dependence PDF showsthat new structural peaks develop as the temperaturedecreases below the Burns temperature even thoughthe average structure remains cubic. The intensitiesof these new peaks increase as the temperaturedecreases. We expect that these new peaks are dueto the formation of PNR below the Burns temperatureand our result show the first direct observation of theformation of PNR below Burns temperature.

M3-D, Dynamics in Chemical Systems, Chair:Dan Neumann (NIST), Room 1123 Blue

M3-D1 (13:30) Applications of vibrational spectros-copy by inelastic neutron scattering to problems inheterogeneous catalysis (Invited)

J. Eckert (LANSCE-12, Los Alamos NationalLaboratory, Los Alamos, NM 87545 and MaterialsResearch Laboratory, University of California, SantaBarbara, CA 93106)

Neutron scattering techniques offer some particularlypowerful ways of accessing issues related to molecu-lar binding and reactions at active sites in realcatalysts. This is because the low absorption cross-sections of neutrons make it relatively easy to carryout in situ measurements in actual reactors or otherrealistic sample environments. Vibrational spectros-copy by means of inelastic neutron scattering (INS) isone such application of neutrons that may be usedfor the study of adsorbate dynamics and thereby toidentify reaction intermediates and products. Experi-mentally, the contrast between adsorbate andframework vibrational spectra is achieved by usingmolecules with strongly scattering atoms (i.e., H)relative to those in the framework, whereby access tothe entire vibrational spectrum of the sorbate isprovided. INS spectra can also readily be computedfrom any theoretical approach that gives frequenciesand atomic vibrational amplitudes because of thesimplicity of the interaction of the neutron with theatomic nucleus. In our application of INS spectros-copy to problems in heterogeneous catalysis we use(1) a combined experimental and theoretical ap-proach to the study of equilibrium sorption com-plexes, or (2) quench a reaction carried out in areactor ex-situ, and examine the results by placingthe cold reactor directly in the INS spectrometer. Iwill describe a number of such studies including thesorption of methylamines in zeolite rho, the decom-

position of methane on supported metal catalysts, Hspillover effects for metal clusters in zeolites, and theepoxidation of propene in H2 and O2 over Aunanoparticles supported on titania. Several importantfindings have emerged from these studies includingdirect evidence for the active species formed in in thepropene epoxidation with H2 and O2. This work wascarried out in collaboration with the groups of D. W.Goodman (Texas A&M University), B. C. Gates (UCDavis) and LANL colleagues L. L. Daemen, M. Hartl,and N. J. Henson. It has benefited from the use offacilities at the Manuel Lujan Jr. Neutron ScatteringCenter, a National User Facility funded as such by theOffice of Science, U. S. Department of Energy.

M3-D2 (14:00) Recent Progress in the Measurementof Proton Momentum Distributions in HydrogenBonded Systems

G. F. Reiter (Physics Department, University ofHouston), J. Mayers, T. Abdul-Redah (ISIS,Rutherford Appleton Laboratory), J.C. Li (PhysicsDepartment, University of Manchester), P. Platzman(Bell Labs-Lucent Technologies)

Recent progress in Neutron Compton Scattering(Deep Inelastic Neutron Scattering) has made pos-sible the detailed measurement of the momentumdistribution of the proton in a variety of hydrogenbonded systems. The distribution is determinedalmost entirely by quantum localization effects, andhence the measurements provide a detailed pictureof the localizing potential. Quantum effects such astunneling are easily observed. We will provide anoverview of the method and discuss the measure-ments in ice, room temperature water, supercriticalwater, water in confined geometries, and water withacid, base and salt impurities added. The supercriticalwater data exhibits a dramatic tunneling motion andprovides additional evidence that water near ahydrophobic surface is in the vapor, not ice phase.The impurity measurements provide a direct observa-tion of the localization of the acid proton and basehydroxyl groups. We will also discuss the ferroelec-trics KDP, DKDP and the structural spin glass RDP-ADP, in which the tunneling motion of the hydrogenbonds that hold the crystal together are an essentialfeature of the observed structural phase transitions.

M3-D3 (14:15) The “Bucket Brigade” Mechanism ofProton Diffusion in Superprotonic Conductors

T. Yildirim, D. A. Neumann, T. J. Udovic (NISTCenter for Neutron Research)

Proton diffusion plays a central role in many pro-cesses ranging from the regulation of biologicalfunctions to the production of electricity in fuel cells.The renewed emphasis on developing the next


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generation of portable sources of power requires thedevelopment of light weight protonic conductingmaterials for use as electrolytic membranes. Further-more, understanding the atomic-scale mechanism ofproton diffusion in candidate materials is necessaryto optimize their performance.

First-principles computational techniques combinedwith neutron scattering measurements providedetailed atomistic information about proton incorpo-ration and dynamics in these materials. Here webriefly describe inelastic (INS) and quasielasticneutron scattering measurements (QNS) onsuperprotonic conductors of the general formulaMHXO4 (M=Rb, Cs, X=S, Se, etc) that reveal detailedinformation on the proton-conduction mechanism.

QNS measurements indicate that the hydrogendynamics is dominated by two types ofreorientational jumps of H-tetrahedra. Even thoughsuch dynamical orientational disorder brings hydro-gen atoms from one molecule closer to the next one,it does not result in long-range proton conductionsince the motions are localized on a single tetrahe-dron. However, when one combines these twomotions with that of the dynamically disorderedhydrogen bond inferred from INS, the mechanism ofproton conduction can be surmised. Namely, theprotons move between two neighboring tetrahedravia dynamically disordered hydrogen bonds. Thetetrahedra then reorient, allowing the protons tomove to a third tetrahedron, again via the dynami-cally disordered hydrogen bonds. Thus the tetrahedraplay the role of a “bucket brigade” by accepting aproton from an adjacent tetrahedron then turningand handing it on to the tetrahedron on the otherside. On the atomic scale, superprotonic conductivityoccurs in the MHXO4 family compounds due to thisefficient mechanism of transporting protons throughthe lattice.

M3-D4 (14:30) Proton dynamics in short N-H—Ohydrogen bonds

M. Hartl, L.L. Daemen (Los Alamos NationalLaboratory), J. Eckert (Los Alamos NationalLaboratory; Materials Research Laboratory,University of California, Santa Barbara), D. Hadzi, J.Stare (National Institute of Chemistry, Hajdrihova19, SI-1000, Ljubljana, Slovenia)

The role of proton dynamics in determining thephysical properties and chemical reactivity of sys-tems with very short hydrogen bonds continues toattract a great deal of theoretical and experimentalefforts. In principle, infrared (IR) spectroscopy isuseful to extract information on proton dynamics

(particularly the X-H stretch). In practice considerablediscrepancies exist between observed frequenciesand intensities and the results of ab initio calcula-tions. Significant broadening in short hydrogen bondsfurther complicates the observation of other modesand the interpretation of the spectrum. The incoher-ent inelastic neutron scattering (IINS) vibrationalspectrum is governed by entirely different (and lesscomplex) neutron-nucleus interactions rather thanphoton-electron interactions. The IINS spectrum iseasier to predict quantitatively from ab initio calcula-tions and does not suffer from the problems men-tioned above for IR spectroscopy. Despite thesefundamental advantages, vibrational spectroscopyusing inelastic neutron scattering remainsunderutilized in the study of hydrogen bonding.

Our study focused on acid-base complexes involvingN-H—O hydrogen bonds. The weak Lewis basespyridine and 3,5-dimethylpyridine (3,5-lutidine) werecomplexed with a number of weak carboxylic acids:benzoic acid, 2,4-dinitrobenzoic acid, and3,5-dinitrobenzoic acid. By varying the substituentson the pyridine or benzoic ring, we were able to tunethe strength of the hydrogen bonding interaction andalter the proton dynamics in the bond in a systematicfashion. For example, in the 3,5-dinitrobenzoic acid+ 3,5-lutidine complex, the proton in this verystrong hydrogen bond is fully disordered between Oand N with two preferred H locations each withaverage occupancy of 0.5 [d(N-H1)=0.82 Å andd(N-H2)=1.65 Å, d(N-H…O)=2.56 Å]. On the otherhand in 2,4-dinitrobenzoic acid + pyridine, thehydrogen bond has the same length as in the preced-ing complex, but the proton is at a single locationnear N [d(N-H)=1.05 Å, d(N-H…O)=2.56 Å]. Weused fully deuterated reagents to synthesize thecomplexes, then selectively deuterated and proto-nated the hydrogen bond. The difference betweenthe spectrum of the protonated and deuteratedmaterials facilitates mode assignments. All our datawere collected on the Filter Difference Spectrometerat Los Alamos National Laboratory. We will present asystematic comparison between IR and IINS data, aswell as a discussion of ab initio modeling results.

M3-D5 (14:45) An inelastic neutron scattering andab initio quasiharmonic lattice dynamics study ofsimple alkali hydrides.

A. J. Ramirez-Cuesta (University of Reading), G. D.Barrera (University of Patagonia, Argentina)

The alkali hydrides are of great interest not only asthe possibly simplest series of solids but also becauseof their possible use in fuel cells. Although there areseveral works on the lattice dynamic of lithium


hydride this is not the case for the other alkalihydrides.

Though atomistic simulations have been widely usedto calculate dynamic properties of solids we foundthat no simple interatomic potential provides a gooddescription of the alkali hydrides.

However, presently available computer software andhardware allowed us to carry out several ab initioquasiharmonic lattice dynamics calculations for thesesolids over a wide range of temperatures and pres-sures. The results presented include dispersioncurves, inelastic neutron scattering spectra andtemperature dependence of lattice parameters andbulk modulae of all alkali hydrides (LiH, NaH, KH,RbH and CsH) and deuterides.

M3-D6 (15:00) Multi-phonon scattering and Ti-induced hydrogen dynamics in sodium alanate(Invited)

Jorge Iniguez (NIST Center for Neutron Research;Department of Materials Science and Engineering,University of Maryland)

We use ab initio methods and neutron inelasticscattering (NIS) to study the structure, energetics, anddynamics of pure and Ti-doped sodium alanate(NaAlH4), focusing on the possibility of substitutionalTi doping. The NIS spectrum is found to exhibitsurprisingly strong and sharp two-phonon features.The calculations reveal that substitutional Ti doping isenergetically possible. Ti prefers to substitute for Naand is a powerful hydrogen attractor that facilitatesmultiple Al—H bond breaking. Our results hint atnew ways of improving the hydrogen dynamics andstorage capacity of the alanates.

Work done in collaboration with Taner Yildirim(NIST), T.J. Udovic (NIST), E.H. Majzoub (SNL), M.Sulic (U. Hawaii), C.M. Jensen (U. Hawaii).

M4-A, Cuprate Superconductors, Chair: YoungLee (MIT), AuditoriumM4-A1 (15:45) Recent Results on Cuprate Super-conductors (Invited)

H. A. Mook (Oak Ridge National Laboratory),Pengcheng Dai (Department of Physics andAstronomy, University of Tennessee; Oak RidgeNational Laboratory)

Neutron scattering results on the cuprate supercon-ductors will be discussed. The emphasis will be onthe most recent results on both the hole and electrondoped materials. Much of the talk will concentrate onthe high-energy magnetic excitations in the YBCOclass of materials that have been determined usingthe ISIS pulsed source. These have a large part of the

total spectral weight and are present above thesuperconducting transition. This makes them a goodcandidate for the glue that establishes the electronpairing and thus the superconductivity. The holedoping dependence of these excitations will beconsidered.

M4-A2 (16:15) Quantum Magnetic Excitations fromStripes in Cuprate Superconductors

J. M. Tranquada (Brookhaven National Laboratory),H. Woo (Brookhaven National Laboratory; ISIS,Rutherford Appleton Laboratory), T. G. Perring(ISIS, Rutherford Appleton Laboratory), H. Goka(IMR, Tohoku Univ.), G. D. Gu, G. Xu (BrookhavenNational Laboratory), M. Fujita, K. Yamada (IMR,Tohoku Univ.)

The nature of the electronic correlations underlyinghigh-temperature superconductivity in layeredcuprates remains a topic of contention. The parentcompounds are antiferromagnetic Mott insulators.Superconductivity is achieved by doping thesematerials with mobile holes, and it coexists withantiferromagnetic fluctuations. In one approach tothe coexistence, the holes are believed to self-organize into stripes that alternate with regions ofantiferromagnetic insulator. Such an unusual elec-tronic state would necessitate a novel mechanism ofsuperconductivity. Measurements of magneticexcitations in superconducting YBa2Cu3O6+x appearto pose a problem for universal applicability of thestripe picture, as they are incompatible with thepredictions for a stripe system based on semiclassicalspin waves. To resolve this issue, we have performedneutron scattering measurements over a wide energyrange on stripe-ordered La1.875Ba0.125CuO4 using theMAPS spectrometer at ISIS. We find, surprisingly, thatthe excitation spectrum is quite similar to that foundin recent studies of YBa2Cu3O6+x, and that thesemiclassical predictions are not relevant. Instead,the measurements at higher energies can be under-stood in terms of the quantum excitations of a two-leg antiferromagnetic spin ladder, where the laddersare defined by the charge stripes. Thus, our resultsprovide support for theories of superconductivitybased on the existence of stripes.

JMT, HW, GDG, and GX are supported by the Office ofScience, U.S.Department of Energy under ContractNo. DE-AC02-98CH10886.

M4-A3 (16:30) Field-Induced Square Vortex Lat-tices in High-Temperature Superconductors

J. Mesot, R. Gilardi (LNS, ETHZ & PSI, Switzerland),S. P. Brown, E. M. Forgan (Univ. Birmingham, UK),A. J. Drew, S. L. Lee (Univ. St-Andrews, UK), C. D.


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Dewhurst, R. Cubitt (Institut Laue Langevin), T.Uefuji, K. Yamada (Tohoku University)

The interest in the vortex matter of high-Tc supercon-ductors has been renewed by the recent observa-tions, by means of small angle neutron scattering(SANS), of square vortex lattices (VL) at high mag-netic fields in La2"xSrxCuO4 [1] and YBa2Cu3O7 [2].These observations are important since a squaresymmetry is indicative of the coupling of the VL to asource of anisotropy in the CuO2 planes, such asthose provided by a d-wave superconducting gap [3],momentum dependent Fermi velocities [4], or thepresence of stripes [5]. In order to discriminatebetween the above- mentioned theoretical models,SANS experiments as a function of doping and up to10.5 Tesla have been performed. The outcome of themeasurements will be presented

We will report here as well on the first SANS mea-surements of an ordered VL in the electron-dopedcuprate superconductor Nd2-xCexCuO4 [6]. A squareVL with the nearest neighbors oriented 45 degreesfrom the Cu-O bond directions is observed down tounusually low magnetic fields. Moreover, the vortexlattice intensity is found to decrease faster thanexpected with increasing magnetic field, possiblyindicating a transition to a more disordered vortexglass phase.

Similarities and differences between electron- andhole-doped high-temperature superconductors will bediscussed.

This work was supported by the Swiss NationalScience Foundation, the Engineering and PhysicalSciences Research Council of the U.K. and theMinistry of Education and Science of Japan.

[1] R. Gilardi et al., Phys. Rev. Lett. 88 (2002) 217003.[2] S.P. Brown et al., Phys. Rev. Lett. 92 (2004)067004.[3] M. Ichioka et al.,Phys. Rev. B, 59, 8902, (1999).[4] N. Nakai et al., Phys. Rev. Lett. 89 (2002) 237004.[5] Franz et al., Phys. Rev. Lett. 88 (2002) 257005.[6] R. Gilardi et al., to be submitted.

M4-A4 (16:45) Novel Dynamic Scaling Regime inHole-Doped Cuprates (Invited)

Ying Chen, Wei Bao (Los Alamos NationalLaboratory), J. E Lorenzo (Laboratoire deCristallographie, CNRS, B.P. 166, 38042 Grenoble,France), Y. Qiu, S. Park (NIST Center for NeutronResearch; University of Maryland, College Park), S.-H. Lee (NIST Center for Neutron Research), J. Sarrao(Los Alamos National Laboratory)

Only 3 % hole doping by Li is sufficient to suppress

the long-range 3-dimensional antiferromagneticorder in La2CuO4, thus allowing experimental studyof quantum spin dynamics of 2-dimensional (2D)spin liquid in a wide temperature range. The spindynamics of such 2D quantum spin liquid wasinvestigated with measurements of the dynamicmagnetic structure factor S(ω,q), using cold neutronspectroscopy, for single crystalline La2Cu1-xLixO4 (x =0.04, 0.06 and 0.1). The S(ω,q) peaks sharply at (π,π)for all these samples, suggesting that the (π,π)correlated dynamic spin clusters in Li-doped La2CuO4

have developed to substantial size below 150 K.Furthermore, S(ω,q) shows a crossover from thequantum critical (QC), ω/T scaling, at high tempera-tures to a novel low temperature regime character-ized by a constant energy scale upon cooling, whichis observed first time experimentally. The observedcrossover possibly corresponds to the theoreticallyexpected crossover from the QC to the quantum-disordered regime of the 2D Heisenberg antiferro-magnetic spin liquid. Possible role played by dopedholes in modifying spin fluctuation spectrum will bediscussed.

M4-A5 (17:15) On the temperature dependence ofthe order parameter in YBCO

M. Yethiraj, D. K. Christen (Oak Ridge NationalLaboratory), D. McK. Paul, S. Crowe (University ofWarwick), M. Arai (KEK - High Energy AcceleratorResearch Organization), L. Porcar (NIST Center forNeutron Research)

An unusual feature of the FLL in YBa2Cu3O7 is thetemperature (T) dependence of the Bragg intensity.Conventional theories predict very little variation inthe intensity between 0 K and ~T /3. Since theLondon penetration depth (of which the Braggintensity is a measure) is an order parameter of thesuperconductivity, the unexpectedly rapid decrease inthe intensity at low T seen in the first measurementsat 0.8 Tesla were extremely interesting, particularlywhat it implied on the mechanism driving thetransition in these materials. However, since disorderresults in a decrease of the integrated Bragg intensity,detailed measurements are needed to gauge theeffect of twin plane defects and lattice structuraldistortions on the Bragg intensity. Recent measure-ments of the temperature dependence of the inten-sity and vortex lattice structure at different fields in aclean but twinned sample of optimally doped YBCOwill be discussed.

M4-A6 (17:30) Field-induced magnetic correlationin high Tc cuprates (Invited)

Kazuyoshi Yamada (Institute for MaterialsResearch, Tohoku University)


We present results of recent neutron scatteringexperiments on superconducting cuprates undermagnetic field and discuss the interplay betweenmagnetic order and high-Tc superconductivity. Inhole-doped La2-xSrxCuO4 (LSCO), magnetic fieldapplied perpendicular to the CuO2 planes of LSCOwith x = 0.12 and 0.10 and of La2CuO4 with stagedexcess oxygen ions enhances the incommensurateelastic peak-intensity without changing both incom-mensurability and onset temperature of field-inducedintensities. In these compounds, no static chargestripe order has ever been induced by magnetic fieldup to ~10 Tesla. On the other hand, forLa1.45Nd0.4Sr0.15CuO4 with a static charge stripe orderno remarkable field-effect has been observed forincommensurate peaks. Therefore, the field-inducedenhancement of spin correlation is only observablein the superconducting samples accompanied bystatic/quasi-static spin-density-wave without staticcharge stripes. In the case of electron-doped super-conductors, clear field-effects have been observed inthe elastic magnetic peak centered at (ππ). In bothNd2-xCexCuO4 and Pr1-x LaCexCuO4 (PLCCO) the fielddependence of the induced component shows a peakat H = 5 ~ 6 Tesla. For PLCCO magnetic field affectsthe onset temperature for the induced magneticcorrelation. Similar to the hole-doped case, the field-induced intensity is observable only in the dopingregion where elastic magnetic peaks are observed inzero field. We compare these results with thoseobserved by impurity-substitution.

Our recent neutron scattering experiments undermagnetic field on LSCO and PLCCO have been donein collaboration with M. Fujita, M. Matsuda, S.Katano, T. Suzuki, C.H. Lee, J.M. Tranquada, C.P.Regnault, B. Khaykovich, S. Wakimoto and R.J.Birgeneau.

M4-B, Neutron Properties and Interactions,Chair: Mohammed Arif (NIST), Room 2101/3/5Green

M4-B1 (15:45) Measurement of the parity-violatinggamma-ray asymmetry in the neutron-protoncapture (Invited)

F. W. Hersman (University of New Hampshire), forthe NPDGamma Collaboration

The NPDGamma experiment is currently beingcommissioned at the Los Alamos Neutron ScienceCenter. The goal of the experiment is to measure theparity-violating gamma asymmetry A gamma in thereaction n + p- > d + gamma. The asymmetry ispredicted to be ~ 5x10-8, and its measurement willprovide a theoretically clean measurement of the

weak pion-nucleon coupling, which is believed to bethe longest range component of the hadronic weakinteraction. The results of the winter 2004 commis-sioning run, including the performance of thepolarized 3He spin filter and analyzer, will be pre-sented. Production data collection with a protontarget will begin in Fall 2004.

M4-B2 (16:15) Search for the Radiative Decay Modeof the Neutron

B. M. Fisher, F. E. Wietfeldt (Tulane University), M.S. Dewey, T. R. Gentile, J. S. Nico, A. K. Thompson(National Institute of Standards and Technology), E.J. Beise, K. G. Kiriluk (University of Maryland,College Park)

Beta-decay of the neutron into a proton, electron,and antineutrino is occasionally accompanied by theemission of a photon. Despite decades of detailedexperimental studies of neutron beta-decay, this rarebranch of a fundamental weak decay has never beenmeasured. An experiment to study the radiative beta-decay of the neutron is currently being developed forthe NG6 fundamental physics beam line at the NISTCenter for Neutron Research. The experiment willmake use of the existing apparatus for the NISTPenning-trap lifetime experiment, which can providesubstantial background reduction by providing anelectron-proton coincidence trigger. Tests and designof a detector for gamma rays in the 100 keV rangeare under development. The need for a large solid-angle gamma ray detector that can operate in astrong magnetic field and at low temperature has ledus to consider scintillating crystals in conjunctionwith avalanche photodiodes. The apparatus has beeninstalled at the NG6 beam line, and tests have begun.The status of the experiment will be discussed.

M4-B3 (16:30) High-precision measurements of then-p, n-d, and n-3He bound coherent scatteringlengths

T. C. Black (University of North Carolina atWilmington), P. R. Huffman (National Institute ofStandards and Technology; North Carolina StateUniversity), M. Arif, D. L. Jacobson, S. A. Werner(National Institute of Standards and Technology), W.M. Snow (Indiana University; IUCF), K. Schoen(University of Missouri - Columbia)

Recent measurements of the n-d and n-3He boundcoherent scattering lengths, conducted at the Neu-tron Interferometer and Optics Facility at NIST, are insignificant disagreement with exact calculations ofthese observables using modern NN+3NF potentials.The bound coherent n-d scattering length wasmeasured to be bnd = (6.665 ± 0.004) fm, whichyields a new world average for this parameter of


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bnd = (6.669 ± 0.003) fm. In the n-3He system, thebound coherent scattering length was measured asbn-3He = (5.857 ± 0.007) fm, which yields a newworld average for this parameter ofbn-3He = (5.854 ± 0.007) fm. Combining thesemeasurements with O. Zimmer’s result for the boundincoherent scattering length ofbi = (-2.365 ± 0.020) fm, one obtains the freesinglet and triplet scattering lengths for the n-3Hesystem; a0 = (7.456 ± 0.026) fm, anda1 = (3.364 ± 0.010) fm, respectively. Our measuredvalue of the n-p bound coherent scattering length,bnp = (-3.7384 ± 0.0020) fm is in agreement withthe previous world average value ofbnp = (-3.7410 ± 0.0020) fm. The extreme precisionof these new measurements renders them suitablefor use in contemporary EFT calculations.

M4-B4 (16:45) Search for New Physics from Neu-tron Beta-Decay

V. Gudkov (Department of Physics and Astronomy,University of South Carolina, Columbia, SC 29208)

New Spallation Neutron Source at the Oak RidgeNational Laboratory will provide unique opportunityto increase significantly the accuracy in measure-ments of parameters of neutron beta-decay. It willimprove the precision of the value of axial-vectorcoupling constant, which is in high demand forneutrino physics, astrophysics, and other applicationsof the theory of weak interactions. Precise measure-ments of neutron decay will lead to the possibility toobtain the Cabibbo-Kobayashi-Maskawa matrixelement in nuclear model independent way. Thevalue of this matrix element dominates the unitaritycondition of the Standard Model which is verysensitive to the possible manifestations of newphysics. Measurements of angular correlations canclarify problems related to the possibility of existenceof exotic interactions and violations of fundamentalsymmetries.

For precise determination of the fundamentalconstants and for an unambiguous search for newphysics in neutron decay experiments, the carefulanalysis of all possible corrections to neutron decayprocess should be done. This talk presents analysis ofthese corrections: including radiative correctionscalculated using both the standard approach [1] andthe effective field theory [2]. The possibility to obtainparameters of neutron beta decay in model indepen-dent way is discussed (see, for example [3]). Thegiven analysis can be used for the estimation of thesensitivity of neutron decay process to new physics.

[1] A. Sirlin, “General Properties of the Electromag-

netic Corrections to the Beta Decay ofa Physical Nucleon”, Phys. Rev. 164 (1967) 1767.[2] S. Ando, H. W. Fearing, V. Gudkov, K. Kubodera, F.Myhrer, S. Nakamura and T. Sato, “Neutron betadecay in effective field theory”, arXiv:nucl-th/0402100 (2004).[3] V. Gudkov, “New generation of neutron decayexperiments”, J. of Neutron Research(2004) in press.

M4-B5 (17:00) Review of fundamental physics withultracold neutrons (Invited)

S. N. Dzhosyuk (Harvard University)Ultracold neutrons (UCN), typically with energies oforder 10-7 eV, allow for both long observation timesand long interaction times with materials, thusmaking UCN a valuable tool for testing fundamentalphysics theories and symmetries. Several experi-ments using UCN aim to improve a precision of themeasurement of the neutron lifetime and the neu-tron beta decay asymmetry coefficient “A.” Whencombined, these parameters will help clarify presentdiscrepancies in our understanding of the weakinteraction. Another experiment, a measurement ofthe neutron electric dipole moment (EDM) using UCNin liquid helium, aims to improve the experimentallimits by two orders of magnitude. This sensitivitywill allow tests of models such as supersymmetry inthe continuing quest to observe CP violation beyondthe Standard Model, that is necessary to explain thecosmological baryon asymmetry. Several new UCNsources are being built in the U.S. and abroad. Thehigher densities of UCN that will soon be availablewill dramatically improve the precision of thesemeasurements and open up the possibilities foradditional condensed matter studies at low Q2. Areview of the current status of the above-mentionedexperiments and new facilities for UCN productionwill be presented.

M4-C, Confinement, Chair: Paul Sokol (PennState), Room 1123 Blue

M4-C1 (15:45) Quasielastic neutron scatteringinvestigation of the translational and rotationaldynamics of supercooled water confined innanoporous silica matrices

Sow-Hsin Chen, Li Liu, Antonio Faraone(Massachusetts Institute of Technology)

Using incoherent quasielastic neutron scattering weinvestigated the dynamics of water confined in twonanoporous alumino-silicate matrices, from ambienttemperature down to deeply supercooled states in atemperature range inaccessible in bulk water. Wecollected data using three instruments with widely


different resolutions, the Fermi chopper, the diskchopper, and the backscattering spectrometers, at theNIST Center for Neutron Research. The confiningsystems were lab synthesized nanoporous silicaglasses MCM-41-S and MCM-48-S. The former matrix(25 Å pore diameter) has 1-D cylindrical tubesarranged in a hexagonal structure whereas the latter(22 Å pore diameter) has a 3-D bicontinous morphol-ogy. Inside the pores of these matrices the freezingprocess of water is strongly suppressed, taking placeat a temperature about 50 K less than in bulk water.Thus, with the combined use of different instru-ments, we were able to study an interesting tempera-ture range, 200 K < T < 300 K. The data from allthe three spectrometers were analyzed using a singleconsistent intermediate scattering function of waterbased on the relaxing cage models for the transla-tional and rotational motions. An exponential slowingdown of the translational and rotational relaxationtimes, as temperature is lowered, has been observed,indicating the existence of a kenetic glass transitiontemperature at about 220 K.

[1] Liao, Ciya, F. Sciortino and S.H. Chen, “Model forDynamics in Supercooled Water,” Phys. Rev. E 60,6776-6787 (1999).[2] Liu, Li, Antonio Faraone and S.H. Chen, “A ModelFor the Rotational Contribution to Quasi-elasticNeutron Scattering Spectra From Supercooled Water,”Phys. Rev. E. 65, 041506-8 (2002).[3] Fraone, A., S.H. Chen, E. Fratini, P. Baglioni, L. Liuand C. Brown, “Rotational Dynamics of HydrationWater in Dicalcium Silicate by Quasi-Elastic NeutronScattering,” Phys. Rev. E. 65, 040501-4 (2002).[4] Faraone, A., Li Liu, Chung-Yuan Mou, Pei-ChunShih, John R.D. Copley, and Sow-Hsin Chen, “Transla-tional and rotational dynamics of water inmesoporous silica materials: MCM-41-S and MCM-48-S,” J. Chem. Phys. 119, 3963-3971(2003).[5] Faraone, A., Li Liu, and Sow-Hsin Chen, “Modelfor translation-rotation coupling of molecular motionin water,” J. Chem. Phys. 119, 6302-6313 (2003).

M4-C2 (16:00) Liquid-Gas Critical PhenomenaUnder Confinement: SANS Studies of CO2 inAerogel

Y. B. Melnichenko, G. D. Wignall (Condensed MatterSciences Division, Oak Ridge National Laboratory),D. R. Cole (Chemical Sciences Division, Oak RidgeNational Laboratory, Oak Ridge, TN 37831, USA), H.Frielinghaus (Forschunszentrum Jülich GmbH,Institut für Festkörperforschung, D-52425 Jülich,Germany)

The effect of spatially fixed (quenched) impurities onphase transitions and critical phenomena remains a

challenging area for both theory and experiment.Small angle neutron scattering (SANS) is a well-established technique for investigating the behaviorof confined binary liquid solutions, as it can probethe correlation length (ξ) and susceptibility (χ) inpores on length scales ~ 1 - 100 nm. We reportresults of the first SANS measurements of the criticalbehavior of a single-component fluid (CO2) in a highlyporous aerogel and compare it with the criticalbehavior of the bulk fluid. We demonstrate that,although the scattering from blank aerogel exceedsthat from CO2 by two orders of magnitude, thetemperature and pressure variation of thermody-namic properties of confined fluids can be extractedand explored. Pressure scans at temperatures, bothfar away and close to the liquid-gas critical tempera-ture, TC reveal the importance of the molecule-surfaceinteractions, which become increasingly important inthe critical region. ξ and χ for the bulk fluid divergeas T~TC and their variation is described by the Isingmodel exponents (ν = 0.63 and γ = 1.24, respec-tively). Furthermore, the scaling exponents ofconfined fluid are close to mean field predictions (ν= 0.5 and γ = 1.0) and the absolute value of ξ doesnot exceed the pore size of aerogel (~ 70 Å) even atT ~ TC. The results demonstrate that quencheddisorder induced by aerogel works to depress densityfluctuations in the critical region. Below TC, the long-lived methastable domains are formed. Despite thenegligible volume occupied by aerogel (< 4 %), themacroscopic phase separation of confined CO2 intocoexisting liquid and gaseous phases characteristic ofthe bulk fluid, is completely suppressed. Experimen-tal data show that critical absorbtion is as importantas the effect of confinement, even in highly poroussystems.

M4-C3 (16:15) Anomalously soft dynamics innanotube-water: a revelation of nanoscale confine-ment (Invited)

A.I. Kolesnikov, C.-K. Loong, P. Thiyagarajan(Intense Pulsed Neutron Source, Argonne NationalLab), J.-M. Zanotti (Intense Pulsed Neutron Source,Argonne National Lab; Laboratoire Léon Brillouin,C.E.A Saclay, 91191 Gif-sur-Yvette Cedex), C.Burnham (Department of Chemistry, University ofUtah, Salt Lake City, Utah 84112), A.P. Moravsky,R.O. Loutfy (MER Corporation, 7960 South KolbRoad, Tucson, AZ 85706)

Quasi-one-dimensional water encapsulated insidesingle-walled open-ended carbon nanotubes, herereferred to as nanotube-water, was studied byneutron scattering (ND, INS and QENS) at differenttemperatures and pressures. This study reveals thatnanotube-water is a new state of water manifested


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by weak hydrogen bonds, extended intermolecularwater-water and O-O distances, short O-H covalentbonds, very large amplitude of water moleculesvibrations, and a continuous transition from solid toliquid state on heating. QENS study at high pressurealso shows that at P = 0.14 GPa the effect of verylarge amplitude of water molecules vibrations inSWNT is suppressed at low temperatures. MDsimulations of nanotubes-water well describe theobserved INS spectra and give a possible structure ofwater inside single-walled carbon nanotubes.

M4-C4 (16:45) Molecular Rotation and Translationof Hydrogen Adsorbed on Planar Graphite and inSingle-Wall Carbon Nanotubes

P.A. Georgiev, D.K. Ross, J. Fernandez-Garcia, I.Morrison (Institute for Materials Research,University of Salford, Salford, M5 4WT)

We present neutron inelastic scattering spectrameasured at 17 K on the TOSCA spectrometer, ISIS,UK, from different amounts of para-Hydrogen withinthe sub- and multilayer region physisorbed on Grafoiland high quality Single-Wall Carbon Nanotubes. Ourresults show that on the graphite surface and forconcentrations of up to the densest monolayer therotational motion of the adsorbed molecules isunperturbed. A downshift of 0.2meV is attributed tothe different Zero Point Energies (ZPE) of the Center-of-Mass (CoM) out of plane motion for the para- andortho- molecular species, as well as, a small increasein the H-H bond length. On the contrary, a 1.5 meVsplitting between the states within the J = 1 manifoldis observed at low surface coverage, where due to thetwice higher binding energy as compared to flatgraphite, the molecules are preferentially adsorbedon the groove sites of the nanotube bundles. Athigher surface coverages the scattering is dominatedby freely rotating molecules adsorbed at the externalconvex tube surface and in higher molecular layers.Our new and unique high-resolution data from a fewconcentrations in the multilayer region shows for firsttime that due to the vertical solid-like behavior of thesecond and possibly even the third molecular layers,the J = 0 to J = 1 rotational line of hydrogenadsorbed on Grafoil is also split. The higher molecu-lar layers show no ZPE effect on the rotational line.The 0 - 1 rotational transition due to moleculesadsorbed between the graphite surface and highermolecular layers is now split. It is anticipated that forthese molecules the mixing between the different m-states of the J = 1 level is now removed and adifferent rotational-translational coupling schemeoperates.

The mean translational kinetic energies as functions

of the surface concentration are derived from thehigh-energy part of each spectrum.

M4-C5 (17:00) Inelastic Neutron Scattering of H2

Adsorbed on Activated CarbonD.G. Narehood, P.C. Eklund, P.E. Sokol (Departmentof Physics and Materials Research Institute,Pennsylvania State University Park, Pennsylvania16802)

Inelastic neutron scattering provides a uniquemicroscopic perspective of the state of moleculesadsorbed on surfaces. We report inelastic neutronscattering studies of H2 adsorbed on an activatedcarbon (AC). Deep inelastic neutron scattering (DINS)has been used to probe the single-particle momen-tum distribution of the adsorbed molecules. Fromthese measurements the mean kinetic energy, whichis directly affected by the extent of localization of themolecules, has been determined. In addition to theDINS measurements, the rotational spectrum of theadsorbed molecules was measured with incidentneutrons with thermal energies. Peaks correspondingto transitions between the J = 0 and J = 1 rotationalstates are present in the collected scattering spectra.These spectra provide information on the ortho-to-para conversion of the adsorbed molecules throughthe time-dependent intensities of the peaks. DINSand rotational spectra have been collected for varioussurface coverages in order to study the importance ofthe affect of H2-H2 interactions versus H2-AC interac-tions on the properties of the adsorbed molecules.This research was supported by the DOE under GrantNo. DE-FG02-01ER45912.

M4-C6 (17:15) Structure and dynamics of oligomermolecules within monolayer films on graphite

E.J. Kintzel, Jr., K.W. Herwig (Spallation NeutronSource, Oak Ridge National Laboratory), I. Peral(NIST Center for Neutron Research; Department ofMaterials Science and Engineering, University ofMaryland)

The structure and dynamics of monolayer films ofthe aromatic molecules o-terphenyl (o-3P), p-terphenyl (p-3P), p-quaterphenyl (p-4P), and p-sexiphenyl (p-6P) adsorbed onto the surface ofgraphite has been carried out using elastic andquasielastic neutron scattering. Structural results ofthe p-phenylene oligomer (p-nP) films indicate anorientation consistent with the long molecular axisparallel to the graphite surface. Initial dynamic resultsindicate a phase change within the p-nP films atapproximately 300-325 K. At temperatures below325 K, the scattering is consistent with reorientationof the phenyl rings around the long molecular axis.At temperatures above 300 K, the scattering is much


stronger and appears at lower momentum transfers,indicating some form of translational motion incombination with reorientation of the phenyl rings.Monolayer o-3P films exhibit molecular motionsconsistent with both reorientations of the phenylrings as well as translations at temperatures as low as190 K. There is no abrupt change in the character ofthe dynamics for the o-3P films.

M4-D, Polymers and Colloids, Chair: MichaelKent (Sandia), Room 2100/2/4 Red

M4-D1 (15:45) Counterion undressing from flexiblepolyelectrolytes (Invited)

V. M. Prabhu, E.J. Amis (NIST Polymer Division),D. Bossev, N. Rosov (NIST Center for NeutronResearch)

At low ionic strength, organic counterions dress aflexible charged polymer as measured directly bysmall-angle neutron scattering (SANS) and neutronspin-echo (NSE) spectroscopy. This dressed state,quantified by the concentration dependence of thestatic correlation length, illustrates the polymer-counterion coupled nature on the nanometer lengthscale. The counterions, made visible by selectivehydrogen and deuterium labeling, undress from thepolymeric template by addition of sodium chloride.The addition of this electrolyte leads to two effects;increased Debye electrostatic screening anddecoupled counterion-polymer correlations. Neutronspin echo spectroscopy measures a slowing-down ofthe effective diffusion coefficient of the labeledcounterions at the length scale of 8 nm, the staticcorrelation length, indicating the nanosecondcounterion dynamics mimics the polymer. Theseexperiments, performed with semidilute solutions oftetramethylammonium poly(styrene sulfonate)[(h–TMA+) d–PSS], apply to relevant biopolymersincluding single and double stranded DNA andunfolded proteins, which undergo orchestrateddynamics of counterions and chain segments to fold,unfold and assemble.

M4-D2 (16:15) The effect of chain architecture onthe dynamics of copolymers in a homopolymermatrix

S. K. Kamath, M. Lay, R. Mehta, M. D. Dadmun(University of Tennessee, Knoxville)

Copolymers can be used as interfacial modifiers inphase separated polymer blends and selectivesurface segregation. Important parameters in thisprocess include the amount of copolymer thatmigrates to the surface and the rate of this process,both of which are altered by changing the copolymermicrostructure. We have monitored the the diffusive

behavior of various copolymers of Styrene(S) andMethylmethacrylate (MMA) in a PMMA matrix usingneutron reflectivity experiments. These results arecompared to results from dynamic Monte Carlosimulations on a model blend containing copolymersof different architectures dispersed in a homopoly-mer matrix. In conjunction, these studies providevaluable insights into the effects of chain architectureon the structure and dynamics of copolymers in ahomopolymer matrix.

M4-D3 (16:30) SANS Microstructure and rheologyof sterically stabilized colloidal dispersions withdepletion attractions

L.N. Krishnamurthy, N.J. Wagner (Center forMolecular and Engineering Thermodynamics,Department of Chemical Engineering, University ofDelaware, Newark, DE 19716)

Colloidal particles are employed in a wide range ofindustries and products. A thorough understanding ofdispersion rheology and stability is critical for suc-cessful formulation and processing of colloidaldispersions for practical applications. These proper-ties are macroscopic manifestations of the micro-scopic interparticle interactions acting between thecolloidal particles. The microscopic forces that canarise from polymer adsorption include bridging,steric, and depletion forces with a strongly coupledelectrosteric force if the polymer is a polyelectrolyte.Rational design of stable dispersions requires thecharacterization of these interparticle interactions.

Rheological and small angle neutron scatteringmeasurements are presented for a model dispersionof silica nanoparticles in a buffered, aqueous gelatinsolution over a range of particle and gelatin concen-trations. There is debate in the literature so towhether free polymer in an adsorbing polymer-colloid mixture can result in an attractive depletioninteraction force. The adsorbed polymer layer andthe resulting large excluded volume clearly dominatethe rheology. However, comparison of SANS measure-ments with analysis of the rheology demonstrates thepresence of weak attractions, which has a profoundinfluence on the stability and rheology of thesesystems.We model the attractive interactions within theclassic Asakura-Yukawa framework for the depletioninteractions. We propose a predictive semi-empiricalmodel to describe the rheology of colloidal systemswith attractive interactions. Excellent quantitativepredictions of zero shear viscosity and SANS for abroad range of particle and polymer concentrationvalidate our model.


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M4-D4 (16:45) Highly Monodispersed SilicaNanoparticles: Controlled Formation and EDLCharacterization by SANS

W. Wang (Oak Ridge National Laboratory), L.Porcar (NIST Center for Neutron Research), W. A.Hamilton (Oak Ridge National Laboratory), P. D.Butler (Oak Ridge National Laboratory; NIST Centerfor Neutron Research), L. Liang (Oak Ridge NationalLaboratory; Cardiff University, Cardiff CF24 0YF,UK), B. Gu (Oak Ridge National Laboratory)

Suspensions of monodispersed colloidal particlesoffer many scientific opportunities for new applica-tions in emerging nanotechnologies, such as ad-vanced coatings, photonic crystals and photonicband-gap materials. The goal of this project is todevelop and apply small angle neutron scattering(SANS) to quantify the electric double layer (EDL)structure associated with silica nanoparticles in anaqueous solution containing organic electrolytes. Theamount and the orientation of the ionic organicmolecules present in the Stern layer, and the result-ing thickness of the EDL all contribute to interactionenergies during particle encounter.

In order to detect small changes in particle size dueto sorption of the organic ions, a high monodispersityof colloidal particles is crucial. Although the prepara-tion of silica nanoparticles has been extensivelystudied, synthesis of highly monodispersed silicacolloids with sizes <100 nm remains a challenge. Weoptimized synthesis and purification procedures toproduce monodispersed silica colloids in size rangeof 20-100 nm by hydrolysis of tetraethoxysilane. Theparticle sizes and polydispersity could be controlledby chemical reagent concentrations, reaction tem-perature, reaction time, or surfactant template media.

These monodispersed silica colloids were studied bySANS over a wide range of scattering vectors. Theseorganic counterions, such as tetraalkylammoniumand alkyltrimethylammonium ions, functionally serveas monovalent simple ions with a high volumedensity and therefore provide a model system tostudy ion adsorption and distribution on silicasurfaces by SANS. The adsorption layer thicknesses ofvarious organic cations at the silica nanoparticle-water interface were studied with contrast matchtechnique.This deuteration accentuated differentdomains relative to others to provide the neededdiscrimination for specific domain structures such asparticle core size, adsorbed monolayer or bilayerthicknesses, and solvent penetration in the organiclayers. We fit the scattering spectra by PolyCoreShellModel to deduce the diameter, the size polydispersity,and the thickness of adsorbed organic layer on thespherical silica particles.

M4-D5 (17:00) Effect of Attractions on the Micro-structure and Rheology of Dense Colloidal Suspen-sions and Gels

V. Gopalakrishnan, S. Ramakrishnan (Departmentof Chemical and Biomolecular Engineering), K.Schweizer (Department of Chemical andBiomolecular Engineering; Department of MateriaslScience and Engineering), C. Zukoski (Departmentof Chemical and Biomolecular Engineering)

Colloidal suspensions and gels are used in a numberof technologically important applications – inks,paints and ceramics to name a few. Control of themicrostructure of the suspension and the resultingflow properties is of utmost importance to achievingthe desired properties in these applications.

Addition of non-adsorbing polymer to a colloidalsuspension (particles of size R) provides one with theability to tune the microstructure and flow propertiesof the suspension with two independent variables –the molecular weight of the added polymer (radius ofgyration Rg) and concentration of the added polymercp. The non-adsorbing polymer induces attractionsbetween the colloidal particles the range of which iscontrolled by Rg/R while the strength of attractions iscontrolled by cp. For Rg/R values less than 0.1, theaddition of increasing amounts of polymer causes thesuspensions to gel thus drastically changing the flowproperties at the gel point (divergent zero shearviscosity and appearance of a nonzero value of theelastic modulus).

In this work, we systematically characterize themicrostructure (SANS and USAXS) and flow proper-ties of the colloidal silica suspensions (suspended indecalin) with the addition of polystyrene. The sizeratio Rg/R used in this work is 0.078 and 0.053. Thereare two regions which we focus on – (1) The equilib-rium fluid : the polymer concentration is varied fromdilute till the point where the suspensions gel and (2)The gel region: the polymer and colloid concentra-tions are varied over a wide range to give rise tosubstantial changes in flow properties. Our goal is tolink the mechanical properties to microstructuresthrough the appropriate models.

Here we report on decreases in the shear raterequired to produce hydroclusters as the strength ofattraction is increased. Hydroclusters are importantin the high shear region where shear thickening isobserved. With increasing strengths of attractionthese clusters form at increasing smaller shear ratesbut shear thickening is lost. This is understood interms of the shear rate dependencies of the hydrody-namic and thermodynamic contributions to thestress.


MU - User Meetings and Reception (McHenry/Chesapeake Rooms; 19:00)

MP - Poster Session: Student Research Award(Main Concourse; 20:00) (Reception continues)

MP1: SANS Study of High Pressure Unfolding ofStaphylococcal Nuclease

A. Paliwal (Johns Hopkins University), D.P. Bossev(NIST Center for Neutron Research), ME Paulaitis(Johns Hopkins University)

Staphylococcal Nuclease (SN) is a 149 residues long,single domain globular protein whose folding charac-teristics conform to the two state model. Reversiblefolding of SN with pH, chemical denaturants andtemperature as perturbing agents has been very wellexamined and characterized.1-2 A series of equilib-rium and kinetics studies of pressure induced unfold-ing of SN by Royer et al.3-4 revealed that the foldingreaction involves significant dehydration and collapseof the chain. The picture that emerges from thesestudies is that of a combination of increased solva-tion and decreased excluded volume in the unfoldedstate relative to the folded state. However, no directefforts have been made towards quantifying thisdifference in the extent of hydration of the foldedand the unfolded states from a large body of avail-able experimental results. Recently, Hummer et al.5

proposed that proteins stabilized by hydrophobicdriving forces at ambient pressure are destabilized atelevated pressures due to water penetration into thehydrophobic core (“protein unfolding”). They arguethat pressure-induced protein unfolding correspondsto the transfer of water into the protein interior,rather than to the transfer of nonpolar residues intowater. This hypothesis, if correct, would resolveKauzmann’s paradox6 for the pressure-induceddenaturation of proteins, which results from the factthat the volume change of transfer of hydrocarbonsinto water is positive at high pressures.

In this study, we present a novel method recentlydeveloped7 to extract the extent of hydration of SN asa function of pressure from our Small Angle NeutronScattering (SANS) results at 25° C. The method,primarily makes use of the radius of gyration, Rg andthe forward scattering intensity, I(0) values obtaineddirectly from the scattering spectra. These hydrationresults are then discussed in context of the proposi-tion put forward by Hummer et al. and the ‘apparent’paradox first pointed out by Kauzmann.

Reference:[1] Shortle D. and Meeker A. K. (1986) Proteins:struct., funct. and genet. 1, 81.[2] Griko Y.; Privalov, P. L.; Sturtevant J.M and

Venyaminov, S. (1988) Proc. Natl. Acad. Sci. U.S.A 85,3343.[3] Vidugiris, G.J.A; Markley, J.L. and Royer, C. A(1995) Biochemistry U.S 34(15), 4909.[4] Panick, G.; Vidugiris, G. J. A; Malessa, R; Rapp, G,Winter, R. and Royer, C. A (1999) Biochemistry U.S38, 4157.[5] Hummer, G.; Garde, S; Paulaitis, M. E. and Pratt,L. R. Proc. Natl. Acad. Sci. U.S.A (1998) 95, 1552.[6] Kauzmann, W. Nature (1987) 325, 763.[7] Lesemann, M.; Nathan, H.; DiNoia, T.; Kirby, K.;McHugh, M. A.; van Zantan J.H. and Paulaitis, M.E.Ind. Eng. Chem. Res. (2003) 42(25), 6425.

MP2: Studying Protein Dimerization on Membranesby Small Angle Neutron Scattering

K. Gupta (Dept. of Chemical and Biomolecular Eng.;Program in Computational Biology, Johns HopkinsUniveristy, Baltimore, MD), J. Pencer (Dept ofChemical and Biomolecualr Engg., Johns HopkinsUniversity, Baltimore, MD.; NIST Center for NeutronResearch), D. Bossev, S. Krueger (NIST Center forNeutron Research), M. Paulaitis (Dept. of Chemicaland Biomolecular Engg.; Program in ComputationalBiology, Johns Hopkins Univeristy, Baltimore, MD)

Clustering/oligomerization of membrane boundreceptors is found to be important in cellular re-sponses. It has been suggested that oligomerization isinduced both by lipid membrane environment andby ligand binding. Though many studies have beenfocused on receptor clustering, the structural featuresof these oligomers are still lacking. We have devel-oped a model system to study the role of membraneenvironment and ligand binding on the structuralorganization of membrane anchored proteins usingsmall angle neutron scattering (SANS). Our modelsystem consists of a mouse IgG Fab fragment co-valently attached to unilamellar DMPC lipid vesicleson which dimerization/oligomerization is induced byanti-Fab antibody. Contrast matching of isotopicallysubstituted phospholipids eliminates the contributionof the bilayer to the observed scattering, resulting ina scattering profile dependent on the structuralorganization of protein complexes on the bilayer. Bycomparing the scattering profiles from proteincomplexes in solution and on the bilayer, we havefound that the complexes on the membrane have asmaller physical size and less flexibility than in thesolution. Our results also suggest that anchoringproteins on a single component bilayer system doesnot increase their dimerization/oligomerizationpotential in the presence of a ligand. One implicationof these results is that lipid domains (rafts) or othercellular components may be required in facilitatingthe oligomerization of membrane bound receptors.


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MP3: Influence of hydration on protein dynamicsJ.H. Roh (University of Akron, Department ofPolymer Science), G. Caliskan (Johns HopkinsUniversity, Department of Biophysics), R. Gregory(Kent State University, Department of Chemistry), I.Peral, Z. Chowdhuri (NIST Center for NeutronResearch), A.P. Sokolov (University of Akron,Department of Polymer Science)

It is obvious that protein dynamics affects signifi-cantly their biological activity. Direct relationshipbetween the protein dynamics and the enzymaticactivity, however, remains unclear. One way toobserve simultaneous changes in protein motionsand their functions is to analyze dependence of theseparameters on hydration level of a protein. Wepresent analysis of internal motion of proteins atdifferent hydration levels in nano- and picosecondtime window. Quasielastic incoherent neutronscattering spectra have been measured in a broadenergy range (from ~1 µeV up to ~10 meV) bycombining data from backscattering and time offlight spectrometers. The data show nonlinearincrease of quasielastic contribution with increase ofhydration level. Three different regions are identified:(i) slight change with hydration up to 0.20 g D2O / 1 gprotein; (ii) strong change with hydration between0.20 and 0.55 g D2O / 1 g protein; (iii) asymptoticbehavior with hydration above 0.55 g D2O / 1 gprotein. The dynamic transition observed in thetemperature dependence of mean square displace-ments (MSDs) around 200 K appears only at hydra-tion levels higher than 0.20 g D2O / 1 g protein. Weascribe the observed variations to a change in theslow relaxation process. It is shown that the intensityof the slow process correlates to the enzyme activity.The results suggest that slow relaxation processmight be the essential internal motion to trigger theonset of enzymatic activity in proteins.

MP4: Neutron diffraction investigation of thestructural deviations of components in cementclinker

V. K. Peterson (NIST Center for Neutron Research;University of Maryland, College Park)

The deviations in structural models of tricalciumsilicate phases in a Rietveld model of cement clinkerafter atomic position refinement using neutronpowder diffraction data were investigated. Results forphase quantification before, and after, atomic posi-tion refinement are reported, and alterations toBragg-R factors of phases are recorded. In thisneutron study, relatively minor adjustments to sometricalcium silicate structural models resulted indecreased R-Bragg factors of those and other phases.

Tricalcium silicate is the major phase in cementclinker, and is crystallographically complex.Tricalcium silicate exhibits polymorphism, and it isusual for several polymorphs to co-exist as a solidsolution in cement clinker. At least seven polymorphsexist, and three have structural solutions that arecommonly used in the Rietveld analysis of clinkers.Full-profile Rietveld methods have the ability todefine the tricalcium silicate form. It is usual toinclude a polymorph of tricalcium silicate in each ofthe three crystal systems encountered when begin-ning a refinement and then exclude the crystalsystem(s) not found. Care must be taken so as not toenable one crystal system to alter itself to compen-sate for others not being modelled.

The crystallography of tricalcium silicate in furthercomplicated as both triclinic and monoclinic forms oftricalcium silicate found in cement clinker arestructurally modulated. The structural models used inthe Rietveld analysis of cement clinker are averagesor approximations only to these true, modulatedstructures. Additionally, only one triclinic and onemonoclinic structural model exist to represent thethree possible forms in each of these crystal systems.

Rietveld refinement is commonly used as a methodof phase quantification of cement. Given that thestructural models for tricalcium silicate may not beaccurate or appropriate descriptions of the tricalciumsilicate forms in cement clinker, the effect of refiningthese structures using data of real cement samples isof interest. Thus, any deviations of the “real” struc-tures from the “model” structures can be investi-gated.

MP5: Fundamental Tests of Ab Initio methods onOrganic based Charge Transfer Crystals usingInelastic Neutron Scattering Spectroscopy

J.A. Ciezak (Syracuse University, Dept of Chemistry,1-014 CST, Syracuse, NY 13244), C.M. Brown (Dept.Mechanical and Nuclear Engineering, University ofMaryland/NIST, Gaithersburg, MD), B.S. Hudson(Syracuse University, Dept of Chemistry, 1-014 CST,Syracuse, NY 13244)

Inelastic neutron scattering (INS) studies of solid-statecharge transfer complexes will be presented incombination with ab initio calculations to provideinsight into both the molecular properties and thecrystalline environment. These crystals undergoelectron transfer from a donor to acceptor uponexcitation and have relatively unique bondingpatterns and structural defects. The donor andacceptor molecules possess electrons that are able tomove along the molecular stacks, making them


similar to one-dimensional conductors. In addition totheir interesting electronic structure, obtaining anaccurate DFT description of these complexes haspresented considerable challenge in the past. Twocharge transfer complexes, TCNQ:Anthracene andTCNE:Naphthalene, will be discussed, in addition to arelatively unique charge transfer complex, which alsohas hydrogen bonds, Quinhydrone. We will show thatDFT calculations can provide an adequate descriptionof isolated complexes of TCNQ:Anthracene andTCNE:Naphthalene. We will also show the potentialuse of the HCTH/120 functional in conjunction withfull periodic boundary conditions to describeQuinhydrone.

MP6: Orientation and Relaxation of Polymer-ClaySolutions

M. Malwitz (Louisiana State University), P. Butler(Oak Ridge National Laboratory), L. Porcar(National Institute of Standards and Technology), G.Schmidt (Louisiana State University)

The influence of shear on viscoelasticpoly(ethylene)oxide (PEO)-clay solutions (Montmoril-lonite, CNA) was investigated by means of rheologyand small-angle neutron scattering (SANS). Steadystate viscosity and SANS were used to measure theshear-induced orientation and relaxation of polymerand clay platelets. Anisotropic scattering patternsdeveloped at much lower shear rates than in pureclay solutions. The scattering anisotropy saturated atlow shear rates and the CNA clay platelets aligned bythe flow, with the surface normal parallel to thegradient direction. Cessation of shear lead to partialand slow randomization of CNA platelets whileextremely fast relaxation was observed for Laponite(LRD) platelets. This work on PEO-CNA network likesolutions is compared to previously reported PEO-LRD networks and focuses on differences andsimilarities in shear orientation, relaxation, and onthe polymer and the clay interactions.

MP7: Structure Determination of SubcolloidalZeolite Precursor Nanoparticles

J. M. Fedeyko, D. Vlachos, R. F. Lobo (Center forCatalytic Science and Technology, Department ofChemical Engineering, University of Delaware,Newark, DE 19713 USA)

Upon mixing a solution of tetrapropylammoniumhydroxide (TPAOH) and tetraethylorthosilicate (TEOS)at room temperature, a segregation of the solutioninto two metastable phases is observed. A continuouswater-rich phase is formed containing most of thewater and a small amount of SiO2 and TPAOH. At thesame time, the silica is microsegregated intonanoparticles (~ 4 nm) that contain most of the

silica, a large fraction of the TPAOH and a smallamount of water. It has been shown that the rate ofgrowth of zeolites is controlled by the addition ofthese subcolloidal silica nanoparticles to the growingsurface. However, many important aspects of theseparticles remain unresolved. For instance, the particleshape, particle size distribution, and fundamentalproperties such as the average composition, internalstructure and charge are completely unknown. Wehave started a comprehensive investigation of thissystem in an attempt to resolve these issues and willuse the information gathered to develop a zeolitegrowth model that describes the system as a functionof intensive variables such as temperature, pressureand composition.

We have conducted contrast matching small-angleneutron scattering experiments in the dilute limit incombination with small-angle x-ray scattering and insitu NMR spectroscopy. Analysis of the SANS patternsof particles prepared in D2O revealed that the par-ticles are ellipsoidal shaped. Our study of the contrastmatching and SAXS experiments indicates that thecore of these particles is composed primarily of silica.In situ 29Si NMR gives information about the connec-tivity of the silica core. We find that about 78% of thesilica groups are Q3(SiO3/2–OH) and 22% ofQ2(SiO2/2–(OH)2). All this information is being usedas input to a simulated annealing code that generatesmodels of the nanoparticles with atomic detail. Wewill present a summary of our results and analysis.

MP8: Electric field alignment of asymmetricdiblock copolymer thin films

Ting Xu, Thomas P. Russell (Department of PolymerScience and Engineering, University ofMassachusetts, Amherst)

Electric fields alignment of asymmetric diblockcopolymer thin films, polystyrene-block-poly(methylmethacrylate), was studied using small angle neutronscattering (SANS) and transmission electron micros-copy (TEM). Starting from a poorly ordered state (ascast), surface fields and opposed electric fields biasedthe cylindrical microdomain orientation. With timeupon annealing, the cylinders are locally disrupted toform ellipsoidal shape microdomains that connectedinto cylindrical microdomains in the applied fielddirection. Starting from an ordered state with cylin-ders parallel to the surface, the applied electric fieldenhanced fluctuations at the interfaces of themicrodomains and disrupted cylindricalmicrodomains into spherical microdomains. Thistransition is similar to thermoreversible cylinder-to-sphere order-order transition. With time, the spheresdeformed into ellipsoids and reconnected forming


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cylindrical microdomains oriented at ~45o withrespect to the applied field. The tilted cylinderssubsequently aligned along the applied field direc-tion. This reorientation process is much slower thanthat from poorly ordered state.

MP9: Short Strong Hydrogen potential surfacesstudied by INS

Timothy Jenkins, Bruce Hudson, Damian Allis, JennCiezak (Syracuse University, Syracuse, NY), DaleBraden (Schrödinger Inc., Portland, OR)

Symmetric hydrogen bonds (e.g., O-H…O) haveequivalent local minima for the H atom positionsseparated by a barrier at the position of equal O-H-Olengths. This barrier decreases in height as the O-Odistances and apparently vanishes for sufficientlyshort distances. The short, strong hydrogen bondsthat occur for small O-O distances are also known as“low barrier” hydrogen bonds. These systems wereexpected to display a failure of the harmonic dynami-cal treatment due to the anharmonic nature of theshort, strong hydrogen bonds. We examined severalco-crystals of varying O-O distances and both inter-molecular and intramolecular hydrogen bonds byvibrational spectroscopy to provide a high-resolutionbasis calculation comparison. Neutron vibrationalspectroscopy results are presented. Comparisoncalculations involving the short, strong hydrogenbond potential surfaces were also carried out usingdensity functional methods. Potential surface modelssuggest that the surface is best fit by a quartic modelresulting in agreement to the vibrational spectra.Vibrational spectrums were determined using FANSat NIST and TOSCA at ISIS, RAL.

MP10: Large Scale Structures in Polymer-ClaySolutions

E. Loizou, M. Malwitz (Louisiana State University),P. Butler (Oak Ridge National Laboratory), L. Porcar,S. Lin-Gibson (National Institute of Standards andTechnology), G Schmidt (Louisiana State University)

The shear-orientation, structure and morphology ofviscoelastic polymer-clay networks is investigated onseveral length scales by means of rheology, micros-copy and small-angle neutron scattering (SANS,USANS).

MP11: A Method to Predict Small-angle NeutronScattering Intensities of Nucleic Acids from High-resolution Structures

J. Zhou (Department. of Chemistry, UMBC,Baltimore, MD), S. Krueger (NIST Center forNeutron Research), S Gregurick (Department ofChemistry, UMBC, Baltimore, MD)

Based on the original program, Xtal2SAS, which

calculates model SANS intensities of proteins fromhigh-resolution structures, we propose a method toobtain model SANS intensities from nucleic acids. Fora high-resolution structure of a nucleic acid, eitherfrom x-ray crystallography or structural prediction,we generate an ellipsoidal cylinder model for eachnucleotide with calculated radii, length and volumefrom the coordinates file, e. g., a PDB file. Eachellipsoidal cylinder is filled with random points of theappropriate neutron scattering length density using aMonte Carlo method, and is superimposed on eachnucleotide to represent the overall structure of thenucleic acid. The distance distribution function, P(r) iscalculated by summing all possible pairs of points inthe structure. Then, the scattering intensity I(Q) isthen calculated through a Fourier transform of P(r).We extend the original program, Xtal2SAS, for bothproteins and nucleic acids, and we test our approachon a few examples of nucleic acids to check theeffectiveness of this method.

MP12: Solvent Induced Stiffness in Poly(ethyleneoxide)

M.L. Alessi (University of Maryland, Department ofChemical Engineering), D.L. Ho (NIST Center forNeutron Research), S.C. Greer (University ofMaryland, Department of Chemical Engineering;Department of Chemistry and Biochemistry)

Poly(ethylene oxide) (PEO) is a simple polymer withrepeating units [- C - C - O -] soluble in organic andaqueous solvents. In all solvents in which PEO haspreviously been studied, the PEO molecule forms acoil in solution. Small-angle neutron scattering ofPEO in deuterated isobutyric acid shows a dramaticstiffening of the polymer chains, resembling a rod.Infrared spectroscopy and polarimetry measure-ments indicate that the rods are helical. PEO hasbeen seen to form a helix in the solid phase and alocal helical structure in aqueous solvents. A globalhelical conformation, however, has not been seenbefore in solution. The formation of nanoscale PEOrods may have applications in nanotechnology.

MP13: The effect of graft density and length on thesurface segregation of graft copolymers in ahomopolymer matrix.

M. A. Lay (University of Tennessee, Knoxville), M.D. Dadmun (University of Tennessee, Knoxville)

The effect of graft density and length on the surfacesegregation of graft copolymers in a homopolymermatrix.

Copolymers may be used to modify polymer inter-faces in polymer blends. Copolymer architectureplays a substantive role in the ability of copolymers


to migrate to an interface. We have recently exam-ined the diffusion of various graft copolymers in aneffort to determine to what extent graft density andlength affect surface segregation. Copolymerscomposed of a PS backbone and PMMA graft seg-ments were prepared via ATRP. Interfacial broaden-ing was studied as a function of annealing time, sothat a diffusion coefficient could be determined. Thisinsight into the architectural influence on surfacesegregation will help us better understand practicalprocesses dependent upon diffusion such as adhe-sion, interface formation, and phase separation.

MP14: Experimental Studies and Modeling of Clay/PolyDicyclopentadiene Resin and CarbonNanofiber/Phenolic Resin Composites

Mitra Yoonessi, Hossein Toghiani (Dave C. SwalmSchool of Chemical Engineering, Mississippi StateUniversity), Charles Pittman, Jr. (Department ofChemistry, Mississippi State University)

Hybrid organic-inorganic nanocomposites havereceived much attention by the researchers duringthe last five years due to their unexpected properties.A large number of different inorganic materials havebeen used to enhance matrix properties.

This work incorporated two types of nanophases,Montmorillonite clay and Carbon nanofibers (CNF)into polyDicyclopentadiene and phenolic resinmatrices. Montmorillonite has a 2:1 structure consist-ing of an alumina octahedral layer sandwichedbetween two silica tetrahedral layers. The crystallinestructure is continuous in the a and b directions, butstacked in the c direction. Carbon nanofibers arerelatively inexpensive reinforcing agents composedof an inner filament made of highly graphitic carbonsheets packed as concentric cones which are alignedat a highly oblique angle along the fiber axis. Theinner filament is covered with a turbostratic CVDcarbon outer layer.

Clay nanocomposites were synthesized by stirringand sonication of organically modified clay intoDicyclopentadiene monomer, which caused expan-sion and further delamination of clay nanolayers (Insitu polymerization). Highly delaminated compositeswere examined using x-ray diffraction, x-ray scatter-ing and high resolution TEM. Composites with 0.5-1weight percentage of clay showed improvements inTg and flexural modulus. These composites were alsostudied using small angle neutron scattering (SANS)and ultra small angle neutron scattering (USANS).The slopes of scattering intensities, I(q), versus wavevector, q, were in the range of –2.5 to –2.7. Thescattering intensities were fitted to the stacked disk

model. The resulting data were compared with HR-TEM analysis.

Carbon nanofibers (PR-19-HT) were dispersed withina resole phenolic resin, Hitco 134A to prepare CNF/phenolic nanocomposites. A solvent processingmethod was used to disperse 1-4 wt % CNF/phenolicresin composites. The viscoelastic properties of thesecomposite were studied by DMTA. These showedimproved glass transition temperatures with in-creases in CNF weight percent up to 4 wt %. Thebending storage modulus below Tg was improved forall composites (1-4 wt %) relative to pure resincontrol samples. A major improvement in E’ wasobserved at temperatures above the Tg, where thestorage bending modulus stayed high up to ~ 300 oC.Improvements in the CNF dispersion were studied byTEM. Better dispersions and surface wetting of thefibers were observed. TEM studies showed that fibershad diameters in the range of 50-100 nm and lengthin the range of 1-2 microns. Nanocomposites con-taining low weight percentages of CNF’s (0.1-1 wt %)were further studied using SANS and USANS. Whenplotted on a logarithmic scale, the slope of thescattering intensities from particles as a function ofwave vector, q, was in the range of –2.9 to -3 for thelow q range. In the high q range, 0.015-0.07 Å-1, theslopes were increased with increasing CNF concen-trations.

MP15: On the Structure of Liquid Hydrogen Fluo-ride

S. E. McLain (The University of Tennessee,Department of Chemistry; Intense Pulsed NeutronSource, Argonne National Lab), C. J. Benmore, J. E.Siewenie (Intense Pulsed Neutron Source, ArgonneNational Lab), J. F. C. Turner (The University ofTennessee, Department of Chemistry; NeutronScience Constortium)

An experimental determination of the partial struc-ture factors for liquid hydrogen fluoride has been indemand from theorists for more than two decades.However this is not a straightforward task, given theinherent difficulty of sample containment due to thechemically aggressive nature of the material. Wepresent the first experimental determination of thepartial structure factors SHH(Q), SHF(Q) and SFF(Q) forliquid hydrogen fluoride at 296 ± 2 K and 1.2 ± 0.2bar. This was accomplished by using a combinationof isotopic substitution in neutron diffraction andhigh energy x-ray diffraction methods. Experimentswere performed in custom built Alloy 400 cells.Despite the dearth of detailed experimental informa-tion, the structure of HF in the liquid state has beenwidely simulated using a variety of inter-atomic


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potentials, as well as ab initio and quantum mechani-cal methods. The predictions range from the liquidbeing comprised of chains to clustering in the liquidstate. Experimentally, the structure of the liquid isfound to be composed of short, hydrogen-boundchains as evidenced by the hydrogen-fluorine partialcorrelation function. The results also show stronginter-chain interactions in the fluorine-fluorine partialradial distribution function. Reverse Monte Carlomodeling and coordination number analyses bothindicate the existence of long winding chains withvery little branching. The neutron diffraction datawere collected on the Glass Liquids and Amorphousmaterials Diffractometer located at Intense PulsedNeutron Source located and the high energy x-raydiffraction data were collect at the 11-IDC beam lineon the BESSRC-CAT at the Advanced Photon Source,both located at Argonne National Laboratory.

MP16: Application of Double CrystalDiffractometers for the Tomographic Reconstruc-tion of Macroscopic Structures

M. Strobl, W. Treimer (University of AppliedSciences (TFH) Berlin; Hahn-Meitner-InstitutBerlin), A. Hilger (Hahn-Meitner-Institut Berlin)

Double crystal diffractometers (DCD) conventionallyare applied for small angle scattering investigationsin the ultra small angle range. In the case of neutrons(USANS) the q-range (app. 10-4-10-1nm-1) overlapsand exceeds the range of small angle neutronscattering (SANS) experiments and enables thecharacterisation of structures with sizes up to some10 µm. It can be shown that such a high angular(momentum) resolution achieved by two perfectsingle crystals provides the possibility to investigatemacroscopic structures in a range (in real space)between approximately 100 µm up to several cm aswell. Smallest beam deviations caused by refractioni.e., by phase gradients can be recorded. Combinedwith tomographic methods which means recordingsuch data under several projection angles the macro-scopic inner structure of test objects could be recon-structed with respect to different interactions withinthe sample. From the angular intensity distributionsrecorded in the DCD (stemming from defined beampaths) three sets of parameters could be deduced.The conventional parameter for tomographic imag-ing, the beam attenuation could be defined as well asa refraction and a USANS parameter. From each ofthem an independent reconstruction of the samplecould be achieved containing redundant and/orcomplimentary (additional) (image) informationabout the sample. While the reconstruction from thebeam attenuation parameter provides an image interms of the attenuation coefficients, the refraction

parameter enables to reconstruct in terms of refrac-tive index and the USANS parameter images areas ofdifferent scattering behaviour (different microscopicstructure). The contrast behaviour is therefore notonly dependent on the sample attenuation anymoreas two more contrast methods could be introduced.Several examples will be given

MP17: A Resonance Detector Technique Opti-mized for Inelastic Neutron Scattering Studies atthe eV Energies in Condensed Matter

C. Andreani (Università degli Studi di Roma “TorVergata”, Physics Department, Via della RicercaScientifica 1,00133 Italy; Istituto Nazionale per laFisica della Materia), G. Gorini, E. Perelli-Cippo(Università degli Studi di Milano-Bicocca,Dipartimento di Fisica; Istituto Nazionale per laFisica della Materia), A. Pietropaolo (IstitutoNazionale per la Fisica della Materia; Universitàdegli Studi di Roma “Tor Vergata”, PhysicsDepartment, Via della Ricerca Scientifica 1,00133Italy), M. Tardocchi (Istituto Nazionale per la Fisicadella Materia; Università degli Studi di Milano-Bicocca, Dipartimento di Fisica), E. M. Schooneveld(ISIS, Rutherford Appleton Laboratory), R. Senesi(Istituto Nazionale per la Fisica della Materia;Università degli Studi di Roma “Tor Vergata”,Physics Department, Via della Ricerca Scientifica1,00133 Italy), N. Rhodes (ISIS, RutherfordAppleton Laboratory)

The talk will address a novel experimental neutronscattering technique (Resonance Detector Tech-nique-RDT) suited for the study of high energyexcitations in condensed matter. The technique isintended for neutron scattering experiments at verylow angle scattering angle (1° < 2θ < 5°) on aninverse geometry instrument. It allows to performHigh energy Inelastic Neutron Scattering (HINS)experiments in an extended (kinematical unlimited)energies transfer, i.e., ω < 300 meV, coupled to lowmomentum transfer, i.e. in range 3 Å-1 < q < 10 Å-1.The RDT exploits a novel concepts for the detectionof scattered neutrons at the eV energies, i.e., reso-nance radiative neutron capture for energy analysis.The detection system consists of scintillator detec-tors which are used to reveal the prompt γ radiationcascade emitted by an absorbing foil after resonancecapture. The analyser foil is used as monochromator,to fix energy of neutron after scattering with thesample. The RDT principles will be revisited ascompared to RFT (Resonance Foil Technique).

Systematic experimental work performed onVESUVIO in RDT configuration using NaI(Tl) and YAPscintillators as well as CZTe solid state detectors, will


be presented. The all set of detector devices wereused coupled to a 238U analyser foils and experimentsfrom a standard Pb samples and results compared tothat measured in the standard RFS configuration.

Results from a series of HINS experiments, off iceand water, performed on the VESUVIO spectrometeroperating at the ISIS pulsed neutron source, will bediscussed. The instrument was specifically sets up inthe Resonance Detector Spectrometer (RDS) configu-ration. These results well compared with previousbest available results on the same system obtainedthrough an Inelastic Neutron Scattering on a directgeometry instrument. In the case of ice the hydrogenprojected density of states has been successfullyderived. In water experimental results include themean kinetic energy in water. As in previous exampleon ice, a satisfactory agreement is found with valuesof <Ek> available from previous experiments.

Future development of this technique will be dis-cussed, new areas of experimental research envis-aged. These include energy excitations in condensedmatter systems: dispersion relations of high energyexcitations in metals, semiconductors and insulators,high lying molecular rotational-vibrational states,molecular electronic excitations and electronic levelin solids.

MP18: Search for Time-Reversal Violation inNeutron Beta Decay

H.P. Mumm (University of Washington), L.J.Broussard (Tulane University), T.E. Chupp, R.L.Cooper, K.P. Coulter (University of Michigan), M.S.Dewey (National Institute of Standards andTechnology), S.J. Freedman, B.K. Fujikawa(University of California-Berkeley/LBNL), A. Garcia(University of Washington), S.R. Hwang (Universityof Michigan), G.L. Jones (Hamilton College), L.J.Lising (University of California-Berkeley/LBNL), J.S.Nico (National Institute of Standards andTechnology), R.G.H. Robertson (University ofWashington), A.K. Thompson (National Institute ofStandards and Technology), C. Trull, F.E. Wietfeldt(Tulane University), J.F. Wilkerson (University ofWashington)

The emiT experiment tests time-reversal symmetryin the beta decay of polarized free neutrons bysearching for the triple correlation Dσ•pe×pp, whereσ is the neutron spin and pe and pp are the decayproduct momenta for the electron and proton,respectively. A nonzero D-coefficient above the smalleffect from final state interactions would be a signalof direct time reversal symmetry (T) violation,independent of charge conjugation-parity (CP)

violation. Various extensions to the Standard Model,such as lepto-quarks and left-right symmetry, cangive rise to a D-coefficient yet do not generatemeasurable electric dipole moments. Consequently, itis important to place the strongest possible limits inneutron decay. In December of 2003 the emiTcollaboration completed a successful data run atNIST. In this run, more than 3x108 neutron decayswere measured, and a signal-to-background ratio ofapproximately 100:1 was obtained. Analysis of thedata is underway, and the collaboration is optimisticthat an improved limit on the D-coefficient will beachieved. Along with a discussion of theoreticalmotivation and the experimental technique, thestatus of the analysis and studies of systematicuncertainties will be presented. This work is sup-ported by DOE, NSF, and NIST.

MP19: Structure and dynamics of Inorganicnanoparticles templated by soft copolymer cubicstructures

D.C. Pozzo, L.M. Walker (Department of ChemicalEngineering, Center for Complex FluidsEngineering, Carnegie Mellon University, PittsburghPA)

The design of nanometer scale inorganic-organiccomposites is one of the most exiting areas ofmaterial science and engineering. Particular attentionis given to structured materials whose order arises atthe molecular level but persists over macroscopiclength scales. This is driven by the potential thatthese new materials have in the development ofoptics, electronics, catalysts, biotechnology devicesand in manufacturing materials. Theoretical ap-proaches demonstrate the phase richness ofnanoparticles embedded in amphiphilic copolymermesophases, but there is a lack of systematic experi-mental studies that characterize the influence ofinorganic fillers on the 3D organized structures. Weare utilizing water-soluble triblock copolymers (PEO-PPO-PEO) to provide thermoreversible micellar-cubictemplates with typical dimensions of tens of nanom-eters. Using rheology and small-angle neutronscattering (SANS), we characterize the influence ofthe addition of inorganic nanoparticles (of similardimensions to the block copolymer micelles) on themacroscopic sample properties and on the localstructure. Using contrast matching techniques wedemonstrate that the template approach is feasible asreasonable quantities of hydrophilic inorganicnanoparticles are incorporated into the block copoly-mer mesosphere without destroying the structure. Itis also found that the cubic structure is transmitted tothe silica particles and that the level of templating isdependent on a number of variables. We quantify the


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results by studying the influence of relative concen-tration, relative dimensions and surface chemistry ofthe inorganic particles. Additionally, using dynamiclight scattering (DLS) and contrast-matched neutronspin echo (NSE) experiments we individually studythe complex motions of the various components thatmake up the composite materials. Furthermore theability to alter these structures using a variety ofexternal parameters including shear and temperaturemake these materials of considerable interest asprocessable templates for inorganic-organicnanocomposites.

MP20: New structural model for Nafion® mem-branes and Study of proton dynamics

O. Diat (UMR 5819 SPrAM CEA Grenoble 17 Av desMartyrs, 38054 Grenoble cedex 9 France), L.Rubatat (UMR 5819 SPrAM CEA Grenoble 17 Av desMartyrs, 38054 Grenoble cedex 9 France;Department of Physics, Simon Fraser University,Burnaby, Canada)

A global understanding of the ionomer Nafion®membrane structure, a benchmark system, from theÅngström up to the micrometer in relation with thetransport properties, is essential for the optimisationof H2/O2 fuel cell system.

We propose a new fibrillar structural model, based onpolymeric chains aggregation in elongated objects,decorated with charges to explain i) the swellingprocess from the dry membrane to colloidal suspen-sion, ii) the birefringence properties, iii) and themechanical degradation in fuel cell operation. Byusing small angles scattering techniques (x-rays &neutrons) and microscopy (AFM & TEM), we havestudied the polymer arrangement in bundles over alarge range of scale and water content. Drawingexperiments have permitted to confirm our model.The main characteristic of the material being toexhibit a hierarchical multi-scale structure, fromnanometric aggregates to micronic domains ofvarying densities, the relaxation times associated tothe proton dynamics in these systems are expectedto range from the pico-second (local jump) to fewtenths of seconds (macroscopic conductivity).

We have started a complete study of the protondynamics with various complementary techniques, inorder to couple these results to the knowledge thatwe have now on the structure. Quasi-elastic neutronscattering studies allowed to measure correlations atvery short times (pico-second) and gradient field-pulsed NMR allows to measure macroscopic diffusioncoefficients in the range of few milliseconds to fewseconds. Intermediary region in between is directlyaccessible by the field cycling NMR relaxometry

technique. Our paper is more especially dedicated tothe interest of “neutron” tools in using contrastvariation method for SANS and QENS.

A.L. Rollet et al., J. Phys. Chem B 106(12), (2002)3033-3036.L.R. Rubatat et al., Macromolecules 35(10), (2002)4050-4055.L. Rubatat et al. under submission to Macromol-ecules;P. van der Heijden et al. submitted to Macromol-ecules.

MP21: Highly Stable Phospholipid UnilamellarVesicles from Spontaneous Vesiculation: A DLS andSANS Study

B. Yue, C-Y. Huang (Chemical Engineering Dept.NJIT), M-P. Nieh (National Research Council, ChalkRiver, Ontario, Canada), C. J. Glinka (NationalInstitute of Standards and Technology), J. Katsaras(National Research Council, Chalk River, Ontario,Canada)

Spontaneously formed unilamellar vesicles (ULVs)composed of short- and long-chain phospholipids,dihexanoyl (DHPC) and dimyristoylphosphorylcholine (DMPC) mixtures doped withnegatively charged dimyristoyl phosphorylglycerol(DMPG) were studied by small angle neutron scatter-ing (SANS) and dynamic light scattering (DLS). Vesicleformation was found to follow a quick bicelle-to-vesicle transition mechanism. The SANS and DLSdata showed that ULVs with narrow size distributionwere highly stable at low lipid concentrations,Clp<0.50 wt.%, and salt concentrations (Cs). ULV sizewas found independent of both Clp and Cs, when theywere below 0.33 wt.% and 0.5 wt.% respectively.Surface charge is found to be an important factor forstabilizing ULVs with a constant size. This observationis not in total agreement with most previous experi-mental results and cannot be completely explainedwith previous theoretical predications based onequilibrium calculations for catanionic surfactantmixtures. The size of ULVs was almost constant overa wide temperature range below and above thephase transition temperature of DMPC, TM, formonths, even after sonication.

MP22: Suppression of Dewetting in PolystyreneThin Films by Polymer Nanoparticles

H. Feng, R. M. Briber (Department of MaterialsScience and Engineering, University of Maryland),V. Y. Lee, R. D. Miller, Ho-Ch Kim (IBM AlmadenResearch Center, 650 Harry Road, San Jose CA95120-6099)

The influence of nanoparticles based on star poly-mers on the dewetting of spun-cast linear polysty-


rene (PS) films is investigated as a function oftemperature. The star polymers have polystyrene-benzocyclobutene copolymer arms which canundergo intra-molecular crosslinking to form morecompact nanoparticles. The addition of a smallamount of nanoparticles (either the uncrosslinkedstar polymer or the intra-molecular crosslinkedpolymer) to the linear PS leads to inhibition ofdewetting in thin (30 nm) films on silicon wafersubstrates at 175°C. The different dewetting behaviorbetween films containing the uncrosslinked starpolymers or the crosslinked nanoparticles suggeststhat the system has the potential for tunabledewetting behavior, depending on the specifics of thestar molecules. Neutron reflection (NR) measure-ments indicate there is an enrichment ofnanoparticles at the polymer-silicon interface in as-cast PS films, and this segregation may be related tothe suppression of dewetting in PS films bynanoparticles. Small angle neutron scattering datashows bulk PS are miscible with 5 wt% ofnanoparticles over the temperature range of 23 °C to175 °C, implying that the segregation is not due tothe immiscibility of PS and nanoparticles.

MP23: Effect of Molecular Architecture on the PoreStructure of NanoporousPoly(methylsilsesquioxane) Thin Films

Z. Lin, R. M. Briber (Department of MaterialsScience and Engineering, University of Maryland),H. C. Kim, W. Volksen, R. D. Miller (IBM AlmadenResearch Center, 650 Harry Road, San Jose CA95120-6099)

Thin films of poly(methylsilsesquioxane) (PMSSQ)containing nanoscopic pores are one of promisingmaterials for ultra low dielectric constant intercon-nect material in next generation microchips. A viableroute to nanoporous PMSSQ films is using the phaseseparation between matrix PMSSQ and organicpolymers (porogen) with subsequent degradation ofthe porogen at high temperature. Previous studiesshow the pore size and morphology depend on theinteraction between PMSSQ and porogen, moleculararchitecture and amount of porogen. In this study, weexamine the effect of porogen molecular architectureon the phase behavior and final pore morphology ofnanoporous PMSSQ using small angle neutronscattering (SANS), neutron reflectivity (NR) andtransmission electron microscopy (TEM). A linear anda star shaped polymer were used as porogens. SANSexperiments were performed as a function of tem-perature. TEM was used to confirm the pore mor-phologies. Depth profiles of pore distribution ob-tained by neutron NR will be also addressed.

MP24: Characterization of Arborescent GraftPolystyrene Molecules by Small Angle NeutronScattering

Kai-Chi Lai, Robert M. Briber (Department ofMaterials Science and Engineering, University ofMaryland), Mario Gauthier (Department ofChemistry, Institute for Polymer Research,University of Waterloo, Waterloo, Ontario N2L 3G1,Canada), Seok-Il Yun (Condensed Matter SciencesDivision, Oak Ridge National Laboratory)

Arborescent graft polymers (AGP) are polymersresulting from successive cycles of randomfunctionalization and subsequent end-grafting ofanionic polymerized chains to form a highlybranched polymer molecule. Small Angle NeutronScattering (SANS) was used to characterize the sizeand shape of generation 3 and generation 4 polysty-rene (PS) based arborescent graft polymers wherethe final generation of the polymer molecule wascomposed of deuterated PS. Contrast variationtechniques were used to match the solvent to theeither the PS core or the deuterated PS shell. A core-shell model was used to fit the SANS data with goodsuccess but the scattering length density of the coreand shell were found to deviate from that of pure PSand deuterated PS respectively leading to the conclu-sion that there is some phase mixing between thefinal generation and the underlying polymer sub-strate molecule. This is consistent with the randomfunctionalization of substrate prior to end-grafting thefinal generation.

MP25: Water Mobility in Small Aerosol-OT ReverseMicelles

M. R. Harpham, N. E. Levinger, B. M. Ladanyi(Colorado State University), K. W. Herwig (OakRidge National Laboratory)

Reverse micelles (RMs) are nanoscale droplets ofpolar solvent surrounded by a surfactant layer innonpolar solvents. We have used quasielastic neutronscattering (QENS) to investigate the mobility of watermolecules in small reverse micelles consisting ofwater/deuterated AOT/perdeuterated isooctane.Water/surfactant ratios of 1, 2.5, and 5 have beeninvestigated using the QENS spectrometer atArgonne National Laboratory, IPNS division. Thisexperimental data is reasonably well-fit by a jump-diffusion/isotropic rotation model, and gives diffusionconstants that increase with w0 and rotationalcorrelation times that decrease with w0. Computersimulations of reverse micelles of these water/surfactant ratios have been performed and used topredict QENS spectra to further investigate thedynamics of the water and make comparisons toexperimental data. A Fourier transform of the


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simulation data convolved with the experimentalinstrument resolution function compares favorably tothe experimental data. The simulations indicate thatthe dynamics of water is slower near the interfacethan at the core, and slower for small RMs than forlarge RM’s. A mode coupling theory (MCT) analysis ofthe translational intermediate scattering function wasperformed. Results from this analysis indicate highlynonexponential behavior, and relaxation times thatdecrease as w0 increases.

MP26: Nucleation of Phase Separation in PolymerBlends

T.J. Rappl (Department of Chemical Engineering,University of California, Berkeley), N.P. Balsara(Department of Chemical Engineering, University ofCalifornia, Berkeley; Material Sciences Division,and Environmental Energies Technology, LawrenceBerkeley National Laboratory)

The work presented is intended to supplement thematerial covered in the talk given by Nitash Balsaraconcerning nucleation of phase separation in poly-mer blends. In this work, neutron scattering wasemployed to investigate the nature of the structuresformed during the onset of homogeneous nucleation,specifically, how the critical nucleus size varies withquench depth. Time-resolved small angle neutronscattering profiles were obtained from off-criticalblends within the metastable regime of the phasediagram, revealing that the critical nucleus sizedecreases with increasing quench depth; this contra-dicts the theoretical prediction of Cahn and Hilliardthat the critical nucleus size should diverge at thespinodal. Recent simulations (Chandler) of nucleationin the 3D Ising model are in agreement with ourexperimental data.

Additionally, within the metastable regime of a givenblend we observed a line of demarcation belowwhich phase separation could not be observed duringexperimental time scales via a direct quench. Thisline of demarcation corresponds well with thepseudospinodal, or limit of metastability, proposed byZ.-G. Wang. A series of double quench experimentswere performed, wherein the system was studiedconsecutively at two separate locations within themetastable regime. A comprehensive comparison ofthe results obtained from direct quench and doublequench experiments will be presented. Of note, thisdouble quench method permitted the study ofnucleation below the limit of metastability and alsorevealed the dissolution of small structures (createdwhile aging below the limit of stability) upon thereduction of quench depth. This dissolution of smallstructures lends credibility to our notion of the critical

nucleus size as measured by time-resolved smallangle neutron scattering.

MP27: Size and shape of mixed micelles of non-ionic surfactants: puzzles and resolution

R. Zhang, P. Somasundaran (Columbia University),C. Glinka, B. Hammouda (NIST Center for NeutronResearch), P. Cummins (Estee Lauder), Q. Zhou(Columbia University)

Mixed surfactants are of considerable interestbecause of synergy in surface activity which dependson compatible molecular interactions. In this regard,in order to develop molecular structure-propertyrelationships that control relevant colloidal phenom-enon in mixed surfactant systems and to developpredictive theoretical models based on such relation-ships, it is necessary to acquire quantitative informa-tion on size and shape of micelles in these complexsystems. Micellar shape has been correlated in thiswork with packing parameter for mixing and surfac-tant molecular structures in dilute solutions of binarynonionic polyethylene oxide nonyl phenolethoxylated decyl ether (NP-10) / nonionic sugar-based n-dodecyl-β-D-maltoside (DM) system using amulti-pronged approach. The packing results suggestthat micelles undergo a sphere to cylinder transitionwith an increase in DM percentage. However, experi-mental results from SANS (small angle neutronscattering) along with those from analytical ultracen-trifuge, cryo-TEM, FT-PGSE (pulsed gradient spinecho)-NMR contradict this prediction. By comparingthe energy changes due to packing using molecularmodeling, NP-10 is found to prefer to form closepacked geometry in water. In order to account forthese effects, we modify the packing parameter bytaking molecular conformation and mixing intoconsideration.

MP28: Rheo-SANS microstructure investigations ofconcentrated anisotropic particle dispersions nearthe shear thickening transition

R. G. Egres, N. J. Wagner (Department of ChemicalEngineering, University of Delaware, Newark, DE19716), L. Porcar, B. S. Greenwald (NIST Center forNeutron Research; University of Maryland, CollegePark)

An experimental Rheo-SANS configuration withrheologically accurate quartz shear cell is describedand validated using a rheometer in the NG7 SANSbeamline at NIST. Rheo-SANS experiments wereperformed on concentrated dispersions of anisotropicparticles exhibiting shear thickening behavior as ameans of exploring microstructure evolution duringshear flow. Concentrated dispersions of anisotropicparticles exhibiting shear thickening behavior are


ubiquitous in industry, yet little has been done toinvestigate the microstructure of these dispersionsduring flow in order to obtain a mechanistic under-standing of this observed rheological behavior. Ourresearch involves rheological and microstucturalinvestigations of stable polyethylene glycol baseddispersions of acicular precipitated calcium carbonate(PCC) particles having three average particle aspectratios. Rheological measurements performed onthese dispersions demonstrate that increased particleaspect ratio results in extensive (discontinuous) shearthickening behavior at lower particle volume frac-tions. Small angle neutron scattering measurementshave been used to determine particle geometry andmicrostructure as a function of concentration andaspect ratio. Rheo-SANS experiments show a signifi-cant degree of particle alignment with flow directionat low to moderate shear rates. Surprisingly, thisalignment is maintained at the higher stressesassociated with shear thickening. These observationsinvalidate earlier hypothesis suggesting that the shearthickening observed in anisotropic particle disper-sions was the result of particle rotations out of flowalignment leading to particle jamming. Rather, theRheo-SANS measurements support the hydroclustermechanism of shear thickening known for sphericalparticle dispersions.

MP29: De-Convoluting the Influences of PlasticDeformation and Heat on Residual Stresses duringFriction Stir Welding of 6061-T6 Aluminum Plates

W. Woo (Material Science and EngineeringDepartment, University of Tennessee, Knoxville, TN37996, USA), H. Choo (Material Science andEngineering Department, University of Tennessee,Knoxville, TN 37996, USA; Metals and CeramicsDivision, Oak Ridge National Laboratory), D. W.Brown (Materials Science and Technology Division,Los Alamos National Laboratory, Los Alamos, NM87545, USA), Z. Feng (Metals and CeramicsDivision, Oak Ridge National Laboratory), P. K Liaw(Material Science and Engineering Department,University of Tennessee, Knoxville, TN 37996, USA),S. A. David, C. R. Hubbard (Metals and CeramicsDivision, Oak Ridge National Laboratory)

Friction-stir welding (FSW) is a solid-state joiningprocess that makes a strong metallurgical bondingthrough (1) a severe plastic deformation caused byrotation of a stirring pin and (2) frictional heatgenerated from pressing shoulder. However, thedeformation and heat necessary for the joining arealso the major sources of residual stresses in thewelds, which are detrimental to the integrity of thejoined component.Three different weld specimens were prepared from

6061-T6 Aluminum plates: (Case 1) a plate processedonly with pin, (Case 2) a plate processed only withthe pressing shoulder, and (Case 3) a plate processedwith both stirring pin and the pressing shoulder, i.e.,a regular friction-stir weld. The longitudinal, trans-verse, and through-thickness strain components weremeasured across the weld line using neutron diffrac-tion and converted to stresses. The comparisonamong the three cases shows distinctly differentresidual-stress profiles clearly revealing de-convolutedeffects from the different welding parameters, i.e.,deformation, heat, or the combination, for the firsttime. The relationships between the welding param-eters and residual stresses will be discussed toprovide a phenomenological understanding of themicro-mechanism of the residual stress formationduring the FSW.

Acknowledgements: This work benefited from the useof the Los Alamos Neutron Science Center (LANSCE)at the Los Alamos National Laboratory. This facility isfunded by the US Department of Energy underContract W-7405-ENG-36. This work is supported bythe NSF International Materials Institutes programunder DMR-0231320.

MP30: Effect of Internal Stress on Hydride Forma-tion in a Hydrogen-Charged Zircoly-4

E. Garlea (Department of Materials Science andEngineering, The University of Tennessee,Knoxville, TN 37996, USA.), H. Choo (Department ofMaterials Science and Engineering, The Universityof Tennessee, Knoxville, TN 37996, USA.; Metalsand Ceramics Division, Oak Ridge NationalLaboratory), D. W. Brown (Los Alamos NationalLaboratory), S. Park, L. L. Daemen (Los AlamosNeutron Science Center, Los Alamos NationalLaboratory), B. Yang, M. M. Morrison, R. A.Buchanan, P. K. Liaw (Department of MaterialsScience and Engineering, The University ofTennessee, Knoxville, TN 37996, USA.), C. R.Hubbard (Metals and Ceramics Division, Oak RidgeNational Laboratory), H. F. Letzring (Pretreatmentand Specialty Products, PPG Industries, Troy, MI48083)

Hydride formation is one of the main degradationsources of zirconium alloys in hydrogen-rich environ-ments. When sufficient hydrogen is available in thesealloys, zirconium-hydride precipitates can be formed.Cracking of the brittle hydrides near a crack tip caninitiate crack growth between hydrides leading topremature failure of the material. Hydride formationis believed to be enhanced by the presence ofresidual or applied stresses. Therefore, the increase instress field ahead of a crack tip may promote precipi-


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tation of additional hydrides. In order to verify this,we investigated the effect of internal stresses onzirconium-hydride-precipitate formation in a zircaloy-4 alloy using neutron and x-ray diffraction.

First, spatially-resolved internal strain measurementswere made on a fatigue pre-cracked compact-tension(CT) specimen using in situ neutron diffraction underapplied loads of 667 and 4,444 newtons. The resultsprovided a basic understanding of the strain profilesnear the crack tip. Second, hydride formation wasinvestigated using two different specimens: (1) a CTspecimen with a fatigue pre-crack, hence with a built-in internal stress and (2) the same CT specimen butwithout the pre-crack. The two specimens wereelectrochemically charged with hydrogen under thesame conditions x-ray diffraction results clearlyshowed that the pre-cracked specimen developedhigher hydride fractions suggesting that the enhancedhydride formation was due to the presence of theinternal stress. Finally, the profile of internal strainsin the hydrogen-charged specimen was measuredusing neutron diffraction to provide an understandingof the effect of hydride on the strain profile near thecrack tip in comparison to the strain data measuredfrom a CT specimen before the hydrogenation.

Acknowledgements: This work benefited from the useof the Los Alamos Neutron Science Center (LANSCE)at the Los Alamos National Laboratory. This facility isfunded by the US Department of Energy underContract W-7405-ENG-36. The authors are grateful tothe National Science Foundation InternationalMaterials Institutes Program (DMR-0231320), Integra-tive Graduate Education and Research TrainingProgram (DGE-9987548), the NSF Combined Re-search and Curriculum Development Programs (EEC-9527527 and EEC-0203415), and Tennessee Ad-vanced Material Laboratory Fellowship Program,managed by Drs. C. Huber, W Jennings, L. Goldberg,M. Poats, and Dr. W. Plummer, respectively.

MP31: Residual Strain Distribution around LudersBands

Y. Sun, B. Yang, T. A Saleh, B. L. Benson, P. K. Liaw(Department of Materials Science and Engineering,The University of Tennessee, Knoxville, TN 37996,USA.), H. Choo (Department of Materials Scienceand Engineering, The University of Tennessee,Knoxville, TN 37996, USA.; Metals and CeramicsDivision, Oak Ridge National Laboratory), M. R.Daymond (ISIS, Rutherford Appleton Laboratory), J.Y. Huang, R. C. Kuo (Institute of Nuclear EnergyResearch (INER), P. O. Box 3-14, 1000 WenhuaRoad, Chiaan Village, Lungtan, Taiwan 325,

Republic of China), J. G. Huang (Taiwan PowerCompany, Taipei, Taiwan)

Lüders bands often indicate the onset of the plasticdeformation at the vicinity of stress concentrationsand inclusions, which may contribute to the crackinitiations. Investigating the evolution process ofLüders bands will help understand the early stages ofthe mechanical damage behaviors. In the currentresearch, Lüders bands have been developed on theplate samples of reactor pressure vessel (RPV) steelduring fatigue tests. In situ thermography detectiontechnique has been applied to control the amount ofplastic deformation created by the Lüders bands. Twospecimens with different amount of plastic deforma-tion (with plastic strains of 1.25% and 1.83%) wereprepared. Residual-strain distributions inside andoutside the Lüders bands have been measured byneutron diffraction technique in various directionsusing ENGIN-X instrument at the ISIS Facility. Insidethe Lüders bands, compression residual strain hasbeen detected in the gauge-length direction, whiletensile residual strain has been detected in the gauge-width direction. Outside the Lüders bands, theresidual strains were close to zero. Based on theneutron results, theoretical models to provide betterunderstanding of the Lüders-bands evolution pro-cesses have been attempted.

Acknowledgement: We would like to give thanks to (1)The National Science Foundation (NSF) InternationalMaterials Institutes (IMI) Program, Under DMR-0231320. (2) Combined Research-Curriculum Devel-opment (CRCD) Program, under EEC-9527527 andEEC-0203415. (3) The Integrative Graduate Educationand Research Training (IGERT) Program, under DGE-9987548, with Dr. C. Huber, Ms. M. Poats, Dr. W.Jennings and Dr. L. Goldberg, as the contract moni-tors, respectively. (4) Mr. D. Fielden who machinedthe samples and grips for us.

MP32: Development of Internal Strains During theFatigue of Haynes 230 Nickel Based Superalloy

T. A. Saleh, M. L. Benson (Department of MaterialsScience and Engineering, The University ofTennessee, Knoxville, TN 37996, USA.), H. Choo(Department of Materials Science and Engineering,University of Tennessee, Knoxville, TN 37996, USA.;Metals and Ceramics Division, Oak Ridge NationalLaboratory), D. W. Brown (Los Alamos NeutronScience Center, Los Alamos National Laboratory),P.K. Liaw, R. A. Buchanan (Department of MaterialsScience and Engineering, University of Tennessee,Knoxville, TN 37996, USA.), D. L . Klarstrom(Haynes International, Inc., Kokomo, IN 46904,USA.), D.G. Park (Korea Atomic Energy Research


Institute, Yuseong P.O. Box 105, Daejeon, 305-600,Korea)

Haynes 230 is a solid solution strengthened, FCC,nickel based superalloy. This alloy is commonly usedin flying and land-based turbines, and in other fatigueintensive applications. In situ neutron diffraction wasused to investigate the behavior of internal strains inthis alloy under both strain-controlled tension/compression, and stress-controlled tension/tensionfatigue conditions. Experiments took place at theSpectrometer for Materials Research at Temperatureand Stress (SMARTS) facility at the Los AlamosNeutron Science Center (LANSCE) and at the ENGIN-X spectrometer at ISIS. Residual strains were seen todevelop and saturate during the first 100 fatiguecycles. Little, if any, strain relaxation was noted as 85% of the fatigue life was reached. Characteristics ofboth in situ lattice strains and residual strains invarious hkl directions during the fatigue deformationwill be discussed in comparison to those observedduring monotonic tensile testing.Acknowledgements: The author acknowledges thefinancial support of the National Science Foundation,the Integrative Graduate Education and ResearchTraining (IGERT) Program, under DGE-9987548, andthe International Materials Institutes (IMI), underDMR-0231320, to the University of Tennessee,Knoxville, with Dr. W. Jennings, Dr. L. Goldberg, andDr. C. Huber as contract monitors, respectively.

MP33: Strain and Texture Analysis of theFerroelastic Behavior of Pb(Zr,Ti)O3

R. C. Rogan, E. Ustundag, S. M. Motahari(Department of Materials Science, CaliforniaInstitute of Technology, Pasadena, California91125), M. R. Daymond (ISIS, Rutherford AppletonLaboratory)

In situ uniaxial compression experiments wereperformed on various Pb(Zr,Ti)O3 or PZT ceramicsusing neutron diffraction. PZTs near the edge of themorphotropic phase boundary as well as single-phase(tetragonal and rhombohedral) specimens wereinvestigated. Analysis of the diffraction patternsallowed for observation of the onset and culminationof domain switching through modeling of the sampletexture using the March-Dollase approach. This modelalso provided quantitative information about domainswitching under applied stress. Elastic lattice straindata suggested a high degree of anisotropy and acomplicated internal stress state. The effectiveness ofelectrical poling and mechanical depoling was alsoevaluated. The contrast between single andmultiphase systems will be highlighted. Results will becompared to the predictions of a new self-consistentmechanics model of ferroelectric constitutive behavior.

MP34: Neutron Residual Stress Measurements ofAluminum Cold Spray Coating

L. Li (State University of New York, Stony Brook, NY11794-2275), V. Luzin (National Institute ofStandards and Technology; State University of NewYork, Stony Brook, NY 11794-2275), R. Neiser(Sandia National Laboratories, Albuquerque, NM87123), H.-J. Prask (National Institute of Standardsand Technology), S. Sampath (State University ofNew York, Stony Brook, NY 11794-2275)

Cold spray technology is a novel method for produc-ing dense, oxide free coatings with some otherspecific qualities that can not be easily achieved bythe traditional thermal spray technique. Cold spray-ing process involves high particle velocities andimpact momentum and less or no thermal input sothat splat formation and coating deposition is verydifferent from the “conventional” thermal sprayprocess. Consequently residual stress formation isdifferent for this process. It has been speculated thatcold spraying produces significantly lower residualstresses than thermal spraying. This investigationwas intended to elucidate this question and providequantitative results on this subject.In this study we investigated residual stress distribu-tion in the aluminum-coating-on-aluminum-substratesample by means of neutron diffraction. Neutrondiffraction stress measurements were performed onthe BT8 diffractometer at the NIST Center for Neu-tron Research (NCNR) with spatial resolution 0.5 mmthrough thickness using a gauge volume of 0.5x0.5x7mm3. The substrate thickness is approximately 3 mmand the coating thickness is about 2 mm, so that thisspatial resolution is sufficient to obtain reliablethrough-thickness profiles of the in-plane stressdistribution. Special care was taken for measure-ments of near-surface points. Since sample surfacepreparation before spraying involves sand (grit)blasting, which is known to produce residual stressestoo, additional experiments on a substrate-onlysample were done to determine the initial stress stateof the substrate before spraying. Other methods ofmaterial characterization (electron microscopy,indentation, etc.) were employed to understandbetter the coating performance.

MP35: Quantum Critical Phase Diagram of aQuantum Magnet

M. B. Stone (Johns Hopkins University; Penn StateUniversity), C. Broholm (Johns Hopkins University;NIST Center for Neutron Research), D. H. Reich(Johns Hopkins University), I. Zaliznyak(Brookhaven National Laboratory), P. Vorderwisch(Hahn-Meitner-Institut Berlin), N. Harrison(National High Magnetic Field Laboratory (LANL))


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Piperazinum hexachlorodicuprate (PHCC) has beenshown to be a quasi-two-dimensional Heisenbergantiferromagnet with a bilayer structure (M. B. Stoneet al. PRB, 64, 144405 (2001)). The bilayer structureand frustrated interactions leads to a cooperativesinglet ground state at T = 0 and H = 0. We presentthe field-temperature phase diagram of this uniquequantum spin liquid as determined by neutronscattering and high field magnetic susceptiblitymeasurements. Two field dependent quantum criticalpoints were accessed: HC1 = 7.6 T which is the fieldthat closes the spin-gap and leads to three-dimen-sional long-range order for sufficiently low T and HC2

= 37 T where the system transitions to a fieldinduced ferromagnetic state. A gapless disorderedphase with short-range spin correlations encloses theantiferromagnetically ordered phase in the field-temperature phase diagram. Close to the low fieldquantum critical point, a minimum in the phaseboundary to long-range order indicates that weakinteractions with lattice or nuclear spin degrees offreedom become important.

MP36: NIST-DCS Neutron Measurements of LatticeDisorder in a dilute Ge-Si Crystal and in a Null-matrix 62Ni-Pt Alloy Crystal

J.A. Rodriguez, S.C. Moss (Physics Department,University of Houston), J.L. Robertson (Oak RidgeNational Laboratory), J.R.D. Copley, D.A. Neumann(NIST Center for Neutron Research), J. Major, V.Bugaev, H. Reichert, H. Dosch (Max Planck Institutefuer Metallforschung, Stuttgart)

Using the disk chopper spectometer (DCS) at NIST inan elastic scattering mode, we have investigated twoalloy crystals: 1) a dilute alloy of Ge in Si (~ 10 %)and 2) a null-matrix crystal of 62Ni0.52Pt0.48, so chosen(62Ni has a negative scattering length) that all effectsdepending on the average lattice scattering (Braggpeaks and Huang diffuse scattering (HDS—due todisplacement-displacement correlations) vanisheswhile the short-range order (SRO) and cross correla-tion between concentration and displacements, oftencalled the size effect scattering (SE), are now given bythe sum of the absolute values of the scatteringlengths of the two components.

The Si-Ge crystal was initially studied in the (-110)plane in reciprocal space. After removing the canscattering and normalizing the data, the planar plotfrom this (previously determined) random alloyshowed pronounced fans of diffuse scattering ema-nating strongly on the low angle side of the Braggpeaks. Selected asymmetric line scans confirmed ourearlier SE and HDS scan (1) along <110>, a suresign that the size of Ge is larger than Si and its

displacement field extends to distant neighbors. Thisdata is currently being analysed in Stuttgart by Prof.Bugaev and his students and additional scans in the(001) plane are underway.The null-matrix data are truly extraordinary. Thereare only tiny specks of Bragg peaks (useful foralignment) and absolutely no HDS about the Braggpositions. The SRO and SE scattering are quiteprominent and are being analysed in real space byRodriguez and Robertson to extract both SRO andindividual species-dependent displacements for eachcoordination shell, and in k-space by Prof. Bugaevand his colleagues.The results as they come out will be discussed in thecontext of the electronic theory of alloy phasestability, determined from data above Tc, the firstorder phase transition temperature.

[1] D. LeBolloc’h et al., Phys. Rev. B 63, 035204(2001)Research supported in Houston by the NSF on DMR-0099573

MP37: Recent Neutron and X-ray ScatteringStudies of the Electron-Doped SuperconductorNd2-xCexCuO4

P.K. Mang (Department of Applied Physics, StanfordUniversity), M. Greven (Department of AppliedPhysics, Stanford University; Stanford SynchrotronRadiation Laboratory)

We have performed a series of studies on the elec-tron-doped high temperature superconductorNd2-xCexCuO4. Inelastic magnetic neutron scatteringmeasurements of the evolution of the spin-spincorrelation length with doping and temperature innon superconducting samples have revealed thatmagnetic correlations in the system are described ata quantitative level by the randomly diluted square-lattice quantum Heisenberg antiferromagnet (SLHAF)[1]. However the low temperature ordered momentevolves more rapidly than for the SLHAF, suggestingthat quantum fluctuations manifest themselvesdifferently for different observables. High energyresolution (~ 6 meV) inelastic x-ray scattering (IXS)has identified an anomalous softening of the highestenergy (~ 70 meV) longitudinal optical phononbranch [2]. Similar features have been observed vianeutron scattering in the hole-doped cuprate super-conductors and a related “kink” structure wasobservered in the electronic dispersion by photoemis-sion studies. These features have been interpreted asevidence for a strong electron-phonon coupling in thecuprate superconductors. We have established theexistence of such a feature in NCCO, and determinedthat the feature is formed for concentrations x >


0.04. Using x-ray diffraction we have established thatthe oxygen-reduction procedure commonly em-ployed to induce superconductivity in NCCO resultsin the decomposition of a small fraction (0.1 % to1 %) of the sample to a cubic phase of Nd2O3 [3].This secondary phase forms epitaxially with thecopper-oxygen plane, but extends only a few latticeconstants along the c-axis. A subset of structuraldiffraction peaks of the secondary phase overlapmagnetic reflections associated with NCCO inreciprocial space, and at low temperatures theapplication of a magnetic field results in a dramaticpolarization of the moment of the Neodymiumatoms. These two effects have led others to mistak-enly report the existence of a quantum phasetransition from a superconducting to an antiferro-magnetic phase.

[1] P.K. Mang et al., cond-mat/030793 (2003).[2] M. d’Astuto et al., Phys. Rev. Lett. 88, 167002(2002).[3] P.K. Mang et al., Nature 426, 139 (2003).

MP38: Nature of Jahn-Teller distortion in LaMnO3:order to disorder

X. Qiu, S. J. L. Billinge (Department of Physics andAstronomy, Michigan State University, E. Lansing,MI, 48824), Th. Proffen (Los Alamos NeutronScience Center, Los Alamos National Laboratory)

One fully Jahn-Teller (JT) distorted MnO6 octahedronin the undoped LaMnO3 contains two long (2.16 Å),two medium (1.96 Å), and two short (1.92 Å) Mn-Obonds. The low temperature orthorhombic phaseresults from the long range cooperative ordering ofthe JT distorted orbitals (long and short Mn-O bondsalternating in ab plane). Excellent agreement be-tween local and average structure studies confirmsthe static nature of the JT distortion. At high tempera-tures across the Jahn-Teller structural phase transi-tion, average structure studies found that the MnO6

octahedron has six almost equidistant Mn-O bonds(delta d < 0.05 Å), and the high temperature orthor-hombic phase is pseudo cubic. However, evidentfrom local structure studies, the MnO6 octahedra arefully JT distorted at all temperatures, suggesting theyare oriented along all directions with equal probabil-ity at high temperatures. Here presented are experi-mental evidences from the combined local andaverage structure analysis using the atomic pairdistribution function (PDF) technique. We furtherargue that the JT distorted orbitals are also dynamic,explaining the observed drastic drop of the resistivityacross JT transition. The “local” ordering length ofMnO6 will also be discussed.

MP39: Field effect and quasi-2D rod magneticstructure on electron-doped superconductor

H. Kang (Department of Physics and Astronomy,University of Tennessee), P. Dai (Department ofPhysics and Astronomy, University of Tennessee;Condensed Matter Sciences Division, Oak RidgeNational Laboratory), Y. Ando, Y. Kurita (ElectricalPhysics Department, Komae ResearchLaboratory,CRIEPI,)

The interplay between the competing phases in high-Tc superconductivity has been one of the importantissues and intensive work has been done on thistopic both experimentally and theoretically. Previousfield-induced effects on hole-doped LSCO suggestthat antiferromagnetism competes with superconduc-tivity. We did a similar field-induced experiment onthe electron-doped superconductor PLCCO (x =0.12) by applying a magnetic field along the c-direction to determine whether the antiferromag-netism is the competing order in high-Tc cupratesregardless hole or electron-doping. We also show thatthe magnetic structure of superconducting sample isquasi-2 dimensional through the result from the 2dimensional rod scan. Comparison of the tempera-ture dependence of the antiferromagnetic peak(0.5,0.5,0) in the superconducting sample and non-superconducting sample shows that the quasi-2dimensional magnetic structure is related to super-conductivity.

MP40: Structural Phase Transitions in Cd2Re2O7

J. He (University of Tennessee, Knoxville; Oak RidgeNational Laboratory), B. Chakoumakos (Oak RidgeNational Laboratory), D. Mandrus (University ofTennessee, Knoxville), M. Guttmann, C. Wilson(CLRC Rutherford Appleton Laboratory, UK), J.Gardner (National Research Council, Chalk River,Ontario, Canada)

The structural phase transitions at and below T* ~200 K in the pyrochlore oxide, Cd2Re2O7, have beenthe subject of a number of studies, however, theexact nature of these structural distortions andsymmetry changes has not been completely eluci-dated. Accompanying with the subtle structuralchanges are dramatic changes in the resistivity andmagnetic susceptibility, and superconductivity isobserved at Tc = 1.0 K. On the other hand, thecontinuous cubic-to-tetragonal structural transition atT*, the breaking of inversion symmetry and thesustained metallic behavior on both sides of T*suggest this compound as the first example of“metallic ferroelectricity” proposed by P.W. Andersonin 1960s. We have collected single-crystal neutrondiffraction data at the SXD instrument at ISIS, andpowder diffraction data at C-2,NPMR, Chalk River


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Laboratory, using isotopically enriched crystallinespecimens. Data sets for several temperatures havebeen collected. We are testing a variety of lowersymmetry structural models to determine the bestdescription of the intermediate- and low-temperaturerange structural modifications before the onset ofsuperconductivity.

MP41: Mesoscopic magnetic and crystallographicphase separation in La1-xCaxMnO3 (0 ≤≤≤≤≤ x ≤≤≤≤≤ 0.20)

H. Terashita, J.J. Neumeier (Department of Physics,Montana State University, Bozeman Montana59717-3840), C.D. Ling (Institut Laue Langevin)

We report on the magnetic and structural propertiesof hole-doped La1-xCaxMnO3 (0 ≤≤≤≤≤ x ≤≤≤≤≤ 0.14). Neutronpowder diffraction and dc-magnetization measure-ments were carried out. We observed two distinctPnma phases as well as ferromagnetic and antiferro-magnetic low-temperature transitions for all samples.Details of the temperature and composition depen-dence of the phase fractions will be discussed in thecontext of the development of the local ferromag-netism, recently observed in this system [1]. Com-parisons will be made with our results in the analo-gous electron-doped Ca1-xLaxMnO3 (0 ≤ x ≤ 0.20) [2].

[1] M. Hennion, F. Moussa, G. Biotteau, J. Rodríguez-Carvajal, L. Pinsard, and A. Revcolevschi, Phys. Rev.Lett. 81, 1957 (1998); M. Hennion, F. Moussa, J.Rodríguez-Carvajal, L. Pinsard, and A. Revcolevschi,Phys. Rev. B 56, R497 (1997); M. Hennion, F. Moussa,G. Biotteau, J. Rodríguez-Carvajal, L. Pinsard, and A.Revcolevschi, Phys. Rev. B 61, 9513 (2000).[2] C. D. Ling, E. Granado, J. J. Neumeier, J. W. Lynn,and D. N. Argyriou, Phys. Rev. B 68, 134439 (2003);E. Granado, C. D. Ling, J. J. Neumeier, J. W. Lynn, andD. N. Argyriou, Phys. Rev. B 68, 134440 (2003).

MP42: The Solvation of Fulleride C605- Anions in

Potassium-Ammonia SolutionsC. A. Howard (Department of Physics & AstronomyUniversity College London, UK; RutherfordAppleton Laboratory, UK), J. C. Wasse, N. T. Skipper,H. Thompson (Department of Physics & AstronomyUniversity College London, UK)

Investigation of fulleride C60 anions in solution is veryimportant, for example, in the applications offullerene purification and separation; the manipula-tion of fullerenes and their derivatives and forstudying isolated fulleride anions. C60 can be sequen-tially reduced in metal ammonia solutions to formhigh concentrations solvated C60

n- (n=1-5) anions [1].

This poster describes the results of new high resolu-tion neutron diffraction studies of C60K5(NH3)250

solutions taken on SANDALS at the ISIS facility.

Second order isotopic substitution of deuterium (D)for hydrogen (H), used together with EmpiricalPotential Structure Refinement (EPSR) provides uswith a detailed picture of the structure in theseliquids [2]. We find a highly developed solventstructure: the C60

5- anion is strongly solvated byapproximately 45 ammonia molecules, locatedaround 7Å from the centre of the fulleride with asecond solvation shell present around this. Thesemolecules direct one of their hydrogen atoms to-wards the centre of a fulleride ion. This strongsolvation shells permit attainment of high concentra-tions of solvent isolated fulleride ions. As well asbeing interesting from the fundamental standpoint,our results demonstrate that wide angle neutrontechniques can be used to investigate the order foundaround large ions in a polar solvent.

[1] Fullagar, W. K. et al., J. Chem. Soc., Chem.Comm. 6, 525-527 (1993)[2] Soper, Mol. Phys. 99, 1503-1516 (2001)

MP43: Annealing-Dependent Phenomena inGa1-xMnxAs

B. J. Kirby (Department of Physics & Astronomy,University of Missouri), J. A. Borchers (NIST Centerfor Neutron Research), J. J. Rhyne (Los AlamosNeutron Science Center, Los Alamos NationalLaboratory; Department of Physics & Astronomy,University of Missouri), S. G. E. te Velthuis, A.Hoffmann (Materials Science Division, ArgonneNational Laboratory), K. V. O’Donovan (NIST Centerfor Neutron Research; Department of MaterialsScience and Engineering, University of Maryland),T. Wojowicz (Department of Physics, University ofNotre Dame; Institute of Physics of the PolishAcademy of Sciences), X. Liu, W. L. Lim, J. K.Furdyna (Department of Physics, University ofNotre Dame)

We have used polarized neutron reflectometry (PNR)to study the dilute ferromagnetic semiconductorGa1-xMnxAs. There is great interest in the develop-ment of high Curie temperature (TC) ferromagneticsemiconductors for use in spintronics applications.Ga1-xMnxAs is a possible candidate for such applica-tions, with TC exceeding 150 K in some cases. Theferromagnetic behavior in this material originatesfrom coupling between spin-5/2 Mn2+ ions substitut-ing for Ga. These substitutional Mn ions (MnGa) areacceptors, generating holes that mediate the ferro-magnetic exchange. However, MnGa are known to bepartially compensated by Mn atoms that exist atinterstitial sites in the lattice (MnI). MnI alignantiferromagnetically with MnGa, and are doubledonors, fighting the ferromagnetic ordering. A very


interesting property of this material is that post-growth annealing greatly increases the magnetizationand TC in Ga1-xMnxAs thin films, as was first shownthrough conventional magnetometry.

PNR is a powerful experimental tool that can be usedto establish magnetic and chemical depth profiles forthin films. We have used PNR to further examine themechanisms through which annealing enhances theferromagnetic ordering in Ga1-xMnxAs. This work hasshown that annealing leads not only to an increasedtotal magnetization, but also to a much more homo-geneous depth distribution of magnetization. Addi-tionally, these measurements have revealed thatannealed films posses a non-magnetic surface layerwith a composition different from the rest of the film.This result strongly corroborates the idea that anneal-ing enhances the ferromagnetism by redistributingMnI to the surface of the film. Additional aspects ofthis work include studies of changes in theGa1-xMnxAs magnetic and chemical depth profilesinduced by varying Mn concentration, varying filmthickness, and the addition of surface capping layers.

MP44: Coherent Inelastic Neutron Scattering Studyof Lattice Dynamics and Vibrational Entropy inPolycrystalline Fe71Ni29 Undergoing a Low Tempera-ture Martensitic Transformation

O. Delaire, M. G. Kresch, T. M Kelley, B. T. Fultz(California Institute of Technology)

Using the Pharos time-of-flight spectrometer at theLujan center, we measured the neutron scatteringfunction S(|Q|,E) for the alloy Fe71Ni29 as function oftemperature from 300K to 80K. We observed in situthe structural and dynamical effects of the fcc-bccmartensitic transformation taking place at lowtemperatures, with an emphasis on the entropy ofthe transformation. To gain insight into the phononentropy of this martensitic transformation, westudied the lattice dynamics across the phase bound-ary. We tried to extract information about the inter-atomic force-constants from the Q- and E- depen-dence of the coherent scattering signal recorded withthe pixelated Pharos detector array. The coherence inthe data can be directly related to the polycrystallineaveraged phonon dispersions for the two phases ofthe material. The inelastic scattering functionSinel(|Q|,E) for the high temperature phase wascompared to a computer simulation based on theBorn-von Karman model and inter-atomic force-constants determined previously. The good agree-ment between the experimental data and the simula-tion suggests new approaches for investigating thelattice dynamics of polycrystals. The vibrationalentropies of the low- and high-temperature phases

were calculated from the phonon DOS curves. Wefound a significant entropy change upon transforma-tion of -0.13 kB per atom, typical of martensitictransformations.

MP45: Inherited Tunneling in Supercritical Water.D. Homouz, G.F. Reiter (Physics Department,University of Houston), P. Platzman (Bell Labs-Lucent Technologies)

It has been observed in Neutron Compton Scatteringmeasurements on supercritical water, that themomentum distribution of the proton appears to beconsistent with the tunneling of the proton along thehydrogen bond over a distance of .3 Å. While therehas been ample evidence of tunneling motionperpendicular to the bond observed by other means,this result was puzzling because of the stiffness of thebond, and the lack of any obvious geometricalinterpretation. Using path integral Monte-Carlomethods, we show that tunneling motion perpendicu-lar to the bond, when coupled to much stiffer har-monic motion along the bond, can show up in themomentum distribution as an apparent tunnelingmotion along the bond direction, with the apparenttunneling distance being characteristic of the trans-verse motion.

MP46: High Resolution Neutron Scattering Experi-ments on Spin Excitations in SrCu2(BO3)2

S. Haravifard (Department of Physics andAstronomy, McMaster University, Hamilton, ON,Canada), B.D. Gaulin (Department of Physics andAstronomy, McMaster University, Hamilton, ON,Canada; Canadian Institute for Advanced Research,180 Dundas St. W., Toronto, Ontario, M5G 1Z8,Canada), S.H. Lee (National Institute of Standardsand Technology), J.P. Castellan (Department ofPhysics and Astronomy, McMaster University,Hamilton, ON, Canada), A.J. Berlinsky (Departmentof Physics and Astronomy, McMaster University,Hamilton, ON, Canada; Canadian Institute forAdvanced Research, 180 Dundas St. W., Toronto,Ontario, M5G 1Z8, Canada), H.A. Dabkowska(Department of Physics and Astronomy, McMasterUniversity, Hamilton, ON, Canada), Y. Qiu (NationalInstitute of Standards and Technology; Departmentof Materials Science and Engineering, University ofMaryland), J.R.D. Copley (National Institute ofStandards and Technology)

We performed high resolution inelastic neutronscattering measurements on SrCu2(

11BO3)2 which hasbeen proposed as a realization of the two dimen-sional Shastry-Sutherland system with an exact dimerground state. Measurements were performed on theDisk Chopper Spectrometer (DCS) and the SPINS


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triple axis spectrometer, located on cold neutronguides at the NIST Center for Neutron Research.Earlier inelastic neutron scattering measurementshave identified three bands of excitations. Weperformed high Q resolution measurements usingSPINS which show distinct Q-dependencies for thesingle and multiple triplet excitations, and that theseexcitations are largely dispersionless perpendicular tothe basal (H,K,0) plane. Since the Q-dependence ofthe spin excitations show little L dependence, highenergy resolution DCS measurements were inte-grated along L, which then could reveal the disper-sion of the three single triplet excitations continu-ously across the (H,0) direction within its tetragonalbasal plane. These correspond to Sz = +1, 0, -1transitions from the singlet ground state. We alsomeasured the temperature dependence of both thesingle and double triplet excitations with SPINS, aswell as that of the single triplet excitations with DCS.We observe identical temperature dependencies forthe single and double triplet excitations and thistemperature dependence to the inelastic scattering iswell described as the complement of the dc suscepti-bility of SrCu2(BO3)2.

MP47: Quantum Percolation in a Two-DimensionalHeisenberg Antiferromagnet

O. P. Vajk (NIST Center for Neutron Research), P. K.Mang (Department of Applied Physics, StanfordUniversity), M. Greven (Department of AppliedPhysics and Stanford Synchrotron RadiationLaboratory, Stanford, CA 94305), J. W. Lynn (NISTCenter for Neutron Research)

The study of quantum phase transitions in thepresence of disorder is at the forefront of research inthe field of strongly correlated electron systems, yetthere have been relatively few experimental modelsystems. One important class of model systems forstudying the effects of quenched disorder is magneticmaterials with random site dilution. Percolation inclassical high-spin magnetic systems has beenstudied extensively, and magnetic order persists inthese materials up to the percolation threshold. Thespin-1/2 square-lattice Heisenberg antiferromagnet(SLHAF) is of particular interest because of its con-nection to high-temperature superconductivity.Previous results for magnetic dilution in the spin-1/2SLHAF have been confined to dilution levels wellbelow the percolation threshold, leaving manyquestions about this complex quantum-impurityproblem unanswered.

Single crystals of La2Cu1-p(Zn,Mg)pO4 at concentra-tions up to and beyond the site percolation thresholdprovide the first experimental realization of quantum

percolation in a spin-1/2 SLHAF. Complementarymagnetometry, neutron scattering, and numericalexperiments demonstrate that La2Cu1-p(Zn,Mg)pO4 isan excellent model material for studying this prob-lem in the low-spin limit. Measurements of theordered moment and spin correlations provideimportant quantitative information for tests oftheories for this complex quantum-impurity problem.Quantum Monte Carlo results for the bilayerHeisenberg antiferromagnet allow the determinationof the quantum-fluctuation versus geometric-disorderphase diagram, and indicate that the properties ofLa2Cu1-p(Zn,Mg)pO4 near the percolation threshold arecontrolled by the effective proximity to a newquantum critical point.

MP48: Magnetic structure of Cu(Mn)/Cusuperlattices

W. Donner, L.B. Carvalho (Department of Physics,University of Houston), J.L. Robertson (ReactorDivision, Oak Ridge National Laboratory)

Cu(Mn) alloys are the prototype for spin-glass behav-ior and at the same time exhibit spin-density wavesof a limited (20 Å) correlation range. We are inter-ested in short-range order in thin films in general andhave chosen Cu(Mn) as a model system to study theeffect of confinement on short-range order. In orderto obtain a large enough number of scatterers for aneutron experiment we prepared superlattices ofCu(Mn)layers separated by Cu. The samples havebeen epitaxially grown by DC-magnetron sputteringonto Si(001) substrates with a Cu(001) buffer layer.They exhibit a mosaic of about 0.7 degrees and showvery little structural disorder as evidenced by high-order structural satellite peaks in x-ray diffractionexperiments.

We will present first results obtained at the High FluxIsotope Reactor in Oak Ridge (HB1A) on sampleswith varying Cu(20 at % Mn) and Cu thickness. Bothstrongly modulated magnetic short-range order andmagnetic long-range order are present in the sampleswhen the Cu(Mn) thickness is below 20 Å.

MP49: Quasi-elastic Neutron Scattering Study ofthe Diffusion of Methyl Iodide Confined in theGelTech-200

Y.J. Glanville, P.E. Sokol (Pennsylvania StateUniversity, Dept. of Physics, University Park, PA,16802), R.M. Dimeo (NIST Center for NeutronResearch), C.M. Brown (NIST Center for NeutronResearch; Department of Materials Science andEngineering, University of Maryland)

The quasi-elastic scattering from methyl iodideconfined in the pores of GelTech glass has been


measured on the Fermi Chopper Spectrometer atNIST. Methyl Iodide is a quantum rigid rotor with abulk freezing temperature of 207 K. Measurementson cooling were carried out at an incident energy of2.5 meV with an energy resolution of 90 meV, with Qvalues ranging from 0.68 to 2.45 Å-1, and tempera-tures ranging from 215 K to 150 K. The measuredQENS spectra could be split into three distinct regionsbased on their Q dependence. The high temperaturescattering, above 205 K, shows a distinct Q2 depen-dence indicating a liquid like jump diffusion. At 203 Kthere is a very dramatic change in the scattering andwe observe a change from a quadratic to a linear Qdependence. We believe this is a transition from aliquid to a geometrically confined solid phase, whichhas a structure like that of a glass. This result issubstantiated by x-ray scattering measurementspreformed by our group. At this sample temperaturethe x-ray spectra showed a Debye-Waller typedampening at high Q indicative of a solid. As thetemperature was lowered further a transition oc-curred where the broadening was independent of Q.

We wish to acknowledge the support of this researchby the funding of the Department of Energy throughgrant DE-FG02-01ER45912, and the Department ofCommerce through their support of the NIST Centerfor Neutron Scattering.

MP50: Role of solvent in protein preservationG. H. Caliskan (The University of Akron, PolymerScience Department), M. T. Cicerone (NIST PolymerDivision), M. Gangoda, R. B. Gregory (Kent StateUniversity, Department of Chemistry), A. Kisliuk(The University of Akron, Polymer ScienceDepartment), I. Peral (University of Maryland,College Park), J. H. Roh, A. P. Sokolov (TheUniversity of Akron, Polymer Science Department)

Protein dynamics span over a broad time range frompicoseconds, where vibrations take place, up to years,the target of pharmaceutical industry forbiopreservation. Understanding the dynamics is vitalin controlling the activity of biological macromol-ecules, and improving the designs for biopreservationformulations. High TG sugars are usual choice forbiopreservation at ambient temperatures. However,glycerol (TG ~ 190 K) is the most effective solvent forlong-term (years) cryo-preservation. The reason forthis difference in effectiveness of the solventsremains unclear.

We measured dynamics of hen egg white lysozymein various solvent conditions, (glycerol, water,trehalose and dry state) in a broad temperature(150 K to 320 K) range. Time-of-Flight Spectrometer

at the National Institute of Standards and TechnologyCenter for Neutron Research offered a broad range ofenergy from ~ 40 µeV up to ~ 65 meV where thefast relaxation (local conformational fluctuations) andslow vibrations of proteins become accessible. Ourresults show that the fast relaxation depends stronglyon the solvent. It is strongly suppressed in liquidglycerol compared to solid trehalose (TG ~390 K) atlow temperatures. At high temperatures (> 270 K), itbecomes enhanced in glycerol and in water environ-ments, as opposed to that in trehalose and in dryconditions. This observation quantitatively agreeswith bioactivity measurements on Myoglobin inglycerol and trehalose at different temperatures. Theresults suggest that the viscosity of the solvent is notthe only parameter affecting the protein dynamics.Fast picosecond relaxations should also be taken intoconsideration. We propose a mechanism that mightexplain extreme biopreservation efficiency of glycerolat low temperatures. Possible implications for devel-opment of better formulations are discussed.

MP51: Cholera Toxin Assault on Lipid MonolayersContaining Ganglioside GM1 : a Neutron andX-Ray Scattering Study at the Air-Liquid Interface

C.E. Miller (Biophysics Graduate Group, Universityof California, Davis; Department of ChemicalEngineering and Material Science, University ofCalifornia, Davis), J. Majewski (Los Alamos NeutronScience Center, Los Alamos National Laboratory), K.Kjær, M. Weygand (Physics Department, RisøNational Laboratory, Denmark), R. Faller(Department of Chemical Engineering and MaterialScience, University of California, Davis), T.L. Kuhl(Department of Chemical Engineering and MaterialScience, University of California, Davis; BiophysicsGraduate Group, University of California, Davis)

Many bacterial toxins bind to and gain entrance totarget cells through specific interactions with mem-brane components. Using neutron/x-ray reflectivityand x-ray grazing incidence diffraction (GID), wehave characterized the structure of mixed DPPE:GM1lipid monolayers before and during the binding ofcholera toxin (CTAB5) or its B subunit (CTB5). Struc-tural parameters such as the density and thickness ofthe lipid layer, extension of the GM1 oligosaccharideheadgroup, and orientation and position of theprotein upon binding are reported. The density of thelipid layer was found to decreases slightly uponprotein binding. However, the alpha subunit of thewhole toxin is clearly located below the B pentamericring, away from the monolayer, and does not pen-etrate into the lipid layer prior to enzymatic cleavage.Using Monte Carlo simulations, the observed mono-layer expansion was found to be consistent with


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geometrical constraints imposed on DPPE by multi-valent binding of GM1 by the toxin. Our findingssuggest that the mechanism of membrane transloca-tion by the protein may be aided by alterations inlipid packing. Both CTAB5 and CTB5 were measured tohave ~50 % coverage when bound to the lipidmonolayer. X-ray GID experiments show that boththe lipid monolayer and the cholera toxin layer arecrystalline. The effects of x-ray beam damage havebeen assessed and the monolayer/toxin structuredoes not change with time after protein binding hassaturated.

TuesdayT1-A, Chemical Applications of SANS, Chair:Charles Glinka (NIST), Room 2101/3/5 Green

T1-A1 (08:30) Probing the Structure of NanoscaleAerosols (Invited)

Barbara Wyslouzil (Department of ChemicalEngineering, Ohio State University), GeraldWilemsk (University of Missouri – Rolla), ReinhardStrey (Universität zu Köln, Germany)

Multicomponent nanometer sized droplets formreadily in the supersonic expansion that occur, forexample, in volcanic eruptions, jet exhausts andturbomachinery. From a fundamental point of view,particles with radii < 10 nm are important becausethey lie in the critical transition zone between largemolecular clusters and bulk materials. The propertiesof the aerosol size distribution, i.e. the numberdensity, the average particle size, and the polydisper-sity together determine the surface area of theaerosol. Differences between the surface and interiorcompositions, on the other hand affect the heteroge-neous chemistry as well as the growth and evapora-tion kinetics. Unlike solid particles, that can becaptured and subjected to further analysis, liquiddroplets must be examined in situ.

Over the past 7 years, we have pioneered the use ofsmall-angle neutron scattering (SANS) to study theproperties of nanodroplet aerosols. With condensedphase volume fractions on the order of 10-6, aerosol-SANS experiments are technically challenging. Theresults from our experiments to date are, however,yielding important insights into particle formationprocesses and into the internal structure of thedroplets themselves. This talk will focus on our effortsto use SANS to find direct evidence for and character-ize surface enrichment in nanodroplets.

T1-A2 (09:00) Neutron Scattering Study of WaxCrystal Modification by Crystallizable Polymers forCrude Oil Production

Robert K. Prud’homme, (Dept ChemicalEngineering, Princeton University, Princeton, NJ08544), H.S. Ashbaugh (Los Alamos NationalLaboratory, Los Alamos, NM 87545), A. Radulescu,D. Schwahn, D. Richter, L. J. Fetters (Institut furFestkoperforschung, Juelich, Germany)

Self-assembly in organic phases is less well studiedthan self-assembly in aqueous phases in part becausethe driving forces for assembly are generally weakerin organic media. Crystallization, however, providessufficient driving force in cases of wax precipitation


Neutrons and Muons, CH-5232 Villigen PSI,Switzerland), J. Zhang (NISSAN Motor Co. Ltd.,Powertrain and Environmental ResearchLaboratory, 1 Natsushima-cho, Yokosuka 237-8523,Japan), K.N. Clausen (Paul Scherrer Institut,Research Department Condensed Matter Researchwith Neutrons and Muons, CH-5232 Villigen PSI,Switzerland)

Fuel cells are envisaged a key role for the develop-ment of the so-called hydrogen economy or for thefuture of individual transport systems in cities andother mobile applications. In Electric fuel cellshydrogen, natural gas or methanol in combinationwith oxygen is converted into electric power andnon-poisonous reaction products (Water and CO2).The development of efficient, long lived, light, lowcost fuel cells is therefore high on the agenda andmany research groups world wide are studying bothmaterials for use in fuel cells and their behaviorduring operation of the cell.

One of the reaction product for low temperatureoperation conditions within fuel cells is water, andsince the humidity inside the so-called gas diffusionlayer of the fuel cell, strongly influences the behaviorand the performance of the whole assembly, it is ofgreat interest to follow the production of water andhow this water is transported out of the cell simulta-neously with measurements of the local currentdensity in an operating fuel cell.

Because of the high neutron attenuation coefficientfor hydrogen in comparison to the structural materi-als of the fuel cell (carbon, aluminum etc.), thequantitative distribution of water can be studied byneutron imaging techniques.

The radiography beam line NEUTRA at the spallationneutron source SINQ has been used for such in situstudies of operating test fuel cells. The accumulationand distribution of water was studied both with acoarse time resolution with integration over about 10s or very fast with up to 30 frames per second. In thefirst case, the image quality allowed for quantitativedetermination of the water distribution. In the latercase, short term changes in the flow field could bedetected.

The paper will describe in detail the experimentalsetup, the methodology to derive quantitative valuesfor the water distribution from the neutron imagesand first results from a test cell. An outlook forfurther developments of the method will be given.

from oil phases. We present results on the self-assembly of co-polymers in organic solutions drivenby crystallization. Polymers of both di-block andrandomly distributed crystallizable domains werestudied. The interesting phenomena occur whenthese polymers co-crystallize with wax phases uponcooling. Using neutron scattering and rheology wepresent a picture of the mechanism of co-assemblythat leads to sterically stabilized wax crystals. Theproper tuning of polymer architecture provides ameans to control gel formation in crude oil produc-tion process.

T1-A3 (09:15) Field and Shear Induced Orienta-tional Order in Magnetic Nanoparticle Dispersionsfrom SANS

Vemuru V. Krishnamurthy, B. He, M. Piao ( MINTCenter, The University of Alabama, Tuscaloosa,Alabama 35487-0209), L. Porcar ( NIST Center forNeutron Research), D. E. Nikles, J. M. Wiest, G. J.Mankey ( MINT Center, The University of Alabama,Tuscaloosa, Alabama 35487-0209)

Acicular magnetic nanoparticles have technologicalapplications. The suitability of nanoparticles formagnetic recording applications depends on thecontrol of the orientational order in an external forcefield, such as a shear flow and a magnetic field. Usingsmall angle neutron scattering, we have investigatedthe orientational order of polydisperse rod shapediron nanoparticles in cyclohexane based magneticdispersions in longitudinal shear flow and transversemagnetic field. The anisotropy of the scatteringintensity observed in 3.2 vol. % and 3.9 vol. % ironnanoparticle dispersions in shear flow and/or mag-netic field, shows that the particles start to orienteither in a shear flow of 100 s-1 or in a magnetic fieldof 8 mT. In zero-applied-field, the orientational orderis measured as a function of steady shear flow. In anapplied field, both the degree of order and the tiltangle of the particles is measured as a function ofsteady shear flow. At zero shear rate, the anisotropy,i.e., the order parameter exhibits hysteresis as afunction of applied magnetic field showing that thenanoparticles order in domains. The scattering fromnanoparticles in the 3.9 vol. % dispersion exhibitssecond order anisotropy in an applied field greaterthan 5 mT.

T1-A4 (09:30) On-line studies of electric fuel cellassemblies by neutron imaging methods

D. Kramer, G. Scherer (Paul Scherrer Institut,General Energy Department, ElectrochemistryLaboratory, CH-5232 Villigen PSI, Switzerland), E.Lehmann (Paul Scherrer Institut, ResearchDepartment Condensed Matter Research with


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heterogeneous membranes. We show evidence, forthe first time using SANS, that nanoscopic domainsform in unilamellar vesicles of a size several orders ofmagnitude smaller than similar vesicles used influorescence microscopy studies. It is found that,while “rafts” form in 1:1:1 mixtures ofDOPC:DPPC:cholesterol and ergosterol, there is nosuch evidence for similar heterogeneities in 1:1:1SOPC:DPPC:cholesterol. Furthermore, it is found thatergosterol has a greater ability to stabilize “rafts” thancholesterol.

T1-B3 (09:15) Neutron Reflectometry Studies ofPolymer Brushes in Confined Geometry

G. S. Smith (HFIR Center for Neutron Scattering,Oak Ridge National Laboratory, Oak Ridge,Tennessee 37831, USA.), T.L. Kuhl (Department ofChemical Engineering and Material Science,University of California, Davis), W.A. Hamilton(HFIR Center for Neutron Scattering, Oak RidgeNational Laboratory, Oak Ridge, Tennessee 37831,USA.), N.A. Alcantar (Department of ChemicalEngineering, University of South Florida, FL 33620,USA.), R.G. Toomey (Center for Ocean Technology,St.Petersburg, FL 33701, USA.), J. Majewski (LosAlamos Neutron Science Center, Los AlamosNational Laboratory)

Polymer molecules at solid or fluid interfaces have anenormous spectrum of applications in a wide varietyof technologies as lubricants, adhesion modifiers, andprotective surface coatings. Because polymer brusheshave a great potential to be used in such applications,there is a need to determine their structure andefficiency in reduced spaces. Using neutronreflectivity and the newly developed Neutron Con-finement Cell, we have directly quantified the densitydistribution of opposing polymer brushes in goodsolvent conditions under confinement. Our measure-ments show that the density profile in the overlapregion between opposing polymer brushes flattensconsistent with predictions from molecular dynamicssimulations. In addition, a significant increase indensity at the anchoring surfaces due to compressionof the brush layers is observed. This compression orcollapse of the brushes in restricted geometriesstrongly suggests that high-density brushes do notinterpenetrate in good solvent conditions.

T1-B4 (09:30) Analysis of Myoglobin Adsorption toCu(II)-IDA and Ni(II)-IDA Functionalized LangmuirMonolayers by Grazing Incidence Neutron and X-ray Techniques

M. S. Kent, H. Yim, D. Y. Sasaki (Sandia NationalLaboratories, Albuquerque, NM 87123), S. Satija(National Institute of Standards and Technology), J.

T1-B, Thin Films and Membranes, Chair: LeeMagid (U. Tennessee), Room 2100/2/4 Red

T1-B1 (08:30) X-ray & Neutron Reflectivity Studiesof Vectorially-Oriented 4-Helix Bundle MaquettePeptides (Invited)

J. K. Blasie, S. Ye, J. Strzalka (Department ofChemistry, University of Pennsylvania)

Bundles of alpha-helices provide a scaffold forbinding prosthetic groups at selected locations withinthe structure to mimic functions exhibited by biologi-cal proteins. For example, histidine residues can bestrategically placed for the axial ligation of metal-loporphyrin prosthetic groups involved in biologicalelectron transfer reactions. The first designed artifi-cial peptides, prepared by solid-phase chemicalsynthesis, used amphipathic di-helices which self-assembled in aqueous solution forming 4-helixbundles. These were called “maquettes” and theyexhibited exceptional stabilities relative to theirnatural counterparts. Nevertheless, to realize anydevice applications based on their functionality, thepeptides must be vectorially-oriented in an ensemble,e.g., at an interface. Incorporation of non-biologicalprosthetic groups further allows for the possibility ofnovel functionality and related device applications.Several examples will be provided concerningmaquette design for vectorial orientation at softinterfaces. Both x-ray and neutron scattering tech-niques are key to ascertaining the detailed nature ofthese maquette structures and their vectorial orienta-tion at soft interfaces. Each of these techniques hasdistinct advantages and disadvantages.

T1-B2 (09:00) Detection by Small-Angle NeutronScattering of Lateral Segregation or “Rafts” inLipid – Cholesterol and Lipid – Ergosterol Mixturesin Large Unilamellar Vesicles

J. Pencer (Dept. of Chemical and BiomolecularEngineering, The Johns Hopkins University; NISTCenter for Neutron Research), S. Krueger (NISTCenter for Neutron Research), R. M. Epand(Biochemistry Department, McMaster University)

Small-angle neutron scattering (SANS) measurementsare used here to identify and characterize lateralheterogeneities or “rafts” in three componentmixtures of lipids and cholesterol or ergosterol in 50nm diameter unilamellar vesicles. By using deuter-ated lipid as the saturated lipid component in mix-tures of lipids and cholesterol, and appropriatecontrast conditions, we are able to enhance thecontrast between heterogeneous membranes and themedium. This allows us to detect the onset of “raft”formation on cooling of homogeneously mixedmembranes, and to measure the form factor of


Majewski (Argonne National Laboratory), T. Gog(Los Alamos National Laboratory)

The adsorption of myoglobin to Langmuir monolay-ers of a metal-chelating lipid in crystalline phase wasstudied using neutron and x-ray reflectivity andgrazing incidence x-ray diffraction (GIXD). In thissystem adsorption is due to the interaction betweenchelated Cu2+ and Ni2+ ions and the histidine moi-eties at the outer surface of the protein. Cu2+ isknown to interact much more strongly with histidinethan Ni2+. Adsorption was examined by NR and XRunder conditions of constant surface area with aninitial pressure of 40 mN/m as well as under constantpressure at 40 mN/m. The adsorbed layer structure inthe final state was examined for a variety of bulkconcentrations on and below the adsorption plateau.In addition, since the adsorption process is ratherslow for this system, the layer characteristics wereobtained as a function of time during the adsorptionprocess. Finally, corresponding GIXD experimentswere performed under the same conditions to followchanges in the packing of the lipid tails upon proteinadsorption. Significant differences in the evolution ofthe adsorbed protein layer are observed for chelatedCu2+ and Ni2+ ions that may indicated differingextents of protein denaturation in the two cases. Inaddition, the disruption of the lipid packing is foundto occur for the constant pressure case (40 mN/m)but not for constant area (initial pressure - 40 mN/m).

T1-C, Magnetic Structures, Chair: TanerYildirim (NIST), Room 1123 Blue

T1-C1 (08:30) Unusual Symmetry of the Kugel-Khomskii Hamiltonian for Orbitons (Invited)

A. B. Harris (University of Pennsylvania,Philadelphia PA 19104)

The Kugel-Khomskii Hamiltonian, HKK, has been usedfor about three decades to describe spin and orbitaldynamics of cubic transition metal (TM) ions having asingle electron in the three-fold degenerate t2g crystalfield levels (α=X, Y, Z). (An X orbital is a dyz

wavefunction, Y=dxz, etc.) In this idealized model theelectron hopping matrix element t(α i,α j) betweennearest neighboring TM ions on a simple cubic latticeis nonzero only for α i=α j and only if α i=α j is not thesame as the axis separating the two ions. KK showedthat their model gives rise to a Heisenberg-like spinHamiltonian with exchange integrals of order t2/U,where U is the on-site Coulomb energy. Becauseelectrons in, say, an X orbital cannot hop along the Xaxis, it is clear that the total number of electrons in Xorbitals in any given plane perpendicular to the Xaxis is a good quantum number. We (ABH, T.Yildirim, A. Aharony, O. Entin-Wohlman, and I.

Korenblit) have shown in Phys. Rev. B69, 035107(2004) that HKK is invariant with respect to a globalrotation of the spin of electrons in, say, X orbitalswhen summed over all ions in a single plane perpen-dicular to the X axis. We will give a qualitativediscussion of this and other symmetries and showhow they appear within numerical and mean fieldcalculations.

The most striking consequence of these symmetriesis that the spin correlations are two dimensional andlong range spin order can not occur at any nonzerotemperature. Since this result is in obvious disagree-ment with experimental results on systems such aslanthanum titanate, we conclude that the KK Hamil-tonian can not be a ‘minimum’ model to describesuch real systems. Stated differently, the KK Hamilto-nian, unlike the Heisenberg Hamiltonian for conven-tional magnetic materials, does not give a zerothorder description of real materials.

Accordingly, it is essential, from the outset, to includethe relevant perturbations that destroy these unusualsymmetries, if one is to understand real materials.Alternatively, although it is probably impossible tofind a real material with these exact symmetries, itmay be possible to construct systems which arenearly ideal and whose anomalous properties wouldbe a consequence of closely approximating theunusual symmetries described here.

T1-C2 (09:00) Commensurate-IncommensurateMagnetic Phase Transition in MagnetoelectricSingle Crystal LiNiPO4

D. Vaknin, J. L. Zarestky (Ames Laboratory andDepartment of Physics and Astronomy, Iowa StateUniversity, Ames, Iowa 50011)

Neutron scattering studies of single-crystal LiNiPO4

reveal a spontaneous first-order commensurate-incommensurate magnetic phase transition. Short-and long-range incommensurate phases are interme-diate between the high temperature paramagneticand the low temperature antiferromagnetic phases.The modulated structure has a predominant antifer-romagnetic component, giving rise to satellite peaksin the vicinity of the fundamental antiferromagneticBragg reflection, and a ferromagnetic componentgiving rise to peaks at small momentum-transfersaround the origin at (0,± Q,0). The wavelength ofthe modulated magnetic structure varies continu-ously with temperature. It is argued that the incom-mensurate short- and long-range phases are due tospin-dimensionality crossover from a continuous tothe discrete Ising state. These observations explainthe anomalous first-order transition seen in the


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magnetoelectric effect of this system.

T1-C3 (09:15) Neutron Scattering Study of TbPtInIntermetallic Compound

V. O. Garlea, J.L. Zarestky, E. Morosan, S.L. Bud’ko,P.C. Canfield, C. Stassis (Ames Laboratory andDepartment of Physics and Astronomy, Iowa StateUniversity, Ames, Iowa 50011)

Neutron diffraction techniques have been used tostudy the magnetic properties of TbPtIn as a functionof temperature and magnetic field. The measure-ments were performed on single crystals, using theHB1A triple-axis spectrometer at the High FluxIsotope Reactor (HFIR). This compound crystallizes inthe hexagonal ZrNiAl-type structure and can bedescribed as the alternate stacking of Tb-Pt and In-Ptlayers perpendicular to the c-axis. The rare-earth sitesform a triangular lattice; in the case of antiferromag-netic coupling between nearest neighbors, thistopology induces a frustration of the magneticinteraction. In the absence of an externally appliedmagnetic field, the compound orders, below approxi-mately 47 K, in an antiferromagnetic structure withpropagation vector k = (½, 0, ½). The magneticmoments were found to be along the [1-20] symme-try direction by measurements in the plane definedby the [101] and [1-20] directions. Measurementsperformed in the a-c plane, at 4.2 K, with a magneticfield applied along the [1-20] direction, reveal atransition from the zero field antiferromagnetic stateto a state with a net ferromagnetic component, atapproximately 2 T, followed by another transition to astate with a larger ferromagnetic component, atapproximately 4 T. Field cooled and zero field cooledmeasurements were also performed with the mag-netic field applied along the [-110] direction, perpen-dicular to the direction of the magnetic moments.Two transitions were observed: one at 2 T and theother at 5.5 T. Of particular interest is the fact thatabove the second transition, at 5.5 T, and up to 6.8 T,we did not observe any antiferromagnetic reflectionsor appreciable changes in the nuclear reflections.Models of the magnetic structure are used in theanalysis of the experimental data.

T1-C4 (09:30) Spin Density Waves in IronAluminides

A. S. Arrott, D.R. Noakes (Virginia State University)The transition from ferromagnetism with increasingAl concentration in the iron-aluminides now appearsto be a change from ferromagnetism to a complexspin density wave state. This discovery by neutrondiffraction opens a new field of investigation thatshould have an impact comparable to that of the spindensity waves in chromium over the past forty years.

If one views the magnetic structure of Cr consideringonly the atoms on the corners of the body centeredcubic lattice, one finds a periodic modulation of thespin polarization over long distances. The same istrue for the spin density wave in the iron aluminides.The difference between Cr and the iron aluminides isthat the polarization of the center atoms of Cr isalmost opposite to that of the corner atoms while forthe iron aluminides the polarization of the centeratoms is almost parallel to that of the corner atoms.The change from the spin density wave state in theiron aluminides to the ferromagnetic state can beviewed as an increase in the spatial period of theantiferromagnetic structure. This treats the wavevectors about the origin as being the most importantones. But if one takes the wave vectors that are closeto the 110 reciprocal lattice vectors as controlling,then the transition is from an incommensurate spindensity wave state to a commensurate spin densitystate where all the atoms are at the positive (ornegative) peaks of wave. It is a trivial statement tosay that every ferromagnet is such a spin densistywave, but in the case of the iron aluminides there is agood reason to adopt that view. The transition fromferromagnetism then appears to be the swingingaway of the spin density wave vector from matchingthe 110 reciprocal lattice vectors to reach the ob-served nearby incommensurate position. Thissuggests that wave vectors spanning the Fermisurface play an important role in the origin offerromagnetism in this highly itinerant electronsystem.

T1-D, Neutron Sources, Chair: Roger Pynn(LANL), Auditorium

T1-D1 (08:30) Status of the Low Energy NeutronSource at Indiana University

D. V. Baxter, J. M. Cameron, V. P. Derenchuk, C.Lavelle, M. A. Lone, M. B. Leuschner, H. O. Meyer, H.Nann, T. Rinckel, W. M. Snow (Indiana UniversityCyclotron Facility, 2401 Milo Sampson Ln,Bloomington IN 47408)

The National Science Foundation has recentlyapproved funding for the LENS (Low Energy NeutronSource) facility at Indiana University and constructionhas begun. LENS represents a new paradigm foreconomically introducing neutron scattering into auniversity or industrial setting. Neutrons are pro-duced in a long-pulse (1 ms) mode through (p,n)reactions on a water-cooled Be target and supplied tothree instrument beam lines. We will describe howLENS will use neutrons to fulfill a three-fold missionin education, materials research, and developingnovel instrumentation. Of particular interest are the


facility’s ability to study cryogenic moderators atsignificantly lower temperatures than is possible atother facilities and the development of instrumentsthat make use of the neutron spin to perform high-precision measurements of momentum transferwithout significant collimation of the beam. Thepotential for these developments to expand signifi-cantly the range of problems amenable to explora-tion with neutron techniques will be discussed.

T1-D2 (08:45) The Australian Replacement Re-search Reactor

R. A. Robinson, S. J. Kennedy (Bragg Institute,Australian Nuclear Science and TechnologyOrganisation, Australia)

The 20-MW Australian Replacement ResearchReactor represents possibly the greatest singleresearch infrastructure investment in Australia’shistory. Construction of the facility has commenced,following award of the construction contract in July2000, and the construction licence in April 2002.First fuel will go into the reactor in November 2005,with the facility at full power in early 2006 and fullycommissioned in July 2006. The project includes alarge state-of-the-art liquid deuterium cold-neutronsource and supermirror guides feeding a largemodern guide hall, in which most of the instrumentsare placed. Alongside the guide hall, there is goodprovision of laboratory, office and space for supportactivities. While the facility has “space” for up to 18instruments, the project has funding for an initial setof 8 instruments, which will be ready when thereactor is fully operational. Instrument performancewill be competitive with the best research-reactorfacilities anywhere. Staff to lead the design effort andman these instruments have been hired on theinternational market from leading overseas facilities,and from within Australia, and 7 out of 8 instrumentshave been specified and costed. At present theinstrumentation project carries > 10 % contingencyand 50 % of procurements have been placed. Anextensive dialogue has taken place with the Austra-lian user community and our international peers, viavarious means including a series of workshops overthe last 2 years covering all 8 instruments, emergingareas of application like biology and the earthsciences, and computing infrastructure for theinstruments.

In December 2002, ANSTO formed the Bragg Insti-tute, with the intent of nurturing strong externalpartnerships, and covering all aspects of neutron andx-ray scattering, including research using synchrotronradiation.

T1-D3 (09:00) The Fundamental Neutron PhysicsBeamline at the Spallation Neutron Source

G. L. Greene (University of Tennessee; Oak RidgeNational Laboratory), T.V. Cianciolo (Oak RidgeNational Laboratory), W.M. Snow (IndianaUniversity), P. Huffman (National Institute ofStandards and Technology; North Carolina StateUniversity), J. D. Bowman, M. Cooper (Los AlamosNational Laboratory), J. Doyle (Harvard University)

The Spallation Neutron Source (SNS), currently underconstruction at Oak Ridge National Laboratory withan anticipated start-up in early 2006, will provide themost intense pulsed beams of cold neutrons in thewould. At a projected power of 1.4 MW, the timeaveraged fluxes and fluences of the SNS will ap-proach those of high flux reactors. One of the flightpaths on the cold, coupled moderator will be devotedto fundamental neutron physics. The fundamentalneutron physics beamline is anticipated to includetwo beamlines; a broad band “cold” beam, and amonochromatic beam of 8.9 Å neutrons for ultra coldneutron experiments. The fundamental neutronphysics beamline will be operated as a user facilitywith experiment selection based on a peer reviewedproposal process. An initial program of five experi-ments in neutron decay, hadronic weak interactionand time reversal symmetry violation have beenproposed. A description of the proposed facility willbe given and project status will be reviewed.

T1-D4 (09:15) Experimental test of the coldcoupled liquid H2 moderator at LANSCE

M. Russina (Los Alamos Neutron Science Center,Los Alamos National Laboratory), F. Mezei (LosAlamos Neutron Science Center, Los AlamosNational Laboratory; Hahn-Meitner-Institut Berlin),P. Lewis, T. Kozlowski (Los Alamos Neutron ScienceCenter, Los Alamos National Laboratory), S. Penttila(Los Alamos National Laboratory)

We present the results of a performance test of thecoupled cold liquid H2 moderator installed at ManuelLujan Jr. Neutron Scattering Center (Lujan Center) atLANSCE. This moderator is the first of its kind everinstalled on a spallation source. To measure themoderator performance we have implemented anovel method based on two-dimensional time-of-flight (TOF) analysis to determine both the pulseshape and the absolute value of the flux. The key ofthe setup was a mechanical chopper with a smalldiaphragm placed close to half way between themoderator and a detector in the beam axis. Thechopper run asynchronously to the source andneutron counts were stored in a two dimensionalhistogram I(to,tch), where to and tch are, respectively,the times elapsed since the last firing of the source


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and the last chopper opening. The method functionswith full efficiency without phasing the chopper tothe source and it is in this sense a precursor examplefor the event recording data collection approach,which will enable us to fully eliminate the effects ofthe jitter of chopper phasing on pulsed sourcespectra.

Using this approach we determined the moderatortime average- and the peak flux, the time structure ofthe pulse as a function of neutron wavelength as wellas observed the influence of radiation on the perfor-mance of the supermirror neutron optics placed closeto the source inside the bulk shield. In addition thetemperature dependence of the moderator character-istics have been checked in the H2 temperature rangeof 20 K to 25 K. For this purpose we used an im-proved experimental setup with higher resolution.The data show that the coupled moderator atLANSCE provides the highest cold neutron flux (bothaverage and peak) at pulsed spallation sources in theworld and that the peak intensity of the pulse ex-ceeds the intensity of the ILL.

T1-D5 (09:30) Technical Concepts for a Long-Wavelength Target Station for the Oak RidgeSpallation Neutron Source (Invited)

J. M. Carpenter (SNS, Oak Ridge NationalLaboratory, IPNS, Argonne National Laboratory)

We describe technical concepts for a second targetstation for the Oak Ridge Spallation Neutron Source(SNS.) From the outset, the design for the SNS hasincluded the capacity for a second target station,which we conceive to be one that emphasizesprovisions for long-wavelength applications. A groupcentered at Argonne has worked out and evaluatedthe design of a Long-Wavelength Target Station(LWTS) with a suite of possible instruments andsupporting scientific cases. The LWTS will use thesame proton delivery system as the High-PowerTarget Station (HPTS) now nearing completion,sharing a fraction of the available beam power inshort, 10-Hz pulses and, for purposes of conceptevaluation, 333 kW of beam power, and comple-menting the capabilities of the HPTS. The conceptincorporates a number of new features, emphasizingcold neutron production and utilization, especiallyextensive use of neutron guides. The instrumentsuite, compiled mainly for reference purposes, willenable measurements that extend the range acces-sible at HPTS.

TP - Poster Session II (Main Concourse; 10:30)

TP1: Influence of Cholesterol and Temperature onthe Thickness of SOPC and DOPC UnilamellarVesicles measured by Small-Angle Neutron Scatter-ing

J. Pencer (Department of Chemical andBiomolecular Engineering, The Johns HopkinsUniversity; NIST Center for Neutron Research)

Cholesterol-rich lateral domains or “rafts” are be-lieved to serve a number of crucial roles in biologicalfunction. The formation of such domains in modelsystems has been shown to depend on the miscibilityof lipids and cholesterol, and, in particular, on thedegree of lipid chain unsaturation. There is evidencethat the miscibility of cholesterol with different lipidsis correlated with its influence on membrane bilayerproperties such as fluidity, acyl-chain order param-eters, and membrane thickness. Thus, measurementsof cholesterol’s influence on lipid bilayer thicknessshould provide information regarding lipid – choles-terol interactions and miscibility.

In this study, small-angle neutron scattering (SANS) isused to characterize the influence of cholesterol onthe thickness of large unilamellar vesicles (LUVs)composed of either stearoyloleoylphosphatidyl-choline (SOPC) or dioleoylphosphatidylcholine(DOPC). It is found that the presence of ~ 40 %cholesterol in SOPC LUVs results in an apparentincrease of membrane thickness of approximately4.5 Å, while ~ 40 % cholesterol in DOPC LUVsresults in an apparent thickness decrease of 1.5 Å.The thickness of SOPC and DOPC LUVs with andwithout cholesterol was also studied as a function oftemperature. It was found that membrane thicknessdecreased linearly with increasing temperature for allmembrane compositions examined. Our resultssuggest that there are significant differences incholesterol’s interactions with SOPC and DOPC overphysiologically relevant temperatures (from 25 °C to55 °C). We comment on the implications of ourresults for the relative efficacy of SOPC and DOPC asnon-raft components in raft-forming lipid mixtures.

TP2: Structural Comparison of Two EUO-typeZeolites Investigated by Neutron Diffraction

I. Peral (Department of Materials Science andEngineering, University of Maryland; NIST Centerfor Neutron Research), C. Y. Jones (NIST Center forNeutron Research), S. P. Varkey (Department ofChemical Engineering, Northwestern University,Evanston, IL 60208), R. F. Lobo (Center for CatalyticScience and Technology, University of Delaware,Newark, DE 19716)


Souverijns et al. [1] found different molecularselectivity properties in two EUO-types zeolites thatare crystallized in presence of two organic templates:hexamethonium (HM) and dibenzylammonium ions(DBDMA). They suggested that this dissimilarity inthe molecular shape selectivity is originated from adifferent distribution of the active sites over the sidepockets and the main channels of the EUO zeolites.We have studied the structure of both zeolites byneutron diffraction to investigate their thesis. Thestructural comparison of the two EUO-type zeolitesagrees with the model proposed by Souverijns et al.[1].[1] W. Souverijns, L. Rombouts, J.A. Martens and P.A.Jacobs, Microporous Materials, 4 (1995) 123.

TP4: Neutron diffraction of ZrBe2D1.5, ZrBe2Hx andinelastic scattering studies of hydride phases inZrBe2H0.6

Z. Chowdhuri (NIST Center for Neutron Research;University of Maryland, College Park), R.L.Cappelletti, T.J. Udovic, Q. Huang (NIST Center forNeutron Research)

ZrBe2 has the P6/mmm structure (also found in MgB2)consisting of triangular nets of Zr separated byhoneycomb nets of Be. The hydrides ZrBe2Hx displaya phase having the same structure in which Hdiffuses among the honeycomb interstitial sites in thetriangular Zr planes. Phases with ordering of the Hatoms on a sublattice of the honeycomb appearbelow an ordering temperature that depends on x.The results of neutron quasielastic scattering mea-surements made at widely different resolutions ontwo spectrometers (DCS: FWHM 64 µeV, and HFBS:FWHM 1 µeV) are reported on a powder sample ofthe ZrBe2H0.6. The data for all momentum transfers(0.3 Å-1 to 1.7 Å-1) at each temperature are analyzedin terms of a one-parameter model for independentparticle hopping on a honeycomb lattice for thequasielastic portion and an additional elastic term.Monte Carlo calculations verify the validity of theindependent particle approximation at this concen-tration. This work utilizes facilities supported in partby the National Science Foundation under AgreementNo. DMR-0086210.

TP5: Hydration-kinetics and Water Content ofCement: Quasi-Elastic Neutron SpectroscopyStudies

N. M. Nemes (NIST Center for Neutron Research;Department of Materials Science and Engineering,University of Maryland), J. C. McLaughlin, D. A.Neumann (NIST Center for Neutron Research), R. A.Livingston (Office of Infrastructure R&D, FederalHighway Administration, McLean, VA 22101)

Portland cement is a complex non-homogeneousmaterial, with many different constituent phases andstructure over a wide range of length scales. Thehydration of Portland cement is a complex processinvolving several simultaneous chemical reactions. Allof these reactions involve water, and as hydrationproceeds, more of the water that is initially mixedwith the cement powder becomes chemically boundinto reaction product phases. Quasi-elastic neutronscattering (QENS) allows for the study of the state ofwater in hydrating cement paste in situ over time andover a wide range of temperatures. QENS provides adirect measure of the conversion of free water tostructurally/chemically bound water and to waterconstrained in the pores of the cement paste.

We studied the hydration kinetics of synthetic cementpaste with varying alite/belite (dicalcium silicate orC2S and tricalcium silicate or C3S) and varying water/cement ratios. The time-dependent free, constrainedand bound water results are analyzed in terms of theAvrami-model for the nucleation and growth regimeand in terms of a diffusion-limited growth model forthe later period. The results reveal the complexnature of the chemistry governing the hydration ofcement as the dependence of the model parameterson the C2S/C3S ratio is highly non-linear.

The role of the water/cement ratio (w/c) on thehydration kinetics has been investigated using QENS.For a range of w/c from 0.3 to 1, the bound-waterindex was extracted from the neutron scatteringdata, and fitted to hydration kinetics model devel-oped in previous QENS studies. The w/c ratio had nosignificant effect on the model parameters for thediffusion limited period, but it did affect the nucle-ation and growth stage.We also studied the water content of mature samplesby drying to varying degrees in saturated salt solu-tions. The results indicate that the free and con-strained water contents are lost at a similar rate.

TP6: Neutron scattering studies of hydrogendynamics in Pr2Fe17HX

E. Mamontov (University of Maryland, College Park;NIST Center for Neutron Research), T. J. Udovic(NIST Center for Neutron Research), O. Isnard(Institut Laue Langevin), J. J. Rush (NIST Center forNeutron Research)

Hydrogen has a profound influence upon the struc-tural and magnetic properties of the fundamentallyinteresting R2Fe17 rare-earth compounds. Typical ofsuch compounds, Pr2Fe17 crystallizes in the Th2Zn17

rhombohedral (R-3m) structure. Hydrogen can insertinto Pr2Fe17 to form the hydrides Pr2Fe17HX. Neutron


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diffraction results indicate that the first three hydro-gen atoms fully occupy the interstitial 9e octahedral(o) sites, whereas the last two hydrogen atomsoccupy one-third of the available interstitial 18gtetrahedral (t) sites [1]. Because the t-site hydrogen isbelieved to occupy only two diametrically opposedsites at the corners of a hexagon composed of six18g sites [2], it is expected that the t-site hydrogenatoms in Pr2Fe17H4 and Pr2Fe17H5 would readily jumpbetween the available 18g sites. Our quasielasticneutron scattering measurements confirm thepresence of localized hydrogen motion in Pr2Fe17H3

and Pr2Fe17H5. The time between jumps is on theorder of 100 ps at 200 K and decreases as tempera-ture is increased. Neutron vibrational spectra ofPr2Fe17HX (x = 3, 5) and Pr2Fe17DX (x = 2, 3, 4, 5) arefound to be consistent with the hydrogen locationsdetermined by diffraction. For example, for Pr2Fe17H3,two peaks centered at ~105 meV and 85 meVcorrespond to the normal modes of the octahedralhydrogens in the ab plane and along the c axis,respectively. For Pr2Fe17H5, the c-axis mode for the o-site hydrogen softens considerably, in part due to thelarge lattice expansion along the c direction causedby the extra hydrogen occupying some of the t sites.In addition to the slightly softened ab-planar modesof the o-site hydrogen, there is extra scatteringintensity at 110 meV and above due to the relativelyhigher-energy normal modes of the t-site hydrogen.

[1] O. Isnard, S. Miraglia, J. L. Soubeyroux, D.Fruchart, and A. Stergiou, J. Less-Common Met. 162,273 (1990).[2] O. Isnard, S. Miraglia, J. L. Soubeyroux, and P.L’Heritier, J. Magn. Mater. 137, 151 (1994).

TP7: Electronic, Magnetic and Structural Propertiesof SrAMnMO6 Double Perovskites (A = Sr, La; M =Mo, Ru)

P. M. Woodward, J. Goldberger, P. N. Santhosh(Department of Chemistry, Ohio State University), P.Karen (Department of Chemistry, University ofOslo), A. R. Moodenbaugh (Department of Materialsand Chemical Science, Brookhaven NationalLaboratory)

The electronic, magnetic and structural properties ofSr2MnMoO6, SrLaMnMoO6 Sr2MnRuO6 andSrLaMnRuO6 have been investigated. Powder diffrac-tion measurements show that both Sr2MnMoO6 andSrLaMnMoO6 adopt long-range, rock salt ordering ofthe transition metal ions, while transition electronmicroscopy reveals short-range cation order inSr2MnRuO6 and SrLaMnRuO6. All indicators suggestthat Sr2MnMoO6 and SrLaMnMoO6 are Mott-insula-tors. They exhibit relatively low conductivities

(1 x 10-2 Ω-1-cm-1 at 290 K), Curie-Weiss magneticbehavior, and well defined transition-metal valenceand spin states: Sr2Mn2+Mo6+O6 adopts a G-typeantiferromagnetic structure (TN ~ 10 K), whereasSrLaMn2+Mo5+O6 is a spin glass (TG ~ 85 K). Theruthenates are more conductive by roughly fourorders of magnitude at room temperature.Sr2MnRuO6 has a room temperature conductivity of1 x 102 Ω-1-cm-1, with a temperature dependencecharacteristic of Mott variable-range hopping behav-ior. It orders antiferromagnetically (C-type) near180 K, and exhibits a cooperative Jahn-Teller distor-tion (orbital ordering). The room-temperature electri-cal conductivity of SrLaMnRuO6 is similar to that ofSr2MnRuO6 (4 x 101 Ω-1-cm-1) and bond distancessuggest that both compounds contain Mn3+. How-ever, the substitution of La3+ for Sr2+ leads to adisappearance of the cooperative Jahn-Teller distor-tion, a change in the conductivity mechanism(diffusion-assisted small-polaron hopping), andstabilizes a ferromagnetic ground state (TC ~ 220 K).

TP8: Investigation of the State of Water in Hydrat-ing Layered and Amorphous Sodium Disilicate(Alkali-Silica Reactants) by Quasi-elastic NeutronScattering.

J.W. Phair, R.A. Livingston (Office of InfrastructureResearch and Development, Federal HighwayAdministration, McLean, VA), C.M. Brown (NISTCenter for Neutron Research; Department ofMaterials Science and Engineering, University ofMaryland), A.J. Benesi (Department of Chemistry,The Pennsylvania State University, University Park,PA)

The structure and state of water within hydratinglayered and amorphous sodium-disilicate weremonitored for the first time using quasi-elasticneutron scattering (QENS) and x-ray diffraction(XRD). The QENS kinetic data collected for the first12 hours of the reaction, were fitted to a modelconsisting of a Lorentzian and a Gaussian functioneach convoluted with the energy resolution of theinstrument. This allows the QENS signal from waterto be associated with two states that include boundand free water, as confirmed by thermogravimetricanalyses and 2H NMR. In situ QENS data werecollected for a set of sodium disilicate and silicamixtures at a series of discrete temperatures between20 and 40 °C. The bound water was successfullymodelled with Langmuir adsorption kinetics toexplain the formation of a layered silicate structurewithin kanemite. Langmuir adsorption kinetics werealso used to model the reaction using amorphousstarting material suggesting the presence of layeredstructure in the reaction product. The presence of the


layered structure in amorphous material was con-firmed by XRD analyses. The consequences this hasfor alkali-silica reaction (ASR) gel reaction and itsswelling mechanism are discussed. Based on theseresults, a standard test for ASR reactivity of aggre-gates could be developed using natrosilite as stan-dard reagent, and the kinetic parameters as a scale ofreactivity.

TP9: Quantitative Texture Analysis of HighlyAbsorbing Materials from Neutron TOF Data

H. Volz, S. Vogel, J. Roberts, D. Williams, A. Lawson,L. Daemen, T. Medina, M. Geelan (Los AlamosNational Laboratory)

The orientation distribution functions (ODF) of rolledfoils of dysprosium and erbium metals were deter-mined from neutron time-of-flight (TOF) data usingfull pattern Rietveld analysis with GSAS. The ODFwere fit with spherical harmonics. Both Dy and Erhave a hexagonal close-packed (hcp) crystal structure,and are strong absorbers for neutrons with thermalabsorption cross-sections of 994 barns for Dy and159 barns for Er at λ = 1.8 Å. Various stacks of foilsof each material, along with combinations of absorb-ing and less-absorbing foils, were measured on theneutron powder diffractometer HIPPO at LANSCE.The focus of this work is on the comparison ofabsorption corrections implemented in the GSASRietveld code, and the impact of strong absorptionon data analysis. We compare our resulting polefigures from the ODF with those in the literature, andfind good agreement.

TP10: Octahedral Tilting Distortions in 2:1 B-siteOrdered Perovskites

Michael Lufaso (Ceramics Division, MSEL, NationalInstitute of Standards and Technology)

Perovskite materials that exhibit a 2:1 ordered cationarrangement and also undergo an octahedral tiltingdistortion exhibit interesting changes in the tempera-ture dependence of the dielectric properties, whencompared to the untilted 2:1 ordered perovskites(e.g., Ba3ZnTa2O9). The onset of octahedral tilting inthe 2:1 B-site cation ordered perovskites is well-known to influence the physical properties; howeverthe crystal structures have not been reported. Poly-crystalline samples of Sr3MM’2O9 (M = Mg, Ni;M’ = Nb, Ta) were synthesized and neutron powderdiffraction data were collected, at the High-IntensityPowder Diffractometer at the Los Alamos NeutronScience Center, as a function of temperature. Thestructural parameters, obtained from a neutron time-of flight data analysis via Rietveld refinement, arecompared.

TP11: Neutron Diffraction Study of Magnetic,Structural, and Charge Ordering in La0.48Ca0.52MnO3

and La0.52Ca0.48MnO3

E. Rodriguez, T. Proffen, A. Llobet, J.J. Rhyne (LosAlamos Neutron Science Center, Los AlamosNational Laboratory)

Mixed valence manganites show an enormously richrange of magnetic, structural, and transport proper-ties with varying stoichiometric composition andtemperature. Neutron powder diffraction studies weredone on the perovskite manganite La1-xCaxMnO3

series for compositions x = 0.48 and x = 0.52. Theinterplay between the magnetic, charge, and struc-tural ordering forms a complex system due to an admixture of Mn4+ and Mn3+ ions in these composi-tions. These two compositions alone exhibit interest-ing physical properties such as coexisting ferromag-netic and anti-ferromagnetic phases at the sametemperature. Studies have shown the x = 0.5composition to be the metal-insulator transition (MIT)interface for this manganite series. Therefore, phaseseparation at lower temperatures and the magnetictransition temperatures are important characteristicsexamined in this analysis. The neutron powdermeasurements were done on two spallation-sourcediffractometers located at the Manuel Lujan Jr.Neutron Scattering Center at Los Alamos NationalLaboratory. In addition to crystallographic andmagnetic structure analysis, a pair-distributionfunction (PDF) study was done as well. A PDFanalysis provides short-range order information ofmanganites such as the distortion of its perovskitestructure due to the Jahn-Teller effect. This studyhopes to understand the magnetic, structural, andtransport properties of these manganites for compo-sitions close to and on opposite sides of the MITboundary.

TP12: Neutron Diffraction Investigation of Shape-Memory Alloys during Mechanical Loading atCryogenic Temperatures

S. Shmalo, T. Woodruff, C.R. Rathod (AMPAC/MMAE, University of Central Florida), V. Livescu,M.A.M. Bourke (Los Alamos National Laboratory),W. Notardonato (NASA Kennedy Space Center), R.Vaidyanathan (AMPAC/MMAE, University of CentralFlorida)

The shape-memory effect refers to a phenomenonwherein a material on being heated, “remembers”and returns to a preset shape due to a phase transfor-mation. In the process of returning to the presetshape, the phase transformation can work againstlarge forces, resulting in their use as actuators. Whileshape-memory alloys have been commercially usedat cryogenic temperatures in single-use applications


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(e.g., couplings), their use at cryogenic temperaturesin cyclic, switch-type applications has been limited bya lack of understanding of the underlying deforma-tion mechanisms (i.e., phase transformation andtwinning) at cryogenic temperatures. Such an under-standing could extend the range of use of shape-memory alloys to, among others, spaceport relatedtechnologies such as latch and/or release mecha-nisms, thermal switches for cryogenic liquefactionand storage systems, fluid-line repair, valves, sealsand self-healing gaskets.

At Los Alamos National Laboratory, in situ diffractionmeasurements at stress and elevated temperaturehave been routinely used to provide quantitative,phase specific information on the evolution of strains,texture and phase volume fractions. However, acapability for simultaneous loading and neutrondiffraction spectra acquisition at cryogenic tempera-tures was unavailable. In order to investigate defor-mation in shape-memory alloys at cryogenic tem-peratures, the design of a low temperature loadingcapability for in situ neutron diffraction measure-ments has been analyzed and implemented on theSpectrometer for Materials Research at Temperatureand Stress (SMARTS). An aluminum vacuum chamberwith liquid nitrogen circulating to cool platens incontact with compression specimens was used.Preliminary results are reported here of quantitative,in situ measurements of evolving internal strains,texture, phase and twin volume fractions in therhombohedral and monoclinic phases of shape-memory NiTiFe at cryogenic temperatures. This workis supported by grants from NASA and NSF (CAREERDMR-0239512).

TP13: Understanding Octahedral Tilting Distortionsin A2M

3+M5+O6 Perovskites (M5+ = Ta, Nb, Sb)P. W. Barnes (The Ohio State University; ArgonneNational Laboratory), P. M. Woodward (The OhioState University), P. Karen (University of Oslo,Norway), M. W. Lufaso (The Ohio State University;National Institute of Standards and Technology)

The perovskite structure with 1:1 M-site cationordering (i.e., double or complex perovskites;A2MM’X6) is a well-known and extensively studiedstructure type in solid- state chemistry. The idealdouble perovskite has cubic symmetry, but many aredistorted from the ideal structure. Structural distor-tions seen in complex perovskites are caused byelectronic factors (e.g., Jahn-Teller ions), random orpartial M-cation ordering, and most commonly,octahedral tilting. Tilting of the octahedra within theperovskite structure leads to lowering of its symme-try. A major factor that influences the degree ofoctahedral tilting in a given compound is the nature

of the cuboctahedral A-cation. Perovskites with Ba2+

as the A-site cation typically exhibit cubic symmetryand those with Ca2+ have orthorhombic or mono-clinic symmetry. Changes (or lack of) in space groupsymmetry for A = Ba2+ and Ca2+ are often easilyseen in the x-ray powder diffraction data (XRPD) oftheir respective compounds. Yet, compounds with A= Sr2+ are prone to subtle octahedral tilting distor-tions that are not readily seen in XRPD, so many aremistakenly assigned to the incorrect space group. Inthis study, twelve pseudo-symmetric doubleperovskites with A = Sr2+ (M3+ = Sc, Cr, Mn, Fe, Co,Ga, Y; M5+ = Nb, Ta, Sb), Ba2YNbO6, and Ca2CrTaO6

were examined by Rietveld refinement of XRPD andneutron powder diffraction data (NPD) in order toappropriately discern their respective crystallographicsymmetry. The approach taken for determiningappropriate possible space groups for these composi-tions, the extent of M-site cation ordering, the degreeof octahedral tilting, and a comparison of the drivingforces behind these two distortions in compoundscontaining transition metal vs. main group metalcations will be discussed.

TP14: Neutron and Thermodynamic Investigationof Alkane Adsorption on MgO(100) Surfaces

R. E. Cook, S. Chanaa, M. J. Farinelli, P. N. Yaron(The University of Tennessee - Department ofChemistry), T. Arnold (Oak Ridge NationalLaboratory - Chemical Sciences Division), L. L.Daemen (Los Alamos Neutron Science Center, LosAlamos National Laboratory), T. Ramirez-Cuesta(ISIS, Rutherford Appleton Laboratory), S. Clarke(University of Cambridge - Department ofChemistry), J. Z. Larese (The University ofTennessee - Department of Chemistry; Oak RidgeNational Laboratory - Chemical Sciences Division)

The adsorption properties of the first four membersof the normal alkanes (methane, ethane, propane,butane) and films on the MgO (100) surface wereinvestigated using neutron scattering and volumetricisotherm techniques. A series of high-resolution,adsorption isotherm measurements were performedusing an automated adsorption apparatus. These datawere used to determine both the two-dimensionalisothermal compressibility and the isosteric heat ofadsorption and to identify regions where phasetransitions might occur. In all cases we find evidencefor the presence of at least three layering transitions.We present our results to date of our investigations ofthe monolayer and multilayer solid phases usingneutron diffraction and inelastic neutron spectros-copy (rotational and vibrational). Some preliminaryindications of the nature of the dynamical propertiesof these solid phases will be presented by making


comparisons of the neutron spectra with calculationsof the molecular-vibrational modes. We will compareour results to other related experimental investiga-tions where appropriate.

TP15: Studies on long range and short rangeordering in Y-doped La2Zr2O7

E.A. Payzant, S.A. Speakman, R.D. Carneim, T.R.Armstrong (Oak Ridge National Laboratory, OakRidge, TN), T.E. Proffen ( Los Alamos NationalLaboratory, Los Alamos, NM)

Selected compositions in the La2Zr2O7-LaYO3 systemhave been produced using glycine-nitrate process, aspotential candidate materials for gas separationmembranes. Refinement of x-ray diffraction datafrom such materials cannot resolve the oxygen sitepositions and occupancies to sufficient precisionbecause of the presence of high-Z scatterers such asLa, Y, and Zr, yet this is precisely the information thatis critical to explain the ion mobility. Neutron scatter-ing data was acquired using the high-resolution totalscattering neutron powder diffractometer NPDF atLANSCE. A combination of structural (i.e., Reitveld)and pair distribution (i.e., PDF) analyses of thediffraction data provide important insight into theproperty-structure relationships in these materials.Research sponsored by the Laboratory DirectedResearch and Development Program of Oak RidgeNational Laboratory (ORNL), managed by UT-Battelle,LLC for the U. S. Department of Energy underContract No. DE-AC05-00OR22725. This work hasbenefited from the use of the Los Alamos NeutronScience Center at the Los Alamos National Labora-tory. This facility is funded by the US Department ofEnergy under Contract W-7405-ENG-36.

TP16: Inelastic Neutron Scattering Spectra ofSimple Porphyrins

N. Verdal, B. S. Hudson (Department of Chemistry,Syracuse University, Syracuse, NY), P. Kozlowski(Department of Chemistry, University of Louisville,Louisville, KY)

Porphine is the simplest of all porphyrins, a group ofmolecules pervasive in biological systems and thus initself an interesting molecule. The biologically activeporphyrin, typically an iron porphyrin, or hemegroup, is often involved in an oxidation/reductionreaction and thus small movements are important tobiological function. In addition, it is used as a probein resonance Raman studies in which the vibrationalspectrum of the resonant group is used to probechanges in the protein environment associated withconformational changes. A more complete under-standing of the porphine vibrations will place theseprobe applications on a more firm basis.

Inelastic neutron scattering (INS) spectra have beencollected for both porphine and zinc porphine usingthe ISIS TOSCA spectrometer. These spectra havebeen compared with the results of both ab initio andthe semi-empirical scaled quantum mechanicalmethod calculations. The scaled quantum mechanicalmethod uses a force field calculated by densityfunctional theory using the B3LYP functional and the6-31G* basis set. These calculations have beenpreviously compared with IR and Raman spectra withgood agreement [see J. Phys. Chem. 1996, 100, 7007-7013]. The advantage of INS is that it is not subject tooptical selection rules and allows a more completecomparison with the frequency and intensity outputfrom ab initio and semi-empirical calculations. Goodagreement between the INS spectra and the scaledquantum mechanical results are observed.

TP17: Neutron Diffraction Studies on theSuperionic-conducting Composite (AgI)0.6(NaPO3)0.4

E. Kartini (R & D Center for Materials Science andTechnology, National Nuclear Energy Agency,Tangerang 15314, Indonesia), M.F. Collins(Deparment of Physics and Astronomy, McMasterUniversity, Hamilton. ON, Canada), A. Purwanto (R& D Center for Materials Science and Technology,National Nuclear Energy Agency, Tangerang 15314,Indonesia; Neutron Science Laboratory, KEK,Tsukuba, Japan), T. Kamiyama (Neutron ScienceLaboratory, KEK, Tsukuba, Japan), K. Itoh (KyotoUniversity Research Reactor Institute, Kumatori-cho, Japan), T. Sakuma (Department of Physics,Ibaraki University, Mito, Japan)

Superionic conductors are of considerable interestfrom both application and fundamental point of view.An ionic conductivity of at least 10-3 S/cm is neededfor use in solid electrolytes, batteries, fuel cells andsensors. We have successfully made a new superioniccomposite (AgI)0.6(NaPO3)0.4 by melt quenching. Thismaterial exhibits a high ionic conductivity of about2 x 10-3 S/cm at ambient temperature, whereas theconductivity of crystalline AgI and NaPO3 glass areorders of magnitude lower. (AgI)0.6(NaPO3)0.4 is acomposite material containing both crystalline andglass phases. To understand the ionic conductionmechanism two neutrons experiments have beenperformed. Firstly to investigate the crystalline phasemeasurements have been made by the high-resolu-tion powder diffractometer VEGA, and secondly, thestructure factor of the glass phase has been mea-sured by the time of flight High Intensity TotalScattering instrument (HIT-II). Both measurementswere performed at the Neutron Science Laboratory(KENS), KEK, Japan.


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TP18: Vibrational Spectroscopy with the NISTFilter-Analyzer Neutron Spectrometer (FANS)

J.B. Leao, T.J. Udovic (NIST Center for NeutronResearch), C.M. Brown (NIST Center for NeutronResearch; Department of Materials Science andEngineering, University of Maryland), D.A.Neumann (NIST Center for Neutron Research)

Neutron vibrational spectroscopy (NVS) is an invalu-able technique for investigating solid-state vibrationaldynamics. In particular, the typical range of energiesaccessible with reactor- and pulse-source-basedneutrons spans the region of important lattice andmolecular vibrations. Moreover, the unique nature ofthe neutron-nucleus interaction permits the observa-tion of all vibrational modes in an NVS experiment,not just those that satisfy appropriate symmetry-based selection rules as in photon spectroscopies.NVS is particularly useful for characterizing hydrog-enous materials since the incoherent scattering crosssection for hydrogen is much larger than for virtuallyall the other elements. Over the past couple of years,neutron vibrational spectra have been collected for abroad array of both hydrogenous andnonhydrogenous systems utilizing the significantlyimproved Filter-Analyzer Neutron Spectrometer(FANS) at the NIST Center for Neutron Research. Herewe exemplify the impact that FANS can have as aunique spectroscopic probe of materials within thefields of physics, chemistry, and biology.

TP19: Progress Toward Thermal Neutron LaueDiffraction at the NCNR

B. H. Toby, C. Y. Jones, A. Santoro, P. C. Brand, T.Prince (NIST Center for Neutron Research), T. D.Pike (Department of Physics & Astronomy, JohnsHopkins University; NIST Center for NeutronResearch), D. L. Jacobson (Physics Laboratory,National Institute for Standards & Technology,Gaithersburg, MD 20899-8461)

A test station is being developed to explore smallmolecule single-crystal neutron diffraction using athermal neutron beam (λ ~ 0.9 Å to 2.5 Å) from theCNBS thermal column. Detection for this simple andcompact prototype will be performed by activatingdysprosium foils, and replicas of the resulting activa-tion patterns will be recorded on image plates. Inconcert, novel algorithms are being developed fordata analysis from these Laue diffractograms. Thegoal of this project is to make maximal use of the fullthermal spectrum and correspondingly reduce thecrystal size needed for data collection.

TP20: Neutron Guides and Scientific NeutronEquipment at CILAS/GMI

P. Gautier-Picard (CILAS, 8 avenue buffon, BP 6319,

45063 Orléans, FRANCE)CILAS company is the world’s leading supplier ofcomplete neutron guides systems. The neutron opticswith multilayer coatings produced by CILAS havebecome an international standard for neutron beamtransportation in the modern research institutes.During the last 30 years, CILAS designed, producedand installed more than 5000 meters of guides inmany European, American and Asian countries. Toreinforce its leadership and presence in neutronresearch, CILAS acquired the company GrenobleModular Instruments (GMI), a leading company inhigh precision mechanics, engineering and manufac-turing of spectrometers and scientific equipment forneutron and synchrotron research. In this article, thedifferences between the different kind of neutronguides using Borkron, borofloat, and float glasses willbe presented. They indeed show different behaviorunder neutron flux as well in coating quality.

TP21: ZrH as a moderator for pulsed spallationneutron sources

B. J. Micklich, J. M. Carpenter (Argonne NationalLaboratory)

Several types of neutron scattering instruments,including spectrometers such as HRMECS at IPNSand perhaps TOF-USANS, could profitably use asource of neutrons prolific in the few hundred meVrange. A moderator of ZrH2, which has energy levelsat ω where ω = 0.137 eV, could provide such aneutron energy spectrum when operated at elevatedtemperature. ZrH2 has seen application as a modera-tor for nuclear reactors, either alone or in the form ofZrH-U fuel elements of a TRIGA reactor, because of itsunusual temperature-dependent thermalizationproperties and its high hydrogen density. ZrH2

(0.07066 atoms/bn-cm) has a higher hydrogen atomdensity than water (0.0662 atoms/bn-cm). Metal alloyphase diagrams for the Zr+H system indicate thatthe material is stable (defined here as a hydrogenpressure less than or equal to about 1 atm) for ZrH1.9

at 800 K or ZrH1.6 at 1200 K. This pressure could besupported by a vacuum-insulated stainless steelcontainer.

We calculated neutron spectral intensities andneutron emission time distributions for a ZrH2

moderator in the H moderator position at IPNS usingthe radiation transport code MCNPX and ZrH2

neutron scattering kernels available for temperaturesbetween 300 K and 1200 K. The moderator wasdecoupled and poisoned with 9.7·1020 at/cm2

gadolinum at the midplane. No attempt was made tooptimize the moderator thickness or the location ofthe poison plate. Our results show that the spectral


intensity over the energy range 0.1 eV to 1 eVincreases as the temperature of the moderatorincreases. Increases up to a factor of three over theinstalled solid methane moderator are seen in thisenergy range. These additional neutrons show up inneutron time distributions that have both higher peakintensities and a broader distribution in time.

TP22: Origin and removal of spurious backgroundpeaks in vibrational spectra measured by filter-analyzer neutron spectrometers

T.J. Udovic, D.A. Neumann, J.B. Leao (NIST Centerfor Neutron Research), C.M. Brown (NIST Center forNeutron Research; Department of Materials Scienceand Engineering, University of Maryland)

Inelastic neutron scattering is an invaluable tech-nique for measuring the vibrational spectra ofmaterials. One of the standard methods for analyzingthe energies of neutrons scattered by vibrationalmodes involves the use of polycrystalline berylliumfilters. We demonstrate that the spurious backgroundfeatures between 50 meV and 85 meV accompany-ing vibrational spectra measured with filter-analyzerneutron spectrometers are due to phonon excitationsof the beryllium filter. These features are significantlyreduced by an auxiliary polycrystalline bismuth filterplaced in front of the main filter. Such a bismuth filtercan result in only a minor attenuation in samplescattering intensity concomitant with a reduction inthe thermal- and fast-neutron background from thesample.

TP23: A multi-rotor T0 chopper for HYSPECV.J. Ghosh, I. A. Zaliznyak, S.M. Shapiro, L. Passell(Brookhaven National Laboratory)

One of the design goals for HYSPEC has been toachieve the highest possible signal-to-backgroundratio. For neutron spectrometers in general, when thesample environment is in the direct line of sight ofthe neutron source the performance of the T0chopper becomes crucial to achieving low beam-related backgrounds and, therefore, high instrumentperformance. The traditional design of these T0choppers involves a single rotor, 30 to 40 cm thick,phased so that it blocks the beam at the time ofarrival of the prompt gamma-rays and the highest-energy neutrons. As the power of the source in-creases, so does the radiation load on the T0 chop-pers. Consequently, the requirements for the amountand type of material of which these choppers aremade become more and more demanding. Inaddition, for optimum efficiency these massive rotorsshould rotate at rates of 60-120 Hz. The design ofthese choppers often becomes a delicate balancebetween neutronic performance and mechanical

safety. We propose the use of a multi-rotor setup forHYSPEC so that we do not have to compromiseeither neutronic efficiency or mechanical perfor-mance. We have studied a setup consisting of twocounter-rotating rotor pairs, where each rotor is a 10cm thick disk, made of tungsten, inconel or stainlesssteel. These counter-rotating pairs act as velocityselectors, the doubling of the effective rotation rateallows us to reduce the beam-related background. Inaddition this setup allows us to use a lot of heavymaterial for stopping the fast neutrons withoutcompromising mechanical safety. The performanceof the HYSPEC multi-rotor T0 chopper setup wasstudied using ray-tracing (MCSTAS) and neutrontransport (MCNP-X) codes. These results will bepresented and compared with the results for atraditional T0 chopper.

TP24: Optimization of a Gd-CsI neutron converterfor a GEM based neutron detector

R. Berliner (Instrumentation Associates Inc.;University of Michigan Department of Nuclear andRadiological Sciences)

In a prototype SNS neutron detector, a CsI screen,covering a layer of metallic Gd, produces low energysecondary electrons (SE) that are then amplified andlocalized by a Gaseous Electron Multiplier1 (GEM)followed by a dual charge-division X-Y pickup anode.The efficiency of the detector is critically dependenton the thickness of the Gd and CsI layers that makeup the active portion of the neutron converter. Thegeometry of the neutron converter for the neutronGEM has been optimized by Monte-Carlo calculationsof primary electron production in the Gd and SEproduction in the CsI layers. Benchmark calculationswith a modified version of Penelope,2 a standardMonte-Carlo electron transport code, were used toreproduce the results of earlier detailed modelanalysis of SE production.3 These calculations werethen extended to analyze realistic GEM neutrondetector geometries. The results of these calculationsand comparison to experimental results with theGEM neutron detector will be presented.

Supported by the DOE SBIR program under grant DE-FG02-03ER83685.

[1] F. Sauli, GEM, a new concept in electron amplifi-cation in gas detectors, Nuc. Inst. And Meth. A386(1997) 531-534.[2] J. Sempau, J.M. Fernandez-Varea, E. Acosta and F.Salvat: Experimental benchmarks of the Monte Carlocode PENELOPE. Nuclear Instruments and MethodsB 207 (2003) 107-123.


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[3] A. Akkerman, A. Gibrekhterman, A. Breskin andR. Chechik, J. Appl. Phys. 72 (11) (1992) 5429-5436.

TP25: The NCNR MBE Facility for In Situ NeutronScattering

J. A. Dura (NIST Center for Neutron Research)A molecular beam epitaxy, MBE, facility has beenbuilt to enable in situ neutron scattering measure-ments during growth of epitaxial layers. Whileretaining the full capabilities of a research MBEchamber, this facility has been optimized for polar-ized neutron reflectometry measurements. Optimiza-tion includes a compact, light weight, portabledesign, a neutron window, controllable magneticfield, large sample area with exceptional growthuniformity, and sample temperatures continuouslycontrollable from 38 K to 1300 K. A load lock cham-ber allows for sample insertion, storage of up to 4samples, and docking with other facilities. The designand performance of this chamber are described here.

TP26: Modifying High Temperature Furnaces toExtend Operating Capabilities

J.S. Fieramosca (Argonne National Laboratory)Sometimes it is possible to modify existing sampleenvironment equipment beyond its originally de-signed operating parameters, such as extending itstemperature range, sample containment, etc., toaccommodate newer and more demanding scientificstudies. The Intense Pulsed Neutron Source (IPNS)has modified one of its high temperature furnaces, avanadium foil vacuum furnace, to satisfy the require-ments of recently proposed user experiments. Thevanadium foil vacuum furnace is a resistive-heatingelement type furnace able to heat samples to 1000oC. It consists of two heat shields, a heating element,a separate sample vacuum housing, and samplecontainer, all cylindrically concentric and constructedof vanadium. The original sample housing maintainsa separate high vacuum around the sample andallows sample changes during the experimentwithout breaking vacuum to the furnace element. Arecently proposed experiment required a modifica-tion to the furnace to accommodate a controlledatmosphere about the sample. The furnace modifica-tion consisted of substituting for the sample housingand container an open-ended fused silica tube withan imbedded silica frit for supporting a powdersample in the beam. The use of fused silica wasdictated by the corrosiveness of the gas used in theexperiment. A controlled atmosphere flows throughthe fused silica tube and over the sample at tempera-ture. Gas composition and flow rates are controlledusing EPICS interfaced automated mass flow control-lers.

TP27: Fast Exchange Refrigerator for NeutronScience (FERNS)

J.E. Rix (Containerless Research, Inc.), L.J.Santodonato (Spallation Neutron Source, Oak RidgeNational Laboratory), J.K.R. Weber (ContainerlessResearch, Inc.)

Modern neutron science can exploit new techniquesthat locate samples in a neutron beam while control-ling experimental variables such as temperature,pressure, and magnetic field. The Fast ExchangeRefrigerator for Neutron Science (FERNS) instrumentis being developed to enable efficient use ofbeamline resources, achieve a high throughput ofsamples, and meet needs expressed by the usercommunity for an capability that combines: (i)reliable cryogenic temperature control, (ii) remoteautomated sample exchange and storage, (iii) rapidthermal response, and (iv) ease-of-use with varioussample experimental configurations. The FERNSinstrument is designed to exploit the fast measure-ment capabilities of high flux beamlines by integrat-ing automated sample handling and cryogenictemperature control via a computerized operatingand sample management system. We present resultsof testing of a prototype FERNS device using acryogenic system, results of cooling and sampleexchange testing, describe software control capabili-ties, and outline plans for a beamline instrument thatcan be programmed to process multiple samples.

Supported by DOE Phase I SBIR contract number DE-FG02-03ER83633.

TP28: Variations on a Theme: The Closed-CycleRefrigerator in Neutron Scattering

B. Clow, E. Fitzgerald, D. Dender (NIST Center forNeutron Research)

The closed-cycle refrigerator is ubiquitous at neutronscattering facilities due to its reliability, ease-of-operation, and useful temperature range. Beingcommon, though, does not mean being boring. Thisbasic platform is shown in a variety of interestingarrangements that show the versatility of this equip-ment and the science that is made possible by its use.

TP29: Development of neutron reflectometer atHANARO

J.S. Lee, C.H. Lee, B.S. Seong, C.M. Shim, G.P. Hong,B.H. Choi, Y.H. Choi, S.J. Cho, E.J. Shin, Y.J. Kim(Korea Atomic Energy Research Institute, YuseongP.O. Box 105, Daejeon, 305-600, Korea)

The neutron reflectometer was developed on ST3horizontal beam port in HANARO, 30 MW researchreactor. According to the characteristics of neutronsource, constant wavelength methods using 0.245


nm with PG monochromator, β = 0.4°, and verticalsample geometry were taken. The dimension of theinstrument is 5.4 m for neutron source-monochroma-tor, 3.0 m for monochromator-sample and 1.6 m forsample-detector. The distance between two slits todefine width of incident beam to sample position is2.4 m. In order to reduce the contamination ofneutron reflection pattern due to the second orderreflection of PG monochromator, PG filter withβ = 3.5° was taken. By the gold wire activationmethod, neutron flux at monochromator and sampleposition was measured to 4.5x109, 4.4x106 n/cm2/sec.After the installation of the instrument, the character-istics of transmitted neutron beam through the slitswere evaluated with neutron camera. And also, bymeasuring neutron reflectivity curve for the typicalsamples like glass and Si, instrument capacity suchas minimum reflectivity, Q range and instrumentalresolution was evaluated. A vacuum furnace andpolarizing accessories will be developed to enhancethe instrument performance.

TP30: New Thermal Triple Axis Spectrometers atthe NCNR

M. Murbach, C. Wrenn, C. Brocker (NIST Center forNeutron Research; Department of Materials Scienceand Engineering, University of Maryland), P. Brand,J. W. Lynn (NIST Center for Neutron Research)

As part of the modernization of the thermal neutronspectrometers, and new state-of-the-art thermalneutron instrument is now being installed at the BT-7thermal beam port. There is a choice of filters andcollimations in the reactor beam that bring neutronsonto a choice of 20×20 cm2 double focusing mono-chromators. The sample stage incorporates a inde-pendent magnet axis in addition to the usual motor-ized sample orientation and rotation angles. Theanalyzer and detector system will be housed in asingle unit on air pads. The analyzer will also providehorizontal focusing capability, or it can use a flatcrystal array coupled with a position-sensitive detec-tor to allow the simultaneous collection of data over arange of (Q,E), or it can use a choice of differentconventional collimators, all remotely and undercomputer control. The analyzer/detector system isdesigned to be self-contained so that it can be easilyinterchanged with a different style of analyzer as newsystems are developed. Guide fields are incorporatedthroughout the instrument to enable polarized beamoperation. A similar spectrometer is being developedfor the BT-9 beam port.

TP31: Concept and performance of the TOF strainscanner POLDI with multiple frame overlap

U. Stuhr, W. Wagner (Paul Scherrer Institut, 5232

Villigen-PSI, Switzerland)POLDI is a new neutron diffraction instrument at theSwiss continuous spallation neutron source SINQ atPSI, primarily dedicated to residual stress investiga-tions. The instrument has realized a novel type oftime-of-flight (TOF) diffractometer allowing multipleframe overlap. Besides for the benefit of higherintensity (as compared to a conventional single-pulsemode), this concept allows an independent tuning ofintensity and resolution, an immense advantage for aflexible adjustment to dedicated experiments. Theconcept makes use of the mutual dependence of theneutron’s arrival time at the detector and the relatedscattering angle to assign the neutrons to the origi-nating pulse at the chopper. The principle concept ofthe instrument, some special components, and theperformance in terms of intensity, resolution andflexibility for strain mapping and structure analysiswill be presented.

TP32: A new polarized Neutron Reflectometer atDhruva Reactor

Surendra Singh, Saibal Basu (Solid State PhysicsDivision, Bhabha Atomic Research Centre, Mumbai–85 INDIA)

A new Polarized Neutron Reflectometer has beeninstalled at Guide Tube Laboratory of Dhruva Reactor,BARC, India. Unlike the conventional q– 2q instru-ment, this instrument uses a linear Position SensitiveDetector and a high precision rotational sample table.This arrangement, immensely, helps collecting datain off specular mode. In this paper we presents thespecification of instrument and few examples ofspecular reflectivity data as well as off specularreflectivity data of a thin films and multilayers,measured by this instrument, both for polarized andunpolarized mode. The reflectivity data are analyzedusing a genetic algorithm based x2 minimizationprogram developed by us.

TP33: New High-Flux SANS Instrumentation at OakRidge National Laboratory

G.W. Lynn, M.V. Buchanan, P.D. Butler, W.T. Heller,D.A.A. Myles, V.S. Urban, G.D. Wignall (Oak RidgeNational Laboratory)

A number of upgrades are in progress at the HighFlux Isotope Reactor (HFIR), including the installationof a supercritical hydrogen moderator (T ~ 20 K)that will be one of the “brightest” cold sourcescurrently available. It will feed four cold neutronguides (CG1-4), each with new instrumentation. CG2and CG3 are reserved for two new small-angleneutron scattering (SANS) instruments. A 40 m SANSinstrument (SANS1), funded by the Department ofEnergy (DOE) Office of Basic Energy Sciences and


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the University of Tennessee, Knoxville is designed forCG2. The 35 m small-angle neutron scattering facility(Bio-SANS on CG3) is optimized for the study ofbiological systems and is the cornerstone of theCenter for Structural Molecular Biology (CSMB),funded by the DOE Office of Biological and Environ-mental Research. The facilities will be housed in arecently completed Guide Hall, along with a suite ofother instruments, including a reflectometer and acold triple-axis spectrometer. Both SANS facilities willhave variable wavelength and large area (1m2) highcount-rate detectors (> 105 Hz) that can translate45 cm off axis to increase the dynamic Q-range(< 0.001 Å-1 to 1.0 Å-1 overall). As the HFIR is one ofonly two reactors with a core flux greater than 1015

neutrons/sec/cm2, the beam intensities (up to107/sec/cm2) will be comparable to the best facilitiesworldwide. This will improve both the quantity andquality of data that we can collect from synthetic andbiological macromolecules, allowing us to increasethroughput, to use smaller sample volumes and toperform kinetic (time-resolved) experiments.

TP34: POWGEN3: A High Resolution Third Genera-tion Powder Diffractometer

J.P. Hodges (Spallation Neutron Source, Oak RidgeNational Laboratory)

POWGEN3 is a fundamental departure from previousdesigns for a powder diffractometer at a spallationneutron source. POWGEN3 may be considered theworld’s first third-generation time-of-flight powderdiffractometer. For the first time, a high-resolutionpowder diffractometer is able to take advantage of ahigh source repetition rate. Combined with asupermirror neutron guide system, POWGEN3 is avery efficient instrument. The high count rates thusachieved together with high-resolution characteristicspresent a big leap forward in performance overprevious diffractometer designs. POWGEN3 will thusprovide unprecedented opportunities for new sciencein the study of crystalline materials.

TP35: Monte Carlo Beam Line Simulation forNeutron Interferometry at NIST

K.P. Schoen (University of Missouri - Columbia),S.A. Werner (University of Missouri - Columbia;National Institute of Standards and Technology)

The uncertainty in neutron interferometry measure-ments is typically limited only by the intensity andnot system resolution. There are several ways toincrease the intensity of neutrons at the interferom-eter, including varying monochromator crystal size,allowing monochromator crystals to be verticallyfocusing, and installing supermirror guides along theflight path leading to the interferometer. A Monte

Carlo beam line simulation was performed for eachof these configurations for the NIST Neutron Interfer-ometer and Optics Facility and compared to theneutron intensity for the current configuration in use.The results for each simulation configuration arepresented; the configuration yielding the largestincrease in neutron intensity provided a gain of afactor of 5 over the current experimental setup.

TP36: Some Effects of Multiple Scattering Encoun-tered in SANS

J. G. Barker (NIST Center for Neutron Research)General methodologies for calculating multiplescattering effects are presented. Several specificexamples of multiple scattering corrections found insmall angle neutron scattering (SANS) are presented.The cases presented here were chosen to provideparticular insights into the more routine problemsencountered in handling multiple scattering, but asyet have not been sufficiently espoused in theconsiderable literature on this subject. For scatteringoccurring at sufficiently small angles, the semi-analytical technique of Schelten & Schmatz [J. Appl.Cryst. (1980), 13, 385-390] was used. Monte Carlosimulations were also used, and were found to be amore robust method of calculating many problems.Power series corrective expressions have beendetermined for the forward cross-section Im(0), andthe radius of gyration Rg, used to characterize thecentral part of the scattering curve for five differentscattering functions: Gaussian shaped scattering, thescattering from spheres, the DAB model, the Sabinefunction (p = 3/2) and Lorentzian scattering. Othercases presented are scattering from narrow Gaussianpeaks, and corrections to power-law scattering atlarge q. Effect of multiple scattering upon the forwardcross-section of isotropically scattering samples, suchas from water and vanadium, are also presented.

TP37: Dynamically Polarized Hydrogen Target as aBroadband, Wavelength Independent Neutron SpinPolarizer

J.K. Zhao (Spallation Neutron Source, Oak RidgeNational Laboratory), V. Garamus, R. Willumeit(GKSS Research Center, Geesthacht, Germany.)

The feasibility of using dynamically polarized hydro-gens as wavelength independent neutron spinpolarizers was investigated. A modified setup of theDynamics Nuclear Polarization station at the GKSSresearch center was used with the standard GKSSsolvent sample as the target. The 2.8mm thicksample consisted of 43.4 % water. The rest is mostlyglycerol with a small amount of EHVA-Cr(v) complexproviding the needed paramagnetic centers. Nonpolarized neutrons (8.5 Å) first pass through the


polarized target. The polarization of the trasmittedneutrons was then analyzed with a supermirroranalyzer. At the highest hydrogen polarization of68.6 % that was achieved during the experiment, thepolarization of the transmitted neutrons was mea-sured at 51.8 %. All the measured polarizations agreenicely with theoretical calcualtions for the usedsample. Further experiments will test the feasibilityof using methane samples as the target, whichtheorectically would allow us to achieve neutronpolarizations of over 95 % with tranmissions greaterthan 30 %.

TP38: A semiconductor based transmission moni-tor for the SAND instrument at IPNS

P. Thiyagarajan (Intense Pulsed Neutron Source,Argonne National Lab), Patrick M. De Lurgio (CIS-EL, Argonne National Laboratory, 9700 South CassAvenue, Argonne, IL 60439), Raymond T. Klann,Charles Fink (NE, Argonne National Laboratory,9700 South Cass Avenue, Argonne, IL 60439),Douglas S. McGregor (Kansas State University, 151Rathbone Hall, Manhattan, KS 66506), IstvanNaday (CIS-EL, Argonne National Laboratory, 9700South Cass Avenue, Argonne, IL 60439), DenisWozniak, Ed Lang (Intense Pulsed Neutron Source,Argonne National Lab)

A semiconductor based neutron detector was devel-oped for the time-of-flight Small Angle NeutronDiffractometer (SAND) instrument at the IntensePulsed Neutron Source, Argonne National Laboratoryfor the simultaneous measurement of transmittedneutron beam intensity and the scattering data.SAND uses neutrons from a pulsed spallation sourcemoderated by a coupled solid methane moderatorthat produces useful neutrons in the wavelengthrange of 0.5 to 14 angstroms that are sorted by time-of-flight into 68 constant δT/T=0.05 channels. Inaddition to allowing effective use of valuable beamtime this detector offers higher precision data in theexperiments involving complicated sample environ-ment and samples. The detector is constructed usinga 0.5 micron thick coating of boron-10 on a gallium-arsenide semiconductor wafer and is mounteddirectly within a cylindrical (2.2 cm dia. and 4.4 cmlong) enriched boron10-carbide beam stop in theSAND instrument. Since this detector is buried insidethe beam stop it does not cause any additionalparasitic background. The boron-10 coating on theGaAs detector enables the detection of the coldneutron spectrum with reasonable efficiency. Thisdetector can be readily adapted for the SANS instru-ments at the steady-state sources as well. This paperdescribes the details of the detector fabrication, thebeam stop monitor design, gamma rejection, radia-

tion resistance and overall performance based on theexperience during several run cycles at the IPNS.

This work benefited from IPNS, ANL funded by U.S.DOE-BES under contract W-31-109-ENG-38 to U ofChicago and SNS, ORNL funded by DOE-BES undercontract DE-AC05-00OR22725 to UT-Battelle, LLC.

TP39: ENGIN-X; from crystals to crankshaftsMark R Daymond (ISIS Facility, RutherfordAppleton Laboratory, Chilton, Didcot, OX11 0QX,UK) and Lyndon Edwards (Dept. of MaterialsEngineering, The Open University, Milton Keynes,MK7 6AA, UK)

ENGIN-X, the recently constructed diffractometer atISIS which was optimised for diffraction engineeringmeasurements of stress, has just finished its firstcomplete year of running. Along with an order ofmagnitude improvement in performance over theprevious instrument, major hardware and softwareimprovements have been implemented that consid-erably simplify the process of planning and executingan experiment for the average user.

These include easy changing all three dimensions ofthe gauge volume, CMM based laser scanning ofobjects prior to experimentation, computer con-trolled positioning and planning of experiments andautomated data analysis.

The performance improvements achieved withENGIN-X and the way that these innovations havesimplified the way that experiments are carried outwill be illustrated through a series of examplescovering fundamental science explorations and thesolution of real industrial problems.

TP40: VISION: A Neutron Vibrational Spectrometerfor SNS

J.Z. Larese (Chemistry Dept., Univ. of Tennessee;Oak Ridge National Laboratory), L.L. Daemen, P.A.Seeger (Los Alamos Neutron Science Center, LosAlamos National Laboratory), B.S. Hudson(Chemistry Dept., Syracuse Univ.), J. Eckert (LosAlamos Neutron Science Center, Los AlamosNational Laboratory)

There is a need in the United States for a state-of-the-art neutron scattering instrument for vibrationalspectroscopy to investigate the structure and dynam-ics of condensed matter systems by the simultaneoususe of elastic diffraction and moderate resolution(1-2% ∆E/E) inelastic scattering over a broad energytransfer range. The use of neutron vibrational spec-troscopy (NVS) is growing at a significant rate inEurope thanks to the second-generation instrumentTOSCA at ISIS, the spallation neutron source at the


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Rutherford-Appleton Laboratory in England.

We will outline our proposal to design a next genera-tion, time of flight (TOF) spectrometer named,VISION, which is not an acronym, to investigate avast array of molecular dynamics and structure.Under optimal conditions this instrument willhave a throughput two orders of magnitude greater

than TOSCA –currently the best instrument in thefield;

- cover an energy transfer range of 0-500 meV(0-4000 cm-1);

- have a 1-2% energy resolution while simulta-neously enabling diffraction studies for structuralcharacterization;

- offer a wide range of sample environments (lowtemperature, high-pressure, flow cell, thermalanalysis, etc).

Our approach will incorporate neutron techniquesdeveloped during the decade since TFXA and TOSCAwere first designed and built. This includes improvedsupermirror technology, parametrically matchedcrystal analyzer-helium gas detectors, efficientelectronics for high rate data acquisition, high-performance data analysis algorithms, novel modera-tor concepts, and well-developed Monte Carlosoftware for neutron optics and instrument designand optimization. This new design combined withthe flux available at SNS will enable time-resolvedvibrational measurements for the first time at aneutron source.

Proposals to form an Instrument Design Team (IDT)and a subsequent proposal describing the scientificbackground for VISION have been presented to theSpallation Neutron Source (SNS) ExperimentalFacilities Advisory Committee (EFAC) and have beenpositively received. (EFAC has enthusiasticallyendorsed the science case presented by the IDT anda beamline position for installation and constructionof VISION has been identified by SNS.)

TP41: Simple functional forms for total crosssections from neutron-nucleus collisions.

P. K. Deb (Department of Physics, The Ohio StateUniversity, Columbus, OH 43210, USA), K. Amos(School of Physics, The University of Melbourne,Victoria 3010, Australia)

Total cross sections have been predicted for neutronsscattering from nuclei ranging in mass from 6 to 238and for projectile energies from 10 MeV to 800 MeV.So also have been the mass variations of those crosssections at selected energies when they have beencalculated using coordinate space optical potentialsformed by full folding effective two -nucleon (NN)

interactions with one body density matrix elements(OBDME) of the nuclear ground states. Good com-parisons with data result when effective NN interac-tions defined by medium modification of free NN tmatrices are used. There is a simple three parameterfunctional form that produces the partial wave totalcross section values determined from those opticalpotential calculations. Adjusting the theoreticaldefined parameter values has enabled us to fit theactual measured data values from the scatteringinvolving 9 nuclei spanning the mass range from 6Lito 238U and for neutron energies from 10 MeV to600 MeV. The parameter values vary smoothly withmass and energy. Total cross sections are wellreproduced by using simple functional form.

TP42: Measurement of the Neutron Lifetime Usinga Proton Trap

F. E. Wletfeldt (Tulane University), M. S. Dewey, D.M. Gilliam, J. S. Nico (National Institute ofStandards and Technology), X. Fei, W. M. Snow(Indiana University), G. L. Greene (University ofTennessee/Ornl), J. Pauwels, R. Eykens, A. Lamberty,J. Van Gestel (IRMM, Belgium)

We describe a recent measurement of the neutronlifetime by the absolute counting of in-beam neu-trons and their decay protons. Protons were confinedin a quasi-Penning trap and counted with a silicondetector. The neutron beam fluence was measuredby capture in a thin 6LiF foil detector with knownabsolute efficiency. The combination of these simulta-neous measurements gives the neutron lifetime:tn = 886.8 ± 1.2 [stat] ± 3.2 [sys] s. The systematicuncertainty is dominated by uncertainties in themass of the 6LiF deposit and the 6Li(n,t) cross section.This is the most precise measurement of the neutronlifetime to date using an in-beam method.

TP43: Some Principal Problems in Physics andNeutron Low Energy Physics

Yu. A. Alexandrov (Senior Scientist of FLNP, JINR,Dubna)

Physics is a single whole, therefore the answers tosome principal questions should be sought for notonly in high-energy physics, but also in other divi-sions of physics, e.g., in low energy neutron physics.Especially since the accuracy of experiments inneutron physics is frequently much higher.

In this report the questions connected with theinternal structure of particles (e.g., of neutron) arediscussed.

The first question deals with the charge neutronradius connected with the value of neutron-electronscattering length determined at low neutron energies.


At present, the obtained accuracy allows us to speaknot only about the value of the charge neutronradius, but also on the division of it into Dirac andFoldy terms. The sign of the Dirac term is connecteddirectly with the fundamental Yukawa theoryexplaining the origin of nuclear forces.

The second question also concerns the subject of thestructure of the neutron, namely its deformation.The notion of deformation (polarizability) of thenucleon in electromagnetic field was introduced inmid 50s. In the report the reasons are given in favorof the opinion that the neutron polarizability wasobserved for the first time in neutron experimentsalready in 1957, i.e. earlier than the proton polariz-ability was detected (1960).

Finally, the third question deals with the search for amagnetic charge of the neutron. The beautifulexperiment (Finkelstein, Shull, Zeilinger, 1986)testifying with high accuracy the absence of amagnetic charge of the neutron is discussed. Theexistence of an isolated magnetic charge in thenature would explain the quantization of electric andmagnetic charges (Dirac, 1931).

TP44: Consequences of the interaction betweendynamical diffraction and the Sagnac effect inLLL perfect single crystal interferometers

K.C. Littrell (Intense Pulsed Neutron Source,Argonne National Lab)

The LLL perfect single crystal interferometer is anexciting tool for exploring a variety of topics offundamental importance in understanding quantummechanics and for precision measurement ofneutron scattering lengths. One of the limiting facorsin many neutron interferometry experiments is theoverall size of the interferometer. Hence, ever-largerinterferometers would seem to be preferable.However, according to the theory of dynamicaldiffraction, neutrons that nearly but not exactlysatisfy the Bragg condition take different trajectoriesthrough the crystal, splitting into two currentbranches at blade of the interferometer; thusthereare sixteen mutually interfering wavefunctions thatcontribute to the measurement of an interferogram.This complexity gives rise to shifts in the measuredphase difference and a loss of contrast of theinterferogram in the presence of potentials whichare dependent on the spatial differences betweenthe trajectories of the neutron through the interfer-ometer. This effect has already been experimentallyverified for the gravitational potential; here wediscuss the similar effects of dynamical diffractionon the phase shift due to the Sagnac effect and their

consequences on the observable contrast in large-scale interferometers.

TP45: Pressure/Temperature Induced Phase Behav-ior of Triblock Copolymer PEO133PPO50PEO133 inElectrolyte Solutions.

Lixin Fan*, L. Guo, P. Thiyagarajan (Intense PulsedNeutron Source, Argonne National Lab)

The pressure/temperature dependent phase behaviorof 5wt.% triblock copolymer PEO133PPO50PEO133(F108) in aqueous solutions containing different[Na2CO3] has been studied by small-angle neutronscattering. These studies show that pressure, tem-perature and sodium carbonate have strong effectson the micellization and phase transition of F108 inthese solutions. At 40 oC, F108 in 0.3M Na2CO3

solution forms spherical interacting micelles. As thepressure increases from 1bar to 1kbar, the micelleassociation number and the radii of the core, coronaand hard sphere decrease. Further increase ofpressure leads to a transition from spherical micellesto rod-like micelles. The radius of the rod-like mi-celles does not change significantly with increasingpressure up to 2kbar, while the length monotonicallyincreases with pressure. The structures formed in thisregion of the phase map are thermodynamicallyreversible. At 55 oC spherical and rodlike micellescoexist in a pressure range of 1 bar to 1 kbar. At 1.7kbar the radius of rod-like micelles jumps to highervalue reflecting the association of rodlike micelles. At2 kbar we observed a lamellar phase. In 0.5M Na2CO3

solution phase transitions from spherical interactingmicelles to rod-like micelles and then to an orderedphase can be observed with increasing pressure evenat room temperature. Interestingly, at higher pres-sures the order in the system decreases with increas-ing pressure leading to a solution of unimers.

This work benefited from the use of Intense PulsedNeutron Source at Argonne National Laboratory,which is funded by the Office of BES, US DOE.

*current address: Advanced Photon Source, ArgonneNational Laboratory, 9700 South Cass Ave, Argonne,IL 60439, USA

TP46: Characterization of Cryptophycin- andDolastatin-Induced Tubulin Rings

H. Boukari (National Institutes of Health, Bethesda,Maryland, USA), S. Krueger (National Institute ofStandards and Technology), R. Nossal, D. L. Sackett(National Institutes of Health, Bethesda, Maryland,USA)

We have applied small-angle neutron scattering(SANS) and dynamic light scattering (DLS) to probe


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interactions of the protein, αβ-tubulin, with eithercryptophycin 1 or dolastatin 10, two small peptidesextracted from marine products. These two peptidesinhibit the polymerization of tubulin into microtu-bules and, instead, induce the formation of tubulinrings of about 24 and 44 nm diameter, respectively[1]. Under the studied conditions, the SANS and DLSmeasurements on cryptophycin-tubulin samplesindicate a narrow structural dispersity with a pre-dominant structure made of 8 tubulin dimers as-sembled into non-interacting rings. In contrast,dolastatin-tubulin samples show additional aggrega-tion of the primary rings, composed mostly of 14dimers, resulting in large structures that settle to thebottom of their container under the effect of gravity.Further modeling of the SANS profiles indicate,remarkably, that the dolastatin-tubulin aggregates areordered structures, most likely columns of rings [2].These rings can be used as potential models forinvestigating the behavior of closed ring polymers,which may intrinsically differ from open-ended linearbiological polymers such as microtubules and actinfilaments.

[1] H. Boukari, R. Nossal, D. L. Sackett, Biochemistry42, 1292 (2003).[2] H. Boukari, V. Chernomordik, S. Krueger, R.Nossal, and D. L. Sackett, Physica B (in press).

TP47: Reflectometry Studies of Multi-Layered Non-Linear Optical Films

E. Watkins, J. Majewski, J. Robinson, H. Wang, P.Chiarelli, J. Casson, F. Trouw (Los Alamos NationalLaboratory)

Neutron and x-ray reflectivity measurements wereused to characterize the structure of non-linearoptical (NLO) films containing S-azo-C18 molecules.Langmuir-Blodgett (LB) multilayers were prepared bythe sequential transfer of S-azo-C18 and stearic acidmolecules on octadecyltrichlorosilane (OTS) coatedquartz and silicon substrates. To provide goodcontrast for neutron measurements, the stearic acidmolecules were deuterated. One and two bilayersamples were prepared for both possible layerorderings. Neutron measurements were performedon the SPEAR reflectometer at the Los AlamosNeutron Science Center (LANSCE) and complemen-tary x-ray reflectivity measurements were used to pindown certain aspects of the molecular architecture.

For the single bilayer samples, the Kiessig fringespacing observed (dQ ~ 0.07 Å-1) corresponds to alength scale of approximately 90 Å and matches thepredicted thickness of the bilayer. Competing lengthscales make it difficult to identify the complementary

fringe spacing for the two-bilayer samples. Boxmodel fitting of the data sets show the following: (1)well packed layers of OTS are present, (2) the densityof the stearic acid layers are low indicating eitherpatchy layers or intermixing of molecules withadjacent layers, (3) the thickness of the layer corre-sponding to the S-azo molecules is greater thanpredicted, and (4) intermixing and disorder isapparent within a single bilayer and the degree ofdisorder increases with additional layers. Despitesecond harmonic generation (SHG) measurementsthat indicate a linear increase in the SHG signal withincreasing bilayer number, reflectivity measurementsshow that the films are disordered on the molecularscale.

TP48: Low Dimensional Magnetism in the Molecu-lar Magnet Cu(pz)2(ClO4)2

F.M. Woodward (NIST Center for Neutron Research),C.P. Landee (Clark University Physics Department,Worcester MA, 01610), M.M. Turnbull (ClarkUniversity Chemistry Department, Worcester MA,01610)

Cu(pz)2(ClO4)2 belongs to a family of compoundscomposed of magnetic Cu2+ ions linked by pyrazinemolecular units forming Cu-pz layered materials.Magnetic susceptibility, isothermal magnetization,electron spin resonance, and neutron scattering dataindicate that the molecular magnet, Cu(pz)2(ClO4)2,exhibits a low dimensional antiferromagnetic charac-ter, conforming to the two dimensional Heisenbergantiferromagnetic model, with a moderate exchangestrength (J = -18 K). The results of an investigation ofCu(pz)2(ClO4)2 via neutron diffraction shows charac-teristics similar to other two dimensional systems.Analysis of neutron diffraction data result in a modelof the spins in the 3D order state.

TP49: Structural Comparison of Supercooled Waterand Intermediate Density Amorphous Ices

J. Urquidi (Dept. of Physics, New Mexico StateUniversity; Los Alamos Neutron Science Center, LosAlamos National Laboratory), C. J. Benmore(Intense Pulsed Neutron Source, Argonne NationalLab), P. A. Egelstaff (Dept. of Physics, University ofGuelph), M. Guthrie (Intense Pulsed Neutron Source,Argonne National Lab), S. E. McLain (Dept. ofChemistry, University of Tennessee), C. A. Tulk(Spallation Neutron Source, Oak Ridge NationalLaboratory), D. D. Klug (National Research Council,Chalk River, Ontario, Canada), J. F. C. Turner (Dept.of Chemistry, University of Tennessee)

Presented here are new neutron diffraction data onultrapure bulk supercooled heavy water measureddown to 262 K. The data are analyzed in terms of the


trends observed in the first sharp diffraction peak(FSDP) parameters. The neutron FSDP position,height and width are compared to literature data forsupercooled water, water under pressure and to thesame parameters obtained for recently discoveredintermediate density amorphous ices. It is found thatthe FSDP parameters in supercooled water and theamorphous ices generally exhibit a similar behavior,suggesting a new structural regime may occur indeeply supercooled water at about Q0~1.83Å-1

(T~251K) associated with increased intermediaterange ordering. It is argued that this structural regimemay be linked to a similar trend in the density, whichappears when the density is plotted as a function ofFSDP position. A detailed comparison of the neutronand x-ray structure factors for supercooled water andintermediate density amorphous ices having thesame FSDP positions is also made. The diffractiondata show that although the overall general structuresare qualitatively very similar, the amorphous icecorrelations are considerably sharper and extend tomuch higher radial distances.

TP50: Inelastic Neutron Scattering Studies of theSingle Molecule Magnet Fe30Mo72

V. O. Garlea (Ames Laboratory and Department ofPhysics and Astronomy, Iowa State University,Ames, Iowa 50011), S. E. Nagler (Oak RidgeNational Laboratory), J. L. Zarestky, C. Stassis, D.Vaknin, P. Kögerler (Ames Laboratory andDepartment of Physics and Astronomy, Iowa StateUniversity, Ames, Iowa 50011), D. F. McMorrow(Risø National Laboratory, DK-4000, Roskilde,Denmark; Department of Physics & AstronomyUniversity College London, UK), C. Niedermayer(Laboratory for Neutron Scattering, Paul ScherrerInstitute & ETH Zurich, CH-5232 Villigen,Switzerland), Y. Qiu (NIST Center for NeutronResearch, Gaithersburg, Maryland, 20899 &Department of Materials Science and Engineering,University of Maryland, College Park, Maryland,20742)

Materials consisting of magnetic molecules are idealprototypes for the study of fundamental problems ofmagnetism at the nanoscale level. The Kepleratematerial Fe30Mo72 is a singlet ground state singlemolecule magnet system with isolated clusters of30 s=5/2 ions on the vertices of an isododeca-hedron. We report cold-neutron inelastic scatteringmeasurements on Fe30Mo72 carried out using thetriple axis spectrometer RITA-II at PSI and the DiscChopper Spectrometer at NIST Center for NeutronResearch. Results for temperatures T < 200 mKreveal a magnetic excitation at an energy transfernear 0.65 meV. The peak broadens and shifts dra-

matically in the presence of an applied magneticfield. The results are discussed in the context of theeffective rotational band model of Luban and co-workers [1].

[1] J. Schnack, M. Luban, and R. Modler, Europhys.Lett. 56, 863 (2001).

TP51: Neutron Diffraction Studies of theTb5(SixGe1-x)4 Magnetoelastic Compounds

J. L. Zarestky, V. O. Garlea (Ames Laboratory andDepartment of Physics and Astronomy, Iowa StateUniversity, Ames, Iowa 50011), C. Y. Jones (NationalInstitute of Standards and Technology), D. L.Schlagel, T. A. Lograsso, A. O. Pecharsky (Materialsand Engineering Physics Program, AmesLaboratory, Ames, Iowa, 50011), V. K. Pecharsky, K.A. Gschneidner Jr. (Materials and EngineeringPhysics Program, Ames Laboratory, Ames, Iowa,50011; Dept. of Materials Science and Engineering,Iowa State University, Ames, Iowa, 50011), C.Stassis (Ames Laboratory and Department ofPhysics and Astronomy, Iowa State University,Ames, Iowa 50011)

The R5(SixGe1-x)4 [1] pseudobinary alloys exhibit anumber of diverse and unique properties associatedwith both their naturally layered crystal structuresand the combined magnetic-crystallographic transfor-mations at low temperatures. In particular, this familyof compounds is attractive for its potential applica-tions as a magnetic refrigerant and/or magnetostric-tive and magnetoresistive transducers. Progress inunderstanding the properties of these compoundshas been hindered by the difficulty of growing singlecrystals. Recently a single crystal of Tb5Si2.2Ge1.8 wasgrown at the Ames Laboratory and this motivated usto initiate a neutron diffraction study of this com-pound as a function of temperature. The singlecrystal measurements were performed using theHB1A triple axis spectrometer at the High FluxIsotope Reactor (HFIR). The measurements per-formed in the a-c and a-b planes indicate the occur-rence, at approximately 115 K, of a phase transitionfrom monoclinic/paramagnetic to an orthorhombic/ferromagnetic structure. Below 50 K, a change in theintensities of selected reflections has been observed.In addition to the single crystal study, neutronpowder diffraction measurements were also per-formed using the BT-1 powder diffractometer at theNIST Center for Neutron Research (NCNR). Models ofthe magnetic structure are used to interpret theexperimental results.

[1] V.K.Pecharsky, K.A.Gschneidner Jr., Phys. Rev.Lett. 78 (1997) 4494


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TP52: Crystal structure and magnetic properties of(Zr,Mn)Coδ+2 compounds.

E. Sherstobitova, A.P. Vokhmyanin (Institute ofMetal Physics Ural Branch or RAS.)

The binary Laves-phase compounds ZrCo2 and ZrMn2

are Pauly paramagnetic. The spontaneous magnetiza-tion was observed in nonstoichiometricZrCo2+x- (Zr1-yCoy)Co2 compounds with x>0.8 andthe Tc of them reached up 160 K. Curie temperature(Tc) of the ternary Zr1-xMnxCoä+2 compounds is about600 K and the magnetization is 100 emu/g at roomtemperature. It is of interest to look into the reasonsof an occurrence of magnetism in that compounds.For that using the x-ray and neutron powder diffrac-tion we studied the crystal and magnetic structure ofZr1-xMnxCo2 and Zr1-xMnxCo2.45 system compounds.Assuming a substitution of Zr-atoms by Mn-atoms,one can consider former system as stochiometric,and the latter as nonstochiometric. We found thatZr0.8Mn0.2Co2 compound crystallized in the MgCu2

type cubic structure, (Fd3m space group). The Zr- andMn-atoms randomly occupy the 8(a) position and Coatoms occupy 16(d)-one. On the x-ray diagram ofZr0.64Mn0.36Co2 compound the peaks can be welldescribed in assumption that space group is Fd3mtoo. However, neutron diagram includes additionalpeaks (for example, (002)), it can be described inassumption of AuBe5 type structure (space groupF-43m). In case of Zr0.64Mn0.36Co2.45 compoundadditional peaks appear on both neutron and x-raydiagrams and they are well described in according toAuBe5 type. For thi! s nonstoichiometric compoundZr- and Mn-atoms distributions are similar as instoichiometric Zr0.64Mn0.36Co2 compound, and the Coatoms occupy 16(e) position fully and 4(a) and 4(c)partly. All the compounds are ferromagnetic. Anappearance of the ferromagnetism in Zr1-xMnxCoä+2

alloys can be considered, within the scope of a modelof the itinerant electrons, which was before suggestedfor an explanation of a magnetic behavior of theZrCo2+x alloys.

TP53: Bose condensation of magnons in anisotro-pic Haldane spin chains

A. Zheludev (Condensed Matter Sciences Division,Oak Ridge National Laboratory), C. L. Broholm(Department of Physics & Astronomy, JohnsHopkins University; NIST Center for NeutronResearch), S. M. Shapiro (Physics Department,Brookhaven National Laboratory), Z. Honda (Facultyof Engineering, Saitama University, Urawa, Saitama338-8570, Japan), K. Katsumata (The RIKEN HarimaInstitute, Mikazuki, Sayo, Hyogo 679-5148, Japan),B. Grenier, L.-P. Regnault (DRFMC/SPSMS/MDN,CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble

Cedex, France)Inelastic neutron scattering experiments on theHaldane-gap quantum antiferromagnet NDMAP areperformed at mK temperatures in magnetic fields ofalmost twice the critical field Hc. Geometries in whichhe field is applied perpendicular [1,2] or parallel [3]to the axis of magnetic anisotropy are both explored.The observed closing of the Haldane gap at Hc [1]leads to a Bose condensation of magnons and theappearance of long-range antiferromagnetic order[4]. This ordered (spin-solid) high-field phase is not tobe confused with a conventional antiferromagnet. Inthe latter model the spectrum consists of two spinwave branches that correspond to spin precessionsaround the direction of ordered staggered magnetiza-tion. In contrast, in NDMAP at H>Hc we clearlyobseve three distinct branches of long-lived massive(gapped) excitations [2,3]. These “breather” statescan not be understood in the framework ofquasiclassical theories. However, more sophisticatedquantum models can account for the observedbehavior quite well. The main conclusion is that ateven H>Hc quantum fluctuations are crucial, and amagnetized anisotropic Haldane spin chain is aquantum spin solid.

[1] A. Zheludev, Y. Chen, Z. Honda, C. Broholm andK. Katsumata, Phys. Rev. lett. 88, 077206 (2002).[2] A. Zheludev, Z. Honda, C. L. Broholm, K.Katsumata, S. M. Shapiro, A. Kolezhuk, S. Park and Y.Qiu, Phys. Rev. B 68, 134438 (2003).[3] A. Zheludev, S. M. Shapiro, Z. Honda, K.Katsumata, B. Grenier, E. Ressouche, L.-P. Regnault,Y. Chen, P. Vorderwisch, H.-J. Mikeska, and A. K.Kolezhuk, Phys. Rev. B, Phys. Rev. B 69, 054414(2004).[4] Y. Chen, Z. Honda, A. Zheludev, C. Broholm, K.Katsumata and S. M. Shapiro, Phys. Rev. Lett. 86,1618 (2001).

TP54: Spin singlet formation in MgTi2O4: evidenceof a helical dimerization pattern

M. Schmidt (ISIS, Rutherford Appleton Laboratory;Department of Physics and Astronomy, MichiganState University, E. Lansing, MI, 48824), W. RatcliffII (Department of Physics and Astronomy, RutgersUniversity, Piscataway, New Jersey 08854, USA), P.G. Radaelli (ISIS, Rutherford Appleton Laboratory;Department of Physics and Astronomy, UniversityCollege London, London, WC1E 6BT, UnitedKingdom), K. Refson (ISIS, Rutherford AppletonLaboratory), N. M. Harrison (Department ofChemistry, Imperial College London, London, SW72AY, United Kingdom; CCLRC, DaresburyLaboratory, Warrington, WA4 4AD, United


Kingdom), S.W. Cheong (Department of Physics andAstronomy, Rutgers University, Piscataway, NewJersey 08854, USA)

The transition metal spinel MgTi2O4 was studiedusing a combination of neutron and x-ray powderdiffraction, electrical resistivity and magnetic suscep-tibility measurements. MgTi2O4 undergoes a metal-insulator transition on cooling below T(M-I) = 260Kand a step-like reduction of the magnetic susceptibil-ity below T(M-I). The temperature dependence oftransport properties suggests an onset of a magneticsinglet state. Using high-resolution synchrotron andneutron powder diffraction, we have solved the low-temperature crystal structure of the oxide. MgTi2O4

has tetragonal crystal structure below 260K (S.G: P4121 2, a=6.02201(1)Å, c=8.48482(2)Å at 200K)which is found to contain dimers with short Ti-Tidistances (the locations of the spin singlets). Theshortest Ti-Ti bonds alternate with longest bonds toform helices running along the tetragonal c axis.Additional band structure calculations based onhybrid exchange density functional theory show that,at low temperatures, MgTi2O4 is an orbitally orderedband insulator.

TP55: Magnetic-field induced transition to staticlong-range magnetic order in underdoped LSCO

B. Khaykovich (Massachusetts Institute ofTechnology), S. Wakimoto (University of Toronto),K. Yamada (Tohoku University), R. J. Birgeneau(University of Toronto), Y. S. Lee, M. A. Kastner(Massachusetts Institute of Technology), P.Vorderwisch, P. Smeibidl (Hahn-Meitner-InstitutBerlin)

High-temperature cuprate superconductors oftenhave dynamic and sometimes static magnetic order,which coexist with superconductivity. UnderdopedLa2-xSrxCuO4 has static magnetic order when x<0.14.At higher doping, the static magnetic order is de-stroyed and a spin-gap opens when it is optimally- orslightly over-doped. We present recent neutronscattering results, which show that applied magneticfield induces static magnetic order in La2-xSrxCuO4.

TP56: Spin fluctuations in superconductingYBa2Cu3O6.35 near the transition to antiferromag-netism

C. Stock (Physics Department, University ofToronto, Toronto, Ontario, Canada), W. J. L. Buyers(National Research Council, Chalk River, Ontario,Canada), R. Liang, D. Peets, D. Bonn, W.N. Hardy(Physics Department, University of BritishColumbia, Vancouver, B. C., Canada), R. J. Birgeneau(Physics Department, University of Toronto,Toronto, Ontario, Canada)

The discovery of superconductivity in the cuprateshas resulted in a vast amount of interest in the spinfluctuations of these nearly two-dimensional materi-als. Despite the extensive research that has occured,there is no generally accepted theory of the pairingmechanism in these materials. Due to the stronginterplay between antiferromagnetism and supercon-ductivity, spin fluctuations are drastically altered bydoping of the parent insulator and are stronglycorrelated with superconductivity. Understanding thespin fluctuations in the cuprates is an important stepto understanding superconductivity.

Despite the vast amount of attention that the bilayerYBa2Cu3O6+x superconductor system has received,little work has been done in investigating the spinfluctuations near the boundary of antiferromag-netism and superconductivity. We present neutronelastic and inelastic scattering results, utilizing bothpolarized and unpolarized beams, on the YBCO6.35

superconductor (Tc=18 K). In contrast to the Ortho-IIYBCO6.5 system (Tc=59 K), we find that the spectralweight of YBCO6.35 has been shifted to very low-energies resulting in a broad over-damped peak ataround 2 meV. In comparison to higher oxygenconcentrations, we speculate that this mode may beinterpreted as a resonance peak. We also observe abroad central peak indicative of slowly fluctuatingcopper spins with correlation lengths of about 20 Å inthe CuO2 plane and about 15 Å along the c-axis. Bycomparing data taken with Ef=5 meV and Ef=14.5meV, we suggest that the properties observed inYBCO6.35 are analogous to the spin-glass phaseobserved in the LSCO system. This suggests that thespin-glass phase may be a common characteristic ofcuprate systems near the transition from antiferro-magnetism to superconductivity.

TP57: A Quantum Multicritical point in CeCu6-xAux

R. A. Robinson (Bragg Institute, Australian NuclearScience and Technology Organisation, Australia), D.Goossens (Bragg Institute, Australian NuclearScience and Technology Organisation, Australia;Research School of Chemistry, Australian NationalUniversity, Canberra, ACT 0200, AUSTRALIA), M. S.Torikachvili (Department of Physics, San DiegoState University, San Diego, CA 92182, USA), K.Kakurai (Advanced Science Research Center, JAERI,Tokai-mura, Ibaraki-ken 319-1195, JAPAN)

CeCu6-xAux is a well-known heavy-fermion system inwhich the ground state is antiferromagneticallyordered for x > 0.1 and temperatures below 1K.Non-Fermi-liquid behaviour occurs around this criticalconcentration. The parent compound, CeCu6, exhibitsa structural phase transition near 230K, where it


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changes from the Pnma orthorhombic room-tem-perature structure to the P21/c monoclinic structure.The monoclinicity increases as temperature falls, withβ reaching 91.44° at 10K. In the work presentedhere, powder neutron diffraction is used to explorethe monoclinicity at 10K as a function of compositionfor 0.0 < x < 0.08, just short of the critical concen-tration. Extrapolation of the square of the monoclinicstrain, (abcos(β))2, suggests that the distortionvanishes by x = 0.14. A reanalysis of single-crystaldiffraction data on the magnetically ordered side ofthe phase diagram indicates that long-range mag-netic order disappears at the same critical concentra-tion. At a minimum, the structural distortion andantiferromagnetism seem to be competing with eachother, and this raises the intriguing possibility thatlattice degrees of freedom are important in the non-Fermi-liquid regime.

TP58: Ferromagnetic quantum critical fluctuationsin Zr1-xNbxZn2 (x=0.05)

D. Sokolov, M. C. Aronson (The University ofMichigan, Ann Arbor), J.W. Lynn, B. Hammouda(NIST Center for Neutron Research), Z. Fisk (FloridaState University)

ZrZn2 is a weak itinerant ferromagnet with the Curietemperature TC=18 K. Magnetization measurementsshowed that doping with Nb acts like a chemicalpressure suppressing both TC and the spontaneousmoment to zero at 5% of Nb. We have studied thedevelopment of long range critical fluctuations aboveTC in both compositions, and below TC in ZrZn2 usingthe NG3 SANS instrument at the NIST Center forNeutron Research.

In undoped ZrZn2 above TC, a suppression of scatter-ing for 0.002 < q < 0.008 Å-1 was observed, suggest-ing the development of extremely long wavelengthcorrelations with lowered temperature. Surprisingly,the magnetic scattering is still temperature depen-dent at the smallest wave vectors at temperatures aslarge as 100 K. It was also observed that the smallangle scattering increases below TC in undopedZrZn2, implying the development of a new scatteringmechanism involving ferromagnetic domains. For thequantum critical composition Zr1-xNbxZn2 (x=0.05),magnetic scattering develops suddenly below 1 K.The scattering is enchanced at small (q < 0.004 Å-1)wave vectors and suppressed at intermediate (q >0.006 Å-1) wave vectors indicating transfer of inten-sity from intermediate (q > 0.006 Å-1) to small (q <0.004 Å-1) wave vectors at lower temperatures,consistent with incipient ferromagnetic correlations,albeit with relatively shorter ranges than those foundin undoped ZrZn2.

The work at the University of Michigan was carriedout under NSF-DMR-9977300 grant.

TP59: Polarized Neutron Studies of Pd40Ni22.5Fe17.5P20

Spin GlassD.H. Yu, E.P. Gilbert (Bragg Institute, AustralianNuclear Science and Technology Organisation,Australia), R. Woodward (School of Physics,University of Western Australia, Perth, 6009,Australia), R.A. Robinson (Bragg Institute,Australian Nuclear Science and TechnologyOrganisation, Australia)

Magnetic metallic glasses have enormous technologi-cal importance in, for example, magnetic recording,magnetic refrigeration and the construction ofelectrical transformers and motors. Traditionallythese amorphous materials were prepared by meltspinning (106 K s-1) to form ribbons. Bulk magneticmetallic glasses based on the quaternary alloy Pd-Ni-Fe-P exhibit interesting phase behaviour dependingon temperature and applied magnetic field. For thealloy of Pd40Ni22.5Fe17.5P20, paramagnetic,superparamagnetic, ferromagnetic and spin glassregions are all evidenced [1]. It is proposed that thecomplex phase transitions in these kinds of materialsmay be due to the materials not being truly amor-phous. The possible large-scale chemical inhomoge-neities within the alloy may lead to clustering ofmagnetic ions. On cooling, frustration due to compet-ing interactions between clusters may result in theobserved spin glass-like behaviour. We will presentpreliminary studies, employing neutron depolariza-tion and small-angle neutron scattering, on the alloyof Pd40Ni22.5Fe17.5P20 as a function of temperature (RTto 5K) and applied magnetic field (0 to 5T).

[1] Shen T. D., Schwarz R. B. and Thompson J. D., J.Appl. Phys. 85, 4110-4119, 1999.

TP60: Magnetic structure and magnetizationdensity in the layered Tb(Dy)BaCo2O5.5

S.N. Barilo (Institute of Solid State &Semiconductor Physics, BAS, Minsk 220072,Belarus), V.P. Plakhty, Yu. P. Chernenkov (PetersburgNuclear Physics Institute RAS - Gatchina, 188300St. Petersburg, Russia), A. Goukassov (LaboratoireLéon Brillouin, C.E.A Saclay, 91191 Gif-sur-YvetteCedex), S. Streule, A. Podlesnyak (Laboratory forNeutron Scattering, Paul Scherrer Institute & ETHZurich, CH-5232 Villigen, Switzerland), S.V.Shiryaev, G.L. Bychkov (Institute of Solid State &Semiconductor Physics, BAS, Minsk 220072,Belarus), A. Furrer (Laboratory for NeutronScattering, Paul Scherrer Institute & ETH Zurich,CH-5232 Villigen, Switzerland)


The cobaltites LnBaCo2O5.5 (Ln = Y,Pr-Ho) presentspin-state, MI and filed-induced transitions, as well ascharge and orbital ordering phenomena. This familyof layered cobaltites displays alternating BaO andLnO0.5 layers along the c-axis and alternating oxygenoctahedral and pyramidal planes along the b-axis. Inspite of the extensive studies, neither magneticstructure nor spin state in two different Co3+ sites aredefinitely established. Precisely oxygenated powdersample of TbBaCo2O5.5 and as large as 50 mm3 fluxgrown single crystals of Tb0.9Dy0.1BaCo2O5.45 havebeen used for neutron diffraction studies in thetemperature range of 7-300 K using the powderdiffractometer DMC of SINQ, Villigen and 5C2, 6T2diffractometers of LLB, Saclay. The results obtainedare rather different of everything, which has beenpublished before. The following 3 phases ofTbBaCo2O5.5 have been offered: 1) A very narrow bytemperature ferrimagnetic phase in the range around260 K (the unit cell doubled along short axis becauseof the spin state ordering in octahedra). The structurepresents a simple ferrimagnetic with all moments arealong a-axis in the octahedra and a simple AFM inpyramids. 2) At T = 230 K an AFM phase doesappear. Magnetic cell is a previous one doubled alongc-axis due to antiferromagnetic ordering with thewave vector k = (0,0,1/2). There is an antitranslationto the upper part of the unit cell. 3) Finally at T ~170 K a transition to another AFM takes place. Nowthe unit cell is doubled along the c-axis because ofthe spin value ordering in pyramids. This low tem-perature AFM phase of a single crystal Tb0.9

Dy0.1BaCo2O5.45 have been studied by elastic neutronscattering in the kl-plane to show peaks indexed as(0,0-l/2) are purely magnetic and can be attributed toappearance below 200 K an AFM phase, consisting offerromagnetic, AFM and nonmagnetic chains. Wehave also reconstructed the spin density distributionin a Tb0.9 Dy0.1BaCo2O5.45 single crystal. Statisticallysignificant flipping ratios for 46 reflections have beenmeasured in the field of 7 T. Refinement have beenmade to reveal the spin density difference betweenoctahedral and pyramidal sites. These results shouldbe considered as preliminary to show the spindensity distribution over the different sites can beobtained for this twinned crystal.

TP61: Low energy nuclear spin excitations inNdGaO3

T. Chatterji, B. Frick (Institut Laue Langevin)We have investigated the low energy excitations inNdGaO3 in the µeV range by a back scatteringneutron spectrometer. The energy scans on aNdGaO3 single crystal revealed inelastic peaks at E =1.650 µeV at T = 50 mK on both energy gain and

energy loss sides. The inelastic peaks move graduallytowards lower energy with increasing temperatureand finally merge with the elastic peak at the elec-tronic magnetic ordering temperature TN = 975 mK.We interpret the inelastic signal observed in NdGaO3

to be due to the excitations of the Nd nuclear spins I= 7/2 of the 143Nd and 145Nd isotopes. In a firstapproximation one can consider these inelastic peaksto arise due to the transitions between the hyperfine-field-split nuclear levels. This is the single-nucleuseffect. However the nuclear spins are coupledthrough Suhl-Nakamura interaction [1,2]. So oneexpects nuclear spin wave excitations (cooperativelattice effect) discussed by de Gennes et al. [3] . Thenuclear spin waves should show dispersions at smallmomentum transfers. Word et al. [4] have discussedthe possibility of measuring nuclear spin waves byinelastic neutron scattering. They have calculated thedifferential scattering cross section and polarizationof neutrons scattered by nuclear spin systemsdescribed by Suhl-Nakamura Hamiltonian in theformalism of van Hove correlation function. In ourexperiment, however, we failed to detect so far theexpected dispersion of the nuclear spin waves. This isperhaps due to the insufficient Q resolution of theback-scattering spectrometer. The dispersion of thenuclear spin waves can probably be measured by aneutron spin echo (NSE) spectrometer using a PG-analyzer at a strong spallation neutron source.

[1] H. Shul, Phys. Rev. 109, 606 (1958)[2] T. Nakamura, Progr. Theotet.Phys. (Kyoto) 20, 542(1958)[3] P.G. de Gennes et al., Phys. Rev. 129, 1105 (1963)[4] R. Word, A. Heidemann and D. Richter, Z. Phys. B28, 23 (1977)

TP62: Transport and magnetic properties of theperovskites Bi1-xCaxMn0.95Cr0.05O3 with x = 0.4, 0.5

C. C. Yang, F. C. Tsao, P. J. Hwang, W.-.H. Li(Department of Physics, National Central University,Chung-Li, 32054 Taiwan), J. W. Lynn (NIST Centerfor Neutron Research), J. R. Sun (State KeyLaboratory of Magnetism, Institute of Physics andCenter for Condensed Matter Physics, ChineseAcademy of Sciences,Beijing 100080, China)

Polycrystalline samples of Bi1-xCaxMn0.95Cr0.05O3 withx=0.4 and 0.5 were prepared by conventionalceramic route. Crystalline structures of the com-pounds were investigated by using the high-resolu-tion neutron diffraction patterns and the Rietveldmethod. At room temperature, they crystallized intoan orthorhombic Pbnm phase. Jahn-Teller distortionwas found at around 280 K for the x =0.4 sample. Acsusceptibility reveals a charge ordered state in both


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samples, which occur at 280 and 285 K for thex = 0.4 and 0.5 samples, respectively. An appliedmagnetic field of strength 9 T can melt the chargeordered state. The transport behavior of bothsamples may be described by using the variable-range hoping mechanism. The magnetic structuresfor both compounds were studied by neutron mag-netic diffraction measurements. The spins of bothcompounds become ordered below 90 K. Spinclusters were realized in both compounds, and phaseseparation was clearly revealed in the x=0.4 com-pound. Detailed magnetic structures will be dis-cussed.

TP63: Magnetic Order and Spin Dynamics inTriangular Magnets

Y. Li, Z. M. Hasan (Princeton University), S. Park, J.W. Lynn (NIST Center for Neutron Research), W.Ratcliff, S. Cheong (Rutgers University)

We have recently studied two classes of triangularspin systems—Seignette magnets and Thiospinels.Our studies of Ba3CoSb2O9, Ba3NiSb2O9 Seignette (2-Dxy Heisenberg) magnets suggest that these systemsexhibit 3-D long-range order at low temperatureswithout coupling to the lattice and exhibit conven-tional spin dynamics. On the other hand, 3-D topo-logically frustrated magnets such as thiospinels takemore complex paths to ordering. For example,ZnCr2S4 first enters a helical long-range orderedphase before coupling to the lattice but only at lowertemperatures achieves a 3-D commensurate orderand exhibits a local resonance similar to the oxidecounterpart. This complex magnetism in this systemis a direct consequence of competing interactionsunder geometrical constraints.

TP64: Magnetic and Structural Studies of theSpinels GeNi2O4 and GeCo2O4

M.K. Crawford, R.L. Harlow, R. Flippen (DuPontCR&D, Wilmington, DE), R.W. Stevens, B.F.Woodfield, J. Boerio-Goates (Brigham YoungUniversity, Provo, UT), P.L. Lee, Y. Zhang (AdvancedPhoton Source, Argonne National Laboratory,Argonne, IL), J. Hormadaly (Ben Gurion University,Beer Sheeva, Israel), R.A. Fisher (Lawrence BerkeleyNational Laboratory), Q. Huang, J. W. Lynn, Y. Qiu,J.R.D. Copley (NIST Center for Neutron Research)

Transition metal oxide spinels that have magneticions located only on the B-sublattice exhibit interest-ing phenomena, including Néel ordering accompa-nied by structural phase transitions. Neutron powderdiffraction measurements show that GeNi2O4 (spin-1)and GeCo2O4 (spin-3/2) become antiferromagnetic atTN = 12 K and 21 K, respectively. However, GeNi2O4

remains cubic, while GeCo2O4 becomes tetragonal,

below TN. Thus the behavior of GeCo2O4 is similar tothat of ZnCr2O4 (spin-3/2), although the Co2+ ion hasunquenched orbital angular momentum and the Cr3+

ion does not. The Néel transition in GeNi2O4 occurs intwo discrete steps, while the other materials havesingle Néel transitions. Neutron inelastic scatteringmeasurements demonstrate that both GeNi2O4 andGeCo2O4 have energy gaps in their Néel states,consistent with the results of heat capacity measure-ments. The Néel transition and magnetic structure ofGeCo2O4 are very sensitive to an applied magneticfield, whereas the Néel transitions in GeNi2O4 areonly weakly affected by a field. In this presentationwe will describe the results of magnetic and struc-tural studies of these materials, and discuss theirdifferent behaviors.

TP65: Neutron Scattering studies of Yb14MnSb11

S. E. Nagler, M. Yethiraj, H. A. Mook, D. G. Mandrus,B. C. Sales (Oak Ridge National Laboratory)

The tetragonal (a=b=16.6 Å, c=21.95 Å) materialYb14MnSb11 is a ferromagnetic semiconductor wherethe only magnetic ion is Mn present at the level 3.8atomic percent. With a magnetic transition near50 K, Yb14MnSb11 is a promising compound forinvestigating the physics of carrier mediated ferro-magnetism in dilute magnetic semiconductorswithout the possible complications of clustering orimpurity phases. We report here on some preliminaryresults of our neutron scattering investigations ofmagnetism in single crystals of Yb14MnSb11.

TP66: Quasielastic scattering in the magneticspinel Co2RuO4

G. E. Granroth, D. Abernathy (Spallation NeutronSource, Oak Ridge National Laboratory; CondensedMatter Sciences Division, Oak Ridge NationalLaboratory), S. E. Nagler (Condensed MatterSciences Division, Oak Ridge National Laboratory),D. Mandrus (Condensed Matter Sciences Division,Oak Ridge National Laboratory; Department ofPhysics and Astronomy, University of Tennessee), V.Keppens (Department of Physics, University ofMississippi, Oxford, MS 38677), J. R. D. Copley(NIST Center for Neutron Research)

Bulk magnetization measurements of the spinelCo2RuO4 have revealed a “spin glass like” groundstate [1]. To further elucidate the properties of thisground state, temperature (T) dependent quasielasticneutron scattering studies have been performedusing the DCS instrument at NIST. For T greater thanthe spin glass transition temperature (Tg ~ 15 K), thequasielastic peak can be fit by a Lorentzian of width181 ± 9 µeV convoluted with the instrumentalresolution. Furthermore the Q dependence of the


scattering is broad and oscillatory consistent withshort range ordered states involving nearest and nextnearest neighbor sites [2]. For T < Tg , approxi-mately 1/3 of this scattering is moved to the elasticposition at a Q corresponding to the (200) position ofthe spinel lattice. The other 2/3 of the scatteringremains in a Lorentzian component of width130 ± 10 µeV. This behavior is consistent with areduction of short time scale dynamics observed in aspin glass.

[1] D. Mandrus, V. Keppens, and B. C. Chakoumakos,Mat. Res. Bull., 34, 1013 (1999).[2] G. E. Granroth et al. to be published.

TP67: Magnetic Excitation Spectrum inCa2-xSrxRuO4

M.D. Lumsden (Condensed Matter SciencesDivision, Oak Ridge National Laboratory), S. Wilson(Department of Physics and Astronomy, Universityof Tennessee), S.E. Nagler (Condensed MatterSciences Division, Oak Ridge National Laboratory),P. Dai (Department of Physics and Astronomy,University of Tennessee; Condensed MatterSciences Division, Oak Ridge National Laboratory),R. Jin (Condensed Matter Sciences Division, OakRidge National Laboratory), D. Mandrus(Condensed Matter Sciences Division, Oak RidgeNational Laboratory; Department of Physics andAstronomy, University of Tennessee)

We have studied the concentration dependence onthe magnetic excitation spectrum in single crystalsamples of Ca2-xSrxRuO4 for 2>x>0.4. For large x,the spectrum is similar to that observed in pureSr2RuO4 with incommensurate excitations stronglypeaked in Q at (+/-0.3,+/-0.3,qz) consistent withFermi-surface nesting wavevectors. As the concentra-tion approaches the quantum critical point at x=0.5,the spectrum evolves into a multipeak structure in Qcentered around the 2d ferromagnetic zone center.The spectrum observed near the quantum criticalconcentration is qualitatively quite similar to thatobserved in Sr3Ru2O7 which is also in the vicinity of aquantum critical point.

TP68: Electronic transport and magnetic propertiesof the natural spin valve Mn0.25NbS2

C.J. Metting, S.E. Lofland (Dept. of Physics andAstronomy, Rowan University, Glassboro, NJ), K.V.Ramanujachary (Dept. of Chemistry andBiochemistry, Rowan University, Glassboro, NJ), J.D.Hettinger (Dept. of Physics and Astronomy, RowanUniversity, Glassboro, NJ), J.W. Lynn (NIST Centerfor Neutron Research, Gaithersburg, MD)

We have completed magnetotransport, magnetiza-

tion, and neutron diffraction studies on polycrystal-line and single crystal samples of Mn1/4NbS2. Thesemetallic intercalated compounds, which alternatebetween four NbS2 layers and one layer of Mn, showferromagnetic order below 100 K which is accompa-nied by sizeable (> 15 %) magnetoresistance inpolycrystalline material. However, the magnetoresis-tance along the a axis, parallel to the ferromagneticMn layers, is very small in the single crystals. Thus itappears that the large magnetoresistance in thepolycrystalline material is a result of transport alongthe c axis, through the Mn layers which act as naturalspin valves between the conducting NbS2 layers.

TP69: DAVE—Software facilitating science at theNCNR

R.M. Dimeo (NIST Center for Neutron Research),R.T. Azuah, L.R. Kneller, Y. Qiu (NIST Center forNeutron Research; University of Maryland, CollegePark)

The DAVE software package is a free suite of tools forreducing, visualizing, and analyzing data collected onthe inelastic neutron spectrometers at the NISTCenter for Neutron Research. The design goal for thesoftware is to provide easy-to-use, powerful tools thatfacilitate data interpretation. This poster presentationwill demonstrate the existing capabilities of thesoftware package and highlight new features such astriple-axis data reduction, neutron spin-echo datareduction, improved data visualization, and modelfitting applications.

This work is based upon activities supported by theNational Science Foundation under Agreement No.DMR-0086210.

TP70: Upgrading Data Analysis Software for theGlass, Liquid and Amorphous materialsDiffractometer at IPNS using ISAW

J.Z. Tao, C.J. Benmore, T.G. Worlton (Intense PulsedNeutron Source, Argonne National Lab), D.Mikkelson, R.L. Mikkelson (University ofWisconsin-Stout), A. Chatterjee, J.P. Hammonds(Intense Pulsed Neutron Source, Argonne NationalLab)

We are porting, upgrading and designing newanalysis software for the GLAD instrument as part oftime-of-flight neutron scattering data visualizationand analysis package ISAW. GLAD has continuousangular coverage from 2θ=3° to 117° using 235 3Helinear position sensitive detectors. Data is currentlyprocessed using the ATLAS data analysis suite pro-duced at ISIS combined with the IPNS Glass AnalysisPackage, which operates on an aging VAX/VMSsystem. The software upgrade has lifted the detector


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grouping restriction imposed by the limited VAX/VMScomputing power, and brought the analysis routinesin line with more sophisticated software developmentmethods and tools. The first stage of the projectconsists of instrument dependent raw data correc-tions: dead-time, delayed neutron, detector efficiencyand conversion of time-of flight to Q. The secondstage involves data normalization with respect to avanadium standard and application of attenuationand multiple-scattering corrections. The new detec-tor-by-detector analysis uses the full Q range avail-able, is not subject to averaging effects, and results ina smoother neutron time-of-flight differential crosssection function. The detector grouping flexibility inISAW will extend the instruments capability to lowerQ-values, which will augment the study of intermedi-ate range order in glasses, supercritical fluids andlayering in clays for example. It will also enable us toinvestigate the feasibility of the anomalous neutrondiffraction technique on a pulsed source.

TP71: Sharing neutron data and softwareT. G. Worlton (Intense Pulsed Neutron Source,Argonne National Lab), D.J. Mikkelson, R. L.Mikkelson, C. Bouzek (University of Wisconsin-Stout), A. Chatterjee, J. P. Hammonds (IntensePulsed Neutron Source, Argonne National Lab)

Neutrons are becoming more important to scientistsin the United States each year and many scientistsnow use more than one neutron scattering facility.Collection of data usually takes a short time, butanalysis of the data can be quite lengthy. Productivityof scientists will be greatly improved by providingsoftware which can automate data reduction andallow them to visualize and analyze data fromdifferent facilities. The NeXus specification forstorage and interchange of neutron scattering datamakes it possible to write software which is useableat different facilities with very little modification. TheISAW package developed at Argonne can be used toread, visualize, and analyze data from differentfacilities which write data in the NeXus format. ISAWis an open source package which includes capabilitiesfor users to write their own scripts and operators tocustomize their data reduction and analysis. We willdemonstrate how a user can write operators andscripts to automate processing of data using ex-amples from the ISAW distribution. Both built-in anduser-written operators will automatically appear inISAW menus and can be used in ISAW scripts withoutrecompiling ISAW. Documentation from user-writtenoperators will also appear automatically in theinteractive help menus.

TP72: New Instrument Control Software at theNCNR

N.C. Maliszewskyj (NIST Center for NeutronResearch), M Doucet (University of Maryland,College Park), S. Pheiffer

The construction and installation of a state of the artthermal triple axis at the NCNR presents us with theopportunity to similarly craft new software thataddresses the needs of our local staff and outsideusers. An autonomous instrument control server willmediate interactions of users with hardware, managedata acquisition, and sequence commands for batchexecution. Client programs incorporating experimentplanning tools will be used to compose scans, issueinstanteous commands to be executed by the server,and provide the first layer of live status information.A tiered permission scheme will permit certain typesof remote operation in this client-server system.

This software is designed with portability in mind. Ahardware abstraction layer (“middleware”) encapsu-lates the most platform dependent portions of thecode while the remainder of the instrument controlserver is essentially a platform independent pythonscript. We will present an architectural overview ofthis suite and an update of the current state of theproject.

TP73: Data Reduction Software for ChopperSpectrometers

T. M. Kelley, B. T. Fultz, M. M. McKerns, M. G.Aivazis (California Institute of Technology)

The raw data of an inelastic chopper spectrometerare time histograms of neutron counts in eachdetector pixel; reducing these histograms to energyand momentum coordinates requires substantialcomputation.With higher pixel counts and shorterdata collection times, upcoming SNS instrumentssuch as ARCS will need highly efficient reductioncodes. We are designing an object-oriented system inwhich compiled and optimized C++ components arebound at run time by the Python interpreter. Thisresults in software that has the flexibility of aninterpreted language and the performance of acompiled language. Where possible, we have pursuedseparation between data structures and algorithmsanalogous to the C++ Standard Template Library. Theobject-oriented nature of the system insulatescomponents that carry out data transformation fromthose that describe instrument properties; this makesa number of the components independent of instru-ment, and they may be reusable for other spectrom-eters.


TP74: Detectors for Neutron Science—How to finda Neutron?

L. Crow, C. Hoffmann (SNS, Oak Ridge NationalLaboratory), G. Smith (Brookhaven NationalLaboratory, R. Copper (SNS, Oak Ridge NationalLaboratory)

Condensed matter physics, chemistry, metallurgy,geo-, and bio-sciences have benefited greatly fromusing neutrons to probe structure, magnetism, anddynamics of materials. In many of these studies,however, presently available neutron detector sys-tems lack the performance to fully exploit futureneutron flux. With the approaching completion ofSNS in 2006 we are challenged to use this window ofopportunity to build a research effort of sustaineddevelopment of gas and scintillation detectors, andfor investigation of new scintillator materials, semi-conductor detectors, new types of gas detectors, andlow efficiency neutron monitors. Neutron detectorresearch has made advances in the past few years –this has happened quietly, but nevertheless hasenabled the establishment of new scientific researchin traditional and new fields.

T2-A, Proteins: Structure and Hydration,Chair: Dean Myles (ORNL), Room 2100/2/4 Red

T2-A1 (13:30) The PCS Neutron Protein Crystallog-raphy Facility at Los Alamos (Invited)

P. Langan, B.P. Schoenborn (Los Alamos NationalLaboratory)

The PCS (Protein Crystallography Station) at LosAlamos Neutron Science Center, is a high perfor-mance neutron protein crystallography beam linefunded by the Office of Biological and EnvironmentalResearch of the U.S. Department of Energy. Beam-time is free to expert and non-expert users and isallocated twice a year through a call for proposalsand a peer review process.

Although most protein structures are determinedusing x-rays, the position of hydrogen atoms and thecoordination, sometimes even the position of watermolecules, cannot be directly determined at resolu-tions typical for most protein crystals. Hydrogenatoms are the primary motive force in most enzy-matic processes. Neutron diffraction is a powerfultechnique for locating hydrogen atoms even atresolutions of 2 Å to 2.5 Å and can therefore provideunique information about enzyme mechanism,protein hydrogen and hydrogen bonding.

For an experiment on the PCS, protein crystals haveto be ~ 1 mm3 in volume. Crystals of perdueteratedprotein can be significantly smaller. Users of the PCShave access to neutron beam-time, perdeuteration

facilities and also support for data reduction andstructure analysis. The beam-line exploits the pulsednature of spallation neutrons and a large electronicdetector in order collect wavelength resolved Lauepatterns using all available neutrons in the wave-length range 1 Å to 5 Å. This talk shall be used todescribe the facility, some groundbreaking resultsfrom our second year of operation, and providesinformation about obtaining beam-time. Futuretechnological developments that will greatly improvethe performance of the PCS facility will also bediscussed, as well as prospects for neutron proteincrystallography at the SNS.

For more information about the PCS and experimen-tal requirements, contact Paul Langan (505) 6658125, [email protected] or Benno P. Schoenborn(505) 665 2033, [email protected]. The PCS isfunded by the Office of Science and the Office ofBiological and Environmental Research of the U.S.Department of Energy.

T2-A2 (14:00) SANS Molecular Modeling of Biologi-cal Macromolecules from Low Resolution to HighResolution Techniques

S. K. Gregurick, J. Zhou (Department of Chemistryand Biochemistry, UMBC, 1000 Hilltop Circle,Baltimore MD, 21250), F. Schwartz (Center forAdvanced Biotechnology, National Institute ofStandards and Technology, 9600 Gudelsky Dr.,Rockville MD, 20850), S. Krueger (NIST Center forNeutron Research)

Within the past decade, small angle scatteringmeasurements (SANS and SAXS) have played animportant role in molecular biology, including thestudies of protein-DNA interactions, protein-proteininteractions, domain interactions within a givenprotein and the study of nucleic acid structures (DNA,RNA and peptide nucleic acids, or PNA). In order tomodel a three-dimensional macromolecular structurefrom an experimental scattering profile (I(Q) vs. Q),we have developed a series of modeling and simula-tion programs. Our talk will highlight our recent workon developing molecular models of proteins andnucleic acid structures, based on small angle neutronscattering data in solution. We shall discuss both themethodology and applicability of our low resolutionMonte Carlo technique, LORES, and our newlydeveloped high resolution technique, Xtal2SAS. Wewill illustrate the ability of both methods to modelSANS intensities of biological structures in solution.In particular, we will focus on the melting of aheterogeneous PNA/DNA construct, the dynamics ofa 10-mer double stranded DNA construct and theprotein CRP, in solution. Our methods will be com-


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pared to other modeling software, when applicable.Our results will illustrate both the power and limita-tions of our current approach to develop a compre-hensive software package for modeling of nucleicacid and protein structures in solution.

T2-A3 (14:15) The role of “anchoring” moleculesand residual water on the stability of biomolecules

A. M. Pivovar, S. Takata, J.E. Curtis (NIST Center forNeutron Research)

In order to slow the deactivation of a biologicallyactive material, biomaterials are commonly storedwithin glass networks formed by small moleculeswith extensive hydrogen bonding interactions (e.g.,saccharides or polyols). The glass network is believedto reduce the rate of deactivation by suppressing thedynamic mobility of biomolecular residues throughthermodynamically favorable interactions betweenthe glass and the surface of the native biomolecule.The “rigidity” imparted on the biomolecule by theglass matrix is dependent upon both the inherentrigidity of the glass and the strength of the interac-tions “anchoring” the biomolecule to the glass. Toascertain the role of the anchoring interactions onbiopreservation, we have measured the ensembletemperature dependent mean square displacementdynamics of lysozyme-glucose composites using theHigh Flux Backscattering Spectrometer at the NISTCenter for Neutron Research. Selective isotopicsubstitution of deuterium for hydrogen permitsexclusive measurement of the dynamics of thebiomolecular component in the mixture and evalua-tion of the total scattering from a fully hydrogenatedsample allows us to ascertain the dynamics of thesugar. As expected, our results indicate that thedynamics of the biomolecule are suppressed throughinteractions with the anchoring sugar when com-pared with a pure lysozyme powder. However, theresults also indicate that the dynamics of the an-chored glucose molecules is less than what is ob-served in a pure glucose glass. We believe theseresults imply a strong dependence between theresidual water present in the mixtures andbiostability enhancement. The details of this conclu-sion and its ramifications on biopreservation formuladesign will be discussed.

T2-A4 (14:30) Hydration Dynamics near a ModelProtein Surface

D. Russo (Department of Bioengineering, Universityof California, Berkeley), G. Hura (Graduate Group inBiophysics, University of California, Berkeley), T.Head-Gordon (Department of Bioengineering,University of California, Berkeley; Graduate Groupin Biophysics, University of California, Berkeley)

The evolution of water dynamics from dilute to veryhigh concentration solutions of a prototypical hydro-phobic amino acid with its polar backbone, N-acetyl-leucine-methylamide (NALMA), is studied by quasi-elastic neutron scattering (QENS) and moleculardynamics (MD) simulation for both the completelydeuterated and completely hydrogenated leucinemonomer. The NALMA-water system and the QENSdata together provide a unique study for characteriz-ing the dynamics of different hydration layers near aprototypical hydrophobic sidechain and the backboneto which it is attached. We observe several unex-pected features in the dynamics of these biologicalsolutions under ambient conditions. The translationaland rotational water dynamics at the highest soluteconcentrations, are found to be highly suppressed ascharacterized by long residential time and slowdiffusion coefficients. The analysis of the more diluteconcentration solutions models the first hydrationshell with the 2.0 M spectra. We find that for outerlayer hydration dynamics that the translationaldiffusion dynamics is still suppressed, although therotational relaxation time and residential time areconverged to bulk-water values. Molecular dynamicsanalysis of the first hydration shell water dynamicsshows spatially heterogeneous water dynamics, withfast water motions near the hydrophobic side chain,and much slower water motions near the hydrophilicbackbone. We discuss the hydration dynamics resultsof this model protein system in the context of proteinfunction and protein-protein recognition

T2-B, Materials Chemistry, Chair: John Larese(U. Tennessee), Room 1123 Blue

T2-B1 (13:30) States of Water in Hydrating PortlandCement

R. A. Livingston (Federal Highway Administration),D. A. Neumann, A. Allen, N. Nemes (NationalInstitute of Standards and Technology)

The essential reaction in the hardening of Portlandcement occurs between tricalcium silicate and water.The kinetics of this reaction are complex with up tofive different stages, but have been characterizedusing neutron scattering methods. These reveal atleast three states of water that are called: free,confined and chemically bound. These can be relatedto the conventional cement chemistry classificationsof non-evaporable water, gel pore water and capillarypore water. Following these states individually as afunction of temperature, particle-size distribution andwater/cement ratio provides insights into the ratecontrolling mechanism of each stage. These can alsobe related to macroscopic property development inthe concrete such time of initial and final set. It has


been proposed that water also exists in a glassy orsolid state in the hydrated cement, but this does notseem possible from thermodynamic considerations.

T2-B2 (13:45) Combined USANS/SANS ContrastMatching to Distinguish Calcium Hydroxide andCalcium-Silicate-Hydrate Gel Contributions toHydrating Cement Microstructures

A. J. Allen (Ceramics Division, MSEL, NationalInstitute of Standards and Technology), J.J. Thomas,J.J. Chen (Department of Civil Engineering,Northwestern University, Evanston, IL), J.G. Barker(NIST Center for Neutron Research)

Characterization and modeling of the microstructureof hydrating cement using both SANS and SAXS haslong been pursued by groups from around the world.The durability and mechanical properties of concreteare intimately connected to the development ofcalcium-silicate-hydrate (CSH) gel within the hydrat-ing cement component. SAS techniques are particu-larly useful because the CSH is amorphous, renderingdiffraction ineffective, and is altered by samplepreparation for electron microscopy. Also, the CSHgel structure (which exhibits fractal properties)extends over length scales appropriate for SAS.Quantifying CSH structure is complicated by thepresence of water (H) in various states ranging fromOH groups to trapped liquid in nanopores. A furthercomplication for conventional SANS and SAXS, andeven for USAXS, is the presence of calcium hydroxide(CH) crystals in intimate mixture with C-S-H, whichmakes it necessary to determine the fine CH struc-ture at all length scales so that CSH can be unam-biguously characterized. Recently, combined USANSand regular SANS measurements performed oncontrast matched cement paste specimens haveallowed the CH morphology to be revealed andsurveyed over the full range of required sizes. All theH in CSH exchanges readily with deuterium oxide (D)in contrast variation studies, while CH is crystallineand does not take part in H/D exchange. Hydratedsamples were studied by USANS and SANS in H/Dmixes of 100 % H, 32 % D (CH contrast match), and80 % D (effective CSH/D contrast match). Corre-sponding samples were also studied after the CHphase was removed by leaching. Comparing leachedand unleached sample data for the various H/D mixeshas allowed the CH and CSH components to bedistinguished to an unprecedented degree, and hashighlighted previously unobserved structures in theUSANS range. A fully quantitative microstructureanalysis of CSH over its whole scale range has thusbeen obtained for the first time.

T2-B3 (14:00) Changes in Ettringite CrystallineStructure Associated with Thermal Dehydration

M. R. Hartman, R. Berliner (University of Michigan,Ann Arbor, MI 48109)

Neutron powder diffraction studies have beenperformed on deuterated ettringite,Ca6[Al(OD)6]2(SO4)3(~26D2O), synthesized in thelaboratory by precipitation from solutions of Ca(OD)2

and Al2(SO4)3 in D2O. Structural studies were per-formed at 10K using Rietveld refinement on fullyhydrated material as well as samples that had beenthermally treated to 6 %, 15 %, 21 %, and 27 %weight loss. Changes in the lattice parameters wereobserved with the c-axis exhibiting a linear contrac-tion from 21.34948(18) Å in the fully hydrated stateto 21.2662(17) Å for the specimen with 27 % weightloss. Conversely, the a-axis was observed to exhibit alinear expansion from a value of 11.16474(7) Å in thefully hydrated state to 11.1849(10) Å in the specimenwith 27 % weight loss. The occupations of thehydroxyl and water sites were refined on the dehy-drated samples to determine the order in which thesesites are depopulated during the dehydration process.In contrast to prior investigations employingthermogravimetric analysis and 27Al NMR, whichproposed an orderly depopulation of specific crystal-line sites, the present study showed that the waterand hydroxyl sites are simultaneously depopulated inthe dehydration process. Additionally, an in situthermal dehydration of ettringite was performed at50 °C by passing dry nitrogen through a column ofettringite. The ettringite sample dehydrated in situwas dehydrated to a weight loss of 26.1 %. Compari-son of the in situ dehydration data showed goodagreement with the structural data of the staticallydehydrated material.

T2-B4 (14:15) Probing the Mechanism of Metal-Halide Network Formation and Crystal Growth(Invited)

J. D. Martin (Department of Chemistry, NorthCarolina State University)

The ability to design the structure of a material, andto control the influence of that structure on thematerial’s properties is fundamentally important tothe development of advanced materials. Crystalengineering has successfully articulated structuralprinciples for the construction diverse materials.However, little is understood regarding themechanism(s) by which networks are templated andcrystals grow. Using a series of low temperaturemelting network liquids ZnCl2, CuAlCl4 and CuGaCl4as well as the templated sodalite-type network[HNMe3]CuZn5Cl12 we are able to articulate funda-mental mechanistic aspects of network formation


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and crystallization reactions. Because several of thesematerials readily form glasses we are able to investi-gate cold crystallization (from the glass) and hotcrystallization (from the melt) allowing us to studycrystallization under nucleation- and growth-con-trolled conditions, respectively. Data from amorphousand crystalline neutron scattering, inelastic neutronscattering, time-resolved synchrotron diffraction, andDSC measurements will be discussed.

T2-B5 (14:45) Neutron Diffraction Studies on MetalPseudohalide between 300 K and 50 K

D. J. Williams, L. Daemen, S. Vogel (Los AlamosNeutron Science Center, Los Alamos NationalLaboratory)

The structural investigation of metal pseudohalidecompounds (e.g., cyanides, cyanates, etc.) has beenthe object of numerous studies over more than acentury. Several unresolved problems remain. Thosehave been addressed inconclusively with x-rayscattering and a variety of other techniques providingindirect structural information. One such outstandingstructural question in binary pseudohalide com-pounds is whether only carbon or only nitrogenatoms in the polyhedron coordination sphere sur-round the metal cation. This structural questionregarding the coordination sphere of the metal cationin cyanide and cyanate compounds is still debatedamong chemists.

The use of powder and single crystal x-ray diffractiontechniques has been limited because the scatteringcontrast between neighboring elements, carbon,nitrogen, and oxygen, is weak. The possibility ofdisorder further complicates the matter. Fourier-Transform Infrared Spectroscopy (FT-IR) has beenused to shed light on the nature of the metal to C orN bonding. However most of the information that isobtained is n(C-N), n(C-O) stretches, and broadn(M-(C, N, O)) stretches at low wave numbers. (Whenthe latter can be observed at all, it usually does notreveal any information about the metal cationpreferred bonding orientation to the cyanide ligand.)Other spectroscopic techniques like Raman and NMRhave had equally limited success. Because of thedifference in neutron scattering length among C, N,and O, powder neutron diffraction should proveuseful in resolving controversial structural issues inbinary pseudo-halides. Similarly, incoherent inelasticneutron scattering is an attractive, alternative toconventional spectroscopies to provide chemicalbonding information on the metal to pseudo-halideligand. With LANSCE’s newly commissioned powderdiffractometer HIPPO (High Pressure PreferredOrientation powder diffractometer) and FDS (Filter

Difference Spectroscopy) a complete structuralinvestigation of AgCN and AuCN was performed at300 K, 200 K, 150 K, 100 K, and 50 K. The resultsconfirm that cyanide ligands in these simple binarycompounds are disordered throughout the crystalstructure. The ordering/disordering of cyanate ligandshas also been investigated (e.g., NaOCN, KOCN,AgOCN…) using neutron scattering to determinewhether the metal cation (e.g., Na, K…) is completelysurrounded by the nitrogen or the oxygen end of acyanate ion (e.g., OCN-M-NCO, NCO-M-NCO,NCO-M-OCN, etc…). These results will be discussedin detail.

T2-B6 (15:00) Single Crystal Analyses of theStructure and Bonding in Transition-Metal SigmaComplexes

A. J. Schultz, T. F. Koetzle, J. A. Cowan, M. E. Miller,X. Wang (Intense Pulsed Neutron Source, ArgonneNational Lab)

In this presentation we will discuss a series ofstructures of B-H and Si-H sigma complexes that wererecently obtained based on data from the IPNS SingleCrystal Diffractometer (SCD). Transition-metal sigmacomplexes are coordination compounds in which twoelectrons in an X-H sigma bond form a dative bondwith a transition metal. This three-center, two-electron bond can be further stabilized by pi-backbonding from the metal to the X-H sigma*antibonding orbital. Transition metal sigma com-plexes are typically reactive intermediates thatprecede oxidative addition of substrates having anX-H bond. Sigma complexes are, therefore, identifiedas intermediates in catalytic hydrogenation (X = H),activation and functionalization of hydrocarbons(X = C), hydrosilylation (X = Si), and hydroboration(X = B) reactions. Characterizing the structure andbonding of the intermediate species is important toour understanding of these reactions and to improv-ing catalytic processes. Single crystal neutron diffrac-tion has played a critical role in characterizing thestructure and bonding of sigma complexes, for whichthe positional and thermal parameters of the hydro-gen atom in close proximity to a metal atom areclearly of utmost importance.

This research was supported by the U.S. DOE, Officeof Basic Energy Sciences, under contract W-31-109-ENG-38.T2-C, Instrumentation, Chair: Kenneth Herwig(ORNL), Auditorium


T2-C1 (13:30) Spin-analyzed diffuse scatteringmeasurements of magnetic thin films with a 3Heanalyzer and a position-sensitive detector

W. C. Chen (National Institute of Standards andTechnology; Indiana University), K.V. O’Donovan(NIST Center for Neutron Research; University ofMaryland, College Park), J.A. Borchers, C.F.Majkrzak, T.R. Gentile (National Institute ofStandards and Technology)

Polarized 3He gas, produced by optical pumping, canbe used to polarize or analyze neutron beamsbecause of the strong spin dependence of theneutron absorption cross section for 3He. 3He spinfilters have been identified as important polarizingelements in the development of polarized neutronscattering instruments for the upcoming spallationneutron source (SNS) because they are broadbandand suitable for divergent scattered beams. Here wereport efficient polarization analysis of diffuselyreflected neutrons in a reflectometry geometry usinga hyperpolarized 3He spin filter in conjunction with aposition-sensitive detector (PSD). We obtained spin-analyzed two-dimensional Qx-Qz reciprocal spacemaps for a patterned array of Co antidots in thesaturated and the demagnetized states. We compareddata obtained from a 3He analyzer and a PSD withthose obtained from a conventional supermirroranalyzer, and they are in good agreement. Thepreliminary results for the upcoming experimentwith a 3He analyzer and a PSD using a patterned dotsample and/or a rare-earth alloy exchange spring willalso be reported. For these experiments, 3He gas ispolarized by the spin-exchange optical pumping(SEOP) method and stored in a uniform magneticfield provided by a shielded solenoid. We address twoimportant issues for achieving the better perfor-mance of the 3He spin-analysis device: high 3Hepolarization and long relaxation time of the cell.Using a spectrally narrowed diode laser array wehave recently achieved 3He polarizations of 74 % to79 % in 3He cells ranging from 260 cm3 to 500 cm3

in volume.

T2-C2 (13:45) Convergent Beam Neutron Crystal-lography

W. M. Gibson, R. Youngman (X-Ray OpticalSystems, Inc., 15 Tech Valley Drive, East Greenbush,NY 12061), A. J. Schultz, J. W. Richardson, J. M.Carpenter, M. E. Miller, E. R. Maxey (Intense PulsedNeutron Source, Argonne National Lab), D. F. R.Mildner, H. H. Chen-Mayer (National Institute ofStandards and Technology)

Two monolithic polycapillary optics of different focallength and beam convergence are used to investigatethe use of focusing lenses for the neutron convergent

beam method for time-of-flight crystallography with abroad wavelength band. The lens of short focallength (15.5 mm) with a beam convergence of16.8 ± 1.0 degrees has a focal width of about 120microns. For a single crystal sample of this diameteron a pulsed neutron source, this lens gives an inte-grated intensity gain of ~ 50 for a (020) Bragg peakin MnF2 with 3.2 Å neutrons and a measured peakwidth (FWHM) of 4.5 degrees. Further measurementson a powder diffractometer show that the expecteddiffracted beam intensities have gains as much as500 for powder samples of this diameter. The degra-dation of resolution is minimized in the back scatter-ing geometry. The intensity gains for the powderdiffraction peaks increase with wavelength andclosely follow the expected transmission of the opticas a function of wavelength.

Work at XOS was supported by the US DOE, BES-MS,contract nos. OF-01385 and DE-FG02-02-ER83575.Work at Argonne National Laboratory was supportedby the US DOE, BES-MS, under contract no. W-31-109-ENG-38. We also thank the NIST Center forNeutron Research.

T2-C3 (14:00) Neutron optical elements from HMIBerlin

Th. Krist, F. Mezei (Hahn-Meitner-Institut Berlin)In the last several years solid-state and other neutronoptical devices have been developed at BENSC,especially polarizers and collimators. We show resultsof a solid state polarizing bender which polarizesneutron beams of arbitrary width and with wave-lengths above 2.4 Å to flipping ratios above 40(polarization above 95%). The mean transmissionamounts to 61 ± 4 % at 4.7 Å. Solid-state collimatorswith absorbing and also with reflecting walls werefirst built in our group and results will be shown, e.g.,of a collimator with a FWHM of 8' and a transmissionabove 70 %. A solid-state radial bender for thepolarization analysis of neutrons over a wide angularrange was built and tested at BENSC. A total angularinterval of 3.8 deg could be analyzed. A solid-stateradial collimator channel was built and tested. Theangular range of the transmitted intensity could bedoubled. Our first experiment on a solid-stateneutron lens will be presented which shows a clearfocusing of neutrons. Results for a solid-state benderused in transmission together with a solid-statecollimator are shown.

Finally the design of a two dimensional polarizationanalyzer for an angular range of 5° in both directionsand first results are presented.


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T2-C4 (14:15) 2D-Multi-Wire Position-SensitiveGaseous Neutron Detectors with Relative Resolu-tions higher than 0.5%

R. Kampmann (Institute for Materials Research,GKSS Research Centre, 21502 Geesthacht, Germany;DENEX Detectors for Neutrons and X-rays GmbH,Moldenweg 9a, 21335 Lueneburg, Germany), M.Marmotti (DENEX Detectors for Neutrons and x-rays GmbH, Moldenweg 9a, 21335 Lueneburg,Germany), R. Georgii (ZWE FRM-II / Physik-Department E21, Technical University Munich,85748 Garching, Germany), M. Haese-Seiller, V.Kudryashov (Institute for Materials Research, GKSSResearch Centre, 21502 Geesthacht, Germany)

Two delay-line based 2D-multi-wire position-sensitivegaseous detectors (MW-PSGD) with very high relativeresolution (Rr) defined as the position resolution inpercentage of the detector dimension have recentlybeen developed for the instruments REFSANS andMIRA at the new German high flux reactor FRM-II.The REFSANS detector has an active area of Aa =(500 mm)2, a wire pitch of 2 mm and Rr = 0.4 %,the MIRA detector is smaller (Aa = (200 mm)2 andhas a wire pitch of 1 mm resulting in Rr = 0.5 %.These Rr-values demonstrate a substantial progress inthe technology of 2D-MW-PSGD’s because hithertothe actual limit of resolution for such detectors hasbeen Rr = 0.8 %. The design, the spatial resolutionand the discrimination of gamma-radiation of thedetectors are presented. Finally, the count ratecapability of these modern delay-line based detectorsis discussed for the case that they are linked tomodern multi-hit TDC based data acquisition sys-tems.

T2-C5 (14:30) Neutron Diffraction from LevitatedLiquids — a Technique for Measurements onLiquids under Extreme Conditions

J.K.R. Weber, J.E. Rix, K.J. Hiera, J.A. Tangeman(Containerless Research, Inc.), C.J. Benmore, J.E.Siewenie (Intense Pulsed Neutron Source, ArgonneNational Lab)

Combining neutron diffraction and containerlesstechniques enables the structure of solids and liquidsto be probed at extreme temperatures and underhighly non-equilibrium conditions. Results comple-ment data obtained by x-ray techniques and permit amore detailed understanding of the relaxation ofliquid structures. This paper will describe the imple-mentation of experiments on molten aluminates andzirconium oxide under containerless conditions athigh temperature. Data were obtained at the GlassLiquids and Amorphous Diffractometer at IPNS usingaerodynamic levitation and CO2 laser beam heatingof 3 mm to 3.5 mm diameter samples. Levitation was

performed in argon gas and using pure vanadiumnozzles. Structure factors were measured for liquidswith the compositions CaAl2O4, Ca67Al66O166,Sr67Al66O166, Y3Al5O12 and ZrO2 at temperatures up to3350 K. Results will be compared to data for glasseswith the same chemical compositions. Plans fordevelopment of a system for SNS research will besummarized.

Supported by DOE under contract numbers DE-FG02-01ER86121 (CRI) and W 31 109 ENG 38 (IPNS).

T2-C6 (14:45) A New In Situ Vapor SorptionApparatus for SANS Measurements

Man-Ho Kim (NIST Center for Neutron Research;Department of Materials Science and Engineering,University of Maryland), Charles J. Glinka (NISTCenter for Neutron Research)

An apparatus for quantitative in situ vapor phasesorption, based on a prototype developed by NIST’sPolymers Division [1], has been constructed for SANSmeasurements. The apparatus facilitates determiningpore size distributions of microporous materials,enhancing scattering contrast in structural studies ofsemi-crystalline polymers, and the adsorption anddesorption of solvent mixtures in porous media forrapid contrast variation with a single sample. Theapparatus consists of a temperature-controlledtitanium sample cell with demountable quartzwindows and variable path length of 1 mm to 5 mm.The cell has ports for evacuating or admitting vaporto the sample space while monitoring and controllingabsolute pressure. The apparatus can also be used tocontinuously flow a carrier gas through the sample.Mass flow controllers in the system allow the carriergas to mix specific molar ratios of saturated vaporfrom two temperature-controlled solvent reservoirs toprovide continuous control of the H/D ratio in thevapor reaching the sample. Examples of vaporcondensation in microporous silica and the selectiveabsorption of deuterated vapor in semi-crystallinepolyethylene will be shown to demonstrate theperformance of the apparatus.

[1] Ronald C. Hedden, Hae-Jeong Lee, and Barry J.Bauer, Langmuir, 2004, 20, 416-422

T2-C7 (15:00) Novel time-of-flight diffractometerfor very high resolution and extreme sampleenvironment.

J. Peters, D. Clemens, K. Lieutenant (Hahn-Meitner-Institut Berlin), F. Mezei (Hahn-Meitner-InstitutBerlin; Los Alamos Neutron Science Center, LosAlamos National Laboratory)

The Extreme Environment Diffractometer (EXED)powder diffractometer is under construction at the


Hahn-Meitner-Institut (HMI) in Berlin. It is based onthe time-of-flight (TOF) principle, which offers anumber of advantages on a continuous sourcecompared with the usual crystal monochromatorinstruments: a) It can provide higher resolutions,matching those achieved by now on synchrotronradiation sources; b) It makes small d spacing readilyaccessible; c) It is more efficient in terms of neutronintensity for conventionally high resolution neutrondiffraction work and d) it facilitates the use of ex-treme sample environment equipment by providinga full coverage of the relevant Q domain at verylimited angular access in scattering angles, forinstance due to the magnet geometry. EXED will beinstalled on an innovative multispectral neutronguide, delivering both the thermal and the coldneutron spectrum to the sample at about 80 m fromthe neutron source. This will assure an exceptionallybroad incoming wavelength band of 0.7 Å to 20 Å,i.e. d spacing from 0.35 Å to 10 Å, or a momentumtransfer Q domain 0.63 Å-1 to 17.9 Å-1 can be studiedin the high resolution backscattering configuration atscattering angles 155° to 178°. The symmetricforward scattering range of 2° to 25° will makeaccessible Q values 0.01 Å-1 to 3.9 Å-1. With 54 mflight-path between the chopper and the sample, thehighest resolution will be achieved using a 36000RPM curved Fermi chopper for 6 µs FWHM pulselength and the resolution will be adjustable accordingto the needs of the experiment by extending thepulse length up to 4000 µs with the help of alternatechoppers (lower resolution straight Fermi chopperand a disc chopper pair with variable slit width). Thehighest resolution in backscattering geometry willachieve δd ~ 3.5x10-4 Å, i.e., δd/d = 2.4x10-4 forcommon d spacing in the 2 Å range. The wavelengthrange to be explored will be defined by the phasesand angular velocities of the choppers and can bescanned continuously.

The instrument is to be equipped with an immobilesteady state magnet (25 T, later envisaged 40 T) oftapered solenoidal shape, which form allows us toachieve higher fields than the conventional split pairdesign. Low temperature and high pressure sampleenvironments will also be available at high magneticfields. Four position sensitive gas detectors with aspace coverage of 50 x 80 cm2 each and a resolutionof 1 cm x 1 cm will be arranged around the sample,to provide fairly full coverage of the forward andbackward scattering angle domains left accessible bythe form of the magnet. EXED can be further ex-tended for small angle and inelastic scattering workin high magnetic fields.

T2-C8 (15:15) Capabilities for Texture Measure-ments of the New Neutron Diffractometer HIPPO

S. C. Vogel (Los Alamos National Laboratory), C.Hartig (Technical University Hamburg-Harburg,21071 Hamburg, Germany), L. Lutterotti (Universityof Trento, Italy; UC Berkeley, Berkeley, CA94720-4767), C.T. Necker (Los Alamos NationalLaboratory), R.B. Von Dreele (Los Alamos NationalLaboratory; Argonne National Laboratory), H.R.Wenk (UC Berkeley, Berkeley, CA94720-4767), D.J.Williams (Los Alamos National Laboratory)

In this presentation we describe the capabilities fortexture measurements of the new neutron time-of-flight diffractometer HIPPO (High Pressure PreferredOrientation) at the Los Alamos Neutron ScienceCenter (LANSCE). The orientation distributionfunction (ODF) is extracted from multiple neutrontime-of-flight histograms using the full-patternanalysis first described by Rietveld. Both, the well-established description of the ODF using sphericalharmonics functions and the WIMV method, morerecently introduced for the analysis of time-of-flightdata, are available to routinely derive the ODF fromHIPPO data. At ambient conditions, total count timeof less than 30 minutes is ample to collect sufficientdata for texture analysis in most cases. The largesample throughput for texture measurements atambient conditions possible with HIPPO requires arobust and reliable, semi-automated data analysis.HIPPO’s unique capabilities to measure large quanti-ties of ambient condition samples and to measuretexture at temperature and uniaxial stress aredescribed. Examples for all types of texture measure-ments are given. We will also critically compare theODF obtained from neutron time-of-flight data withthe ODF obtained from x-ray diffraction or electronback-scatter diffraction for selected cases.

T2-D, Heavy Fermion Systems, Chair: RaymondOsborn (ANL), Room 2101/3/5 Green

T2-D1 (13:30) Recent progress on heavy fermion f-electron systems (Invited)

M. B. Maple (Dept. of Physics and Inst. for Pureand Applied Physical Sciences; University ofCalifornia, San Diego)

Heavy fermion compounds are metallic compoundscontaining a sublattice of rare earth (R) or actinide(A) ions, which have electronic specific heat Ce

coefficients γ = Ce/T with enormous values as largeas several J/mol K2, corresponding to quasiparticlemasses of several hundred times the free electronmass. For most heavy fermion compounds, whichare based on Ce, Yb, or U, the nonmagnetic heavyFermi liquid ground state is believed to be associated


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with the Kondo effect arising from an antiferromag-netic exchange interaction between conductionelectron spins and magnetic moments of the R or Aions with partially-filled f-electron shells (Kondolattice). The nonmagnetic heavy Fermi liquid groundstate is unstable with respect to the formation ofother novel strongly correlated electron states,including unusual magnetically ordered states,unconventional (non s-wave) superconductivity withan energy gap that has line or point nodes on theFermi surface, which sometimes coexists withmagnetic order, and non-Fermi liquid (NFL) behaviorin the normal state physical properties in the vicinityof a quantum critical point (QCP). NFL behavior and/or superconductivity have been observed underpressure in both antiferromagnetic (e.g., CeIn3,CePd2Si2 ) and ferromagnetic (e.g., UGe2) heavyfermion compounds in the vicinity of the criticalpressure where the magnetic ordering temperature issuppressed to 0 K (magnetic QCP). This suggests thatmagnetic dipole moment fluctuations are responsiblefor the NFL behavior and mediate the pairing ofsuperconducting electrons in at least some of thesematerials. Heavy fermion behavior has been ob-served in several Pr compounds with nonmagneticPr3+ ionic ground states in the crystalline electric fieldthat appears to be due to the interaction between thecharges of the conduction electrons and Pr3+ electricquadrupole moments. One of these heavy fermion Prcompounds, PrOs4Sb12, was found to exhibit uncon-ventional superconductivity. In this compound, thesuperconducting state appears to consist of severaldistinct superconducting phases and to break timereversal symmetry, suggesting that the superconduc-tivity may involve triplet spin pairing of electrons.The basic properties of heavy fermion systems withemphasis on recent developments are reviewed inthis talk. This research was supported by the U. S.Department of Energy under Grant No. DE-FG02-04ER46105 and the National Science Foundationunder Grant No. DMR-0335173.

T2-D2 (14:00) Coexistence of superconductivityand magnetism in heavy fermion family of com-pounds: CeMIn5

A. Llobet (Los Alamos Neutron Science Center, LosAlamos National Laboratory), A.D. Christianson(Los Alamos National Laboratory; Colorado StateUniversity), J.S. Gardner (NIST Center for NeutronResearch), W. Bao, N.O. Moreno, P.G. Pagliuso, J.L.Sarrao (Los Alamos National Laboratory), J.W. Lynn(NIST Center for Neutron Research; Center forSuperconductivity Research, University ofMaryland, College Park, MD 20742), J.M. Mignot(Laboratoire Léon Brillouin, C.E.A Saclay, 91191 Gif-

sur-Yvette Cedex), K. Prokes (Hahn-Meitner-InstitutBerlin)

We report the first evidence of the correlationbetween long-range magnetic order and the develop-ment of a superconducting ground state in the Ce-based heavy fermion family of compoundsCeRh1-xMxIn5 (M = Ir, Co). Our neutron diffractionstudy describes the evolution of the magnetic struc-ture with Ir or Co doping. Upon doping, the groundstate is driven from an AFM helical structure(ki=(1/2, 1/2, 0.297)) in CeRhIn5 to a more complexmagnetic structure characterized by commensurateand incommensurate components. Remarkably, thepresence of the commensurate propagation vectorseems strongly correlated with the development ofsuperconductivity in this alloy series. Further, themagnetic structure is unaffected by the developmentof the superconducting state and a large Ce staggeredmagnetic moment coexists with superconductivity atlow temperatures. Hydrostatic pressures as well asthe application of magnetic fields have been alsoused to destroy or induce the superconducting state,and neutron diffraction studies reveal the interplaybetween magnetism and superconductivity in thisseries of heavy fermion compounds. This study lendscredibility to the idea that the formation of theunconventional superconducting state may befavored by specific types of magnetic fluctuations. Italso provides more evidence of the possible duality ofthe 4f electrons in these Ce-based compounds.

T2-D3 (14:15) Crystalline Electric Field Effects inCeMIn5: Superconductivity and the Influence ofKondo Spin Fluctuations

A. D. Christianson (University of California atIrvine), E. D. Bauer (Los Alamos NationalLaboratory), J. M. Lawrence (University ofCalifornia at Irvine), P. S. Riseborough (TempleUniversity, Philadelphia, Pennsylvania 19122), N. O.Moreno, P. G. Pagliuso, J. L. Sarrao, J. D. Thompson,M. P. Hehlen, F. R. Trouw (Los Alamos NationalLaboratory), E. A. Goremychkin (Argonne NationalLaboratory), R. J. McQueeney (LANL and Iowa StateUniversity, Ames, Iowa 50011)

We have measured the crystalline electric fieldexcitations (CEF) of the CeMIn5 (M = Co, Rh, Ir)series of heavy fermion superconductors by means ofinelastic neutron scattering (INS). Fits to a CEF modelreproduce the INS spectra and the high temperaturemagnetic susceptibility. The CEF parameters, energylevel splittings, and wavefunctions are tabulated foreach member of the CeMIn5 series and compared toeach other as well as to the results of previousmeasurements. Our results indicate that the CEF levelsplitting in all three materials is similar, and can be


thought of as being derived from the cubic parentcompound CeIn3 in which an excited state quartet at~12 meV is split into two doublets by the lowersymmetry of the tetragonal environment of theCeMIn5 materials. In each case, the CEF excitationsare observed as broad lines in the INS spectrum. Weattribute this broadening to Kondo hybridization ofthe localized f moments with the conduction elec-trons. The evolution of the superconducting transitiontemperatures in the different members of CeMIn5 canthen be understood as a direct consequence of thestrength of this hybridization. Due to the importanceof Kondo spin fluctuations in these materials, we alsopresent calculations within the non-crossing approxi-mation to the Anderson impurity model including theeffect of CEF level splitting for the INS spectra andthe magnetic susceptibility.

T2-D4 (14:30) Crystal fields in UO2 - revisitedH. Nakotte, R. Rajaram (Physics Department, NewMexico State University, Las Cruces NM 88003), R.McQueeney (Los Alamos Neutron Science Center,Los Alamos National Laboratory), S. Kern (PhysicsDepartment, Colorado State University, Fort CollinsCO 80524), G.H. Lander (Institute for TransuraniumCompounds, D-76125 Karlsuhe, Germany)

Uranium Dioxide (UO2) is an important nuclear fuelmaterial. We performed high-resolution inelasticneutron scattering using PHAROS at the Los Alamosspallation source LANSCE in order to re-investigatethe crystal field splitting in UO2, determined with theknowledge of the dipole-allowed transitions. Weobtained the crystal field parameters and the 5felectron eigen functions for UO2. The fourth- andsixth-degree crystal field parameters were found tobe V4= -116.24 and V6=25.78, in good agreementwith previously published results by Amoretti et al.[1]. On the other hand, these previous studies didreveal four crystal-field excitations in the 150 meV to180 meV range, only three of which can be explainedby the crystal-field model. Our experiments on adifferent UO2 sample show that the previouslyobserved peak at about 180 meV is a spurious one,thus it is not intrinsic to UO2.

[1] G. Amoretti et al., Phys. Rev. B 15 (1989) 1856

T2-D5 (14:45) Unusual phonon softening in delta-phase plutonium (Invited)

R. J. McQueeney (Iowa State University/AmesLaboratory), A. C. Lawson, A. Migliori (Los AlamosNational Laboratory), T. M. Kelley, B. Fultz(California Institute of Technology), J. C. Lashley(Los Alamos National Laboratory)

The phonon density-of-states and adiabatic sound

velocities were measured on fcc-stabilized242Pu0.95Al0.05. The phonon frequencies and soundvelocities decrease considerably (soften) with increas-ing temperature despite negligible thermal expan-sion. The frequency softening of the transversebranch along the (111) direction is anomalously large(~ 30 %) and is very sensitive to alloy composition.The large magnitude of the phonon softening is notobserved in any other fcc metals and may arise froman unusual temperature dependence of the electronicstructure in this narrow 5f-band metal.

T3-A, Charge, Orbital, and Spin Ordering inOxides, Chair: Michael Crawford (Dupont),Auditorium

T3-A1 (15:45) Charge, orbital and spin ordering inRBaFe2O5+x perovskites (Invited)

P. M. Woodward (Department of Chemistry, OhioState University), P. Karen (Department ofChemistry, University of Oslo)

Transition-metal oxides adopting the perovskitestructure (or closely related structure types) are wellknown for their interesting electronic properties (i.e.High TC superconductivity, colossal magnetoresis-tance, charge disproportionation, etc.). The oxygen-deficient double perovskites RBaFe2O5+x

(R = Nd, Sm, Tb, Ho, Y) are among the more inter-esting classes of perovskite related compounds.When x = 0 these compounds contain square-pyramidal iron with an average valence of +2.5. Bychanging temperature all three Robin-Day classes ofiron mixed-valence can be observed. In the hightemperature paramagnetic state all iron atoms areequivalent. Upon cooling antiferromagnetism sets in,followed by a two-step charge-localization process.The localization of the conduction electrons triggersphenomena such as charge and orbital ordering,reorientation of the antiferromagnetic structure andin some cases induced magnetism of the rare-earthsublattice. Variable temperature high-resolutionsynchrotron x-ray and neutron powder diffractionmeasurements, neutron thermodiffractometry,transport and magnetic susceptibility measurementsare used to characterize the behavior of this interest-ing family of compounds.

T3-A2 (16:15) Charge Ordering, Long and ShortRange Magnetic Ordering in the Mn3+/Mn4+ Oxide,Pb3Mn7O15.

J.E. Greedan, J. Barbier, J.F. Britten, N. Penin, H.Ghazi (BIMR and Chemistry Dept., McMasterUniversity, Hamilton CANADA), C.R. Wiebe(Department of Physics and Astronomy, McMasterUniversity, Hamilton, ON, Canada), H. Dabkowska


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(BIMR, McMaster University, Hamilton,CANADA),I.P. Swainson (National Research Council, ChalkRiver, Ontario, Canada)

Manganate Mn3+/Mn4+ oxides have been of intenseinterest in recent years. In particular the perovskitebased materials, A1-xLnxO3( A = divalent alkalineearth, Ln = trivalent lanthanide) exhibit chargeordering, a variety of magnetic phenomena,metalinsulator transitions and of course, CMR. As well, thespinel LiMn2Mn4O4 shows partial charge ordering,complex long range and short range ordering and isof interest as a battery cathode. Pb3Mn7O15 is anunder-investigated manganate with approximatelyequal concentrations of Mn3+ and Mn4+ and isstructurally related to spinel in that the Mn-O octahe-dra are linked by edge-sharing. The compound formsin an orthorhombic structure (Cmcm) with pro-nounced hexagonal pseudo-symmetry. Neutronpowder diffraction was instrumental in confirmingthe Cmcm structure at room temperature and thatthe charge ordering is only partial. The Mn sublatticeis based on layers of edge-sharing triangles and isthus prone to geometric frustration. This is reflectedin the magnetic susceptibility that shows an extendedregion of short range order from above 350 K to 72 Kfollowed by magnetic transitions at 72 K and 55 K.The magnetic structure between 72 K and 55 K isdescribed by k = (000) while a larger cell, k = (1/21/2 0), sets in below 55 K. Neutron diffuse scatteringis clearly seen in the form of a broad Lorentzianbackground centered at Q = 1.36 Å-1 which isobserved over the range from ~ 60 K (below the firstmagnetic transition) to at least 180 K. The correlationlength derived from the Lorentzian peak width is~ 4.6 Å which is three Mn neighbor distances,slightly longer than found for LiMn2O4.

T3-A3 (16:30) Magnetic Field Induced Metal-Insulator Transition in Pr1-x(Ca1-ySry)xMnO3

(x = 0.45, y = 0.15)F. Ye, J. A. Fernandez-Baca (Condensed MatterSciences Division, Oak Ridge National Laboratory),P. Dai (Condensed Matter Sciences Division, OakRidge National Laboratory; Department of Physicsand Astronomy, University of Tennessee), Y.Tomioka (Correlated Electron Research Center,National Institute of Advanced Industrial Scienceand Technology), Y. Tokura (Department of AppliedPhysics, University of Tokyo)

Recently, the electronic phase diagram ofPr1-x(Ca1-ySry)xMnO3 (x = 0.45) has been studied inthe vicinity of the metal-insulator transition bound-ary. By controlling the eg electron bandwidth W, theground state can be tuned to change from a charged-ordered (CO) and orbitally-ordered (OO) state

(y ≤ 0.2) to a ferromagnetic metallic state (y > 0.25).This system has been reported to exhibit bicriticalfeatures near y = 0.25. We have used elastic andinelastic neutron scattering to study the magneticcorrelations and spin dynamics of the sample nearthe insulator-metal boundary. The insulating CO/OOground state of y = 0.15 can be melted by theapplication of external field. The evolution of the CO/OO when a magnetic field is applied will be dis-cussed in the context of the competing interactionsthat may be responsible for the CMR effect.

This work was supported by the U.S. DOE underContract No.DE-AC05-00OR22725 with UT-Batelle,LLC; and by NSF grant DMR-0139882.

T3-A4 (16:45) Spin dynamics of CMR manganitesT. Chatterji (Institut Laue Langevin), N. Shannon(Max Planck Institute for PKS, Dresden, Germany),L.P. Regnault ( CEA, Grenoble, France)

We have investigated the spin dynamics of the hole-doped infinite-layer and bilayer manganites,La0.7Ba0.3MnO3 and La1.2Sr1.8Mn2O7, showing colossalmagnetoresistive properties close to the ferromag-netic transition temperatures, by inelastic neutronscattering. The infinite-layer manganiteLa0.7Ba0.3MnO3 is a three-dimensional high-TC ferro-magnet with TC = 350 K whereas the bilayer manga-nite La1.2Sr1.8Mn2O7 is a quasi-two-dimensional low-TC

ferromagnet with TC = 120 K. The spin dynamics ofthese ferromagnets at low temperature, show impor-tant deviations from that expected for a localizedHeisenberg ferromagnet. The spin wave stiffness andbandwidth scaled to kBTC show that these ferromag-nets are closer to the itinerant ferromagnets. Theexperimentally determined spin wave dispersions inboth these ferromagets at low temperatures showzone-boundary softening. Also the spin waves areheavily damped especially close to the zone bound-ary. We developed a spin wave theory of theseferromagnets on the basis of minimal double ex-change model. This model reproduces qualitativelyboth the softening and damping of the spin waves.According to this model retaded interaction betweenspin waves mediated by the charge susceptibility ofthe itinerant electrons generates interaction betweennon-nearest-neighbor spins, and so modifies the spinwave dispersion. Also the spin waves can decay intolower energy states by giving up energy to electron-hole pairs and so become damped. However, thismodel falls short to reproduce quantitatively theexperimental results. We have measured the tem-perature dependence of the spin waves in theseferromagnets. The temperature dependence of thespin waves of the hole-doped ferromagnets shows


deviations from that expected from the localizedHeisenberg model. These deviations can be ex-plained qualitatively from the minimal doubleexchange model. The spin excitations in theseferromagnets are found to persist above the orderingtemperatures.

T3-A5 (17:00) Structure and Magnetism in Sr-Doped Rare Earth Cobaltates

M. James (Bragg Institute, Australian NuclearScience and Technology Organisation, Australia),D. J. Goossens, R. L. Withers (Research School ofChemistry, Australian National University,Canberra, ACT 0200, AUSTRALIA)

Substantial interest has recently been generated byrare earth cobaltate compounds as cathode materialsfor solid oxide fuel cells. We have synthesized a widerange of single- phase perovskite-based rare earthcobaltates (Ln1-xSrxCoO3-d) (Ln = La3+, Pr3+, Nd3+,Sm3+, Gd3+, Dy3+, Y3+, Ho3+, Er3+, Tm3+ and Yb3+;0.60 < x < 1.00). For the first time we have mappedthe perovskite phase boundaries for these materials(synthesized under 1 atmosphere of oxygen). Acombination of electron and x-ray diffraction of thesecompounds reveals three different classes of tetrago-nal superstructures. A phase boundary exists be-tween compounds containing large and small rareearths (between Nd3+ and Sm3+) and also at thehighest Sr-doping levels (x > 0.90). Powder neutrondiffraction has been used in conjunction with theother diffraction techniques to reveal cation andoxygen vacancy ordering within these materials.

These phases show mixed valence (3+/4+) cobaltoxidation states that increases with Sr content;exceeding 50 % Co(IV) for the compositionsLn0.05Sr0.95CoO3-d. A range of magnetic behaviors hasbeen observed using susceptibility techniques and ina number of instances we have observed orderedferromagnetism at elevated temperatures (~ 300 K).In these cases, the magnetic structures of thesematerials were further characterized by powderneutron diffraction.

T3-A6 (17:15) Spin and lattice correlations inLa1-xSrxCoO3 cobaltites

S. Rosenkranz, P.J. Chupas, R. Osborn, J.F. Mitchell(Argonne National Laboratory), J.W. Lynn (NISTCenter for Neutron Research), D. Louca (VirginiaUniversity)

The cobaltites La1-xSrxCoO3 show intriguing spin,lattice, and orbital properties similar to the onesobserved in colossal magnetoresistive manganites.The x = 0 parent compound is a non-magneticinsulator at low temperatures, but shows evidence ofspin-state transitions of the cobalt ions above 100 K

from low-spin to intermediate and/or high-spinconfigurations. Upon doping, these systems showspin glass-like behavior with a sharp transition toferromagnetic order at x ~ 0.2. There is a concomi-tant metal-insulator transition, which appears analo-gous to similar transitions in the phase diagram ofCMR manganites. We have recently succeeded ingrowing large (~ 5 g), high-quality, single crystals ofthese compounds, which are suitable for studying indetail the spin, lattice, and orbital correlations, andtheir possible connection to transport properties. Ourneutron and synchrotron x-ray scattering investiga-tions of x = 0.2 doped system reveal a relativelylarge gap in the spin-wave excitation spectrum below,and the existence of structural distortions above Tc .

This work is supported by US DOE BES-DMS W-31-109-ENG-38 and the NSF.

T3-B, Polymer Dynamics, Chair: Jyotsana Lal(ANL), Room 2100/2/4 Red

T3-B1 (15:45) The Influence of Environment onPolymer Mobility: Quasielastic Neutron Scatteringon PEO/PMMA Blends (Invited)

J. K. Maranas, V. Garcia-Sakai, C. Chen(Pennsylvania State University), Z. Chowdhuri, I.Peral, N. Rosov (National Institute of Standards andTechnology)

The focus of this presentation is the use ofquasielastic neutron scattering to assess mobility inpolymers. Background on the dynamic behavior ofpolymers on time-scales assessable by neutroninstruments will be covered. We are interested in thechanges in this mobility when the environment ofthe polymer is changed in some way. One mightimagine doing so by introducing nanoparticles,placing a neat polymer in a mixture, or incorporatingthe polymer as a di- or tri-block copolymer – materi-als with nanoscale ordered regions. One of thesemanipulations, changes that occur when the polymeris placed in a mixture, will be illustrated with mea-surements made over the last year on backscattering,time-of-flight and neutron spin echo spectrometerson a blend of poly(methylmethacrylate) [PMMA]and poly(ethylene oxide) [PEO]. These two constitu-ent polymers have dynamic behavior separated bymany orders of magnitude, a behavior that we findpersists in the mixture using incoherent scatteringwith selective deuteration to isolate the dynamicresponses of each component in turn. One challengefaced with this system is the extremely stretchednature of the relaxations – the decay is very slow andthus not much is observed within the typical timewindows of neutron spectrometers. Another chal-


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lenge is to separate each components motion incoherent measurements where labeling is lesshelpful. We will discuss the potential for usingchemically realistic simulations to assist in meetingthese challenges.

T3-B2 (16:15) Dynamics in Thin Polymer FilmsC. L. Soles, J. F. Douglas, W.-L. Wu (NIST PolymerDivision)

Incoherent neutron scattering is presented as apowerful tool for interpreting changes in the molecu-lar dynamics as a function of film thickness for arange of polymers. Motions on a time scale ofapproximately a nanosecond and faster are quanti-fied in terms of a mean-square atomic displacement(MSD) from the Debye-Waller factor. We find that thinfilm confinement generally leads to a reduction ofthe MSD in comparison to the bulk material, thiseffect becoming especially pronounced when the filmthickness approaches the unperturbed dimensions ofthe macromolecule. Generally we always observe asuppression (never an enhancement) of the MSD attemperatures T above the bulk calorimetric glasstransition temperature, Tg. Below Tg, the reduction inthe magnitude of the MSD depends upon the poly-mer and the length scales being probed. Polymerswith extensive segmental or local mobility in theglass are particularly susceptible to reductions of theMSD with confinement, especially at the Q vectorsprobing longer length scales, while materials lackingthese sub-Tg motions are relatively less sensitive. Wealso demonstrate that a reduced MSD correlates witha reduced mobility at long time and spatial scales, asmeasured by diffusion in the thin polymer films.Finally, we find that this reduced thin film mobility isnot reliably predicted by thermodynamics assess-ments of an apparent Tg, as measured bydiscontinuities or kinks in the T dependence of thethermal expansion, specific volume, index of refrac-tion, specific heat, etc. This is illustrated throughseries polycarbonate films simultaneously character-ized with specular x-ray reflectivity and beampositron annihilation lifetime spectroscopy. In total,these measurements illustrate that the MSD is apowerful and predictive tool for understandingdynamic changes in thin polymer films.

T3-B3 (16:30) Applying Neutron Scattering toPolymer Coating Research

L. Sung (Building and Fire Research Laboratory,National Institute of Standards and Technology,Gaithersburg, MD 20899), D. L. Ho (NIST Center forNeutron Research), X. Gu, S. Scierka (Building andFire Research Laboratory, National Institute ofStandards and Technology, Gaithersburg, MD

20899), J. Barker (NIST Center for NeutronResearch)

Nanostructure and heterogeneity of coating materialsare the key parameters to affect the physical andmechanical properties of coatings and their servicelife. It is curial to understand the relationship be-tween the nanostructure, heterogeneity and thedurability of coating materials for surface life predic-tion. Complementary to the conventional micro-scopic characterization tools often used in coatingindustry, small angle neutron scattering (SANS)technique provides bulk spatial information in a largesample area without extensive manual labor, and isproven to be useful for assessing the state of struc-ture and dispersion of polymer coating materials.This outcome may help to bring a new solution to along-standing pigment dispersion measurementproblem in the coating industry. In this presentation,SANS studies on (1) the effect of pigment concentra-tion on spatial distribution (dispersion) of pigmentaryor nanoparticles in acrylic coatings and (2) the effectof nanostructure on UV degradation of fluoropolymerbased coatings will be reported and compared tomicroscopy results.

T3-B4 (16:45) Intramolecular Diffusive Motion inAlkane Monolayers Studied by High-ResolutionQuasielastic Neutron Scattering and MolecularDynamics Simulations

H. Taub (Department of Physics and Astronomy andUniversity of Missouri Research Reactor, Universityof Missouri-Columbia, Columbia, Missouri 65211),F.Y. Hansen (Department of Chemistry, TechnicalUniversity of Denmark, IK 207 DTU, DK-2800Lyngby, Denmark), L. Criswell (Department ofPhysics and Astronomy and University of MissouriResearch Reactor, University of Missouri-Columbia,Columbia, Missouri 65211), D. Fuhrmann(Department of Physics and Astronomy andUniversity of Missouri Research Reactor, Universityof Missouri-Columbia, Columbia, Missouri 65211;Infineon Technologies, Memory Products, Balanstr.73, D-81541 Munich, Germany), K.W. Herwig(Spallation Neutron Source, Oak Ridge NationalLaboratory), A. Diama, H. Mo (Department ofPhysics and Astronomy and University of MissouriResearch Reactor, University of Missouri-Columbia,Columbia, Missouri 65211), R.M. Dimeo, D.A.Neumann (NIST Center for Neutron Research), U.G.Volkmann (Facultad de Física, PontificiaUniversidad Católica de Chile, Santiago 22, Chile)

Monolayers of intermediate-length alkane moleculessuch as tetracosane (n-C24H50 or C24) serve asprototypes for studying the interfacial dynamics ofmore complex polymers, including bilayer lipid


membranes. Molecular dynamics simulations of aC24 monolayer adsorbed on a graphite basal-planesurface show that there are diffusive motions associ-ated with the creation and annihilation of gauchedefects occurring on a time scale in the range 0.1 nsto 4 ns. We present evidence that these relativelyslow motions are observable by high-energy-resolu-tion quasielastic neutron scattering (QNS) thusdemonstrating QNS as a technique, complementaryto nuclear magnetic resonance, for studying confor-mational dynamics on a nanosecond time scale inmolecular monolayers.1,2

[1] F.Y. Hansen et al., Phys. Rev. Lett. 92, 046103(2004).[2] This work was supported by the NSF under GrantNos. DMR-9802476 and DMR-0109057, by theChilean government under FONDECYT Grant No.1010548, and by the U.S. Department of Energythrough grant DE-FG02-01ER45912. The neutronscattering facilities in this work are supported in partby the National Science Foundation under AgreementNo. DMR-0086210.

T3-B5 (17:00) Neutron Spin Echo Study of theLocal Dynamics in a Polymer Micellar Solution

Hasan Yardimci (Department of Physics &Astronomy, Johns Hopkins University), BrianChung, James Harden (Department of ChemicalEngineering, Johns Hopkins University), RobertLeheny (Department of Physics & Astronomy, JohnsHopkins University)

We investigate the local dynamics of aqueous solu-tions of the triblock copolymer polyethylene oxide –polypropylene oxide – polyethylene oxide (PluronicF108) by neutron spin echo (NSE). In solution thepluronic self-associates into spherical micellescomposed of cores of polypropylene oxide (PPO)with corona of solvated polyethylene oxide (PEO).Depending on concentration and temperature, whichaffect the conformation of the corona chains andhence influence the interactions between micelles,the micelles order in either a liquid or crystal state. Inparticular, as the PEO becomes less hydrophilic withincreasing temperature, collapse of the corona drivesa melting transition on heating. Our small angleneutron scattering measurements on Pluronic F108solution demonstrate the changes in the structure onheating from room temperature associated with theformation of micelles and their ordering into a crystalfollowed by melting of the crystal upon furtherheating.

The micellar dynamics as probed in NSE show a clearsystematic dependence on concentration and

temperature as the phase boundaries betweenpolymer solution, micelle crystal and micelle liquidare traversed. However, these local dynamics aresurprisingly insensitive to phase behavior andmacroscopic rheology. For example, the relaxationtime of a 21 % micellar solution changes only by afactor of approximately four across the meltingtransition near 80 °C. Analysis of the wave-vectordependence across the transition over the range of0.02 < Q < 0.12 Å-1 indicates the specific localmicellar motions probed by NSE.T3-C, Mechanical Behavior and Residual Stress, Chair:Camden Hubbard (ORNL), Room 1123 Blue

T3-C1 (15:45) Neutron Diffraction Studies ofMicromechanics of Material Deformation (Invited)

E. Ustundag (Department of Materials Science,California Institute of Technology, Pasadena,California 91125)

Neutron powder diffraction offers unique opportuni-ties to study material deformation in situ under avariety of conditions. In addition to phase informa-tion, one can also collect data on texture and latticestrain as a function of stress, temperature andsample environment. The diffraction data are thencomplemented with micromechanics modeling forfull interpretation and to obtain the in situ constitu-tive behavior of the material. The latter is verydifficult to deduce from ex situ tests and is crucial forpredicting the long term performance in service.

The recent construction of dedicated engineeringdiffractometers such as SMARTS at the Los AlamosNeutron Science Center has elevated the engineeringneutron diffraction field to a new level of sophistica-tion. It is now possible to perform tests at stressesexceeding 3 GPa, temperatures above 1500 °C and innumerous controlled environments. These capabili-ties allow the in situ investigation of most practicalmaterials. This presentation will describe recent workon bulk metallic glass composites, structural ceramicsand metal matrix composites. It will also offer insightinto exciting future developments.

T3-C2 (16:15) Implications of Different Strengthen-ing Mechanisms on Intergranular Strains in Vari-ous Aluminum Alloys

T. A. Saleh, J. W. Jeon (Department of MaterialsScience and Engineering, The University ofTennessee, Knoxville, TN 37996, USA.), J. Pang, C.R. Hubbard (Metals and Ceramics Division, OakRidge National Laboratory), D. W. Brown (LosAlamos Neutron Science Center, Los AlamosNational Laboratory), H. Choo (Department ofMaterials Science and Engineering, The University


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of Tennessee, Knoxville, TN 37996, USA.; Metalsand Ceramics Division, Oak Ridge NationalLaboratory), P. K. Liaw (Department of MaterialsScience and Engineering, The University ofTennessee, Knoxville, TN 37996, USA.), M. A. M.Bourke (Los Alamos Neutron Science Center, LosAlamos National Laboratory)

The presence of intergranular strains in deformedpolycrystalline samples due to inhomogeneousdeformation is widely recognized. However, theeffects of different types of strengthening mecha-nisms in alloys on the generation of intergranularstrains have not been studied systematically. In thisexperiment, lattice strains were measured fordifferent (hkl) reflections in a series of Al alloys underuniaxial tensile load up to 7 % plastic strain. Precipi-tation-strengthened Al-2024, Al-7075-T6, Al-6061,and solid-solution strengthened Al-5083 alloys werestudied. Both Al-2024 and Al-7075-T6 showed similarlattice strain responses. Reflection (200) shows thelargest response with residual strains, upon unloadingfrom 150 MPa, of -1000 µε and +850 µε parallel andtransverse to the tensile axis for Al-2024. The corre-sponding strain values for Al7075-T6 were -700 µεand +720 µε respectively. The behavior of the solid-solution strengthened Al-5083 differs from theprecipitation-strengthened alloys with the largestresidual strain found in reflection (311), not the (200),with a compressive strain of -1000 µε along thetensile axis. Lattice strains for the other reflections inAl-5083 are within ± 300 µε for both the longitudinaland transverse directions compared to the otheralloys. The differences between the Al-5083 sampleand the other alloys will be discussed in context ofthe effect of strengthening mechanism as well astexture.

This work benefited from the use of the Los AlamosNeutron Science Center (LANSCE) at the Los AlamosNational Laboratory. This facility is funded by the USDepartment of Energy under Contract W-7405-ENG-36. This research was also sponsored by the AssistantSecretary for Energy Efficiency and RenewableEnergy, Office of FreedomCAR and Vehicle Technolo-gies, as part of the High Temperature MaterialsLaboratory User Program, Oak Ridge NationalLaboratory, managed by UT-Battelle, LLC, for the U.S.Department of Energy under contract number DE-AC05-00OR22725.

Additionally, this work is supported by the NSFInternational Materials Institutes (IMI) Program underContract DMR-0231320, with Dr. Carmen Huber asthe program director.

T3-C3 (16:30) Residual Stresses in Deep DrawnCups as Standard Specimens for SpringbackCharacterization

T. Gnaeupel-Herold (NIST Center for NeutronResearch; Department of Materials Science andEngineering, University of Maryland), T. J. Foecke(NIST Metallurgy Division), H. J. Prask (NIST Centerfor Neutron Research)

Springback is the elastic shape change of a sheetmetal part after forming upon removal of the die. It iscreated by residual stresses which, in turn, originatefrom plastic strains that are inhomogeneous bothwithin the sheet plane and through thickness. Onefocus of current efforts for a more accurate predictionof springback are the measurement and modeling ofresidual stresses in deep drawn cups which areconsidered as promising candidates to becomestandard specimens for springback characterization.From neutron and synchrotron strain measurementsthe residual stresses were found to vary non-linearlyin all three directions. The most pronounced changeswere found in the through-thickness direction withsimilar general features regardless of material orsheet thickness.

T3-C4 (16:45) Using inter- and intra-granularstrains as a guide to understand fatigue behaviorsof polycrystalline engineering materials

X.-L. Wang (Spallation Neutron Source, Oak RidgeNational Laboratory; Metals and Ceramics Division,Oak Ridge National Laboratory), A. D. Stoica, Y. D.Wang (Spallation Neutron Source, Oak RidgeNational Laboratory), D. J. Horton (SpallationNeutron Source, Oak Ridge National Laboratory;Department of Materials Science and Engineering,The University of Tennessee, Knoxville, TN 37996,USA.), H. Tian, P. K. Liaw (Department of MaterialsScience and Engineering, The University ofTennessee, Knoxville, TN 37996, USA.), E. Maxey, J.W. Richardson (Intense Pulsed Neutron Source,Argonne National Lab)

Time-of-flight neutron diffraction technique providesreliable data on inter- and intra-granular grain-orientation-dependent strains generated during theplastic deformation of polycrystalline materials [1-2].A study of 316 stainless steel samples at differentstages of fatigue life provides experimental evidenceof the effect of cyclic loading on grain-levelmicromechanics [3]. The experimental data showthat residual inter-granular strains develop after eachhalf loading cycle as a result of the elastic anisotropy,which induce a highly heterogeneous loading redistri-bution at the grain level. In the early stage of fatiguelife the grain-orientation-dependent inter-granularstrains oscillate between two extremes states corre-


sponding to the ends of a tensile or compressive halfloading cycle showing almost identical symmetry buta sign reversal [4]. In the late stage, the inter-granularstrains vanish for tests ending in tension, but aresurprisingly stable for tests ending in compression.The different behaviors in tension and compressionare related to the crack initiation and could be linkedto a crack closure mechanism. Separately, thediffraction line broadening analysis allows probingthe intra-granular strains and evaluating the storedenergy, which is a fingerprint of the material harden-ing process and can be directly related to the succes-sive stages of deformation. As the intra-granularstrains are mainly induced by immobile dislocations,the diffraction response to the lattice distortion ishighly anisotropic and can be used to identify theaverage dislocation character and distribution. In thecase of 316 stainless steel, neutron diffraction datahave shown that the immobile dislocations generatedby cyclic loading are mainly edge, rather than screw,type. This finding was corroborated by recent trans-mission electron microscopy studies.

This research was supported by Division of MaterialsSciences and Engineering, Office of Basic EnergySciences, U.S. Department of Energy under ContractDE-AC05-00OR22725 with UT-Battelle, LLC.

[1] X.-L. Wang, Y. D. Wang, and J. W. Richardson, J.Appl. Cryst., 35, 533-537 (2002)[2] Y. D. Wang, X.-L Wang, A. D. Stoica, J. W.Richardson, and R. Lin Peng, J. Appl. Cryst. 36, 14-22(2003).[3] Y.D. Wang, H. Tian, A. D. Stoica, X.-L. Wang, P. K.Liaw, and J.W. Richardson, Nature Materials, 2, 103-106 (2003).[4] X.-L. Wang, et al., Mat. Sci. Eng. (in press)

T3-C5 (17:00) Small-Angle Neutron Scattering: aPioneering Tool to Comprehend Processing–Structure–Property Relationships in ThermalBarrier Coatings

A. Kulkarni (Dept. of Matls Sci and Eng, Univ. atStony Brook, Stony Brook, NY 11794-2275)

Thermal barrier coatings (TBCs) are extensivelyapplied on hot sections in gas turbine engines toprovide protection against thermo-mechanical andhot corrosion environments. Critical properties of theTBCs are governed by the nature and architecture ofthe void microstructures, an enhanced understandingof which will lead to improvements in coatingperformance during service. These ceramic TBCs arepresently deposited using plasma spray and electronbeam physical vapor deposition (EB-PVD) processes,each producing distinctive microstructures. A

multidisciplinary approach involving advancedneutron scattering and x-ray imaging techniques hasbeen undertaken, in this joint NIST-SUNY StonyBrook program, to establish the salient processing–structure–property relationships in TBCs. Microstruc-ture information on porosity, void orientation distri-bution, mean opening dimensions and internalsurface areas is obtained and important connectionsare established with the measured deposit properties,such as thermal conductivity and elastic modulus. Inparticular, SANS has succeeded in a) establishingrational process-induced porosity-property correla-tions and b) quantifying the sintering kinetics andphase stability of TBCs during the high-temperatureconditions encountered in service. The microstruc-tural parameters determined by SANS studies havebeen assembled into a finite element model thatshows promise for providing a truly predictivecapability for determining coating properties andperformance. SANS is increasingly recognized as asuccessful research tool in advanced TBC develop-ment.

T3-C6 (17:15) Quantitative Texture Analysis ofExperimentally Deformed Fine-grained D2O ice byNeutron Diffraction

S.M. McDaniel (Los Alamos National Laboratory;University of Washington), K.A. Bennett (Office OfBasic Energy Sciences/DOE), W.B. Durham(Lawrence Livermore National Laboratory), E.D.Waddington (University of Washington), V. Luzin(NIST Center for Neutron Research)

Quantitative textures measurements of fine-grain D20ice experimentally deformed polycrystalline D20 icecylinders were performed by neutron diffraction onBT-8 at the NIST Neutron Research Reactor. The aimwas to determine the primary mechanism of icedeformation, grain-size sensitive (GSS) creep ordislocation creep. Textures in three samples (2samples approximately 1 inch diameter X 1 inchlong, 1 sample a 8mm sphere, grain size 10-100microns) of deuterated hexagonal ice were measuredby neutron diffraction using 4 principal diffractionpeaks (100), (002), (101) and (102), with λ= 1.878 Å,and a He-3 displex closed-cycle cryostat in conjunc-tion with a four-circle gonimeter. Experimental polefigures were collected using the so-called hexagonalgrid with angular resolution of less than 5 degrees.The Orientation Distribution Functions for eachsample were calculated using POPLA and BEARTEXtexture packages.

Comparison of experimental pole figures to recalcu-lated figures show good experimental accuracy.Samples were deformed at T=222 K, 224 K, and 226


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K, and to 30 %, 22.5 % and 30 % strain, respec-tively. All samples show typical fiber texture commonto hexagonal ice, with (001) parallel to the sampleaxes, and the axes of compression. Texture analysesreveal a similar pole distribution in all samples, withtwice as many (001) poles parallel to the compressionaxis than to the perpendicular axis. Under thedeformation conditions, grain-size sensitive (GSS)creep was expected to dominate, resulting in notexture development. However, the neutron dataresults indicate significant texture and grain growth,suggesting that deformation may be dominated bydislocation creep over GSS and temperature condi-tions, even at very low temperatures, for fine-grainedice.

TB: Banquet at College Park Aviation Museum(19:00) (Buses depart Inn starting at 18:30)

WednesdayW1-A, Neutron Sources (Plenary), Chair:Michael Rowe (NIST), Auditorium

W1-A1 (08:30) An Overview of North AmericanNeutron Sources (Plenary)

R. M. Briber (Neutron Scattering Society ofAmerica; Department of Materials Science andEngineering, University of Maryland)

An overview of recent developments at NorthAmerican neutron sources will be presented. Newinstruments, both in the development stage andrecently brought on-line will be discussed. In addi-tion, source upgrades and procedures for submittingbeam time proposals will be covered.

W1-A2 (09:00) Neutron Scattering Worldwide:Contrasting Perspectives (Plenary)

J. Mesot (Laboratory for Neutron Scattering, PaulScherrer Institute & ETH Zurich, CH-5232 Villigen,Switzerland)

After decades of incremental steps, the neutronscattering landscape has started to change and willdo so even more rapidly in the coming years.

While third generation sources are being realized inthe US (SNS) and Japan (J-PARC), a 20 MW ResearchReplacement Reactor is under construction inAustralia. With the recent decision to put the ESSproject on hold, the future of neutron scattering inEurope appears, at first sight, less bright. The severeconsequences of this decision for the Europeanneutron scattering community will, however, beattenuated by both the start of the FRM-II reactor inMunich (Germany) and various developments atexisting sources. This includes, among others, therealization of a second target at ISIS (United King-dom), an upgrade of instrumentation at the InstituteLaue-Langevin (Grenoble-France), the construction ofa second guide hall at Hahn-Meitner-Institute (Berlin-Germany), or an upgrade of the continuous spallationsource SINQ (Villigen-Switzerland).

A survey of the above-mentioned projects, togetherwith a summary of the planned developments atrunning sources worldwide will be presented.

W1-A3 (09:30) The Spallation Neutron Source:Overview (Plenary)

T. E. Mason (Oak Ridge National Laboratory)The Spallation Neutron Source will use an acceleratorto produce the most intense beams of pulsed neu-trons in the world when it is complete in 2006. The


project is being built by a collaboration of six U.S.Department of Energy laboratories. It will serve adiverse community of users with interests in con-densed matter physics, chemistry, engineeringmaterials, biology, and beyond. The constructionphase of the SNS is over 75 % complete and, to-gether with initiatives such as the Center forNanophase Materials Science, will offer the neutronscattering community unprecedented new capabili-ties.

WP - Poster Session III (Main Concourse; 10:30)

WP3: Using Deuterated Actin to Reveal the Confor-mation of Ca2+-Activated Intact Gelsolin Bound toMonomeric and Filamentous Actin by Small AngleNeutron Scattering.

Ashish, J.K. Krueger (UNC Charlotte ChemistryDepartment)

This work attempts to elucidate the conformationalchanges of Ca2+-activated gelsolin when it binds toactin through the use of small angle neutron scatter-ing contrast variation experiments using specificallydeuterated actin. In the presence of Ca2+, gelsolinbinds to monomeric G-actin in a 1:2 molar ratio,effectively catalyzing the nucleation step in actinpolymerization. In an apparently contradictory roleCa2+-gelsolin also participates in severing the fila-mentous F-actin and capping the resultant fragments.Gelsolin is comprised of six structurally similardomains, G1 through G6. In the Ca2+-free inactivestate, these domains of intact gelsolin are packed in amanner where none of the actin-binding sites areaccessible. Activation by Ca2+ causes large conforma-tional changes altering the relative positions andorientations of the six domains, which exposesseveral actin-binding surfaces. We have small-anglex-ray scattering data that follows the conformationalchanges within gelsolin as a result of binding Ca2+

and although new x-ray crystallographic data hasbeen obtained on the N- and C-terminal halves ofgelsolin +/- an actin monomer, there is no directstructural information on intact Ca2+-activatedgelsolin or intact Ca2+-activated gelsolin bound toeither two monomers of G-actin or to filamentousF-actin. For our neutron scattering studies on thegelsolin-actin complexes, deuterated actin wasobtained from the slime mold Dictyosteliumdiscoideum, which was fed deuterated Escherichiacoli. The actin was purified by ion-exchange and gelfiltration chromatography. NMR and mass spectros-copy on non-deuterated and deuterated actin wasused to determine the level of actin deuteration.Using small-angle x-ray scattering, we will first

optimize the experimental conditions to obtainstructural data of Ca2+-activated gelsolin bound totwo actin monomers. Small-angle neutron scatteringexperiments are planned in which we will varysolvent’s deuterium composition and use the result-ant data to extract out the basic scattering functionfor the actin-bound Ca2+-gelsolin. Comparison of themolecular shapes obtained from the neutron scatter-ing data with those obtained from x-ray studies, willprovide insight into the mechanism by which Ca2+-gelsolin interacts with, and regulates actin polymer-ization.

WP4: Phase-sensitive Neutron ReflectometryStudies of a Biomineralization Peptide

S. Krueger (NIST Center for Neutron Research), U.A.Perez-Salas (Dept. of Physiology & Biophysics, Univ.of Calif. Irvine, Med. Sci. I, D-346, Irvine, CA 92697-4560; NIST Center for Neutron Research), D.J.McGillivray (Department of Biophysics, JohnsHopkins Univ., 3400 N. Charles St., Baltimore, MD21218-2685; NIST Center for Neutron Research), C.F. Majkrzak, N.F. Berk (NIST Center for NeutronResearch), W.J. Shaw (Battelle Labs, PO Box 999,MS K2-57, Richland, WA 99352)

A phase-sensitive neutron reflectometry (NR) methodwas used to study the surface orientation of thebiomineralization peptide, LRAP. Naturally occurringbiominerals possess an impressive array of strength,order and nanostructure, resulting directly fromprotein controlled-nucleation and templated mineralgrowth. The secondary and tertiary structures ofbiomineralization proteins are often implicated inthese processes. However, very few techniques existwhich can quantitatively characterize secondarystructure of surface immobilized proteins. Phase-sensitive NR methods provide an essentially exactdetermination of the neutron scattering lengthdensity (SLD) profile perpendicular to the plane ofthe surface, limited only by sample integrity and thequality of the data.

LRAP is a 59-amino acid residue variant of thebiomineralization protein, amelogenin, a protein thatis found to control tooth enamel development.Peptides for the NR measurements were preparedwith 7 amino acids near the C-terminus of the LRAPlabeled with deuterium in order to increase theirneutron SLD with respect to the non-labeled residues.The peptide was bound to an 11Å-thick C11-ethyleneoxide layer with a COO- group presented at thesurface. The entire system was supported on planar,gold-coated substrates and measured in a humiditychamber filled with Argon gas saturated with D2O at~92% humidity. The phase-sensitive NR method


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used to determine the orientation of the LRAPpeptide on this surface will be described and theresultant compositional depth profiles, derived fromthe SLD profiles, will be presented.

WP5: SANS Reveals that Protein Kinase A RIαααααDimer Undergoes a Large Conformational Changeupon Binding C Subunits

W. T. Heller (Condensed Matter Sciences Division,Oak Ridge National Laboratory), D. Vigil, S. Brown(Department of Chemistry and Biochemistry andHoward Hughes Medical Institute, University ofCalifornia, San Diego, La Jolla, CA 92037), D. K.Blumenthal (Departments of Pharmacology andToxicology and Biochemistry, University of Utah,Salt Lake City, UT 84112), S. S. Taylor (Departmentof Chemistry and Biochemistry and Howard HughesMedical Institute, University of California, SanDiego, La Jolla, CA 92037), J. Trewhella (BioscienceDivision Los Alamos National Laboratory)

Small-angle neutron scattering with contrast variationwas used to study the type Iα isoform of the cAMP-dependent protein kinase A (PKA) holoenzyme insolution. PKA consists of two catalytic (C) subunitsbound to a regulatory (R) subunit dimer. Informationon the shapes and dispositions of the C subunits andR subunit homodimer within a holoenzyme reconsti-tuted with deuterated R subunits was derived fromthe data. The study demonstrates for the first timethat a large-scale conformational change occurswithin the R subunit homodimer upon binding the Csubunits. The results infer that inhibition of C subunitactivity is a multi-step process involving local confor-mational changes both in the cAMP-binding domainsand the linker region of the R subunit that impact theglobal structure of the R subunit dimer. The scatter-ing data also show that, despite extensive sequencehomology between the isoforms, the type Iα holoen-zyme adopts a significantly more compact conforma-tion than the type IIα isoform. A model of the type Iαholoenzyme was constructed to fit the SANS datausing available structures of the component subunitsand domains. In this model, the type Iα holoenzymeforms a flattened V shape with the R subunit dimer-ization domain at the point of the V and the Rsubunit cAMP-binding domains and the C subunits atthe ends.

WP6: Dynamics in Lecithin/Cholesterol Membranesby Deuterium Labeling

D. Worcester (Biology Division, University ofMissouri, Columbia, MO 65211), J. Torbet (School ofMedicine, University of Pennsylvania, Philadelphia,PA 19104), H. Kaiser (Research Reactor, Universityof Missouri, Columbia, MO 65211), E. Oldfield, C.

Lea (Chemical & Life Sciences, 600 S. MatthewsAve., Urbana, IL 61801)

Dynamic properties of lecithin/cholesterol mem-branes were measured by deuterium labeling andneutron diffraction from multi-layers. Deuterium wasintroduced at specific molecular sites to provide alocalized label for difference analysis. Onehydrocabon chain of dimyristoyl-phosphatidylcholinewas labeled at seven different methylene groups andat the terminal methyl group. The methyl groups ofthe lecithin choline were labeled and cholesterol waslabeled with five deuterium near the hydroxyl group.B-values of the Debye-Waller factors were obtainedby fitting difference structure factors in reciprocalspace. Diffraction patterns with at least eight ordersof Bragg diffraction were obtained for hydrationranging from 58% to nearly 100% relative humidity.Positions of the label were readily determined withuncertainty less than 1% of the repeat unit. The B-values were more difficult to determine and uncer-tainties were about 10%. The results show cleardifferences in the B-values of the different moleculargroups. The cholesterol label had the smallest B-value, as expected for the rigid steroid ring. Thehydrocarbon chain of dimyristoyl-phosphatidylcho-line is well-ordered, with similar B-values along thechain. The results indicate that molecular packing isan important aspect of the preferential interaction ofcholesterol with saturated lipids.

WP7: A SANS Contrast Variation Study to ElucidateStructural Requirements for the Initial RecognitionStep between Myosin Light Chain Kinase and ItsActivatory Protein, Calmodulin

J.K. Krueger, N. Modi (University North CarolinaCharlotte), W.T. Heller (Oak Ridge NationalLaboratory), D.J. Black, A. Persechini (University ofMissouri Kansas City), J.T. Stull (University of TexasSouthwestern Medical Center at Dallas), C.-S. Tung,J. Trewhella (Los Alamos National Laboratory)

A wide variety of Ca2+-dependent processes in thecell are regulated by the ubiquitous proteincalmodulin via interactions with and subsequentactivation of a diverse array of target proteinsincluding a number of kinases, (proteins responsiblefor phosphorylation of other proteins). The Ca2+ -calmodulin (CaM)-dependent activation of myosinlight chain kinase (MLCK) has served as a model forCaM-kinase interactions. We have collected small-angle neutron scattering data at several contrasts(0%, 15%, 30%, 70% and 80% D2O) on MLCKcomplexed with 60%-deuterated mutant CaM(delNCam). This mutant CaM missing an N-terminalleader sequence [residues #1-8 (A1DQLTEEQ8)]binds MLCK with high affinity but fails to activate


catalysis. The small-angle scattering data reveal thatdelNCaM occupies a position near the catalytic cleftin its complex with the kinase, whereas the nativeprotein translocates to a position near the C-terminalend of the catalytic core. Interestingly, the SANS datashow that the CaM is in the collapsed state, suggest-ing that the delNCaM has bound to the autoinhibitorysequence of MLCK, rather than simply docking ontothe surface of the MLCK in the extended state. Amolecular model built from our SANS data will beused to provide the molecular boundaries for theindividual protein components within the complexfor which high-resolution crystal structures areknown. The result will be a model of what is theinitial recognition step in the CaM/MLCK interactionproviding a detailed atomic description of the bindingevents between CaM and MLCK prior to the kinaseactivation step.

WP8: Compaction of a Bacterial Group I Ribozymeby cations studied by SANS and SAXS

U.A. Perez-Salas (National Institute of Standardsand Technology; University of California at Irvine),G.H. Caliskan (National Institute of Standards andTechnology; Johns Hopkins University), P. Rangan(Johns Hopkins University; New York University), SKrueger (National Institute of Standards andTechnology), R.M. Briber, D. Thirumalai (Universityof Maryland, College Park), S.A. Woodson (JohnsHopkins University)

Counterions are critical to the self-assembly of RNAtertiary structure because they neutralize the largeelectrostatic forces which oppose the folding process.Changes in the size and shape of the Azoarcus groupI ribozyme as a function of Mg2+ and Na+ concentra-tion were followed by small angle neutron scattering(SANS) experiments performed at the NIST Center forNeutron research. In low salt buffer, the RNA wasexpanded, with an average radius of gyration (Rg) of53 ± 1 Å. A highly cooperative transition to acompact form (Rg ) 31.5 ± 0.5 Å was observedbetween 1.6 and 1.7 mM MgCl2. The collapsetransition, which is unusually sharp in Mg2+, has thecharacteristics of a first-order phase transition. Partialdigestion with ribonuclease T1 under identicalconditions showed that this transition correlated withthe assembly of double helices in the ribozyme core.Fivefold higher Mg2+ concentrations were requiredfor self-splicing, indicating that compaction occursbefore native tertiary interactions are fully stabilized.No further decrease in Rg was observed between 1.7and 20 mM MgCl2, indicating that the intermediateshave the same dimensions as the native ribozyme,within the uncertainty of the data (±1 Å). A moregradual transition to a final Rg of approximately

33.5 Å was observed between 0.45 and 2 M NaCl.This confirms the expectation that monovalent ionsnot only are less efficient in charge neutralization butalso contract the RNA less efficiently than multivalentions.

Complementary small angle x-ray scattering experi-ments were recently preformed at the AdvancedPhoton Source at Argonne National Laboratory on theBasic Energy Sciences Synchrotron Radiation Center(BESSRC) beamline and on the Biophysics Collabora-tive Access Team (Bio-CAT). These preliminaryexperiments, which followed the size of the Azoarcusgroup I ribozyme as a function of the concentrationof Na+, Mg2+, Ca2+ and Co3+ cations, show that theefficiency of charge neutralization increases with theincreasing valence of the condensing cation. Asobserved in the SANS experiment, the collapse theribozyme into a compact state does not coincide withself splicing activity yet the dimensions of theribozyme in the compact state show no furtherdecrease in Rg even after native conditions arereached. The compact intermediates in Na+, Ca2+

and Co3+, at their corresponding transition concen-trations, show similar dimensions and only a coupleof Å larger than the compact state in Mg2+. It is alsoobserved that the transition to a collapsed state inMg2+ and Ca2+ occurs at different cation concentra-tions, indicative of a cation size effect. In contrastwith Na+, a ten-fold increase in Ca2+ beyond thecollapse transition concentration shows the ribozymecompacting further to a dimension equivalent to thecompact state in Mg2+. Although it is predicted thatthe Rg of the ribozyme is inversely proportional tothe square of the cation valence, no furthercompactation of the ribozyme in Co3+ could beobserved because it precipitated out of solutionbefore this could occur.

WP9: The Center for Structural Molecular Biologyat Oak Ridge National Laboratory

V.S. Urban (Chemical Sciences Division, Oak RidgeNational Laboratory), W.T Heller, G.W. Lynn(Chemical Sciences Division, Oak Ridge NationalLaboratory; Condensed Matter Sciences Division,Oak Ridge National Laboratory), P.D Butler, G.D.Wignall (Condensed Matter Sciences Division, OakRidge National Laboratory), M.V. Buchanan, D.A.A.Myles (Chemical Sciences Division, Oak RidgeNational Laboratory)

A Center for Structural Molecular Biology (CSMB),which is funded by the Department of Energy’s(DOE) Office of Biological and Environmental Re-search (OBER), has been established at Oak RidgeNational Laboratory (ORNL). The CSMB will integrate


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the existing strengths in the neutron sciences atORNL with new capabilities being developed incomputational biology and stable isotope labeling ofproteins and make them available to a broad usercommunity. The cornerstone of the CSMB is a small-angle neutron scattering instrument (Bio-SANS) thatis currently under construction at the High FluxIsotope Reactor (HFIR) at ORNL. Bio-SANS will have aneutron flux and performance that is unprecedentedin the US and that will provide the user communitywith world-leading capabilities in the field. Thedevelopment of new computational methods for theanalysis of biological scattering data and of facilitiesfor the selective H/D labeling of complex macromo-lecular assemblies will provide the tools necessary tofully exploit these advantages in the application ofSANS to complex problems in biology. Bio-SANS willbe a critical resource for the US structural biologycommunity and the CSMB will provide a wide rangeof scientific and educational opportunities for scien-tists and students working in the field.

Research sponsored by the Office of Biological andEnvironmental Research, U.S. Department of Energy,under contract No. DE-AC05-00OR22725 with OakRidge National Laboratory, managed and operated byUT-Battelle, LLC.

WP10: Oxidation of propane in zeolite Y studiedby in situ inelastic neutron scattering

M. Hartl, L.L. Daemen (Los Alamos Neutron ScienceCenter, Los Alamos National Laboratory), J. Eckert(Los Alamos Neutron Science Center, Los AlamosNational Laboratory; Materials ResearchLaboratory, University of California, SantaBarbara), B. Mojet, J. Xu (Department of Chemistry,University of Twente)

Short alkanes, such as propane, are present in naturalgas and in volatile petroleum fractions. These mol-ecules can be converted by oxidation into an impor-tant feedstock for the production of synthetic materi-als (plastics) and fine chemicals. Zeolites containingalkaline or alkaline earth cations have been shown tobe promising materials (F. Blatter, H. Sun, S.Vasenkov, H. Frei, Catal. Today, 41 (1998) 297) for theoxidation of these small hydrocarbons by low-temperature catalysis in the presence of smalloxidant molecules such as O2 . At the present time,however, the interaction between these zeolites andthe oxidized reactants has not been studied exten-sively. Frei and collaborators discussed a possiblealkane-oxygen charge transfer state stabilized by theelectrostatic field of the cations in the zeolite, but thishas not been established.

The electrostatic field inside the pore structure ofzeolite Y and the available space for the reactants onthe inner surface of the catalyst can be varied byusing different cations (Na+ and Ca2+) in zeolite Ywith similar ionic radii but different positive charge.Vibrational spectroscopy by incoherent inelasticneutron scattering (IINS), as well as variety of otherin situ techniques, have resulted in an improvedunderstanding of the activation of the reactantmolecules and the desorption of the oxidationproducts. Information on the adsorption sites, surfacebonding, and local chemical environment can beinferred from the IINS spectra of the adsorbedmolecules. Vibrational spectra of the zeolites NaY,CaY and NaCaY were recorded after their calcinationin vacuum, after the adsorption of propane andoxygen inside the zeolite, and after the oxidation ofpropane by oxygen. Our results combined with IRspectroscopic studies provide useful insights into thesorbate-zeolite host interaction as well as the mecha-nism of the oxidation reaction, which should lead tothe design and development of new catalysts for theselective oxidation of hydrocarbons.

WP11: Neutron and Thermodtnamic investigationsof H2 on MgO Surfaces

T. Arnold (Oak Ridge National Laboratory), L.Frazier (University of Tennessee), A. Ramirez-Cuesta (ISIS, Rutherford Appleton Laboratory), R.Hinde (University of Tennessee), J. Z. Larese (OakRidge National Laboratory; University of Tennessee)

We will discuss recent thermodynamic and neutronscattering measurements that probe the growth ofmolecular hydrogen films on MgO (100) surfaces. Ourthermodynamic investigations indicate that attemperatures in the neighborhood of 10K, 6 or 7layering transitions are easily observable. Usinginelastic neutron techniques we have identified afeature in the spectrum that we believe can beassociated with the ortho-para rotational transition inthe neighborhood of 11 meV (88 cm-1). This feature issignificantly lower than the equivalent transition inbulk H2 which appears at 14.7 meV. The position andshape of this feature has been recorded as a functionof temperature. Distinct shifts in the peak positionand symmetry are recorded between one and threelayers. In the vicinity of three layers a sharp featurenear the bulk transition appears and continues togrow in intensity with additional increases in thehydrogen film thickness. Comparison of these resultswith simple calculations and structural data will bemade. Relationship of these data to others recordedwhen H2 is adsorbed other metal oxide materials willbe discussed.


WP12: The pillared perovskites La5Os3MO16

(M=Mn, Co) Synthesis, crystal structure andmagnetism

Lisheng Chi (National Research Council, ChalkRiver, Ontario, Canada; Department of Chemistry &Brockhouse Institute for Materials Research,McMaster University, Hamilton, Ontario L8S 4M1,Canada), Ian Swainson (National Research Council,Chalk River, Ontario, Canada), John E. Greedan (;Department of Chemistry & Brockhouse Institutefor Materials Research,McMaster University,Hamilton, Ontario L8S 4M1, Canada)

Two new Os-containing compounds La5Os3MnO16,La5Os3CoO16 with pillared perovskite type structureshave been synthesized by solid state reactions.Rietveld profile refinement revealed that bothcompounds crystallize in space group C-1 with cellparameters a=7.9648(9) Å, 7.9360(7) Å; b=8.062(1)Å, 8.0481(7) Å; c=10.156(2) Å, 10.0788(8) Å;α=90.25(1)°, 90.300(4)°; β=95.5(1)°, 95.340(4)°;γ=89.95(2)°, 89.914(6)° for La5Os3MnO16 andLa5Os3CoO16 , respectively. The structure consists ofcorner-sharing, site-ordered octahedral layers ofcomposition Os5+M2+O6, pillared by diamagneticOs2O10 triply-bonded dimers and separated by> 10 Å. SQUID measurements in the paramagneticregime show nearly spin only effective moments forOs5+(S = 3/2) and the M2+ ions. La5Os3MnO16 hastwo magnetic transitions at 178 K and 78 K, corre-sponding to long range ordering and spin reorienta-tion, respectively. Isothermal magnetization data arecharacteristic of meta-magnetic behavior.La5Os3CoO16 has a single magnetic transition at 36 K.The magnetic structure of La5Os3MnO16 consists offerrimagnetically coupled Os5+ and Mn2+ momentswithin the layers which then coupleantiferromagnetically between layers. The orderedmoments are 3.7(2) µB for Mn and 1.9(2) µB for Osand are parallel to the c-axis.

WP13: Evaluating Organoclays for Nanocompositesby Small-Angle Scattering and Microscopy

D.L. Ho (University of Maryland, College Park; NISTCenter for Neutron Research), C.J. Glinka (NationalInstitute of Standards and Technology), R.M. Briber(University of Maryland, College Park)

Understanding the structure of organophilic clays andthe interaction between clay platelets dispersed inorganic solvents is important to characterizingnanocomposites formed by organophilic clays andpolymers. In order to understand and optimizepotential processing conditions, organically modifiedmontmorillonite clays were dispersed in a number oforganic solvents covering a range of solubilityparameters and characterized using small-angle

neutron scattering and wide-angle x-ray scatteringtechniques. The organic modifier was dimethyldihydrogenated tallow ammonium. Both as-received(unextracted) and purified (extracted) organicallymodified clays were studied. The scattering profilesand dispersion behavior in organic solvents of thedry powder of unextracted and of extracted dimethyldihydrogenated tallow montmorillonite are signifi-cantly different confirming that the organic modifiersare present in excess in the unextracted material asreported by the industrial provider. The scatteringdata show that both unextracted and extractedorganically modified clay platelets were fully exfoli-ated in chloroform while the platelets retain theirlamellar structure and swell to a similar extent inbenzene, toluene and p-xylene, but the extractedmaterial has a stronger tendency to gel. The scatter-ing profiles indicate that the swollen tactoids ofextracted material are thinner, and therefore morenumerous, which may account for the bulk suspen-sion behavior. The extracted clay dispersion exhibiteda concentration dependence to the scattering for allthe organic solvents studied except chloroform whilethe unextracted clay dispersion did not. Neither theextracted nor the unextracted dispersions exhibitedany temperature dependence to the scattering. Thethickness of unmodified montmorillonite plateletswas found to be 9.9 Å while that of organicallymodified montmorillonite platelets was determinedto be 24.3 Å using wide angle x-ray scattering. Thelateral size of organically modified montmorilloniteplatelets was observed to be in the range of0.4 micron to 1.0 micron using atomic force micros-copy.

WP14: Small angle neutron scattering from single-wall carbon nanotube suspensions: evidence forisolated rigid rods and rod networks

W. Zhou (MSE Dept., U. Penn.), M. F. Islam (Dept. ofPhysics & Astronomy, U. Penn.), H. Wang (MSEDept., Michigan Tech), D. L. Ho (NIST Center forNeutron Research), A. G. Yodh (Dept. of Physics &Astronomy, U. Penn.), K. I. Winey, J. E. Fischer (MSEDept., U. Penn.)

We report small angle neutron scattering (SANS) fromdilute suspensions of purified individual single wallcarbon nanotubes (SWNTs) in D2O with addedsodium dodecylbenzene sulfonate (NaDDBS) ionicsurfactant. The scattered intensity scales as Q-1 forscattered wave vector, Q, in the range0.005 < Q < 0.02 Å-1. The Q-1 behavior is character-istic of isolated rigid rods. A crossover of the scat-tered intensity power law dependence from Q-1 to Q-2

is observed at ~0.004 Å-1, suggesting the SWNTsform a loose network at 0.1 wt % with a mesh size of


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~160 nm. SANS profiles from several other disper-sions of SWNTs do not exhibit isolated rigid rodbehavior; evidently the SWNTs in these systems arenot isolated and form aggregates.

WP15: Study of Oxygen Dissolution in a2-Ti3Al:Combining the Analysis of Pair DistributionFunctions from Total Scattering with First Prin-ciples Calculations

I. Peral (NIST Center for Neutron Research;Department of Materials Science and Engineering,University of Maryland), E. Copland (Case WesternReserve University and Materials Division, NASAGlenn Research Center, Cleveland, OH 44135 USA),X. Qiu (Department of Physics and Astronomy,Michigan State University, E. Lansing, MI, 48824),S. Short (Materials Science Division, ArgonneNational Laboratory), C. Y. Jones (NIST Center forNeutron Research)

The most promising of the g-TiAl-based intermetallicalloys for application as high-temperature structuralcomponents are g-TiAl+a2-Ti3A mixtures based onthe composition Ti-48 atom% Al. Oxygen interstitialsstabilize a2-Ti3Al relative to g-TiAl, thus ina2-Ti3Al+g-TiAl mixtures a2-Ti3Al behaves as anoxygen scavenger. However, limited data are avail-able on the dissolution of O in a2-Ti3Al.

Recently, high-resolution constant wavelengthneutron powder diffraction data were used to refinethe crystal structures of several a2-Ti3Al alloys withvarying O content [1]. This study confirmed that Oresides in octahedral sites surrounded by six Tiatoms, as proposed by Menand et al. [2]. From thiswork, it was possible to obtain the average structure,that is, the atomic composition in the unit cell andthe atomic positions of the atoms. However, there isno complete information about the local environ-ment of the atoms. A more thorough investigation ofthe effect of oxygen interstitials on the structure andstability of a2-Ti3Al is required to understand thedramatic difference in O affinity and the behavior ofthe duplex alloys.

We have measured the total scattering from twospecimens of a2-Ti3Al alloys with O weight percent-ages of 0.025 % and 7.7 %, to determine from thePair Distribution Function (PDF) the various correla-tion lengths for O, Ti, and Al. The comparison of theexperimental PDF to the calculated PDFs of a num-ber of local structure models shows that the averagestructure can describe most of the features of theexperimental PDFs and that the PDF is sensitive tothe different possible local environments of theatoms. The sampling of the different local structure

models is a work still in progress as well as the modelrefinement to the experimental PDFs. We use DensityFunctional Theory to probe the energy of models thatdescribe different local structures.

From our preliminary modeling and model refine-ment, it is observed that the agreement experiment-model is better for local structural models where theatoms that present positional disorder in the system(the aluminum atoms that can be distributed over thetitanium sites and the oxygen atoms) are distributedrandomly, rather than for models where the alumi-num atoms cluster around the oxygen atoms.

[1] Jones C. Y., Luecke W. E. and Copland E. (submit-ted to Intermetallics)[2] Menand A., Huguet A., Nerac-Partaix A., ActaMater. 1996, 44(12), 4729-4737.

WP16: Structure of a Liquid Crystalline Polymer Inan Amorphous Polymer Matrix

R. Metha, M. D. Dadmun (Department of Chemistry,University of Tennessee, Knoxville, TN 37923)

Molecular composites, composed of uniformlydispersed rigid-rod liquid crystalline polymer (LCP)molecules in a flexible amorphous polymer matrix,have remained hitherto elusive due to a scarcity ofmiscible systems containing a LCP and an amor-phous polymer. The production of such a blend witha large miscibility window, which is experimentallyaccessible, has become possible by modifying thearchitecture of the flexible polymer, so as to inducefavorable enthalpic interactions between the flexiblepolymer and LCP. Specifically, liquid crystallinepolyurethanes (LCPU) are found to be miscible with acopolymer of styrene and vinyl phenol. Here miscibil-ity is promoted by realizing intermolecular hydrogenbonding between the carbonyl groups of the ure-thane linkages with the hydroxyl groups present inthe styrenic matrix.

Availability of a truly miscible molecular compositepresents a unique opportunity of studying theconfirmation of polymer chains containing rigid-rodsthat are uniformly dispersed in a flexible coil matrix.A system consisting of the LCPU and the deuteratedstyrenic copolymer containing 10 % vinyl phenol isexamined by Small Angle Neutron Scattering at theNational Center for Neutron Research at the NationalInstitute of Standard and Technology, and the Insti-tute of Solid State Research (IFF) at Jülich. The radiusof gyration of the LCPU is determined by fitting thelow angle portion of the scattering curve to thetraditional Guinier and Zimm methods. The confor-mation of LCPU molecules is also determined byanalysis of the scattering curve using a wormlike


model and Kratky Porod analysis.

Support towards this work by NSF DMR-0241214, TheJoint Institute of Neutron Sciences at the University ofTennessee, NCNR (NIST), and IFF (FZ-Jülich) isgratefully acknowledged.

WP17: Influence of Plastic Deformation on theStress-Induced Transformation in Superelastic NiTi

C.R. Rathod (AMPAC/MMAE, University of CentralFlorida), B. Clausen, M.A.M. Bourke (Los AlamosNational Laboratory), R. Vaidyanathan (AMPAC/MMAE, University of Central Florida)

The superelastic effect in NiTi occurs due to a revers-ible stress-induced phase transformation from a cubicB2 austenite phase to a monoclinic B19’ martensitephase. There is usually a hysteresis associated withthe forward and reverse transformations whichtranslates to a hysteresis in the stress-strain curveduring loading and unloading. This hysteresis isreduced in cold-worked NiTi and the macroscopicstress-strain response is more linear, a phenomenoncalled linear superelasticity. Here we report on in situneutron diffraction measurements during loadingand unloading in plastically deformed (up to 11%)NiTi. The experiments relate the macroscopic stress-strain behavior (from an extensometer) with thetexture, phase volume fraction and strain evolution(from neutron diffraction spectra) in linearsuperelastic NiTi. The roles of starting texture andcyclic loading following plastic deformation are alsoinvestigated. This work is supported by NSF (CAREERDMR-0239512).

WP18: Structure of potentially superconductingsilver fluorites

S. Mclain (University of Tennessee; ArgonneNational Laboratory), J. Turner (University ofTennessee), T. Proffen (Los Alamos NationalLaboratory), M. Dolgos (University of Tennessee)

High temperature superconducting cuprates havebeen investigated extensively in recent years.Spin-1/2 ions that possess similar or identical struc-tural chemistry to the Cu(II) ions in the high Tccuprates are rare. One such ion is Ag(II), which, beingunstable in an oxide lattice context is stable invarious fluoride phases, that are structurally analo-gous to the 214 Ag2CuO4. Here we present the resultsof neutron scattering studies on the fluoride-based214 analog Cs2AgF4, which displays the stronglycorrelated spin interactions expected of a S=1/2 ionin a structure similar to that of K2CuF4.

Understanding of these materials obviously requiresa detailed understanding of the atomic structure. Ithas become more and more apparent that structure

analysis based on Bragg intensities alone gives anincomplete picture, completely ignoring disorder orthe local structure of these materials. One approachto extract local structural information from the totalscattering pattern, i.e. Bragg and diffuse scattering, isthe Pair Distribution Function (PDF) method. Muchprogress has been made understanding the localstructure of cuprates using the PDF [1].

Variable temperature neutron diffraction studies onNPDF at LANSCE over a Q range of 50 Å-1 haveallowed both Bragg analysis of the long range orderand pair distribution function (PDF) analysis of thelocal structure of this material. The structure and thetemperature behavior of the structure will be pre-sented and parallels drawn with similar PDF studieson structurally related cuprate and manganitematerials.

[1] E. S. Bozin, S. J. L. Billinge, H. Takagi and G. H.Kwei, Neutron diffraction evidence of microscopiccharge inhomogeneities in the CuO2 plane of super-conducting La2-xSrxCu4 ( 0≤ x ≤ 0.30), Phys. Rev. Lett.84, 5856 (2000).

WP19: Neutron investigations of selectedheteropolyacids

C. M. Brown (Department of Materials Science andEngineering, University of Maryland; NIST Centerfor Neutron Research), R. Burns (Chemistry, Schoolof Environmental and Life Sciences, The Universityof Newcastle, Australia), E. Gilbert, J. Schulz (BraggInstitute, Australian Nuclear Science andTechnology Organisation, Australia)

Heteropolyacids and their hydrates have been citedas the fastest proton conductors known, possibleelectrolytes for solid acid batteries, composites forpolymer membrane fuel cells and industrial catalysts.Examples of the latter include the oxidation ofmethacrolein, and the oxidative dehydrogenation ofisobutyric acid, both of which yield methacrylic acid.The product, when reacted with methanol, givesmethyl methacrylate, which in turn is polymerized toform poly(methyl methacrylate) or PMMA. However,despite their commercial use, their structure andcatalytic function at a molecular level remainsunclear. Consequently, we have initiated investiga-tions into the structure and vibrational spectroscopyfrom a series of catalysts of the typeCs3-nHn[PMo12O40] where n is varied from 0 to 3, witha goal to resolving these fundamental issues.

WP20: Dynamics of water in zeolites — a QENSstudy of the effects of charge, confinement, andhydration level

W. A. Kamitakahara (NIST Center for Neutron


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Research), N. Wada (Toyo University, Saitama, 350-8585 Japan)

We have made a series of quasielastic neutronscattering (QENS) measurements on water moleculesconfined to the pores of zeolite materials, comparingthe effects of several factors that influence theirmotion. The most important factor determining thespeed of translational diffusion arises from thecharges on the aluminosilicate framework andcounterbalancing cations. Using the high flux back-scattering spectrometer (HFBS) at NIST, we observethat the QENS broadening is roughly an order ofmagnitude larger at 300 K in a high-silica, nearlyneutral, zeolite (Si/Al ratio r=180) than in a highlycharged zeolite (NaX, r=1.25), while spectra forzeolites with r =14.5 and r=2.75 show intermediatebroadening. All of these materials are Na-zeoliteswith the same basic structure, i.e., faujasite, so thatthe charge effect can be isolated. The degree ofhydration also influences the motions significantly. Asthe water content is varied from a mass fraction of0.1 to 0.3 in several of the zeolites, we observe aroughly proportional amount of QENS broadening.Reducing the hydration level not only slows the watermotions, it also increases the temperature width overwhich the motions freeze out. The effects of substitut-ing a 2+ cation (Ca) for Na+ are also under investiga-tion. In fixed-window scans (E=0, T varied), water inthe nearly neutral zeolite shows structure and largehysteresis in the freezing transition, unlike thetransitions in the more highly charged zeolites, whichshow smaller hysteresis and smooth transitions. Thiswork employed facilities supported in part by theNational Science Foundation under agreement No.DMR-0086210.

WP21: Protein Solvent Coupling in Native andGlass Environments

J. E. Curtis, D. A. Neumann (NIST Center forNeutron Research), D. J. Tobias (ChemistryDepartment, University of California, Irvine 92697)

Recent experimental and computational studies haveconclusively shown that water is essential in theactivation of dynamical motions required for biologi-cally relevant protein function. We have found thatthe microscopic origins of this affect in nativeenvironments are directly related to the temperaturedependence of the diffusion of water from theprotein surface. We are extending our studies ofprotein dynamics through the use of moleculardynamics simulations of the protein RNase A in bothnative and non-native glassy environments. We havefound that binary glass mixtures can reduce proteindynamics at high temperature. Detailed analysis ofthe microscopic origins of this effect will be pre-sented.

WP22: Structure of polymer-nanocomposites – ASANS and USAXS study

R. A. Narayanan, P. Thiyagarajan (Intense PulsedNeutron Source, Argonne National Lab), B.J. Ash,S.S. Sternstein, A.J. Zhu, L. Schadler (MaterialsScience and Engineering Department, RensselaerPolytechnic Institute, Troy, NY- 12180)

Alumina/ polymethylmethacrylate (PMMA)nanocomposites synthesized by an in situ free-radicalpolymerization in the presence of 38 nm aluminananoparticles exhibit unusual brittle-to-ductiletransition with a large increase in the strain-to-failure.In order to understand the molecular mechanismsresponsible for the reinforcement of polymericmaterials by nano-sized inorganic fillers, we haveundertaken small-angle neutron (SANS) and ultrasmall angle x-ray scattering (USAXS) measurementson alumina-PMMA and silica-PVAc nanocomposites,in combination with studies on their mechanicalbehavior. SANS studies of alumina-PMMA compositesshow a large degree of aggregation and agglomera-tion of alumina that depends on the size of thenanoparticles. Moreover, composites containing 5and 10 wt.% deuterated PMMA indicate that additionof nanoparticles does not seem to affect the Rg of thepolymer (PMMA). These results have to be investi-gated further by contrast matching the scatteringfrom the alumina using appropriate mixture ofdeuterated and normal PMMA. USAXS data on silica-PVAc nanocomposites a large degree of aggregationof silica is observed. The particles show an averageaggregation of about 250 Å which is significantlyreduced in the case of surface treated fillers. Evi-dence suggests that the surface fractal dimension,which is a measure of surface roughness, is directlyrelated to reinforcement characteristics of thecomposite.

This work benefited from a grant from Office ofNaval Research to LS at RPI, and IPNS and APSfacilities funded by DOE under contract no. W-31-109-ENG-38 to the University of Chicago. UNICATfacility is supported by the DOE, the State of Illinois-IBHE-HECA, NSF, NIST (U.S. DOC) and UOP LLC.

WP23: The crystalline enol of1,3-cyclohexanedione and its complex withbenzene: vibrational spectra, simulation of struc-ture and dynamics and evidence for cooperativehydrogen bonding

B. S. Hudson, D. G. Allis, Y. Lan (Department ofChemistry, Syracuse University, Syracuse, NY), D. A.Braden (Schrödinger Inc., Portland, OR), C. T.Middleton, T. Jenkins (Department of Chemistry,Syracuse University, Syracuse, NY), R. Withnall(School of Chemical and Life Sciences, University of


Greenwich, Chatham Maritime Campus, Chatham,Kent ME4 4TB, UK.), S. Baronov (SyracuseUniversity/NSF REU Participant, Summer 2000.Current address: Department of Chemistry, MoscowState University, Moscow, Russia.), C. M. Brown(Department of Materials Science and Engineering,University of Maryland, College Park, MD 20742-2115 and NIST Center for Neutron Research,National Institute of Standards and Technology,Gaithersburg, MD 20899-8562)

The inelastic incoherent neutron scattering spectra of1,3-cyclohexanedione (CHD) in its crystalline enolform and its cyclamer complexes with benzene andbenzene-d6 are compared with each other, with IRand Raman spectra and with the results of calcula-tions using density functional theory (DFT). We havealso determined the INS spectra of a variety ofmethyl and deuterium substituted derivatives ofCHD. Deuterium isotopic substitution can be used toconfirm spectra assignments. The crystal packing ofthe CHD enol is a linear hydrogen-bonded chain withconjugated donor and acceptor groups analogous tothat found in peptide hydrogen bonding. Methylsubstitution can have very large effects on the crystalpacking of CHD. The benzene complex is a closedhexameric hydrogen-bonded cycle. A DFT treatmentis applied to the full hexamer of the benzene:CHDcomplex. The CHD chain is treated as a series offinite linear clusters by DFT, while the infinite one-dimensional chain and the three-dimensional crystalare treated by periodic DFT. Comparison is madewith both the observed crystal structures and thevibrational spectra. The very good to excellentagreement of the computed vibrational spectra withexperiment demonstrates that the models andcomputational treatments used are reliable. Thetheoretical treatment of linear chain clusters exhibitsa continuous change with increasing chain length,converging to values near the observed crystalstructure. Emphasis is placed on the cooperativenature of hydrogen bonding in CHD as revealed bythese systematic trends. The calculations show thatthe energy of a linear chain of hydrogen bonded CHDmolecules becomes increasingly stable and increas-ingly more dipolar as that chain length increases.This is consistent with the hypothesis that thecooperative hydrogen bonding of CHD is due topolarization of the structure. The significance of thiseffect with regard to the analogous case of peptidehydrogen bonding and its relevance to the stability ofthe globular form of proteins will be discussed. Theability of DFT methods to treat hydrogen bonding insolids appears to be roughly as accurate as the crystalstructure determinations.

WP24: NCNR High Pressure Sample EnvironmentJ.B. Leao, D.C. Dender (NIST Center for NeutronResearch)

The NIST Center for Neutron Research currentlyprovides a variety of pressure apparatus ranging from20 MPa to as high as 400 Mpa that are speciallydesigned for neutron spectroscopy. Most of thepressure equipment can be mounted in a variety ofinstruments throughout NCNR’s facility allowing forexperimental flexibility and maximizing beam timeuse. The available NIST Center for Neutron Researchpressure equipment, as well as a few experimentalresults that explore its diversified use in neutronspectroscopy, is presented here.

WP25: Application of high frequency ultrasoundfor the simultaneous upgrade intensity and resolu-tion of the double crystal and Bonse - Hartdiffractometers

E. Iolin, L. Rusevich (Institute of Physical Energetic,21 Aizkraukles, LV-1006 Riga, Latvia), M. Strobl, W.Treimer (Hahn-Meitner-Institut Berlin; University ofApplied Sciences (TFH) Berlin), P. Mikula (NuclearPhysics Institute, 25068 Rez near Prague, CzechRepublic)

It is known that neutron Double Crystal (DCD) andBonse-Hart (BHD) diffractometers are used for theultra small angle scattering research. However, thistechnique is flux limited. It is also known that h.f.ultrasound leads to the increasing of the difractedbeam intensity at the perfect s.c. Unfortunately thisincreasing is accompanied by a loss of the momen-tum resolution. Some time ago it was argued (E.Iolin,Zh.Tekhn.Fiz.Pis’ma 15, 52,1989) that it should bepossible to improve simultaneously resolution andintensity for the case of DCD. It could be achieved bythe excitation of the h.f ultrasound with the samefrequency in monochromator AND analyser. Such aperspective is especially interesting for the case ofBHD. Ultrasonic satellites exist as additional zones ofthe almost total reflections for the case of symmetri-cal Bragg scattering. Reflectivity between phononsatellites is suppressed due to the multiply reflectionsinside BHD. Each satellite is narrow, but they arenumerous. The whole effective diffracted neutronbeam phase space volume is increased that’s led tothe upgrade of the diffractometer parameters.Here we report the first results of correspondingexperiments. We excited longitudinal and transversal(LAW, TAW) acoustic waves with frequency 70.27 MHzin Si(111) plate and analysed the reflected beam bymeans of similar Si plate (DCD regime) or by triple-bounces BH analyser, respectively. The neutronswavelength was 0.523 nm. Using the triple bounceBH analyser we observed a strong improvement of


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phonon satellites contrast with moderate, ~20 %,loss of the main peak intensity. This was due to thesuppression of of the wings of the Darwin curve. Inthis case BH analyser “allows” to observe up to ±3ultrasonic phonon satellites.

We studied DCD with simultaneously ultrasonicallyexcited monochromator (LAW) AND analyzer (TAW).We observed ~25 % narrowing of the main peak, itsintensity increasing up to 70 % and simultaneouslythe ultrasonic phonon satellites contrast is stronglyimproved in this “double-sound” case. These resultswere observed for the first time. It seems that ourapproach can be also applied for the improvement ofthe neutron imaging for the case of the refractioncontrast.

WP26: ToF-Neutron Reflectometer REFSANS atFRM-II Munich / Germany: Design and Potential forInvestigations on Surfaces and Interfaces

R. Kampmann, M. Haese-Seiller, V. Kudryashov(Institut für Werkstoffforschung, GKSS-Forschungszentrum Geesthacht GmbH, D-21502Geesthacht, Germany), A. Okorokov, B. Toperverg(Petersburg Nuclear Physics Institute, Gatchina,188350, Russian Federation), A. Schreyer (Institutfür Werkstoffforschung, GKSS-ForschungszentrumGeesthacht GmbH, D-21502 Geesthacht, Germany),E. Sackmann (Physik-Department E22, TechnicalUniversity Munich, 85748 Garching, Germany)

The reflectometer REFSANS is being built at the highflux reactor FRM-II in Munich. Novel time-of-flight(TOF) design and neutron optics allow for equalresolution adjustment of both the wavelength and theincidence angle to measure the specular reflectivityat maximum beam intensity over an extremely largerange of momentum transfer of~0.02 nm-1<q <20.0 nm-1. The resolution inmomentum transfer can be set in the wide range of0.25 %<∆q/q<15 % (FWHM). At low q-resolution,beam intensities are expected to be sufficiently highto measure minimum reflectivities of R ~ 10-10.REFSANS also provides new perspectives for charac-terizing lateral surface structures by means of small-angle scattering at grazing incidence (GI-SANS). Suchexperiments can be performed with the highestbeam flux at a low wavelength resolution of∆λ/λ ~10 % and with novel scattering geometries, inparticular the option to focus 13 point-collimated orslit height-smeared beams in the detector plane.Polarized neutrons can be used optionally for allmentioned scattering geometries and 3He-basedpolarization analysis will be made available in 2005.REFSANS is being put into operation this year andwill be open for national as well as internationalusers.

WP27: The Upgraded General Purpose PowderDiffractometer at IPNS-ANL

J. W. Richardson, E. R. Maxey, Y. Li, A. Huq (IPNSDivision, Argonne National Laboratory)

The General Purpose Powder Diffractometer (GPPD)at IPNS has been upgraded according to a newconcept for neutron powder diffractometer designthat combines in an optimal way the strengths ofreactor-based angle-dispersive and pulsed-sourcetime-of-flight instrument designs. The key to thisperformance is to combine a continuous detectorbank, extending over a large solid angle from backscattering to forward scattering, with time focusingtechniques that allow all scattered neutrons to becombined into a single histogram. Without changingany instrument hardware, performance can besoftware/electronically optimized with respect toresolution, count rate, and d-spacing range to matchthe experiment being performed. A ~20 times datarate increase is achieved in high intensity mode,where detectors covering a 75° 2-theta range aretime-focused and summed. Changing chopperphasing allows the optimum resolution to be movedto d-spacings up to 6-8 Å for the study of larger unitcells, mixed phases, or subtle distortions.

The instrument now operates with: (1) a new DataAcquisition System capable of measuring full spectrafor each detector and with EPICS-based processcontrol, (2) one T0 and a frame-definition chopperproviding wavelength-band selection and 15 Hzeffective operation, (3) a 15 meter m=3 supermirrorguide system with measured neutron gain factor >6terminating 1 m (top) and 2 m (sides) from thesample position, (4) an incident flight pathlength of25 m (up from 20 m) to reduce the moderator pulse-width contribution to peak shape resolution, and (5)no initial change in the L-CH4 moderator poisoningdepth.

This work is funded by the U.S. Department ofEnergy under Contract W-31-109-ENG-38.

WP28: Recent Technical Progress on High P-TNeutron Diffraction

Y. Zhao, L.L. Daemen, K. Lokshin, C. Pantea, J.Qian, S.C. Vogel, D.J. Williams, J. Zhang (LosAlamos National Laboratory)

We will present the most recent progress made atLANSCE on High P-T Neutron Diffraction. We havedeveloped a 500-ton toroidal press, TAP-98, toconduct simultaneous high pressure (up to 20 GPa)and high temperature (1700 K) neutron diffractionexperiments. TAP-98 can be loaded into the HIPPO(High-Pressure and Preferred-OrientationDiffractometer) and we have performed high P-T


neutron diffraction experiments usingHIPPO + TAP-98 for the first time in the run cycle of2002. We have also developed a large crystal anvilcell, ZAP-01, to conduct experiments at high pres-sures and low temperatures. This cell can be used forintegrated experimental techniques of neutrondiffraction, laser spectroscopy, and ultrasonicinterferometery. Most recently, construction of thenew TAP-PLUS cell started, a 2000 ton press forneutron diffraction experiments which will run on adedicated beam-line.

WP29: Commissioning User-Ready Sample Envi-ronment Devices at ORNL

L. J. Santodonato (Spallation Neutron Source, OakRidge National Laboratory), G. B. Taylor (HFIRCenter for Neutron Scattering, Oak Ridge NationalLaboratory, Oak Ridge, Tennessee 37831, USA)

The first sample environment devices for the Spalla-tion Neutron Source (SNS) have arrived, and we arealready testing, debugging, and commissioning themfor scientific research (presently at the High FluxIsotope Reactor (HFIR)). Scientific and technicalteams from the HFIR and the SNS are collaboratingon these efforts. Ultimately, we are working toestablish a rigorous testing program to help bothfacilities maintain highly reliable sample environmentinventories. These seemingly mundane tests alsoform a basis for more exciting endeavors such asprototype development, equipment upgrades, andthe training of our growing technical teams. Thisposter highlights some of our recent efforts andresults.

WP30: Sample Environment Coordination at theNCNR

E. Fitzgerald, B. Clow, J. Leao, D. Dender (NISTCenter for Neutron Research)

The provision of sample environment for neutronscattering experiments is a multi-faceted exercise, thebroad nature of which often goes unnoticed by guestresearchers. This vital infrastucture is built uponknowledge and skills from physics, chemistry,electronics, machining, computer science, engineer-ing, health physics, and management. By drawing onrecent examples, we show how these multipleresources are brought to bear to ensure a smoothlyfunctioning facility at the NIST Center for NeutronResearch.

WP31: Vibrational spectra of methyl derivatives ofbenzene selected as potential cold moderatormaterials

I. Natkaniec (Frank Laboratory of Neutron Physics,JINR, 141980 Dubna, Russia; H. Niewodniczanski

Institute of Nuclear Physics, PAS, 31-342 Krakow,Poland), K. Holderna-Natkaniec (Department ofPhysics, A. Mickiewicz University, 61-614 Poznan,Poland), J. Kalus (Institute of Physics, University ofBayreuth, D-95440 Bayreuth, Germany), I. Majerz(Faculty of Chemistry, University of Wroclaw, 50-383 Wroclaw, Poland)

Vibrational spectra of selected methyl derivatives ofbenzene: toluene, m- and p-xylene, mesitylene(1,3,5-trimethylbezene) and pseudocumene(1,2,4-trimethylbenzene), measured by inelasticincoherent neutron scattering (IINS) at 20 K, arecompared with the amplitude weighted vibrationaldensity of states calculated by the DFT quantumchemistry method. The IINS spectra were measuredon the inverted geometry time-of-flight spectrometerNERA at the high flux pulsed reactor IBR-2 of theJoint Institute for Nuclear Research in Dubna. Thecalculation performed with the B3LYP/6-311++G**

basis set, gives quite satisfactory characteristics ofinternal modes, except for the frequencies of methyllibrational modes. Internal barriers for methylrotations of the investigated molecules are quite low,except for the two methyl groups which are con-nected to the neighboring carbon atoms of aromaticring of pseudocumene molecule. The asymmetricmolecules of toluene and m-xylene in solid phaseform the crystals with low external barriers formethyl rotations. The mesitylene molecule containsthe largest number of methyl groups around thearomatic ring with low internal rotational barriers.The external barriers caused by crystal packingsignificantly increase the frequencies of methyllibrations in the low temperature phase III of mesity-lene. The disordered phase II of solid mesitylene,which has low external rotational barriers of methyl,and additional density of states at low frequencies,caused by protonic glass state, is not stable at lowtemperatures. It is shown that mesitylene in solutionwith toluene, m-xylene or pseudocumene formsglassy solids, which are stable in the whole tempera-ture range below the melting point. The IINS spectraof these glassy states also indicate relatively lowbarriers for methyl rotations, and additional densityof states at low frequencies (boson peak) typical fordisordered solids, which make these materials morepreferable as potential solid moderators for very coldneutron sources.

WP32: When Thin is Sexy – The Future of NeutronReflectometry in Australia

M. James, A. Nelson, J. C. Schulz (Bragg Institute,Australian Nuclear Science and TechnologyOrganisation, Australia)

Neutron reflectometry is used to probe the structure


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of surfaces, thin-films or buried interfaces as well asprocesses occurring at surfaces and interfaces.Applications cover adsorbed surfactant layers, self-assembled monolayers, biological membranes,electrochemical and catalytic interfaces, polymercoatings and photosensitive films. Contrast variationand selective deuteration of hydrogenous materialsare important aspects of the neutron-based tech-nique. Neutron reflectometry probes the structure ofmaterials normal to the surface at depths of up toseveral thousand Å, with an effective depth resolutionof a few Å.

Neutron reflectometry experiments have beenperformed by a number of Australian researchers atoverseas facilities for more than a decade, howeverthis capability has previously been absent in thiscountry. We report instrument details as well ascommissioning experiment results from Australia’sfirst neutron reflectometer at the 10 MW HIFARfacility at Lucas Heights. This instrument has nowbecome part of the AINSE User Program and isaccepting beam time proposals from Australian andInternational researchers.

A neutron reflectometer has been recognised as oneof the highest priority instruments to be constructedat the new 20 MW research reactor facility at LucasHeights (due for completion in 2006). In this presen-tation we also report the design of the horizontalsample, time-of-flight reflectometer to be constructedat the new research facility.

WP33: NPDF: A new high-resolution total scatter-ing powder diffractometer

Th. Proffen (Los Alamos Neutron Science Center,Los Alamos National Laboratory)

Knowing the atomic structure of materials usuallymeans determining the crystal structure. However,many modern materials are complex, and their realstructure often is deviated locally from the averagecrystal structure in significant ways. It is thus neces-sary to know the structure on various length scales,since properties are more directly governed by localatomic arrangements. But the conventional crystallo-graphic approach cannot provide a complete picture;it has to be complemented by local probes such asthe Pair Distribution Function (PDF) method.

The Neutron Powder Diffractometer NPD has recentlybeen upgraded to become NPDF by adding a largenumber of detectors to the backscattering region ofthe instrument. The upgrade was funded by theNational Science Foundation, Los Alamos NationalLaboratory, University of Pennsylvania and otheracademic institutions. On September 27th, 2002 the

shutter of NPDF opened for the first time. A standarddata set suitable for PDF analysis can be obtained inonly two hours. This puts NPDF at the cutting edge oflocal structure determination but also serve asdevelopment platform for this new structure analysistool for disordered and nano-structured materials.The instrument is available to general users since the2003 run cycle.

WP34: A Time-of-Flight Ultra-Small-Angle NeutronScattering Instrument Performance Gain Over ItsReactor-Based Analog

M. Agamalian (Oak Ridge National Laboratory), J.M. Carpenter (Oak Ridge National Laboratory;Argonne National Laboratory), K. C. Littrell(Argonne National Laboratory), A. Stoica, C. Rehm(Oak Ridge National Laboratory), P. Thiyagarajan(Argonne National Laboratory)

We present the current version of the conceptualdesign of a Bonse-Hart Time-of-Flight Ultra-Small-Angle Neutron Scattering (TOF-USANS) Double-Crystal Diffractometer for use at the SNS 25 mm H2Oor 60 mm H2 moderator. This instrument consists ofa 15 m-long supermirror neutron guide, 2D focusedSi(2,2,0) bent pre-monochromator and Si(220) triple-bounce channel-cut crystals in a parallel double-crystal arrangement. The TOF technique allows theseparation of seven wavelengths simultaneouslysatisfying the Bragg condition in the range,0.5 Å < λ < 3.7 Á, providing the opportunity tocollect seven sets of USANS data at once. The small-est measurable scattering vector, Qmin, decreaseswith the increase of the order of Bragg reflection andreaches the value Qmin ≈ 2×10-6 Å-1 for theSi(14,14,0) reflection, about one order of magnitudesmaller than for conventional reactor-based USANSinstruments. The overall flux at the sample position isestimated to be as high as ~ 13000 n/(cm2 sec) forthe 25 mm H2O moderator and ~ 120000 n/(cm2

sec) for the 60 mm H2 moderator, the latter valuebeing seven times higher than that achieved at theNIST reactor Bonse-Hart USANS, the world’s bestinstrument of this type. Besides, the multi-wavelengthperformance of the TOF-USANS instrument allowsvariation of the Bonse-Hart collimation, which cannotbe done at reactor-based USANS. This advantagegives the scattered intensity gain factor, which isproportional to the square width of the total Darwinplateau. The Bonse-Hart variable collimation gainfactor depends of the order Bragg reflection; thisfactor calculated for the first Bragg peak is as high as~19 over the reactor-based analogue. Parallelmeasurements at different wavelengths may provevery helpful for diagnosing multiple and inelasticscattering in USANS experiments, as well as the


refraction effects. Moreover, time-of-flight operationis likely to reduce the background.

WP35: Neutron Polarization Evolution Calculationsalong the SNS Magnetism Reflectometer BeamLine

A. A. Parizzi, F. Klose (Spallation Neutron Source,Oak Ridge National Laboratory), V. Christoph(University of Applied Sciences, Dresden (Germany))

In polarized neutron scattering instruments, mostpolarization devices apply magnetic fields of differentspace and time profiles for achieving the desiredconditioning of the beam. Magnetic fields created atan individual device often impose fringe/stray fieldsonto other devices in the beam line, which may affectboth their functionalities and the overall neutronpolarization evolution.

For the SNS Magnetism Reflectometer, it is desirablethat different sample environment magnets anddifferent beam conditioning devices can be used invariable conditions. Spin polarizers and analyzers,broad-band spin flippers and other polarized neutrondevices must be capable of working reliably in thevicinity of small magnetic fields generated forexample by an iron-yoke electromagnet as well as inmuch larger magnetic fields created, for example, bya high-field superconducting magnet. The latter maynot only impose relatively large stray fields along thebeam path, but also produce relatively large fieldgradients.

In this paper, we present calculations treating themagnetic field interference between devices, theeffect of sample environment magnets and theresultant polarization evolution of neutrons along thebeam line. Calculations are presented for severalpolarized-beam set ups that will be adopted fordifferent desired experimental conditions at the SNSMagnetism Reflectometer.

WP36: The Advanced Neutron Diffractometer /Reflectometer: a New CNBT Instrument at the NISTCenter for Neutron Research

J. A. Dura, D. Pierce, C. F. Majkrzak (NIST Center forNeutron Research), K. V. O’Donovan, U. Perez-Salas(University of California—Irvine and NIST Centerfor Neutron Research)

The Advanced Neutron Diffractometer / Reflectome-ter, AND/R, completed in July 2003, is the center-piece of the Cold Neutrons for Biology and Technol-ogy, CNBT, program, funded by the NIH, NationalCenter for Research Resources (NCRR). This instru-ment is dedicated to diffraction, reflectometry, anddiffuse scattering measurement for research on

biological membranes and related materials.

It was modeled after and is located just upstream ofthe NG1 polarized beam reflectometer. Like the NG1reflectometer, the AND/R has a horizontal scatteringplane, which provides unrestricted access to higherscattering angles. Other features common to bothinstruments are the polarized beam capability toenable the use of magnetic reference layers for phaseinversion of data, and a vertically focussing mono-chromator to increase the flux on the sample.

Additional features make the instrument well suitedfor both reflectometry and diffraction investigationsof biological systems. First, the AND/R can operateusing either a larger 2" pencil detector (increasing theflux at higher momentum transfer, Q) or a 2-dimen-sional position sensitive detector (PSD). By simulta-neously measuring non-specular scattering fromlarge areas in reciprocal space, the PSD will make itmuch more efficient to obtain information on in-plane structures. Also, the sample tables will accom-modate larger sample environments (up to 10.2"from tabletop to beam center and up to 1000 Lbs) oran Eulerian cradle (for diffraction experiments fromsingle crystals). Optical benches, both inside andoutside the shutter, and within the detector shielding,will make customization and upgrades of the neutronoptical components simpler to implement. Anincreased number of motorized axes as well asadditional supporting software provided by a dedi-cated programmer in the CNBT program will makethis a more user friendly instrument.

In addition to serving the needs of the CNBT partnersand collaborators, 25% of the time on this instru-ment is available to the general user community.

This material is based on work supported by theNational Institutes of Health under grant no. 1 R01RR14812 and The Regents of the University ofCalifornia.

WP37: Developing ARCS: a status report on thewide Angular-Range Chopper Spectrometer at theSNS

D. L. Abernathy (Spallation Neutron Source, OakRidge National Laboratory), B. T. Fultz (CaliforniaInstitute of Technology)

The U.S. Department of Energy has funded ARCS, awide Angular-Range Chopper Spectrometer, to beconstructed on beam line 18 at the SpallationNeutron Source. ARCS will be optimized to provide ahigh neutron flux at the sample and a large solidangle of detector coverage. The source-sampledistance will be 13.6 m, and the secondary flight


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path will be 3.0 m at all angles from -20° to 140°horizontally and ±30° vertically. The incidentneutrons energy will vary between 10 and 1000 meVwith a resolution of 2% or above at the elastic line.Combining the high flux from the SNS with a detectorcoverage of almost one-fourth of the possible solidangle will allow data collection rates roughly 10 to100 times that currently possible at existing instru-ments.

The project is currently at its midpoint, and a numberof technical and user oriented issues are beingaddressed in the course of turning the concept of theinstrument into reality. For example, the detectorswill be placed inside the same vacuum space as thesample and so have been extensively tested to provethe electronic design for operation in vacuum. Twodifferent neutron chopper designs for blocking theprompt pulse of radiation from the target andmoderator have been evaluated. Another issue thatwill have a great impact on the user experience at theinstrument is the overall access and features aroundthe sample region. Because of the unprecedentedpower of the SNS source, careful consideration of theshielding around the instrument is needed to mini-mize background while allowing for complex sampleenvironment equipment.

WP38: Progress on the New High Intensity ColdNeutron Spectrometer, MACS.

C. L. Broholm, T. D. Pike, P. K. Hundertmark (JohnsHopkins University; NIST Center for NeutronResearch), P. C. Brand, J. W. Lynn, D. L. Pierce, J.Moyer, J. G. LaRock (NIST Center for NeutronResearch), S. A. Smee, G. Scharfstein (JohnsHopkins University)

A new high intensity neutron spectrometer is underdevelopment at the NIST Center for Neutron Re-search. The instrument will cover the energy transferrange from -10 to 17 meV with typical energyresolution 0.2 meV. The distinguishing feature of theMulti Axis Crystal Spectrometer is ultra high sensitiv-ity to slowly propagating excitations in condensedmatter. This is achieved by (1) Relaxing wave vectorresolution transverse to the incident beam whilemaintaining high energy resolution (2) Increasing thesolid angle of the detection system through multiplecrystal analyzer channels. The instrument will beparticularly well suited for mapping the wave vectordependence of neutron scattering at fixed energytransfer. For experiments that can use the fulldivergence of the incident beam and that benefitfrom all twenty detection channels the gain insensitivity compared to a conventional cold neutrontriple axis spectrometer will be at least two orders of

magnitude. MACS will therefore enable energyresolved neutron scattering experiments on a broadclass of compounds early in the materials develop-ment cycle.

This poster reports on progress in the design of someof the intricate components of MACS that are crucialfor enabling its performance. In particular we de-scribe the mechanical design of the double crystalanalyzer system that is key to increasing the solidangle of the detection system while maintaining theflexibility and high signal to noise ratio of a conven-tional triple axis spectrometer. A single steppingmotor translates and rotates the two verticallyfocusing crystal assemblies of a detection channeland orients the blades of a coarse backgroundsuppressing collimator situated between them. Wealso describe the incident beam line that allows largesolid angle access to the NIST cold source. It is basedon a doubly focusing monochromator that translatesalong the white beam as the incident energy isvaried. This approach enables a compact instrumentand highly effective incident beam line shielding toimprove the signal to noise ratio.

(a) R. Hammond and J. D. Orndorff from JohnsHopkins University are also authors on this poster.(b) The MACS project is funded by NIST, NSF DMR-0116585, and JHU.

WP39: Design of a Single Crystal MacromolecularNeutron Diffractometer at SNS

P. Thiyagarajan, Arthur Schultz (Intense PulsedNeutron Source, Argonne National Lab), ChristineRehm, Jason Hodges, W.T. Lee (Spallation NeutronSource, Oak Ridge National Laboratory), AndrewMesecar (Department of Medicinal Chemistry andPharmacognosy, University of Illinois, Chicago)

Neutron Macromolecular Crystallography (NMC) isable to accurately determine proton locations,protonation states and hydration, and hydrogen/deuterium exchange in macromolecular crystals evenat a moderate resolution (2 Å to 2.5 Å). In order toexploit the high neutron flux that will becomeavailable by 2006 at the Spallation Neutron Source(SNS), and to leverage the enormous interest shownby the macromolecular crystallography community, itis proposed to develop a dedicated best-in-class highthroughput and high resolution time-of-flight singlecrystal macromolecular neutron diffractometer(MaNDi) at the SNS. MaNDi has been designed to beable to collect a full hemisphere of Bragg data with aresolution of 1.5 to 2 Å on a crystal with a latticeconstant up to 150 Å in a few days. A thoroughevaluation of the instrument performance at different


moderators using analytical equations and Monte-Carlo simulations show that the decoupled hydrogenmoderator at SNS would be the best choice forMaNDi. State-of-the-art neutron guides and optics willbe used for efficient beam transport and optimizationof collimation at the sample. To reduce the radiationdamage and the instrument background a curvedguide will be used to steer the beam gently so thatthe crystal will be out of line of sight of the modera-tor. The high throughput is accomplished by the useof a wide band width of cold neutrons (1.8 Å).

This work at IPNS was funded by the U.S. DOE, BES-Materials Science, under Contract W-31-109-ENG-38to U. Chicago, and SNS funded by U.S. DOE, BES-MatSci. under contract DE-AC05-00OR22725UT-Battelle,LLC and ORAU.

WP40: The effects of gravity on the operation ofmultiple confocal pinhole SANS instruments

K.C. Littrell (Intense Pulsed Neutron Source,Argonne National Lab)

One of the most promising methods for increasingthe flux on sample in broad-bandwidth Time-of-flightsmall angle scattering instruments while maintainingthe ability to measure small minimum momentumtransfers Qmin is through the use of multiple, confo-cal “pinhole” apertures. Since the apertures them-selves are wavelength independent, such an instru-ment would be expected to be wavelength indepen-dent as well. However, the effects of gravity producea vertical dispersion of the neutron beam which canbecome significant compared to Qmin as the overalllength of the instrument increases or the size of theindividual apertures or the detector pixel decreases.In this work, we extend the description of how to usematerial prisms to correct for this gravitationalchromatic aberration for single pinhole instrumentsto encompass multiple-confocal pinhole geometries.A further concern is that when multiple apertures areseparated by solid walls, these walls are invariablystraight for ease of manufacturing, while the trajec-tory of the neutron is parabolic and wavelength-dependent, leading to a wavelength-dependentattenuation of the beam. We quantify this effect as afunction of the vertical geometry of the pinholes.

WP41: A Neutron Analyzer with Horizontal Focus-ing for Triple Axis Spectrometers

I. Zoto, E. Abdel-Raouf, S. Al-Ghamdi, Vemuru V.Krishnamurthy, G. J. Mankey (MINT Center, TheUniversity of Alabama, Tuscaloosa, Alabama35487-0209), J. L. Robertson (Condensed MatterSciences Division, Oak Ridge National Laboratory)

Triple axis spectrometers have been extensively used

to study a variety of excitations in condensed matter.We report the design of the Bragg Angle Multi-crystalAnalyzer (BAMA) for using with a triple axis spec-trometer at the High Flux Isotope Reactor. BAMA willenable the measurements of spin dynamics inmagnetic thin films and magnetic devices. A typicaltriple axis spectrometer contains one crystal as ananalyzer, and there is no focusing of the scatteredneutron beam. Recently horizontal focusing has beenused in multi-crystal analyzers. There are two multi-crystal analyzers worldwide. One was developed bythe Riso National Laboratory and is currently locatedat the Swiss Spallation Neutron Source. It is know bythe acronym RITA for reinvented triple axis spectrom-eter. The other is used at the NIST Research Reactorin the spin-polarized triple axis spectrometer. Ourdesign incorporates nine analyzer blades driven byindividual motors. The motor interface for positioningthe individual analyzer crystals is through anEthernet controller. The design incorporates closed-loop picomotors manufactured by New Focus. Themotors are designed as a micrometer drive for linearactuation and the analyzer blades are mounteddirectly to the micrometer screw to achieve angularcontrol with a small linear translation. Thepicomotors are compact enough to be incorporatedin a modular instrument design with nine 20 mmwide graphite blades. The computer code for drivingthe analyzer will be tested first with an optical analogusing diffraction gratings and visible light from a lightemitting diode. This project is funded by NSF DMR02-81637 and DOE/EPSCoR DE-FG02-02ER45966.

WP42: Rheo-SANS at the NCNRL. Porcar, B.S. Greenwald (NIST Center for NeutronResearch; University of Maryland, College Park),C.J. Glinka (NIST Center for Neutron Research), N.Wagner (University of Delaware, Newark, DE19716), S.-M. Choi (Korea Advanced Institute ofScience and Technology, Daejeon, Korea), J.C. Schulz(Australian Nuclear Science and TechnologyOrganisation, NSW, Australia)

Shear flow presents a great technological interestbecause shear-induced complex fluid phases haveprofound effects on industrial material processing. Inorder to correlate the unique flow properties exhib-ited by these complex fluids with their structuraldeformation, we have developed a device to performsimultaneous measurement of rheology and structureby Small Angle Neutron Scattering (SANS). Quartzand titanium Couette type flow cells have beendesigned to fit into a commercial rheometer Thesetup allows scattering measurements from a rangeof configurations using both the so-called radialconfiguration, where the incident neutron beam is


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parallel to the velocity gradient, to the tangential,where the incident neutron beam is parallel to theflow direction. Couette cells with gaps of 0.5 or 1 mmare available and can operate at temperaturesranging from –20 °C to 150 °C with a solvent trappreventing sample evaporation. The apparatus allowsmany different rheological tests to be performed e.g.,simple shear flow either at constant shear stress orconstant shear rate, creep and creep recovery as wellas amplitude oscillatory shear deformation, whilesimultaneously recording scattering data. To illustratethe performance of the equipment, we give a briefreport of recent experiments carried out on colloidalsuspensions and surfactant mesophases.

WP43: Applications in Physics of the newDiffractometer HIPPO at LANSCE

D.J. Williams, S.C. Vogel (Los Alamos NationalLaboratory), M.A. Rodriguez, M.A. Mangan (SandiaNational Laboratories, Albuquerque, NM 87123),M.E. Manley, E.J. Peterson (Los Alamos NationalLaboratory), J.L. Jones (The University of New SouthWales, Sydney, Australia 2052), R.J. McQueeney(Los Alamos National Laboratory; Iowa StateUniversity), W. Palosz (Marshall Space Flight Center,AL 35812), B. Palosz (High Pressure ResearchCenter, Polish Academy of Sciences, Warsaw, 01-142, Poland)

The High-Pressure Preferred Orientation (HIPPO)neutron diffractometer is the first third-generationneutron time-of-flight powder diffractometer that wasconstructed in the United States. It utilizes extremelyhigh neutron count-rates by virtue of a short (9 m)initial flight path viewing a high intensity watermoderator and 1360 3He detector tubes covering4.5 m2 of detector area from 10 ° to 150 ° in scatter-ing angles. HIPPO was designed and manufacturedas a joint effort between LANSCE and the Universityof California with the goals of attaining world-classscience and making neutron powder diffractometryan accessible and available tool to the national usercommunity. On this poster, we give an overview ofapplications of HIPPO to physics-related investiga-tions. Structural changes during charging anduncharging of a commercial Li-ion cell were studiedas well as the crystal structure of highly texturedmagnetic and non-magnetic thin films consisting ofErbium (high Z) and hydrogen (low Z, deuterated forthis study). Texture changes of piezo-electric materi-als with temperature and processing method wereexamined as well as the crystal structure of supercon-ductors and pair-distribution function (PDF) on nano-particle materials.

WP44: Interaction of paraffin wax gels withrandom crystalline/amorphous hydrocarboncopolymers

R. K. Prud’homme (Department of ChemicalEngineering, Princeton University, Princeton, NJ08544), H. S. Ashbaugh (Los Alamos NationalLaboratory, Los Alamos, NM 87545), A. Radulescu,D. Schwahn, D. Richter, L. J. Fetters (Institut furFestkoperforschung, Julich, Germany)

The control mechanisms involved in the modificationof wax crystal dimensions in crude oils and refinedfuels are of joint scientific and practical interest. Anunderstanding of these mechanisms allows strategiesto be devleoped that lead to decreases in crude oilpour points or (for refined fuels) cold filter pluggingpoints. The attainment of these goals involves thecontrol and modification of wax crystals that sponta-neously form in mixed hydrocarbon systems upondecreasing temperature. This work reports on theinfluence of random crystalline-amorphous blockcopolymers (ethylene-butene) upon the rheology ofmodel oils. In a parallel fashion small-angle neutronscattering was exploited to gain microscopic insightas to how added poly(ethylene-butene) copolmersmodify the wax crystal structures. The copolymerswith diferent contents of polyethyelene are highlyselective with respect to wax crystal modification.Thus, the copolymer with the highest crystallinetendency is more efficient for the larger wax mol-ecules while the less crystalline one is more efficientfor the lower waxes.

WP46: SANS method to study of mixture systemsof surfactants SDS+TX-100 and CTAB+TX-100

A. Rajewska (Insititute of Atomic Energy, 05-400Swierk-Otwock, Poland; Joint Institute for NuclearResearch, LNP, 141980 Dubna, Moscow region,Russia), R. F. Bakeeva (Kazan State TechnologicalUniversity, Kazan, Russia)

The mixing of amphiphiles in water may lead to theformation of mixed micelles which often present newproperties with respect to the pure componentsolutions [1, 2]. Two mixture systems of classicsurfactants: SDS ( sodium dodecyl sulphate )+TX-100(Triton-X-100) (anionic + non-ionic) andCTAB+TX-100 (cationic + non-ionic) in watersolution were investigated for temperatures 30 o,50 o, 70 o for compositions 1:1, 2:1, 3:1 with thetime-of-flight small-angle neutron scattering (TOFSANS) spectrometer (YuMO) of the IBR-2 on pulsedneutron source [3] at FLNP, JINR in Dubna (Russia).Measurements have covered Q range from 8x10-3 to0.4 Å-1. The SANS measurements of aqueous solu-tions of nonionic / ionic surfactants have shown thatthe mixed micelles are formed. From the measured


dependence of the scattered intensity on the scatter-ing angle, we derived the aggregation number andthe electric charge of the mixed micelle at variouscompositions and ionic strengths.

[1] Clint J., J. Chem.Soc., Faraday Trans., 1,1327(1975); Moroi Y., Akisada H., et al., J. Colloid. Inter-face Sci., 61, 233 (1977);Corti M., Degiorgio V., et al.,J. Phys. Chem., 86, 2533 (1982); Cantu L., Corti M.,Degiorgio V., J. Phys.. Chem., 94, 793 (1990)[2] Rathman J., Scamehorn J. F., J. Phys. Chem., 88,580 (1984); Treiner C.,Amar Khoida A., et al., J.Colloid Interface Sci., 128, 416 (1989)[3] Ostanievich Yu. M., Makromol. Chem. Macromol.Symp., 15, 91 (1988)

WP47: Influence of chain stiffness on the proper-ties of polyelectrolyte solutions

S. I. Yun, Y. B. Melnichenko, G. D. Wignall, K. Hong,J. Mays (Oak Ridge National Laboratory)

Model systems for obtaining structural informationon atomic-level interactions in polyelectrolyte solu-tions should incorporate primary features of theinteractions of interest. For example, the effect ofchain stiffness on polyelectrolyte conformation andcounterion interactions can best be understoodthrough the preparation of polyelectrolytes in whichthe same charge groups are attached to backbonestructures of varying stiffness. For a ionizable group(sulfonate), the effect of chain stiffness can beelucidated through studies of poly(styrene sulfonate)(PSS) as a flexible example; poly(cyclohexadienesulfonate) (PCHDS) as a “semiflexible” backbonestructure. Small-angle neutron scattering (SANS) ofPCHDS-h solutions have shown that the polyelectro-lyte peak was observed to be much less pronouncedand less dependent of polymer concentrationcompared to PSS. Finding peak position requiredworking out an empirical procedure in order tosubtract the contribution of excess scattering at smallQs. Preliminary data analysis shows that the peakposition for solutions of PCHDS in D2O scales withthe polymer concentration (zero salt) with exponent~ 0.1 to be compared with the scaling predictions of0.5 for flexible chains.

WP48: Correction of tangential Couette SANS dataL. Porcar (NIST Center for Neutron Research;University of Maryland, College Park), W. A.Hamilton, P. D. Butler (Condensed Matter SciencesDivision, Oak Ridge National Laboratory)

In SANS Couette shear cell measurements conversionto an absolute scale for the radial scattering configu-ration can be done in the standard manner using thedirect beam as a primary standard and then correct-

ing for sample and cell transmissions and the samplethickness (simply twice the Couette gap). Absolutecalibration in the tangential geometry is moreproblematic – the geometrical limitations of asym-metries of sample path and absorption lead to clearasymmetries in the observed scattering patterns.

We recently found a simple and effective way tocorrect tangential scattering: from the tangentialtransmission we obtain an effective thickness consis-tent with the radial transmission and its knownthickness [1]. However, even after these corrections,in some cases (usually for high scattering angles), aresidual geometry dependent asymmetry is observedin our corrected tangential configuration scatteringpatterns because of neutrons scattered toward thecell axis traverse a significantly longer path throughthe sample fluid than those scattered away. As wouldbe expected this effect is more pronounced for highsample absorption, scattering angle and sampleannulus width.

To correct for this effect we propose to use a “sensi-tivity file” obtained from a mixture of heavy and lightwater matching the sample absorption in the samegeometry tangential scattering configuration and thussubjecting evenly scattered incoherent neutrons to asimilar absorption (re-scattering) geometry to thatexperienced in the sample. Furthermore, it is alsopossible to create a “calculated sensitivity” based onsample’s absorption and geometrical considerationswhich allow correction of the scattering asymmetryobserved in the tangential configuration to a verygood approximation. We will discuss the limits ofvalidity of such approaches.

[1] L. Porcar, W. A. Hamilton, P.D. Butler, and G.G.Warr, A new vapor barrier couette shear cell, forsmall angle neutron scattering measurements,Review of Scientific Instruments 73, 2345 (2002)

WP49: Low Energy Excitation of Poly(methylmethacrylate)

M.-H. Kim, C.M. Brown (NIST Center for NeutronResearch; Department of Materials Science andEngineering, University of Maryland)

The relative contributions of poly(methyl methacry-late) side groups (ester, alpha-methyl, and main chainCH2) to the low energy Boson excitation were studiedby isotopic substitution using the Fermi-ChopperTime-Of-Flight Neutron Spectrometer. The enhance-ment of the dynamic structure factor, S(Q, w) ob-served around 1.8 meV is dominated by the methylvibration on the ester group (-COOCH3). The relativecontributions follow the order -COOCH3 >>-alpha-CH3> -CH2-.


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WP50: Effect of High Ionic Strength on InterfacialProperties, Lamellarity and Polydispersity ofUnilamellar Vesicles Prepared By Extrusion

J. Pencer (Department of Chemical andBiomolecular Engineering, The Johns HopkinsUniversity; NIST Center for Neutron Research), S.Krueger (NIST Center for Neutron Research), M. E.Paulaitis (Department of Chemical andBiomolecular Engineering, The Johns HopkinsUniversity)

Small-angle neutron scattering is used to determinethe vesicle and bilayer form factors of DOPC vesiclesprepared by extrusion in distilled water and 3 MNaCl. We find that vesicles prepared in the presenceof 3 M NaCl exhibit a higher degree ofmultilamellarity and are significantly more polydis-perse than those prepared in the absence of NaCl.Contrast variation studies are also performed, toobserve possible NaCl induced changes to bilayerdensity. Finally, osmotic downshifts are performed todiscern between inter and intravesicular correlations.Our observations are consistant with salt-inducedattraction between DOPC bilayers. Since this resultcannot be explained on the basis of charge screen-ing, we discuss two other possible sources of attrac-tive interactions, osmotic dehydration and chargefluctuations.

WP51: Structural Studies of Single Bilayer LipidMembranes on a Patterned Surface

G.S. Smith (HFIR Center for Neutron Scattering,Oak Ridge National Laboratory, Oak Ridge,Tennessee 37831, USA.), S.M. Baker (Harvey MuddCollege, Dept. of Chemistry, Claremont, CA 91711), J.Tan (Harvey Mudd College, Dept. of Chemistry,Claremont, CA 91711; Columbia University, AppliedPhysics and Applied Mathematics Dept., New York,NY 10027-8351), T. McQueen (Harvey Mudd College,Dept. of Chemistry, Claremont, CA 91711), J.Majewski (Los Alamos Neutron Science Center, LosAlamos National Laboratory)

One of the mechanisms by which proteins transportmaterials across living cell membranes is by formingpores in the lipid bilayer surrounding the cell. Thepores consist of aggregates of protein moleculeswhich form tubular structures which span the mem-brane. The transport through one of these pores mayeither be active, requiring an energy productionreaction like the hydrolysis of ATP, or passive, wherethe molecule diffuses in the thermodynamicallyfavorable direction. One clear requirement for theinsertion and activation of the pores is a free mem-brane where the proteins can protrude from eachsurface. In this paper, we examine the utility of usingtemplated surfaces as a means for creating regions of

unsupported lipid bilayer films. The templates withpores sizes on the order of tens of nanometers wereprepared by phase segregation of diblock copolymerson a silicon oxide surface. The polymer templateswere either coated with gold or reactively etched tothe silicon surface to form hydrophilic (gold or siliconoxide, respectively) surfaces. Finally, we depositedbilayers of dimyrystoyl phophatidylcholine on thetemplates either by a combination of Langmuir-Blodgett deposition and vesicle fusion or by vesiclefusion alone. We present neutron reflectometry andAtomic Force Microscopy measurements of thesevarious samples and show that we have achieved thedesired architecture over large areas of the substrate.

WP52: Effects of Temperature and Salts on theMicelle Structure of Triblock Copolymer P84 inAqueous Solutions

L. Guo, P. Thiyagarajan (Intense Pulsed NeutronSource, Argonne National Lab)

We investigated the phase behavior of aqueoussolutions of a triblock copolymer Pluronic P84(EO19PO43EO19) at different copolymer and sodiumcarbonate concentrations and temperatures by usingsmall angle neutron scattering (SANS). We obtainedinformation on the shape and size of Pluronic P84micelles, aggregation number and the volumefraction of the micelles. The results show that tem-perature and carbonate ion concentration havestrong influence on the phase behavior of the triblockcopolymer. The micelle aggregation number and sizeincrease with polymer and carbonate ion concentra-tions as well as temperature. The CMT decreases withincreasing temperature and carbonate ion concentra-tion. At high temperatures and carbonate ion concen-trations, spherical to cylindrical micelle transforma-tion occurs. Phase separation is observed at suffi-ciently high temperatures and carbonate ion concen-trations.

This work benefited from the use of the IntensePulsed Neutron Source at Argonne National Labora-tory funded by the Office of BES, US DOE under thecontract # W-31-109-ENG-38. We thank DenisWozniak at IPNS for his assistance with the SANSexperiments.

WP53: Annealing induced structural changes andmicrocracking in Mo-Mo3Si

X.-L. Wang (Spallation Neutron Source, Oak RidgeNational Laboratory; Metals and Ceramics Division,Oak Ridge National Laboratory), J. H. Schneibel(Metals and Ceramics Division, Oak Ridge NationalLaboratory), Y. D. Wang, A. D. Stoica (SpallationNeutron Source, Oak Ridge National Laboratory), J.


W. Richardson (Intense Pulsed Neutron Source,Argonne National Lab)

An outstanding issue in the processing of Mo-Mo3Siintermetallic composites is that microcracks developafter annealing at high temperatures [1], whichsignificantly degrade the mechanical properties ofthe composite materials. The formation ofmicrocracks is difficult to understand from the viewpoint of differential thermal stresses that developduring cooling, which were estimated to be ~ 100MPa for both phases. It is unlikely such a level ofresidual stress would cause microcracking at anystage during cooling. In order to determine thenature of microcracking in Mo-Mo3Si, we haveconducted a systematic study of Mo-Mo3Si compos-ites using a combination of in situ neutron diffrac-tion, composition analysis, and scanning electronmicroscopy.

In situ neutron diffraction measurements at 1300 ºCrevealed a significant increase of the lattice param-eter in the α-Mo phase as a function of annealingtime, whereas the lattice parameter of the Mo3Siphase shows a corresponding decrease. At the sametime, the diffraction peak widths of both phasesincreased, unexpectedly, with increasing annealingtime, giving evidence that plastic deformationoccurred at high temperature. X-ray and neutrondiffraction measurements made before and afterannealing confirmed that the changes in latticeparameters are irreversible, i.e., due to plasticdeformation. Because the as-cast materials wereobtained off-equilibrium by fast cooling, the α-Mophase is known to be super-saturated with Si. The insitu neutron diffraction data therefore suggest thathigh-temperature plastic deformation during anneal-ing was due to diffusion of Si atoms from α-Mo toMo3Si. This finding was corroborated by microscopystudies which demonstrated that the microcracksalmost always started at the interface of α-Mo andMo3Si grains and grew into Mo3Si. Furthermore, crackdensity measurements via microscopy indicated thatas the annealing time increased more cracks wereformed. Based on these experimental observations, itis clear that mcirocracking in Mo3Si occurred at hightemperature. Quite possibly, the diffusion of Si duringhigh-temperature annealing created a highly inhomo-geneous microstructure at the interface where crackswere initiated when the elastic energy exceeded thetensile limit of the Mo3Si phase.

This research was supported by the Division ofMaterials Science and Engineering, U.S. Departmentof Energy. Oak Ridge National Laboratory is managedby UT-Battelle, LLC, under contract DE-AC05-

00OR22725 with the US Department of Energy.

[1] J. H. Schneibel, C. T. Liu, D. S. Easton, and C. A.Carmichael, “Microstructure and mechanical proper-ties of Mo-Mo3Si-Mo5SiB2 silicides,” Mater. Sci. Eng.A261, 78-83 (1999).

WP54: Residual Stresses by Neutron Diffractionand Microstructural Characterisation by SANS ofMaterials and Components of TechnologicalInterest

Massimo Rogante (Nuclear Engineering Laboratory,DIENCA, University of Bologna, Via dei Colli 16,40136 Bologna; Rogante Engineering Office,Contrada San Michele, 61 / P. O. Box 189, 62012Civitanova Marche, Italy)

The adoption of neutron techniques, among the othernon-destructive diagnostics, is becoming more andmore relevant in studying materials and componentsof industrial interest. In this paper, neutron diffrac-tion for Residual Stresses (RS) measurements andSmall Angle Neutron Scattering (SANS) for micro-structural characterisation—especially related to theprecipitate distribution—are considered. The basictheoretical aspects and some industrial applicationsof each technique are reported. In particular, RSdetermination in weldings, in extruded specimensand in a component for nuclear/traditional energyindustry is presented. SANS measurements are finallyreported, concerning materials and components forenergy and automotive industry.

WP55: Neutron Residual Stress Measurements onRail Sections for Different Production Conditions

V. Luzin (National Institute of Standards andTechnology; State University of New York, StonyBrook, NY 11794-2275), J. Gordon (Volpe NationalTransportation Systems Center, Cambridge, MA02142), T. Gnaupel-Herold (National Institute ofStandards and Technology; University of Maryland,College Park), H.J. Prask (National Institute ofStandards and Technology)

Rail sectioning with subsequent neutron or synchro-tron x-ray diffraction experiments is the mosteffective technique for assessment of the residualstresses in the rails. In this study we present theresults of stress measurements performed on the BT8diffractometer at the NIST Center for NeutronResearch (NCNR) on rails that were produced undervarious conditions. Specifically, these are air-cooled,air-cooled and roller-straightened, head-hardenedand head-hardened and roller-straightened. Inaddition, a head-hardened and roller-straightened railwas also studied after service to elucidate evolutionof the service-induced residual stresses. Neutron


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strain measurements with 3x3x3 mm3 spatialresolution were successfully employed fortransversally-cut sections to verify the difference inthe stress state depending on the production process.Although examination of slices allows determinationof only two-dimensional stresses in the plane of theslice, additional measurements on obliquely-cutslices, which were also carried out, and utilization ofFEM gives the possibility of reconstructing the fulltriaxial stress distribution. Together, these approachesprovide a better understanding of rail fabrication andthe possibility of improving the durability and safetyof rails in the future.

WP56: An analysis of copper precipitation in thethermally aged FeCu alloy using micro magnetictechnique and SANS

D.G. Park (Korea Atomic Energy Research Institute,Yuseong P.O. Box 105, Daejeon, 305-600, Korea),M.N. Lee (Pohang University of Science andTechnology, Materials Science and Engineering,Hyoja-Dong, Nam-Gu, Pohang, Kyungsangbuk-Do,790-784, Korea), J.H. Kim, S.C. Kwon (Korea AtomicEnergy Research Institute, Yuseong P.O. Box 105,Daejeon, 305-600, Korea), Y.M. Koo (PohangUniversity of Science and Technology, MaterialsScience and Engineering, Hyoja-Dong, Nam-Gu,Pohang, Kyungsangbuk-Do, 790-784, Korea), J.H.Hong (Korea Atomic Energy Research Institute,Yuseong P.O. Box 105, Daejeon, 305-600, Korea)

In order to study the effect of the copper precipitatein the steel embrittlement under neutron irradiation,the characteristic of nano size defects were investi-gated in the thermal aged FeCu model alloys. Thecopper precipitation leads to a distortion of thecrystal lattice surrounding the copper precipitates andyields internal micro-stress [1]. To verify the role ofcopper precipitation, microhardness test, stressrelated magnetic Barkhausen noise measurementsand small angle neutron scattering (SANS) undermagnetic field experiments were carried out. Theresults on precipitation composition, number density,size distribution and matrix composition obtainedusing high resolution TEM and SANS are comparedand contrasted. The diameter of copper precipitatesgiven by SANS varied from 3~10 nm, and increasedcontinuously with aging time. For the thermally agedalloy, the most notable results include the clearobservation of copper-rich precipitates, evidence forthe retention of a significant copper fraction in solidsolution at the peak of hardening, for a bimodaldistribution of particle sizes in the averaged condi-tion.[1] I. Altpeter et al., Nucl. Eng. Design, 206 (2001)337-350

WP57: In situ deformation studies using HIPPO/CRATES

S.C. Vogel, T. Medina, E. Meyer, D.J. Williams (LosAlamos National Laboratory), T. Brissier (LosAlamos National Laboratory; HTW Saarbruecken,66117 Saarbruecken, Germany), C. Hartig, J.Laakmann, O. Meyer, H. Mecking (TU Hamburg-Harburg, 21071 Hamburg, Germany)

In situ neutron diffraction deformation studies ofmetals, alloys and composites using strain derivedfrom peak-shifts are well established for more thantwo decades. However, the peak-shift measures bydefinition only the elastic strain. To obtain furtherinsight into the deformation mechanisms which areactive to achieve a given amount of plastic deforma-tion, the texture is also an important quantity. Thetexture, or orientation distribution function (ODF), isaccessible via peak intensity changes in a diffractionexperiment. The texture changes are differently forinstance for slip, twinning or grain boundary sliding,allowing differentiation between these mechanismsby a neutron diffraction experiment. Understandingof the deformation mechanisms is of fundamentalinterest for modeling of materials behavior. Wedescribe the system HIPPO/CRATES which allows tostudy in situ both the anisotropic elastic strainevolution via the change in peak shift as well as thechange in texture via the changes in peak intensity.CRATES, a load-frame for the High Pressure PreferredOrientation diffractometer HIPPO at LANSCE, allowsto apply uni-axial stresses up to 100 kN in tension orcompression to a specimen. It is equipped withrotation and translation stages for increase of polefigure coverage and alignment, respectively. HIPPO’slarge detector area allows to measure the full ODFwith few sample rotations and provides anisotropicelastic strain information for 20 to 100 differentdiffraction vectors. First results from an investigationof metals with a hexagonal close packed crystalstructure (Mg and Zr alloys) are presented.

WP58: Second Generation Neutron Residual StressMapping Facility at ORNL

C. R. Hubbard, M.C. Wright, S. Spooner, E. A.Payzant, S. Craig, A. Stoica (Oak Ridge NationalLaboratory)

The replacement of the beryllium reflector at theHigh Flux Isotope Reactor (HFIR) at Oak RidgeNational Laboratory (ORNL) presented an opportu-nity to make major upgrades of beam tubes, shutters,shielding, neutron optics and instrumentation. Theupgrade of the Neutron Residual Stess mappingFacility (NRSF) at HFIR is one of the major instru-ment upgrades taking advantage of this specialopportunity. The NRSF upgrade aims to return to


operation an improved world class strain mappingand research instrument at HFIR, a high flux steadystate reactor, and reintegrating it into the ResidualStress User Center suite of instruments used to studyresidual stress and materials behavior using neutrondiffraction as well as laboratory and synchrotron x-ray diffraction.

The upgrades of NRSF aim to greatly improve thesystem’s capabilities and create a second generationstrain mapping facility. The upgrades include utiliz-ing: (a) the new larger and higher flux beam at HB-2;(b) a new multiwafer Si, doubly focusing, two crystalmonochromator which yields a choice of wavelengths(from 0.145 nm to 0.227 nm) and supports horizon-tal bending of the monochromator to achieve optimalfocusing; (c) two new very stable high precisiongoniometers, one of which is capable of quite largespecimens while the other will enable strain tensorand highly textured specimen studies; and (d) and anarray of seven 40 x 100 mm active area 1-D positionsensitive detectors. The flux on specimen is predictedto be of the order of 108 neutrons/cm2/sec. Estimatesof the various gains indicate that approximately a 10-fold improvement in strain measurement capabilitywill be achieved.

As of March 1st we have initiated radiological tests ofthe shielding and expect in April and May to com-plete the installation and launch commissioning ofthe new facility. User access to this instrument is viathe High Temperature Materials Laboratory UserProgram ( http://html.ornl.gov/ ). The results ofmonochromator tests, calibration of the instrument,and initial performance tests will be highlighted.

Research sponsored by the Assistant Secretary forEnergy Efficiency and Renewable Energy, Office ofFreedomCAR and Vehicle Technologies, as part of theHigh Temperature Materials Laboratory User Pro-gram, Oak Ridge National Laboratory, managed byUT-Battelle, LLC, for the U.S. Department of Energyunder contract number DE-AC05-00OR22725.

WP59: Comprehensive analysis of spin dynamicsin stripe-ordered La2-xSrxNiO4

H. Woo (Physics Department, Brookhaven NationalLaboratory; ISIS, Rutherford Appleton Laboratory),J. M. Tranquada (Physics Department, BrookhavenNational Laboratory), A. T. Boothroyd (University ofOxford, U. K.), K. Nakajima (University of Tokyo,Japan), T. G. Perring, C. Frost (ISIS, RutherfordAppleton Laboratory), P. G. Freeman, D.Prabhakaran (University of Oxford, U. K.), K.Yamada (University of Tokyo, Japan)

The nature of the magnetic excitations in stripe-

ordered nickelates and cuprates is a topic of consider-able current interest. Here we will present measure-ments of spin waves in La2-xSrxNiO4 ( x = 0.275 and1/3). The data, collected on the MAPS spectrometerat ISIS, provide a comprehensive mapping of the spinexcitations throughout the two-dimensional Brillouinzone. We analyze the results using linear spin-wavetheory[1], and show that the data provide a clearchoice between two alternative models for effectiveexchange coupling through the charge stripes. Thesuccess of semi-classical spin-wave theory for de-scribing excitations in stripe-ordered nickelatescontrasts with its failure in the recently studied caseof La1.875Ba0.125CuO4 [2].

HW and JMT are supported by the Office of Science,U.S. DOE under Contract No. DE-AC02-98CH10886.

[1] Boothroyd et al. Phys. Rev. B 67, 100407(R)(2003).[2] Tranquada et al., cond-mat/0401621.

WP60: Structure and Dynamic of the SuperionicConductor AgI-Ag2S-AgPO3 measured by HIT-II atKENS and MARI at ISIS.

E. Kartini (R & D Center for Materials Science andTechnology, National Nuclear Energy Agency,Tangerang 15314, Indonesia), M. Arai, H. Iwase(Neutron Science Laboratory, KEK, Tsukuba, Japan),K. Itoh (Kyoto University Research Reactor Institute,Kumatori-cho, Japan), S Bennington (ISIS,Rutherford Appleton Laboratory), M.F. Collins(Department of Physics and Astronomy, McMasterUniversity, Hamilton, ON, Canada), S.J. Kennedy(Bragg Institute, Australian Nuclear Science andTechnology Organisation, Australia)

Superionic conducting glasses are of considerabletechnological interest because of their use in batter-ies, displays, sensors and fuel-cells. One of the mainscientific challenges is to explain how the disorderedstructure of the mixture is related to the high ionicconductivity that can be achieved at ambient tem-perature. This work presents the relation between theionic conductivity on the superionic glassesAgI-Ag2S-AgPO3 and the appearance of a prepeak atlow Q~0.6-0.9 Å-1 in the structure factor S(Q) mea-sured by a time-of flight HIT-II instruments at KENS,Japan and the existence of Boson Peaks at lowE~2.5 meV in the dynamic structure factor S(Q,E)measured by the time-of flight MARI instrument atISIS, UK. These materials exhibited good conductivityat ambient temperatures. With increasing mol % ofAgI+Ag2S, the results show (i) rapidly increasingconductivity (ii) slowly decreasing glass transitiontemperature (iii) increasing intensity and decreasing


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Q of the prepeak (iv) increasing the intensity anddecreasing energy of the Boson peak. There is astrong correlation between the ionic conductivity andthe existence and intensity of both the prepeak andthe Boson peak.

WP61: Quantum momentum distribution andkinetic energy in solid 4He

S. Diallo, H. R. Glyde (Department of Physics andAstronomy, University of Delaware, Newark, DE19716), R. T. Azuah (Department of MaterialsScience and Engineering, University of Maryland;NIST Center for Neutron Research)

We present measurements of neutron scatteringfrom solid 4He at high momentum transfer. The solidis held close to the melting line at molar volume 21.0cm3/mol and temperature T=1.6 K. From the data,we determine the shape of the momentum distribu-tion, n(k), of atoms in the solid and the leading FinalState contribution to the scattering. We show thatn(k) in this highly anharmonic, quantum solid differssignificantly from a Gaussian. The n(k) is moresharply peaked with larger occupation of low mo-mentum states than in a Maxwell-Boltzmann distribu-tion, as found in liquid 4He and predicted qualita-tively by Path Integral Monte Carlo calculations. Theatomic kinetic energy is <K> = 24.25+/-0.2 K. Ifn(k) is assumed to be Gaussian, as is usually thepractice, a <K> 10 % smaller is obtained.

WP62: Effect of the metal-insulator transition onoxygen phonons in Ca-doped YBa2Cu3O6

S. Chang (Ames Laboratory), R. J. McQueeney(Ames Laboratory; Iowa State University), P. Dai(Oak Ridge National Laboratory; University ofTennessee, Knoxville), F. Dogan (University ofMissouri - Rolla), F. R. Trouw (Los Alamos NationalLaboratory)

High-temperature superconductors are based onantiferromagnetic insulating materials caused bystrong electronic correlations. Doping charge carriers(holes) into this system creates a two-dimensionalcorrelated metallic state in the CuO2 plane thatbecomes superconducting at low temperatures. Thedevelopment of the metallic state with hole dopingand the metallic state itself still remain poorlyunderstood. Inelastic neutron scattering measure-ments of the lattice dynamics show evidence ofstrong and unusual electron-lattice coupling in manyhigh-Tc compounds with the primary effect being thelarge softening of oxygen optical phonons in theenergy range from 55-80 meV. Here we present thephonon density-of-states as a function of hole dopingin YBa2Cu3O6 obtained from inelastic neutron scatter-ing experiments. The holes were introduced via the

systematic replacement of Y by Ca (Y1-xCaxBa2Cu3O6),where the Ca concentrations were chosen to straddlethe metal-insulator transition (MIT) at x~0.2.Changes in the oxygen phonon modes at higherenergies arising from electron-phonon coupling(55-80 meV) are well separated from any introducedCa modes (<40 meV), similar to the unambiguousexperiments LSCO where holes are introduced by Srdoping. In addition, Ca doping has the advantage ofavoiding new oxygen phonon states, as happenswhen holes are introduced by increasing the oxygencontent. We see clear changes in the phonon density-of-states when doping across the MIT, which weattribute to coupling of holes to oxygen phonons.

WP63: Neutron Investigation of Low TemperatureMagnetization Steps in CMR Manganites

F.M. Woodward, J.W. Lynn (NIST Center for NeutronResearch), M.B. Stone, P. Schiffer (Department ofPhysics and Materials Research Institute,Pennsylvania State University, University Park, PA16082), D.N. Argyriou (Hahn-Meitner-InstitutBerlin), L.C. Chapon (ISIS, Rutherford AppletonLaboratory), J.F. Mitchell (Materials ScienceDivision, Argonne National Laboratory)

The doped manganite Pr0.7(CaxSr1-x)0.3MnO3 (x=0.00.7,0.75), shows anomalous steps in bulk magnetiza-tion and resistivity as a function of applied field forT<2 K, both in powdered and single crystal samples.Neutron diffraction was used as a probe to investi-gate the nature of these steps. Ferromagnetic andantiferromagnetic intensity as a function of field weremeasured in a single crystal sample at T=2 K. Onincreasing the field from the virgin state the antiferro-magnetic phase abruptly disappears at H = 1.75 T,with a concomitant increase in the ferromagneticintensity. Once the transition occurs, the systemremains fixed in the new state when the field isreturned to zero. Details of the magnetic and crystal-lographic structures as a function of field will bepresented.

WP64: Distortions and orientations of fullerideions in K4C60, Rb4C60 and Cs4C60

N. M. Nemes (NIST Center for Neutron Research;Department of Materials Science and Engineering,University of Maryland), Gy. Klupp, G. Oszlanyi, K.Kamaras (Research Institute for Solid State Physicsand Optics, Hungarian Academy of Sciences, P. O.Box 49, H-1525 Budapest, Hungary), C. Brown(NIST Center for Neutron Research; Department ofMaterials Science and Engineering, University ofMaryland), J. Leao (NIST Center for NeutronResearch)

A4C60 compounds (A = K, Rb, Cs) are good candi-


dates for the Mott-Jahn-Teller insulating state. Wehave previously shown that in these materials asplitting of vibrational lines occurs on cooling, thetransition temperature depending on the counterion.We will now present new low temperature neutrondiffraction, inelastic neutron scattering and near-IRdata on K4C60, Rb4C60 and Cs4C60 to prove that thesplitting of the vibrational and electronic excitationsis not coupled to a structural phase transition; rather,the driving force behind this change is an interplaybetween the molecular Jahn-Teller effect and thecrystal potential. Between room temperature and 5K, Cs4C60 is orthorhombic while K4C60 and Rb4C60 aretetragonal; their low-temperature vibrational spectraare, however, identical. Since the molecular pointgroup compatible with the crystal structure is thesame in both space groups, the picture we suggest isorientational order in Cs4C60 and static disorder inK4C60 and Rb4C60 between the two standard orienta-tions. With increasing thermal energy, the moleculesstart to rotate and induce a dynamic disorder. Whenthe time scale of the rotation reaches that of themeasurement, the apparent symmetry changes frombiaxial to uniaxial. We will discuss this point bycomparing our results to methods with different timeconstants (NMR and ESR).

WP65: Proton Tunneling in Supercritical WaterG.F. Reiter (Physics Department, University ofHouston), J.C. Li (Physics Department, University ofManchester), J. Mayers, T. Abdul-Redah (ISIS,Rutherford Appleton Laboratory), P. Platzman (BellLabs-Lucent Technologies)

Neutron Compton Scattering measurements can givea detailed measurement of the momentum distribu-tion of light ions in solids and liquids. We present themomentum distribution in ice, room temperaturewater, supercritical water, and confined supercriticalwater. While the ice and room temperature waterdata can be interpreted in terms of nearly harmonicpotentials, the supercritical water data shows clearevidence of tunneling, apparently along the bond,over distances of about 0.3 Å. Confinement byhydrophobic surfaces of C60 reduces slightly thatdistance. The data is consistent with vapor phase atthe hydrophobic surfaces, and inconsistent with icephase formation. The strong anharmonicity makesclassical simulations of dubious value in describingsupercritical water. We interpret the data in terms of‘inherited tunneling’ from the motion transverse tothe bond.

WP66: Deep Inelastic Neutron Scattering fromwater in the 1-40 eV energy range employing theResonance Detector Spectrometer configuration

R. Senesi, C. Andreani, A. Filabozzi (Universita degliStudi di Roma Tor Vergata, V. Ric. Scientifica 100133 Roma Italy; INFM UdR Roma Tor Vergata), G.Gorini (Università degli Studi di Milano-Bicocca,Dipartimento di Fisica; Istituto Nazionale per laFisica della Materia), S. Nufris (Universita degliStudi di Roma Tor Vergata, V. Ric. Scientifica 100133 Roma Italy; INFM UdR Roma Tor Vergata), E.Perelli-Cippo (Università degli Studi di Milano-Bicocca, Dipartimento di Fisica; Istituto Nazionaleper la Fisica della Materia), A. Pietropaolo(Universita degli Studi di Roma Tor Vergata, V. Ric.Scientifica 1 00133 Roma Italy; INFM UdR RomaTor Vergata), N. Rhodes, E. M. Schooneveld (ISIS,Rutherford Appleton Laboratory), M. Tardocchi(Istituto Nazionale per la Fisica della Materia;Università degli Studi di Milano-Bicocca,Dipartimento di Fisica)

The Resonance Detector Spectrometer configurationhas recently been revised on the VESUVIO inversegeometry spectrometer at ISIS spallation source. Itappears as the most promising approach for electronVolt neutron spctroscopy due to its effectiveness indetecting neutron up to 70 eV final energy. Weemployed this experimental configuration onVESUVIO spectrometer for Deep Inelastic NeutronScattering measurements from a water sample. Thishas been done in order both to test the behavior ofthe detection system and to derive the single protonwave vector distribution and mean kinetic energy, attwo different thermodynamic conditions, up to finalneutron energies of about 37 eV. The results havebeen compared with those obtained through asimultaneous measurement on VESUVIO, carried outin the standard Resonance Filter Spectrometerconfiguration. These measurements provide a furtherconfirmation of the effectiveness of the ResonanceDetector Spectrometer configuration for electron Voltneutron spectroscopy on inverse geometry instru-ments operating at pulsed neutron sources.

WP67: Crystal structure and phase transition ofK0.2(NH4)0.8CI mixed salt at low and high tempera-ture

G. Batdemberel (Mongolian University of Scienceand Technology, Ulaanbaatar, Mongolia; DarmstadtUniversity of Technology, Darmstadt, Germany),A.N. Skomorokhov (Institute for Physics and PowerEngineering, Obninsk, Russia; DarmstadtUniversity of Technology, Darmstadt, Germany), L.Smirnov, A.I. Beskrovny (Joint Institute for NuclearResearch, Dubna, Russia), H. Fuess (Darmstadt


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University of Technology, Darmstadt, Germany), D.Sangaa (National University of Mongolia,Ulaanbaatar, Mongolia), Sh. Chadraabal (MongolianUniversity of Science and Technology, Ulaanbaatar,Mongolia)

Have been carried out the crystal structure studies ofK0.2(NH4)0.8Cl at room temperature by x-ray andneutron diffraction techniques. It was established thatthe K0.2(NH0.8)Cl compound has CsCI structure withthe Pm3m space group. By using of the x-ray powderdiffraction determined lattice parameters, K, N, CIatom positions and the thermal factors. From theneutron powder diffraction data determined hydro-gen atom position. High-resolution differentialcalorimetric analysis observed phase transition pointsat the low temperature T=232 K and at the hightemperatures T=425 K, 458 K, 478 K, 513 K and573 K. On diffractograms obtained at 232 K tempera-ture appeared along with CsCI structural reflectionsthe low intensity peaks corresponding to superstruc-ture and if in diffraction data Rietveld refinementprocedure to be accounted these superstructurereflections the essential CsCI structure transforms tothe tetragonal setting distorted by C3v symmetry. Atthe high temperature points: 425 K, 458 K, 478 K,513 K and 573 K except the CsCI structure peakshave been observed the low intensity diffractionpeaks with a monoclinic symmetry and at the point478 K occurred a transition of the CsCI structure tothe NaCI structure with Fm3m space group.

WP68: Vibrational Entropy of Dissolving Ag in AlT. Swan-Wood, M. Kresch, J. Lin, M. McKerns, B.Fultz (California Institute of Technology)

There is an unusually strong increase with tempera-ture of the solubility of Ag in fcc Al. This phenomenais not unique to the Al-Ag system and is seen inmany binary alloys, particularly those where theimpurity has a mass ratio of at least 3 to that of thematrix atom. We hypothesize that low-frequencyresonance modes associated with massive soluteatoms make a large contribution to the vibrationalentropy of mixing. Inelastic neutron scatteringspectra were measured on LRMECS at the IPNS fromAl, Al-7 at. % Ag, Al-60 at. % Ag, and a 2-phaseregion (Al-7 at. % Ag and Al-60 at % Ag) at roomtemperature. Phonon density of state (DOS) curveswere obtained by correcting for multi-phononscattering, Debye-Waller effects, and the thermalfactor. The difference in phonon scattering efficien-cies of Al and Ag (neutron-weighting) is not large, butwe developed methods for correcting this neutronweighting through computer simulations of the latticedynamics. The phonon DOS from the Al-7%Ag alloyshowed a large resonance mode at low energies. This

resonance mode made a significant contribution of0.160 +/- 0.006 kB/atom to the vibrational entropy ofthe alloy compared to fcc Al, a significant fraction ofthe total neutron-weight-corrected entropy of mixingof 0.09 +/- 0.01 kB/atom, but there is also a stiffeningof some of the vibrational modes. The hcp phase,60% Ag, showed a large softening of its phonon DOScompared to Al-7% Ag. A full correction for theneutron weighting is not possible, but assuming it isnot large we deduce a vibrational entropy forAl-60%Ag that is 1.35 kB/atom larger than for fcc Al.Vibrational entropy makes a large contribution to thethermodynamics of phase stability in the Al-Agsystem. The mass and probably the size of Ag atomsmay be responsible for some of the trends.

WP69: Neutron Diffraction Study of Phase Trans-formations and Mechanical Properties in Ni[AlFe]Alloys

L. Yang (Dept. of Chemical and MaterialsEngineering, University of Cincinnati, Cincinnati,OH 45221-0012; Spallation Neutron Source, OakRidge National Laboratory), X.-L. Wang (SpallationNeutron Source, Oak Ridge National Laboratory;Metals and Ceramics Division, Oak Ridge NationalLaboratory), J. A. Fernandez-baca (CondensedMatter Sciences Division, Oak Ridge NationalLaboratory), A. D. Stoica (Spallation NeutronSource, Oak Ridge National Laboratory), C. T. Liu(Metals and Ceramics Division, Oak Ridge NationalLaboratory), J. W. Richardson (Intense PulsedNeutron Source, Argonne National Lab)

Phase transformations in NiAl alloys are complex andhave been a subject of extensive experimental andtheoretical studies. The martensitic transformation inNiAl alloys involves the formation of long periodstacking orders, which can be either B2-2M(3R, L10)or B2-17M(7R) depending on the composition. Whenmagnetic transitional atoms (e.g., Fe, Mn) are added,various types of magnetic properties appear due tothe competition of ferromagnetic and antiferromag-netic interactions. The study by Morito et al. [1,2] onNi50[AlxMn50-x] shows a continuous martensitictransformation of B2-10M-14M, and a magneticphase transition from a paramagnetic to an antiferro-magnetic and finally to a spin glass state. It is not yetclear whether or how the martensitic and magneticphase transformations are related.

Our interest in Ni[AlFe] alloys was prompted by arecent systematic study that reported an unusualsoftening behavior in mechanical properties [3].First-principle calculations revealed that when Featoms are added, a localized moment of 2.4 µB

develops at the Fe site. The calculations further


suggest that the magnetic interactions enlarge theatomic size of the Fe atom, which lead to the increaseof the lattice parameter and hence the softeningeffect. If these explanations hold, magnetic interac-tions may be explored as a new mechanism to alterthe mechanical property of metallic materials, whichwould open up a new way in the design of metallicmaterials for structural applications.

We have carried out preliminary characterizations ofNi[AlFe] alloys. Magnetic susceptibility measurementsconfirmed that when Fe replaces Al, a localizedmoment develops. Upon cooling, a paramagnetic toferromagnetic transformation was observed, and thesystem goes to a spin-glass state below 12 K. Neutrondiffraction data collected at High Flux Isotope Reactorshowed an intensity gain at low temperatures, whichfollowed a Q-dependence reminiscent of magneticscattering. Meanwhile, high-resolution powderdiffraction data collected at IPNS revealed extraBragg peaks below 20 K. Upon warming up, theseextra peaks disappear at temperatures above 50 K.While the experimental data are still being analyzed,the thermal hystersis and Q-dependence of the extrapeaks suggest that they came from a martensiticphase transformation. More systematic studies areunderway to determine the structure and the natureof phase transformations in Ni[AlFe] alloys and theirrelationship with the usual mechanical properties.

This research was supported by Division of MaterialsSciences and Engineering, Office of Basic EnergySciences, U.S. Department of Energy under ContractDE-AC05-00OR22725 with UT-Battelle, LLC.

[1] S. Morito, K. Otsuka, Mat. Sci. Engr., A208, 1996,47-55[2] S. Morito, T. Kakeshita, K. Hirata and K. Otsuka,Acta Mater., 46, 1998, 5377-5384[3] C.T. Liu, C.L. Fu, L.M. Pike, and D.S. Easton, ActaMater., 50, 2002, 3205-3212

WP70: PDF analysis of local distortions in Ti2Sband CeTe3

H. J. Kim, X. Qiu, S. J. L. Billinge (Department ofPhysics & Astronomy, and Center for FundamentalMaterials Research Michigan State University, EastLansing, Michigan 48824), S. Derakhshan, A.Assoud, E. Dashjav, H. Kleinke (Department ofChemistry University of Waterloo, Waterloo, ON,Canada N2L 3G), C. Malliakas, T. Kyratsi, M. G.Kanatzidis (Department of Chemistry, and Centerfor Fundamental Materials Research Michigan StateUniversity, East Lansing, Michigan 48824), P.J.Chupas, C.P. Gray (State University of New York,Stony Brook, NY 11794-2275), P.L. Lee (Advanced

Photon Source, Argonne National Laboratory,Argonne, IL)

Recent years have seen enormous progress indeveloping novel electronic materials. Mountingevidence suggests that structures, defects, andinteractions on nanometer length-scales are inti-mately connected to their remarkable properties.Therefore, precisely resolving these structures isinevitable for the ultimate understanding of theproperties of the materials and it requires advancedlocal techniques such as atomic Pair DistributionFunction (PDF) analysis. Local distortions in twomaterials, Ti2Sb and CeTe3, are investigated usingPDF analysis. The single crystal x-ray study on a newbinary antimonide Ti2Sb suggests a new type ofdistortion in the Ti square planar nets. The PDFanalysis on this system verifies that Ti nets deform tosquares and rhombs in order to enhance Ti-Tibonding. Formation of 1:1:7 superstructure on alayered chalcogenide CeTe3, also known as a charge-density wave material, is observed by the singlecrystal x-ray and TEM studies. The chemical, physical,and electronic properties of this material are largelydecided by Te square nets whose average Te-Te bond(~3.1 Å) is larger than the normal covalent Te-Tebond (~2.8 Å). The PDF measurements suggest thatlocal structural distortions occur in the Te square netsforming short bonds around 2.8 Å resulting in a 1:1:7superstructure.

WP71: Acoustic Mode Confinement in Nano-Crystalline Yttria

M.P. Hehlen, F.R. Trouw, J.T. Mang (Los AlamosNational Laboratory), R.M. Laine (University ofMichigan, Ann Arbor, MI 48109)

Nano-crystalline cubic yttria (Y2O3) was prepared byliquid-feed flame spray pyrolysis. The mean particlediameter was 21 nm as determined by small-anglex-ray scattering and assuming polydisperse spheres.Inelastic neutron scattering from nano-crystalline andcoarse-grained Y2O3 at 15 K was measured with anincident energy of 90 meV (∆E/E~6%) on the Pharosspectrometer at LANSCE. The phonon density ofstates (PDOS) of both the nano-crystalline and thecoarse-grained Y2O3 exhibits a number of wellresolved peaks in the 15-75 meV range that are inagreement with optical phonons observed by Ramanscattering and infrared absorption. Relative to coarse-grained Y2O3, the PDOS of nano-Y2O3 is substantiallyenhanced in the 5-30 meV range by a broad asym-metric band peaking at 10 meV. This additionalphonon density is due to acoustic modes becomingconfined on the length scale of the nano-particles.The confined acoustic modes are analyzed using amodel of homogeneous, elastic spheres as well as


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molecular dynamics calculations.

WP72: SANS Data Reduction and Analysis UsingISAW

A. Chatterjee (Intense Pulsed Neutron Source,Argonne National Lab), R. Mikkelson, D. Mikkelson,M. Miller, B. Serum, C. Bouzek (University ofWisconsin-Stout), J. Hammonds, T. Worlton, J. Tao(Intense Pulsed Neutron Source, Argonne NationalLab)

Small-angle neutron scattering (SANS) instrumentsprobe sizes and shapes on length scales of~ 0.5 – 100 nm. A wide range of systems thatinclude biological, chemical, solid-state can bestudied using SANS. Typically, these instruments uselow-angle forward scattering techniques and havearea detectors the data from which is reduced toproduce scattering intensity, I(q). A number of stepsprecede the calculation of I(q) like calculation of thebeam center, sensitivity of the detector pixels,transmission coefficients etc. Integrated SpectralAnalysis Workbench (ISAW) is a software packagedeveloped at IPNS to reduce, analyze and visualizeneutron scattering data. It has recently startedsupporting the upgraded small-angle neutron scatter-ing instrument (SAND) at IPNS. ISAW provides acollection of scripts and wizards that do all the stepsin the SAND data treatment. The scripts and wizardsmake use of java operators in ISAW. To processmultiple runs, ISAW provides a script that processesfiles in a batch mode. The q bins can be 1 or 2dimensional with a resolution that can be set in thescripts. A number of viewers that come with ISAWcan be used to look at the reduced files and theoutput from some viewers of data collected on SANDwill be presented.

WP73: SPICE – Spectrometer Instrument ControlEnvironment

M.D. Lumsden, J.L. Robertson, M. Yethiraj (HFIRCenter for Neutron Scattering, Oak Ridge NationalLaboratory, Oak Ridge, Tennessee 37831, USA.)

We have developed a LabVIEW-based data acquisitionsystem for neutron scattering instruments with initialimplementation on the triple-axis spectrometer. Thesoftware is written with a modular framework toallow easy expansion to handle different instruments,commands, and user interfaces. At the core of thesoftware is a command-line parsing engine whichsequentially executes commands from an executionstack. Commands can be added to the executionstack via by directly typing into the command line,from the included graphical user interface or fromweb-based interfaces. The hardware interface layer isbased on object-oriented programming concepts

allowing easy addition and removal of hardware.Flexibility is achieved through an alias structure, theability to write lists of commands into a macro, theability to produce custom scans, and full scriptingthrough an ActiveX interface with Python. Userdownloadable executables allow monitoring of theinstrument status remotely and basic data analysisand visualization. The triple-axis version of SPICEincorporates a full UB-matrix implementation whichcan handle general crystal symmetry and move-ments out of the scattering plane. This program hasbeen successfully running the HB1A, HB1 and HB3triple-axis spectrometers at the High-Flux IsotopeReactor for over 1 year and is being extended tooperate the powder diffractometer and wide-angleneutron diffractometer (WAND).

WP74: New Software for Single Crystal, Time-of-Flight Neutron Scattering Instruments

Dennis Mikkelson (University of Wisconsin-Stout),Arthur Schultz (Argonne National Laboratory), PeterPeterson (Oak Ridge National Laboratory), RuthMikkelson (University of Wisconsin-Stout), ThomasWorlton, John Hammonds, John Cowan, MarthaMiller (Argonne National Laboratory), Chris Bouzek,Michael Miller (University of Wisconsin-Stout)

Single crystal time-of-flight neutron scatteringexperiments provide information about three dimen-sional regions in reciprocal space. A new set ofsoftware tools for single crystal diffractometers hasbeen developed. The software includes componentsfor instrument calibration, data visualization, findingand indexing peaks, fitting orientation matrices andpeak integration. The instrument calibration softwareadjusts multiple instrument parameters to minimizethe sum squared differences between calculated peakpositions and measured peak positions in reciprocalspace, for a known sample. User friendly “wizards”guide the user through the data reduction process.This software is currently in use at the single crystaldiffractometer at IPNS and can process single crystaldata from NeXus files. This software was developedin the context of the Integrated Spectral AnalysisWorkbench (ISAW) project at the Intense PulsedNeutron Source Division of Argonne National Labora-tory, with support from the National Science Founda-tion.

WP75: DANSE – distributed data analysis forneutron scattering

M.M. McKerns, M.A.G. Aivazis, T.M. Kelley, S.J. Kim,B. Fultz (California Institute of Technology)

The DANSE system will merge the various computa-tional tasks of neutron scattering into a unified,component-based runtime environment. Standard


components will implement data analysis, visualiza-tion, modeling, and instrument simulation for allmajor areas of neutron scattering. A core technologyof DANSE is an open source software framework thatsupports the components and mediates their interac-tions. Within the DANSE environment, users will beable to mix and match different software compo-nents without compilation, and execute calculationsseamlessly across distributed resources. DANSE willprovide tools to help instrument scientists and expertusers migrate their existing routines (written in anyof a number of languages) to components, and aninterface that allows new and casual users to access astock set of standard analysis applications or config-ure their own new computing procedures for novelexperiments. The modular structure of DANSEparallels the steps of data analysis performed byscientists, thus making it a natural environment forcreating flexible computing procedures. DANSE willlower barriers to sharing software, and extend theexperimentalist’s toolkit with capabilities of analysisand interpretation such as high-performance simula-tions (band structure, molecular dynamics, etc.), co-analysis of data from multiple experiments, and real-time feedback for experiment control.

WP76: NCNR reflectometry softwareP.A. Kienzle (NIST Center for Neutron Research;University of Maryland, College Park), K.V.O’Donovan (NIST Center for Neutron Research;University of California at Irvine)

At the NCNR we have been developing a graphicaluser interface (GUI) for our data reduction andanalysis tools. We support the reduction of raw datafor monochromatic source neutron and x-ray reflec-tometry for NCNR data formats. For analysis we use amulti-layer model evaluated using the Parrat formal-ism. Interfaces are approximated by a series oflayers, which allows the interface effects to becomputed accurately even for very broad interfaces.Arbitrary constraints between the parameters for thedifferent layers can be programmed by the user. Wesupport polarized beam data, allowing us to reduceand analyze magnetic as well as nuclear effects onreflectivity.

The GUI for reduction strives to be flexible whileconveniently supporting the common operationsrequired for selection and manipulation of the data.The GUI for analysis is distinct from others in that itallows direct manipulation of the scattering lengthdensity profile rather than entering layer parametersby hand. Our software is based on an underlyingscripting language (Tcl/Tk) with direct access availablewithin the program. For those cases where the GUI

has not anticipated the needs of the user, the user isfree to modify data from the console without aban-doning the entire GUI. Thus our software is suitedboth to the new user performing standard measure-ments as well as the expert user performing newtypes of measurements on our instruments.

Since the introduction of our software at the NCNR,the benefits have been great. Data reduction tasksthat used to take hours can now be done in minutes.The results are more reliable since the data is in viewat every step in the transformation, which makesinstrumental errors easier to detect. Training time fornew users is considerably reduced, leading to a morepleasant experience for our users and freeing timefor our support staff.

WP77: The State of NeXusP.F. Peterson (Spallation Neutron Source, Oak RidgeNational Laboratory)

During the course of the last year, the NeXus dataformat for neutron and x-ray scattering has under-gone several changes which improve usability andincrease the number of applications available. TheNeXus International Advisory Committee has beenformed, with representation from eleven facilitiesaround the world, including all the US neutronscattering facilities. This committee is charged withproviding formal ratification for the instrumentcomponents, defined in XML. I will present recentchanges to the abstract programmer’s interface (API),enhanced data browsing and validation utilities, anda selection of software that is NeXus aware.

WP78: Neutron spin echo study of AOT reversemicelles with application to metallic nanoparticlesynthesis and compressible fluids

Christopher L. Kitchens and Christopher B. Roberts(Department of Chemical Engineering, AuburnUniversity, AL 36830), Dobrin Bossev (University ofMaryland, College Park; National Institute ofStandards and Technology)

The common surfactant, AOT(Sodium bis-2-ethylhexyl-sulfosuccinate), formsthermodynamically stable water-in-oilmicroemulsions containing self-assembled sphericalreverse micelles. The reverse micelles consist of asmall water pools encased in an AOT surfactantmonolayer and dispersed within a bulk organic fluid.The nanometer sized water core acts as a “nano-reactor” for aqueous phase reactions, eg. metallicnanoparticle synthesis within the micelle cores. It hasbeen demonstrated that the metallic nanoparticlegrowth rate and the average particle size synthesizedare influenced by the size of the reverse micelle,


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represented by W where W=[H2O]/[AOT] and thethermophysical properties of the bulk alkane solvent,specifically the solvent interactions with the surfac-tant tails. Studies of reverse micelle dynamics insolution have shown that adjustable parameters suchas the bulk solvent properties and W influence theintermicellar exchange rate. In this work, we proposeto use Small Angle Neutron Scattering (SANS) corre-lated with Neutron Spin Echo (NSE) Spectroscopy tostudy reverse micelle dynamics as a function of thebulk d-alkane solvent and the size of the reversemicelles. NSE offers the unique ability to performdynamic measurements of thermally induced shapefluctuation in the AOT surfactant monolayer, howeverthe time averaged, static SANS measurements arenecessary to obtain pertinent information from thedynamic system, specifically the bending elasticmodulus and saddle-splay elastic modulus.

W2-A, Mechanical Behavior and ResidualStress, Chair: Henry Prask (NIST), Room 1123Blue

W2-A1 (13:30) Residual Stress and Texture inEngineering Materials (Invited)

J. H. Root (National Research Council, Chalk River,Ontario, Canada)

Because neutrons penetrate easily through manyengineering materials, neutron diffraction can oftenbe applied to determine distributions of stress orcrystallographic texture, non-destructively, insideintact engineering components. Experimentalknowledge obtained by neutron diffraction hasrefined ideas about the deformation of polycrystallinematerials and validated simulations of materialbehaviour during processing, service and failures.This knowledge has proven to be of great interest tovarious industries, because it can address issues ofsafety, regulations, competitiveness and marketpenetration. In parallel, neutron diffraction measure-ments of residual stress and texture have openednew opportunities for fundamental materials science,attracted a new user community to the sphere ofneutron scattering and stimulated the developmentof new neutron instruments and methods. Thispresentation will provide some illustrations ofresidual stress and texture studies at Chalk RiverLaboratories, where materials science and engineer-ing projects occupy more than one third of availableneutron beam time. We shall consider the state of theart, as practised at neutron facilities worldwide, andlist some of the experimental and scientific chal-lenges in this field.

W2-A2 (14:00) The use of neutron diffraction andpolycrystal plasticity modeling to understanddeformation in hexagonal metals.

D. W. Brown, M. A. M. Bourke, W.R. Blumenthal,S.C. Vogel, C. N. Tome (Los Alamos NationalLaboratory), T. M. Holden (Northern StressTechnologies), K. Conlon (Chalk River), S.R. Agnew(Universtiy of Virginia)

Due to the high crystallographic symmetry of body-centered and face-centered cubic metals, plasticdeformation is relatively simple because one uniqueslip mode can provide arbitrary deformation. This isnot true in lower symmetry hexagonal metals, whereprismatic and basal slip (the usual favored modes)are insufficient to provide arbitrary deformation.Often, either pyramidal slip and/or deformationtwinning must be activated to accommodate theimposed plastic deformation. The varied difficulty ofactivating each of these deformation mechanismsresults in highly anisotropic yield surface and subse-quent mechanical properties. Further, the incipientactivity of each deformation mode may be manipu-lated through control of the crystallographic texture,opening new opportunities for the optimization ofmechanical properties for a given application. Thistalk will highlight studies done by several researchersat the neutron scattering center at Los Alamos overthe past two years focused on the combined use ofneutron diffraction measurements and computationalmodeling to understand micro-mechanical deforma-tion mechanisms in hexagonal metals, in particularBe, Mg, Ti, and Zr.

W2-A3 (14:15) Residual stresses in cold-drawneutectoid wires

J. Ruiz-Hervias (NIST Center for Neutron Research;Departamento de Ciencia de Materiales,Universidad Politecnica de Madrid. c/ ProfesorAranguren s/n, E-28040 Madrid (SPAIN)), V. Luzin,H. Prask, T. Gnaeupel-Herold (NIST Center forNeutron Research), M. Elices (Departamento deCiencia de Materiales, Universidad Politecnica deMadrid. c/ Profesor Aranguren s/n, E-28040 Madrid(SPAIN))

Textures and residual stresses have been determinedin cold-drawn eutectoid steel wires (pearlitic micro-structure composed of ferrite and cementite phases)by neutron diffraction using the BT8 diffractometer atthe NIST Center for Neutron Research (NCNR).Samples corresponding to different stages in thedrawing process, and consequently subjected todifferent plastic deformation were examined. Thewire sizes ranged from 10.5 to 5.2 mm diameter andall had the same composition (plain carbon steel with0.8% C). Stress profiles along three principal direc-


tions (axial, radial and hoop) were obtained for theferrite phase for all the samples with spatial resolu-tion through the wire diameter better then 1 mm.The gauge volume for the radial and hoop compo-nents was 0.5x15x0.5 mm3, whereas for the axialcomponent it was 1x1x1 mm3. Different reflectionshad to be used because diffraction peak intensity wassignificantly diminished in certain directions due totexture. The results are consistent with earliermeasurements, but are the first which examineresidual stress evolution for different processingstages in commercial wires.

W2-A4 (14:30) Residual Stress Determination inThermally Sprayed Metallic Coatings by NeutronDiffraction

W. Wagner, T. Keller (Paul Scherrer Institut, 5232Villigen-PSI, Switzerland), N. Margadant (EMPASwiss Federal Laboratories for Materials Testingand Research, Thun, Switzerland), T. Pirling(Institut Laue Langevin)

Thermally sprayed coatings are nowadays widelyapplied in industrial technology for surface protectionor improvement of surface properties for specificapplications. Among others, residual stresses oftenplay a crucial role in the performance and lifetime ofsuch coatings and therefore, their determination is ofgeneral interest.

The present study investigates metallic NiCrAlYdeposits (chemical composition 67wt. % Ni, 22wt. %Cr, 10wt. % Al, 1wt. % Y) on steel substrates. Neu-tron diffraction was used to obtain spatially resolvedstrain and stress profiles in the deposits and theunderlying steel substrates. For the neutron diffrac-tion measurements special emphasis was given to ahigh spatial resolution when entering the surface andcrossing the interface to the substrate. Samples offour different spray techniques were analyzed:atmospheric and water-stabilized plasma spraying(APS and WSP), flame spraying (FS) and wire arcspraying (WAS). The results are quantitatively com-pared with the average in-plane residual stressdetermined by complementary mechanicalprofilometry (bending tests). While the stress profilesfrom the surface to the interface in the deposits aresimilar for all investigated spray techniques, theirabsolute values and gradients vary strongly. This isattributed to different quenching stresses from theimpinging particles, different thermal histories thedeposit/substrate systems undergo during thespraying and subsequent cooling, and also to differ-ent coating properties. In the WSP- and WAS-depos-its, a gradient in the stress free lattice parameter wasobserved. Crack formation is found to be a dominant

mechanism for stress relaxation in the surface plane.

W2-B, Lipids and Micelles, Chair: ShendaBaker (Harvey Mudd), Room 2100/2/4 Red

W2-B1 (13:30) Surface constraints and membranephase miscibility gaps (Invited)

W. A. Hamilton (Condensed Matter SciencesDivision, Oak Ridge National Laboratory), L. Porcar(NIST Center for Neutron Research), G.S. Smith(Condensed Matter Sciences Division, Oak RidgeNational Laboratory)

In many surfactant membrane systems the competi-tion between intrinsic curvature and membranecomposition leads to large miscibility gaps in whichmembrane phases of very different geometriescoexist in the bulk. Depending on the phase geom-etries we would expect the bulk equilibrium balanceto be affected by the ordering potential exerted by aproximate surface. In this work we consider asituation in which the effect should be relativelystrong: when one of the coexisting phases, the so-called L3 “sponge”, is a manifestly isotropic convolu-tion of membranes for which any accommodation toa flat surface will represent a significant distortion,whereas for the other, a regularly stacked Lα lamellarphase, it should not. Using neutron reflectivity and“Near-Surface” SANS (NS-SANS) we have tracked atemperature driven L3 to biphasic L3+Lα transition inan AOT membrane solution near the quartz surfaceof a reflection geometry sample cell. The NR signalallows us to probe the membrane conformation to adepth of order 1000 Å, a relatively few membraneseparations from the solid-solution interface (theexpected range of any ordering potential), while theNS-SANS signal allows simultaneous monitoring of“bulk” phase behavior corresponding to the surfacesignal to depths of tens of µm. While these are staticmeasurements, we note that these phases are tosome extent stabilized by hydrodynamic fluctuations.These have well known structural consequences inthe bulk, such as logarithmic correction of the scalingof characteristic lengths with respect to dilution. Inthe vicinity of the surface these fluctuation modeswill inhibited, narrowing their spectrum, so thesurface may be expected to frustrate these mem-brane phases dynamically as well as geometrically.

* Research sponsored by the U.S. Department ofEnergy under contract DE-AC05-00OR22725 withORNL managed by UT-Battelle, LLC.

W2-B2 (14:00) Structural Characterization andSolution Behavior of Polymerized Rod-like Surfac-tant Micelles

Michael J. Gerber, Lynn M. Walker (Department of


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Chemical Engineering, Center for Complex FluidsEngineering, Carnegie Mellon University, PittsburghPA)

The polymerization of elongated micellar structuresoffers a novel approach to the production of highaspect ratio, water-soluble amphiphilic nanorods. Acationic surfactant is used as a template to polymer-ize a vinyl-containing counterion,cetyltrimethylammonium 4-vinylbenzoate (CTVB)based on procedures presented by Kline (Kline, S. R.,Langmuir 15:2726 1999). The surfactant-polyacidaggregate that forms results in high aspect rationanoparticles. In this work, the influence of initiatorconcentration on particle length and structure ischaracterized. Small angle neutron scattering andlight scattering are combined to characterize thedimensions and the solution behavior of the poly-merized aggregates. Scattering provides evidencethat the aggregates have a net negative charge,explaining their solubility and stability. NMR studiesreinforce this observation and indicate that thesurfactant is able to dissociate while the polymerizedcounterion is trapped in the aggregate. Finally, GPCof the polymer extracted from the aggregates indi-cates that approximately 2 chains are immobilized ineach aggregate. Results demonstrate our ability tocontrol aggregate dimensions and properties. Thisprocedure offers an inexpensive and simple approachto generate nanorods with a diameter of 4nm andaspect ratios ranging from 20 to 60.

W2-B3 (14:15) Formation of Lipid MembranesAssembled on Ordered Nanocomposite andNanoporous Silica Thin-Films: A NeutronReflectivity Study

D. A. Doshi, A.M. Dattelbaum, E.B. Watkins, J.Majewski, A.P. Shreve (Los Alamos NationalLaboratory), A.N. Parikh (University of California-Davis)

Ordered nanocomposite and nanoporous silica thin-films are promising platforms for supporting lipidmembrane architectures that mimic biologicalsystems. In this study we have systematically investi-gated the viability and the interfacial characteristicsof phospholipid membranes formed on ordered silicathin-films using neutron reflectivity. The non-destruc-tive nature and long penetration depth of neutrons(compared to x-rays) makes neutron reflectivity anideal technique to study the soft silica film-mem-brane and membrane-water interfaces. Silica thin-films used here were prepared via an evaporationinduced self-assembly process, which involves thehierarchical organization of organic surfactant andinorganic silica building blocks. POPC (1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphocholine) lipid mem-

branes were then deposited on the silica thin-filmsurfaces by vesicle fusion. The nature of the silicathin-film surface was found to be critical for thevesicle fusion process. In case of vesicle fusion on aself-assembled nanocomposite silica film, where thetemplating surfactant is present, a low-density lipidmembrane was formed. When the templatingsurfactant was removed via photo-calcination, adensely packed lipid bilayer formed on the surface.The silica surfaces were also modified with a self-assembled silane monolayer prior to lipid membraneformation. A detailed analysis of all the thin-film/lipidmembrane interfaces and structures formed will bepresented.

W2-B4 (14:30) Neutron Spin-Echo Study of Dynam-ics of Hydrophobically Modified Polymer DopedSurfactant Bilayers

R. K. Prud’homme (Department of ChemicalEngineering, Princeton University, Princeton, NJ08544-5263), B.-S. Yang (Bristol-Myers Squibb, OneSquibb Drive, New Brunswick, NJ 08903), J. Lal(Intense Pulsed Neutron Source, Argonne NationalLaboratory, Argonne, IL 60439), M. Mihailescu, M.Monkenbusch, D. Richter (Institut furFestkorperforschung-Forschungszentrum Julich D-52425 Julich, Germany), J. S. Huang (Department ofChemical Engineering, Princeton University,Princeton, NJ 08544-5263), J. Kohn (Department ofChemistry, Rutgers University, Piscataway, NJ08854), W. B. Russel (Department of ChemicalEngineering, Princeton University, Princeton, NJ08544-5263)

We characterize the effect of adsorbedhydrophobically modified polymers (hm-polymers)on the dynamics of surfactant bilayers by small-angleneutron scattering (SANS) and neutron spin-echo(NSE) spectroscopy. Two kinds of hm-polymers, (a)hydrophobically modified poly(acrylate) (hmPAA)with tetradecyl (C14) sidegroups randomly grafted tothe poly(acrylate) backbone and (b)poly(PEG6k-lysine-stearylamide) (hmPEG) with equallyspaced hydrophobes, are added to bilayers ofpenta(ethylene glycol) dodecyl ether (C12E5) andhexanol. Both bare and polymer doped membraneexhibit a stretched exponential relaxation in the formof I(q) ≅ S(q)exp(-Γqt)

2/3, where S(q) is the staticstructure factor and Γq is the relaxation rate. Therelaxation rate depends subtly on the surface-coverage of polymer. At high surface coverage,polymer slows down the relaxation by 20 %;whereas at low surface coverage, polymer enhancesthe rate relative to the bare membranes. Hinderedflow of solvent through the adsorbed polymer layerat high coverage appears to explain retardation. The


faster dynamics at low polymer coverage may be dueto stiffening of the membrane or lateral diffusion ofthe dilute adsorbed polymer chains. The q rangecovered by the static and dynamic measurementscoincide. The slowest relaxation rate occurs at lengthscales (i.e., q vectors) of the diffraction peak corre-sponding to interlamellar spacings. The quality of theNSE data available invites the development of newtheories of the dynamics of lamellar phase liquidcrystalline fluids.

W2-C, Cobaltates, Chair: James Jorgensen(ANL), Auditorium

W2-C1 (13:30) Structural and Physical Properties ofthe NaxCoO2 system (Invited)

Y. S. Lee (Massachusetts Institute of Technology)Sodium cobalt oxide, NaxCoO2 (with x ~ 0.7), hasreceived considerable attention due to its unusualthermal electric properties. Recent studies haverevealed anomalous non-Fermi liquid behavior intransport properties which point to the importance ofstrong correlations. Interest in this material escalatedwith the discovery of superconductivity inNaxCoO2 + yH2O when the sodium concentration isreduced to about 0.3 and water is intercalatedbetween the layers. We have developed a novelelectrochemical de-intercalation method and haveused this to successfully produce single crystalsamples of NaxCoO2 with a wide range of composi-tions (x=0.3 to 0.75). We have performed scatteringexperiments on both hydrated superconductors andnon-hydrated samples. We will discuss our resultsand how they relate to our measurements of thephysical properties in this interesting class of materi-als.

W2-C2 (14:00) Crystal structure of NaxCoO2 (x from1 to 0.3) at room temperature

Q. Huang (NIST Center for Neutron Research), M.L.Foo (Department of Chemistry, PrincetonUniversity, Princeton NJ), J.W. Lynn (NIST Center forNeutron Research), H.W. Zandbergen (NationalCentre for High Resolution Electron Microscopy,Technical University Delft, The Netherland), B. Toby(NIST Center for Neutron Research), R.J. Cava(Department of Chemistry, Princeton University,Princeton NJ)

The crystal structure of NaxCoO2 (x from 1 to 0.3) hasbeen studied using the neutron powder diffractiontechnique. The structure consists of layers of edge-shared CoO6 octahedra in a triangular lattice (hexago-nal lattice a

H~2.85 and c

H~10.8 Å), with Na ions

occupying ordered or disordered positions in theinterleaving planes that form by four different Na

ions order/disorder configurations. For x=1 the Naions are completely ordered and fully occupy the 2d(2/3, 1/3, 1/4) site of a P6

3/mmc symmetry. At x=0.5

the Na ions occupy the 2a and 2b sites of Pnmmsymmetry (ao~1.73aH, bo~2aH, co ~ cH), formingzigzag chains. In the range of x between 1 and 0.75,the Na ions randomly occupy the 2b(0, 0, ¼) and2c(2/3, 1/3, 1/4) sites of P6

3/mmc symmetry and the

occupancy at the 2c site increases with x increasing.For x between 0.75 and 0.5 and between 0.5 and0.3, the Na randomly occupy the 2b(0, 0, ¼) and6h(2x, x, ¼) sites in P6

3/mmc and the occupancy at

the 6h site decreases with decreasing x. Structuralparameters as a function of x indicate slope changesat x=0.75.

W2-C3 (14:15) Crystal Structure of the SodiumCobaltate Deuterate SuperconductorNaxCoO2 4xD2O (x=1/3)

M. Avdeev, J.D. Jorgensen, D.G. Hinks, J.C. Burley, S.Short, P.W. Barnes (Materials Science Division,Argonne National Laboratory)

Neutron and x-ray powder diffraction have been usedto investigate the crystal structures of a sample of thenewly-discovered superconducting sodium cobaltatedeuterate compound with compositionNa0.31(3)CoO2*1.25(2)D2O and its anhydrous parentcompound Na0.61(1)CoO2. The deuterate superconduct-ing compound is formed by coordinating four D2Omolecules (two above and two below) to each Na ionin a way that gives Na-O distances nearly equal tothose in the parent compound. One deuteron of theD2O molecule is hydrogen bonded to an oxygenatom in the CoO2 plane and the oxygen atom and thesecond deuteron of each D2O molecule lie approxi-mately in a plane between the Na layer and the CoO2

layers. This coordination of Na by four D2O moleculesleads to ordering of the Na ions and D2O molecules.The sample studied here, which has Tc=4.5 K, has arefined composition of Na0.31(3)CoO2*1.25(2)D2O, inagreement with the expected 1:4 ratio of Na to D2O.The crystal structure of the intermediate monolayerhydrate is discussed.

W2-C4 (14:30) Spin structure and dynamics in thehalf-doped La1.5Sr0.5CoO4 (Invited)

I. A. Zaliznyak, J. M. Tranquada, G. Gu (PhysicsDepartment, Brookhaven National Laboratory), R.W. Erwin (National Institute of Standards andTechnology), Y. Moritomo (Center for IntegratedResearch in Science and Engineering (CIRSE),Nagoya University, Nagoya 464-8601, Japan)

Magnetic order and spin dynamics in the charge-ordered phases of the doped, strongly correlatedtransition metal oxides such as superconducting


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cuprates, magnetoresistive manganites, etc., are atthe focus of the modern condensed matter research.The interplay of charge, spin and/or orbital degrees offreedom in these systems results in non-trivialground states and leads to many fascinating physicalproperties, such as a magnetic field driven metal-insulator transition, etc. In order to understand therelative importance of the various interactions it isimperative to explore the properties of differentmaterials in the strongly correlated oxides family.Here we report a study of the charge and spin opderand the spin dynamics in the half-doped cobaltate,La1.5Sr0.5CoO4, by elastic and inelastic neutronscattering. We find a short-range correlated, glassycharge order (CO) which occurs at a very hightemperature, Tc = 825(25) K. It is of the checker-board type, which is not unexpected at half doping,and is essentially two-dimensional. This orderingdoes not seem to depend on the spin order, which isincommensurate and occurs only below Ts ~ 30 K.The spin system, on the contrary, is essentiallydefined by the charge-ordered ground state, whereCo3+ ions are in the S=1, intermediate spin (IS) state.As a result, these ions seem to be quenched to theSz = 0 state at low T by the strong single-ion anisot-ropy, and do not participate in the static magneticordering. However, they bridge the magnetic Co2+

ions and introduce a diagonal, frustrating couplingbetween them. Peculiar coupling of the Co2+ andCo3+ spin systems leads to a very unusual spindynamics, where a well-defined 2D spin waves withbandwidth ∆SW ~ 15 meV are followed by a broadcontinuum scattering at E > 20 meV.

W2-D, Low Dimensional Magnetism, Chair:Stephen Nagler (ORNL), Room 2101/3/5 Green

W2-D1 (13:30) Spin Echo Study of the Dynamics ofSpin Ice (Invited)

G. Ehlers (Spallation Neutron Source, Oak RidgeNational Laboratory), J. S. Gardner (PhysicsDepartment, Brookhaven National Laboratory; NISTCenter for Neutron Research), N. Rosov (NISTCenter for Neutron Research), W. Häussler (InstitutLaue Langevin), S. T. Bramwell, J. Lago (Departmentof Chemistry, University College London, 20 GordonStreet, London WC1H 0AJ, UK)

Neutron spin echo measurements have been per-formed at NIST and at ILL on the spin ice relatedmaterials Ho2-xYxTi2O7 (0 ≤ x ≤ 1.8) to study the spinrelaxation processes in the paramagnetic phase(T>1 K) [1]. A cross-over from a thermally activatedsingle-ion process to a temperature independentquantum mechanical process occurs at T ≈ 15 K insamples with moderate magnetic dilution (x ≤ 1.1).

However in very dilute samples x ≥ 1.6 another,faster relaxation process appears at relatively hightemperature (up to at least T ≈ 55 K). Our neutrondata will be discussed in relation to complementarya.c. susceptibility and µSR results.

[1] G. Ehlers, A. L. Cornelius, M. Orendac, M.Krajnakova, T. Fennell, S. T. Bramwell, and J. S.Gardner, J Phys: Condens. Matter 15, L9 (2003).

W2-D2 (14:00) Spin-waves in antiferromagneticKagome lattice

K. Matan (Department of Physics, MIT), D. Grohol,D. Nocera (Department of Chemistry, MIT), S. -H.Lee (National Institute of Standards andTechnology), S. Nagler (HFIR Center for NeutronScattering, Oak Ridge National Laboratory, OakRidge, Tennessee 37831, USA.), Y. S. Lee(Department of Physics, MIT)

We have used inelastic neutron scattering to studyspin-waves in single crystal samples of the antiferro-magnetic kagome lattice compound, KFe3(OH)6(SO4)2.The 5/2 Fe3+ spins on the kagome lattice order threedimensionally for temperatures below the Neeltemperature, TN = 65 K. Spin-waves were measuredat T = 10 K, much lower than TN. We have observeda novel weakly dispersive “zero-energy mode”, whichis a consequence of the geometrical frustration. Aspin Hamiltonian, which includes nearest-neighbor,second-nearest-neighbor interactions, easy-plane andeasy-axis anisotropies, provides a good fit to our spin-wave data. We will discuss the implications of ourresults for the physics of the ideal kagome lattice.

W2-D3 (14:15) Spin, orbital, and lattice couplingsin a geometrically frustrated magnet CdV2O4

Z. Zhang, A. Visinoiu, D. Louca (Department ofPhysics, University of Virginia), Y. Qiu, S. Park(NIST Center for Neutron Research), T. Proffen, J.Thompson (Los Alamos National Laboratory), S.-H.Lee (NIST Center for Neutron Research)

The microscopic properties of the vanadate spinelsare distinctly different from those of the chromatesdue to the intrinsic orbital degeneracy of the vana-dium ion. We studied a vanadate compound, CdV2O4,to investigate how the orbital degree of freedomcouples to the lattice and spin. CdV2O4 undergoes acubic-to-tetragonal transition at 87 K and a magneticlong range order at 35 K. This contrasts with thechromates where a tetragonal distortion and amagnetic long range order occurs simultaneously dueto a spin-lattice coupling. We have performed neu-tron diffraction and inelastic neutron scatteringmeasurements on a powder sample of CdV2O4. Uponcooling, the Q-lineshape of the inelastic scattering


intensity changes from symmetric in the cubic phaseto asymmetric in the tetragonal phase. This indicatesthat the vanadate becomes a system of weaklycoupled straight chains in the tetragonal phase. Wewill discuss implication of the results to the interplaybetween the orbital, spin and lattice degrees offreedom in the vanadates.

W2-D4 (14:30) Cooperative ordering of gapped andgapless spin networks in Cu2Fe2Ge4O13

T. Masuda (Condensed Matter Sciences Division,Oak Ridge National Laboratory), B. Grenier(DRFMC/SPSMS/MDN Cntre dEtudes Nucleares), A.Zheludev (Condensed Matter Sciences Division, OakRidge National Laboratory), S. Imai, K. Uchinokura(Department of Advanced Materials Science, theUniversity of Tokyo), E Ressouche (DRFMC/SPSMS/MDN Cntre dEtudes Nucleares), S. Park (NISTCenter for Neutron Research)

The unusual magnetic properties of a novel low-dimensional quantum ferrimagnet Cu2Fe2Ge4O13 arestudied by neutron scattering and bulk methods. Thecrystal structure of this material contains chains ofFe3+ ions intercalated by paired Cu2+ sites. Themagnetic susceptibility in the high temperatureregion is described by the simple sum of classicalS=5/2 spin chains and S=1/2 quantum dimers. Inthe 3D ordered state neutron diffraction revealsstrongly reduced moments on Cu2+ and large mo-ments on Fe3+, respectively. The observed linearrelation between mCu and mFe is consistent with theCu2+-spins being bound in a gapped spin-singletstate. Low-energy spin excitations up to 10 meVenergy transfer are studied by cold neutron inelasticscattering. The measured dispersion relation can beunderstood as that of Fe3+ spin chains with effectiveinter-chain coupling. A combination of experimentaltechnique reveals that the material can be describedin terms of two subsystems with distinct energyscales. Magnetic ordering in this case is a cooperativephenomenon caused by interactions between thesetwo units.

This work was carried out under DOE Contract No.DE-AC05-00OR22725.

W2-D5 (14:45) Dynamics of a Z2xZ2 invariant(non-Haldane) S=1 quantum chain

A. Zheludev (Condensed Matter Sciences Division,Oak Ridge National Laboratory), L.-P. Regnault(MDN/DRFMC/SPSMS CEA-Grenoble, France), M.Hagiwara (RIKEN, Waco, Japan), T. Masuda(Condensed Matter Sciences Division, Oak RidgeNational Laboratory)

Integral antiferromagnetic spin chains are bestknown for having an exotic spin liquid ground state

and the Haldane gap in the magnetic excitationspectrum. Considerably less attention has been givento a different spin liquid realized in integral spinchains with alternating exchange interactions. Inpractice, the two ground states and the correspond-ing excitation spectra are notoriously difficult todistinguish, due to the fact that they only differ intopological “hidden” spin correlators.

We present two series of inelastic neutron scatteringexperiments on a bond-alternating S-1 quantum spinchain compound NTENP. In the first series of mea-surements [1] we exploit the Hohenberg-Brinkman1st moment sum rule to directly measure the distri-bution of exchange energies in the ground state. Theresults allow us to unambiguously identify NTENP asa Z2xZ2 invariant (non-Haldane) spin liquid. We thenproceed to study the spin dynamics in NTENP instrong external magnetic fields [2]. At Hc=11 T weobserve a closing of the spin gap and a field-inducedBose-condensation of magnons. Surprisingly, the high-field state is very similar to that of a classical one-dimensional magnet. The excitation spectrumconsists of a doublet of conventional spin-wave-likeexcitations. Such behavior is in stark contrast withthat previously seen in the Haldane-gap antiferro-magnet NDMAP in similar conditions [3]. Here thehigh-field phase is a quantum spin solid characterizedby a triplet of coherent breather excitations.

[1] A. Zheludev, T. Masuda, B. Sales, D. Mandrus, T.Papenbrock, T. Barnes, S. Park, cond-mat/0310741.[2] M. Hagiwara, L.-P. Regnault and A. Zheludev, tobe published (2004)[3] A. Zheludev et al., cond-mat/0308545; Phys. Rev.B 68, 134438 (2003); Phys. Rev. Lett. 88, 077206(2002), and references therein.

W2-D6 (15:00) Bound spinons in an antiferromag-netic S=1/2 chain with a staggered field (Invited)

M. Kenzelmann (Department of Physics &Astronomy, Johns Hopkins University; NIST Centerfor Neutron Research), Y. Chen (Los AlamosNational Laboratory), C. Broholm (Department ofPhysics & Astronomy, Johns Hopkins University;NIST Center for Neutron Research), D. Reich(Department of Physics & Astronomy, JohnsHopkins University), C.D. Batista (Los AlamosNational Laboratory), Y. Qiu, S. Park (Department ofMaterials Science and Engineering, University ofMaryland)

Strongly-correlated charge and spin degrees offreedom can lead to cooperative many-body stateswhich are believed to have wide implications for themacroscopic properties of complex solids. Theemergent character of such states can give rise to


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non-linear excitations which are very different fromthose in more conventional systems like the Fermiliquids or ordered magnetic structures.We haverecently studied the antiferromagnetic S=1/2 chainin high uniform and staggered fields using variouscold neutron scattering techniques. We have foundthat the spinon excitations bind under the influenceof the staggered field and appear as well-definedexcitations in the neutron spectra. This is in starkcontrast to broad neutron scattering spectra observedfrom S=1/2 chains in zero field. In the long wave-length limit, the experiments are in excellent quanti-tative agreement with predictions of soliton andbreather excitations of the quantum sine-Gordonmodel. On finite length scales, we find that a map-ping of the Hamiltonian to a gas of interactingfermions with spin explains the dispersion of theobserved excitations surprisingly well.

W3-A, Breakout Sessions, Chair: Shenda Baker(Harvey Mudd)

W3-A1: Breakout Session: Perspectives for NeutronScattering of Biomembrane Systems

M. Loesche, S. H. White, D. J. Tobias, J. K. BlasieNeutron scattering of biological systems has for sometime been under represented in this country. Conse-quently, there is a noticeable gap in the levels ofactivity in this area between the US and other worldregions. The CNBT (“Cold Neutrons in Biology andTechnology”) initiative aims at closing this gap bypromoting structural characterization ofbiomembrane systems using a concerted approachthat involves neutron and x-ray scattering, high-performance computing, and NMR spectroscopy.With the advent of the AND/R, a new neutronspectrometer at NCNR’s NG-1 guide which is gearedtoward reflectometry and diffraction studies ofmembranous systems, US neutron science is on theleap back to making an impact on biology-relatedproblems. This is also important in view of the SNScoming on-line in a few years, an event which willprovide a dramatic boost to neutron-related sciencein a much broader context. We will discussprospectives and opportunities of the CNBT inmembrane science, aiming at potential outside usersfrom the life science and biotech communities.

W3-A2: Breakout session on Use of Depleted UTargets at Low and Medium Power SpallationSource

Jim Rhyne (LANL/LANSCE) and Ray Teller (ANL/IPNS)

The development of cubic uranium metallic phasescreates the possibility of the use of these materials inmedium power spallation neutron sources allowing

an increase of perhaps 70-80% in neutron productionper proton. The purpose of this session is to: 1)present the case of the use of these materials; 2) toassess the interest within the community to developa new generation of U targets; and 3) initiate adiscussion about the issues that would arise shouldsuch a development be deemed worthwhile.

W3-A3: Breakout Session on the SNS MagnetismReflectometer

F. Klose (Spallation Neutron Source, Oak RidgeNational Laboratory)

This session will review the progress in design, thestatus of procurements and the planned scientificprogram of the SNS Magnetism Reflectometer. TheInstrument Advisory Team of the instrument andother interested scientists are welcome to attend.

W3-A4: Breakout Session: Portable software forneutron scattering

T. G. Worlton (Intense Pulsed Neutron Source,Argonne National Lab), D. J. Mikkelson (Universityof Wisconsin-Stout), P.F. Peterson (SpallationNeutron Source, Oak Ridge National Laboratory)

Development of portable software for neutronscattering will facilitate use of neutron facilities byvisiting scientists. Adoption of a NeXus data formatfor storage and interchange of data can help makethis possible, but work on file definitions for someneutron instruments is still incomplete. Tools such asISAW and NXvalid can be used as a tools to examine,visualize, and analyze data from NeXus files and arecurrently being used at LANSCE and IPNS. Scientistsfrom Argonne, Los Alamos, SNS, and the Universityof Wisconsin-Stout are collaborating on specificationsfor NeXus files which will contain all the informationneeded for visualization and analysis. In this sessionwe will discuss information which should be stored inNeXus files and tools which can be used to read,visualize, reduce, and analyze the data.

W3-A5: Breakout Session on Doing Science withNeutron Scattering Data

B. Fultz (California Institute of Technology), X-L.Wang ( Spallation Neutron Source, Oak RidgeNational Laboratory)

The purpose of this breakout session is to describetoday’s software for the analysis of neutron scatteringdata, describe new developments, and seek view-points on future needs. The focus of the session willbe on the science enabled by software, with lessemphasis on specific software packages or softwareengineeering. For example, the leaders may steer thediscussion towards how new computing resources forsimulations, modeling, and visualization enable new


experiments, or elevate the sophistication of experi-ments possible today.

The session will be divided into one-hour sub-sessions on the topics below. Each will begin with ascheduled 12-15 minute presentation. “Flash presen-tations” follow—attendees who prepare 2-3viewgraph transparencies prior to the session will begiven 3-5 minutes for a brief presentation. Opendiscussion will follow the flash presentations.

3-4 PM Diffraction and Engineering Diffraction(Simon Billinge and Ersan Ustundag)4-5 PM SANS and Reflectometry (Paul Butler and PaulKienzle)5-5:30 PM Inelastic Scattering (Frans Trouw andBrent Fultz)

W3-A6: Breakout Session on Sample Environmentat Neutron Scattering Facilities

K. J. Volin (Intense Pulsed Neutron Source, ArgonneNational Lab), D. C. Dender (NIST Center forNeutron Research), J. S. Fieramosca (Intense PulsedNeutron Source, Argonne National Lab), L. J.Santodonato (Spallation Neutron Source, Oak RidgeNational Laboratory)

Sample environment staff from some of the majorUS neutron scattering facilities will make presenta-tions and facilitate open discussion on topics relevantto the use of sample environment for neutronscattering experiments. Presentations will be madeon: a prototype system called the Fast ExchangeRefrigerator for Neutron Science (FERNS) [1], amodular system that combines familiar cryogenictechnology with more recent automation technology;modifying existing sample environment equipmentbeyond its originally designed operating parametersto accommodate newer and more demandingscientific studies; and pitfalls and successful strate-gies to employ when contracting for new equipment.Lessons learned during the performance of neutronscattering experiments using a variety of sampleenvironments will also be presented and discussed,including experiences with equipment, operations,and procedures and how these experiences changedthe way sample environments are handled.

[1] A collaborative effort with R. Weber and J. Rix ofContainerless Research, Inc., conducted under aDepartment of Energy Small Business InnovationResearch grant.

W3-A7: Breakout session on the Fermi Chopperspectrometers for the SNS

D. Abernathy (Spallation Neutron Source, Oak RidgeNational Laboratory), B. Fultz (California Institute

of Technology), B. Gaulin (Department of Physicsand Astronomy, McMaster University, Hamilton,ON, Canada), G. Granroth (Spallation NeutronSource, Oak Ridge National Laboratory), S. Nagler(Condensed Matter Sciences Division, Oak RidgeNational Laboratory)

The ARCS and SEQUOIA spectrometers are the wideangle and high resolution Fermi chopper spectrom-eters planned for the SNS. This breakout session willprovide the IDT’s, and other interested parties, withupdates on the design and procurements of the twospectrometers. Furthermore the community will havethe opportunity to share their preferences on severaldesign issues. Specifically we will discuss require-ments for sample access and the optimization ofchopper slit packages.

W3-A8: Breakout session for VISION, an neutronvibrational spectrometer for SNS

J.Z. Larese (Chemistry Department,, University ofTennessee; Oak Ridge National Laboratory), B.S.Hudson (Chemistry Department, SyracuseUniversity), L.L. Daemen (LANSCE, Los AlamosNational Laboratory)

At this breakout discussion we will discuss theVISION project, a neutron vibrational spectrometerfor the SNS. We encourage all interested participantsof the ACNS to attend. At the breakout session we willprovide information on the purpose, performanceand status of the VISION project in the form of ashort presentation. VISION has been designated bySNS as one of the viable instruments for inclusion inthe first target station instrument suite. We will followthe informational segment with a town meeting orround table discussion to address community inclu-sion, outreach and participation by members of theneutron community. We will close with a brief teammeeting to discuss and develop a strategy to movethe project into the next (design and engineering)phase and to discuss funding and technical issuesthat are relevant to the project at the time of theACNS meeting. Several members of the VISION teamwill be called upon to give a brief highlight of thetypes of science possible with such an instrument.There is a need in the United States for a state-of-the-art neutron scattering instrument for vibrationalspectroscopy to investigate the structure and dynam-ics of condensed matter systems by the simultaneoususe of elastic diffraction and moderate resolution(1-2% ∆E/E) inelastic scattering over a broad energytransfer range. The use of neutron vibrational spec-troscopy (NVS) is growing at a significant rate inEurope thanks to the second-generation instrumentTOSCA at ISIS, the spallation neutron source at theRutherford-Appleton Laboratory in England. We


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propose to design a next generation, time of flight(TOF) spectrometer named, VISION, which is not anacronym, to investigate a vast array of moleculardynamics and structure. Under optimal conditionsthis instrument will - have a throughput two orders ofmagnitude greater than TOSCA –currently the bestinstrument in the field; - cover an energy transferrange of 0-500 meV (0-4000 cm-1 ); - have a 1-2%energy resolution while simultaneously enablingdiffraction studies for structural characterization; -offer a wide range of sample environments (lowtemperature, high-pressure, flow cell, thermal analy-sis, etc). Our approach will incorporate neutrontechniques developed during the decade since TFXAand TOSCA were first designed and built. Thisincludes improved supermirror technology, para-metrically matched crystal analyzer–helium gasdetectors, efficient electronics for high rate dataacquisition, high-performance data analysis algo-rithms, novel moderator concepts, as well as the useof (by now) well-developed Monte Carlo software forneutron optics and instrument design and optimiza-tion. The flux available at SNS will enable for the firsttime time-resolved vibrational measurements at aneutron source. Proposals to form an InstrumentDesign Team (IDT) and a subsequent proposaldescribing the scientific background for VISION havebeen presented to the Spallation Neutron Source(SNS) Experimental Facilities Advisory Committee(EFAC) and have been positively received. (EFAC hasenthusiastically endorsed the science case presentedby the IDT and a beamline position for installationand construction of VISION has been identified bySNS.) We are confident that VISION’s broader impactwill be that an entirely new segment of users will bebrought into the U.S. neutron community. This isexemplified by the extraordinary expansion in recentyears of the community of scientists in the UnitedKingdom and the European Union using TOSCA atISIS. Indeed, TOSCA is now routinely oversubscribedby a factor of 1.5 to 2. The demand for beam time isso great that only a few days per year are available toinvestigate novel applications. Furthermore, theVISION instrument will introduce a new generationof students and researchers to the use of neutronvibrational spectroscopy in the study of new materi-als and a wide range of engineering problems,especially those materials that have interestingstructure and dynamics on the nanometer lengthscale and topics of commercial importance. VISIONwill substantially expand the range and flexibility ofneutron investigations in in the United States. It willopen new and fruitful directions for studies of atomicand molecular dynamics and structure in condensedmatter.

W3-A9: Breakout Session on Detectors and SCD forSNS

Christina Hoffmann (SNS, Oak Ridge NationalLaboratory), R. Bau, T. F. Koetzle and A. J. Schultz

A best-in-class single-crystal diffractometer (SCD)utilizing the time-of-flight Laue technique is underdevelopment for the Spallation Neutron Source (SNS).The 2 MW SNS, currently under construction in OakRidge, TN, USA, is scheduled to begin operation in2006. Because sample volumes will approach thoseof typical “x-ray crystals,” SNS SCD promises torevolutionize the application of single-crystal neutrondiffraction as we know it, particularly from theviewpoint of the practicing synthetic chemist. Theinstrument will be specifically optimized for high-throughput on samples with moderate-size unit cells,up to ca. 50 Å on edge. Provision is also intended forthe measurement of diffuse scattering and for theproduction of polarized beams to facilitate the studyof magnetic structures. The authors are executiveofficers of the Instrument Development Team (IDT)for the SCD, which will be operated in a broadlybased user mode.

We want to invite the IDT and interested researchersto participate in this breakout session to voice theuser community’s future needs for single-crystalneutron diffraction. The session will provide anopportunity to actively define an instrument that isoptimized for the community’s needs. It will also bean opportunity to update the user community onrecent instrument design studies and developments.Progress has been made on development of polar-ized neutron options for white beam single-crystaldiffraction, on neutron detector design concepts, andon evaluation of options for neutron beam focusing.

W3-A10: Breakout Session on HYSPEC: A NovelDirect Geometry Polarized Beam Inealstic Instru-ment for the SNS

M. Hagen (Spallation Neutron Source, Oak RidgeNational Laboratory), S. M. Shapiro I. A. Zaliznyak(Brookhaven National Laboratory)

HYSPEC is a direct geometry inelastic scatteringspectrometer for single crystal and polarized neutronstudies at the SNS. The instrument combines time-of-flight spectroscopy and focusing Bragg optics toenhance the monochromatic neutron flux on smallsamples. It is a moderate resolution instrumentoptimized for an incident energy range of 3.6–60meV. HYSPEC will be designed to do polarizedneutron studies using a Heusler crystal monochroma-tor and supermirror bender analyzers for the polar-ization analysis of the scattered neutrons. There willbe presentations describing the instrument design


and estimated performance along with the importantsimulations aimed at keeping the background to aminimum. This breakout session will serve as an IDTMeeting, but is open to all who have an interest inlearning about HYSPEC and have the desire to use apolarized beam inelastic scattering instrument.

ThursdayMorning Visit to the NIST Center for NeutronResearch (Buses depart the Inn at 8:30)


Author IndexAAbdel-Raouf, E: WP41Abdul-Redah, T: M3-D2, WP65Abernathy, DL: W3-A7, TP66, WP37Agamalian, M: M2-C4, WP34Agnew, SR: W2-A2Aivazis, MAG: TP73, WP75Al-Ghamdi, S: WP41Alcantar, NA: T1-B3Alessi, ML: MP12Alexandrov, YuA: TP43Allen, A: T2-B1Allen, AJ: T2-B2Allis, Damian: MP9Allis, DG: WP23Amis, EJ: M4-D1Amos, K: TP41Ando, Y: MP39Andreani, C: MP17, WP66Angelopoulos, Marie: M2-B5Ankner, JF: M2-C5Arai, M: M4-A5, WP60Argyriou, DN: WP63Arif, M: M4-B3Arleth, L: M2-B2Armstrong, TR: TP15Arnold, T: TP14, WP11Aronson, MC: TP58Arrott, AS: T1-C4Ashbaugh, HS: T1-A2, WP44Ash, BJ: WP22Ashish, : WP3Assoud, A: WP70Avdeev, M: W2-C3Azuah, RT: TP69, WP61

BBakeeva, RF: WP46Baker, SM: WP51Balsara, NP: M2-B1, MP26Bao, W: M4-A4, T2-D2Bau, R: W3-A9Barbier, J: T3-A2Barilo, SN: TP60Barker, JG: M2-B6, M2-C4, T2-B2, T3-B3, TP36Barnes, PW: W2-C3, TP13Baronov, S: WP23Barrera, GD: M3-D5Batdemberel, G: WP67Batista, CD: W2-D6Bauer, ED: T2-D3Baxter, DV: T1-D1Beise, EJ: M4-B2


Benesi, AJ: TP8Benmore, CJ: T2-C5, MP15, TP49, TP70Bennett, KA: T3-C6Bennington, S: WP60Benson, ML: M3-A5, MP31, MP32Berk, NF: M3-B3, WP4Berliner, R: T2-B3, TP24Berlinsky, AJ: MP46Beskrovny, AI: WP67Billinge, SJL: MP38, WP70Birgeneau, RJ: M3-C1, TP55, TP56Black, DJ: WP7Black, TC: M4-B3Blasie, JK: T1-B1, W3-A1Bleuel, M: M2-C3Blumenthal, DK: WP5Blumenthal, WR: W2-A2Boatner, LA: M3-C6Boerio-Goates, J: TP64Bonn, D: TP56Boothroyd, AT: WP59Borchers, JA: M2-A3, M2-A5, T2-C1, MP43Bossev, DP: MP1, M3-B5, M4-D1, MP2, WP78Boukari, H: TP46Bourke, MAM: T3-C2, W2-A2, TP12, WP17Bouzek, C: TP71, WP72, WP74Bowman, JD: T1-D3Braden, DA: MP9, WP23Bramwell, ST: W2-D1Brand, PC: TP19, TP30, WP38Briber, RM: W1-A1, MP22, MP24, MP23, WP13, WP8Brissier, T: WP57Britten, JF: T3-A2Brocker, C: TP30Broholm, CL: M3-C4, MP35, TP53, W2-D6, WP38Broussard, LJ: MP18Brown, CM: MP49, MP5, TP18, TP22, TP8, WP19, WP23, WP49,

WP64Brown, DW: M3-A5, T3-C2, W2-A2, MP29, MP30, MP32Brown, SP: M4-A3, WP5Buchanan, MV: TP33, WP9Buchanan, RA: M3-A5, MP30, MP32Bud’ko, SL: T1-C3Bugaev, V: MP36Burley, JC: W2-C3Burnham, C: M4-C3Burns, R: WP19Butler, PD: M4-D4, MP6, MP10, TP33, WP48, WP9Buyers, WJL: TP56Bychkov, GL: TP60

CCaliskan, GH: M3-B4, MP3, MP50, WP8Cameron, JM: T1-D1


Caneba, GT: M2-B6Canfield, PC: T1-C3Cappelletti, RL: TP4Carey, MJ: M2-A5Carneim, RD: TP15Carpenter, JM: T1-D5, T2-C2, TP21, WP34Carvalho, LB: MP48Casson, J: TP47Castellan, JP: MP46Cava, RJ: W2-C2Chadraabal, Sh: WP67Chakoumakos, B: MP40Chanaa, S: TP14Chang, S: WP62Chapon, LC: WP63Chatterjee, A: TP70, TP71, WP72Chatterji, T: T3-A4, TP61Chen-Mayer, HH: T2-C2Chen, C: T3-B1Chen, JJ: T2-B2Chen, Sow-Hsin: M4-C1Chen, WC: T2-C1Chen, Y: M4-A4, W2-D6Cheong, S-W: M3-C2, M3-C4, TP54, TP63Chernenkov, YuP: TP60Chiarelli, P: TP47Chien, CL: M2-A2Chi, Lisheng: WP12Choi, BH: TP29Choi, S-M: WP42Choi, YH: TP29Choo, H: M3-A5, T3-C2, MP29, MP30, MP31, MP32Cho, SJ: TP29Chowdhuri, Z: T3-B1, MP3, TP4Christen, DK: M4-A5Christianson, AD: T2-D2, T2-D3Christoph, V: WP35Chung, Brian: T3-B5Chupas, PJ: T3-A6, WP70Chupp, TE: MP18Cianciolo, TV: T1-D3Cicerone, MT: M3-B4, MP50Ciezak, JA: MP5Ciezak, Jenn: MP9Clarke, S: TP14Clausen, B: WP17Clausen, KN: T1-A4Clemens, D: T2-C7Clow, B: TP28, WP30Cole, DR: M4-C2Collins, MF: TP17, WP60Conlon, K: W2-A2Cook, RE: TP14Cooper, M: T1-D3Cooper, RL: MP18, TP74


Copland, E: WP15Copley, JRD: MP36, MP46, TP64, TP66Coulter, KP: MP18Cowan, JA: T2-B6, WP74Craig, S: WP58Crawford, MK: TP64Criswell, L: T3-B4Crow, L: TP74Crowe, S: M4-A5Cubitt, R: M4-A3Cummins, P: MP27Curtis, JE: T2-A3, WP21

DDabkowska, HA: MP46, T3-A2Dadmun, MD: M2-B3, M4-D2, MP13, WP16Daemen, LL: M3-D4, W3-A8, MP30, T2-B5, TP9, TP14, TP40, WP10,

WP28Dai, P: M4-A1, T3-A3, MP39, TP67, WP62Darling, T: M3-C7Dashjav, E: WP70Dattelbaum, AM: W2-B3Daud, SofianM: M3-B2David, SA: MP29Daymond, MR: M3-A5, MP31, MP33, TP39De Lurgio, PM: TP38Deb, PK: TP41Delaire, O: M3-A3, MP44Dender, DC: TP28, W3-A6, WP24, WP30Derakhshan, S: WP70Derenchuk, VP: T1-D1Dewey, MS: M4-B2, MP18, TP42Dewhurst, CD: M4-A3Diallo, S: WP61Diama, A: T3-B4Diat, O: MP20Dimeo, RM: M2-D2, T3-B4, MP49, TP69Dmowksi, W: M3-C7Dogan, F: WP62Dolgos, M: WP18Donner, W: MP48Dosch, H: MP36Doshi, DA: W2-B3Doucet, M: TP72Douglas, JF: T3-B2Doyle, J: T1-D3Drew, AJ: M4-A3Drews, AR: M2-C4Dufour, C: M2-A3Dumesnil, K: M2-A3Dura, JA: TP25, WP36Durham, WB: T3-C6Dzhosyuk, SN: M4-B5


EEckert, J: M3-D1, M3-D4, TP40, WP10Edwards, L TP39Egami, T: M3-C7Egelstaff, PA: TP49Egres, RG: MP28Ehlers, G: W2-D1Eklund, PC: M4-C5Elashvili, I: M3-B1Elices, M: W2-A3Epand, RM: T1-B2Erwin, RW: M3-C2, M3-C6, W2-C4Eykens, R: TP42

FFaller, R: MP51Fan, Lixin: TP45Faraone, Antonio: M4-C1Farinelli, MJ: TP14Fedeyko, JM: MP7Fei, X: TP42Felcher, GP: M2-A2Feng, H: MP22Feng, Z: MP29Fernandez-baca, JA: T3-A3, WP69Fernandez-Garcia, J: M4-C4Fetters, LJ: WP44Fieramosca, JS: W3-A6, TP26Filabozzi, A: WP66Fink, Charles: TP38Fischer, JE: M2-B4, WP14Fisher, BM: M4-B2Fisher, RA: TP64Fisk, Z: TP58Fitzgerald, E: TP28, WP30Flippen, R: TP64Foecke, TJ: T3-C3Foo, ML: W2-C2Forgan, EM: M4-A3Frazier, L: WP11Freedman, SJ: MP18Freeman, PG: WP59Frick, B: TP61Frielinghaus, H: M4-C2Frost, C: WP59Fuess, H: WP67Fuhrmann, D: T3-B4Fujikawa, BK: MP18Fujita, M: M4-A2Fultz, BT: M3-A3, MP44, T2-D5, TP73, W3-A5, W3-A7, WP37, WP68,

WP75Furdyna, JK: MP43Furrer, A: TP60


GGaehler, R: M2-C3Gangoda, M: M3-B4, MP50Garamus, V: TP37Garcia-Sakai, V: T3-B1Garcia, A: MP18Gardner, JS: MP40, T2-D2, W2-D1Garlea, E: MP30Garlea, VO: M3-A2, T1-C3, TP50, TP51Gaulin, BD: MP46, W3-A7Gauthier, M: MP24Gauthier-Picard, P: TP20Geelan, M: TP9Gehring, PM: M3-C3, M3-C5Gentile, TR: M4-B2, T2-C1Georgiev, PA: M4-C4Georgii, R: T2-C4Gerber, MichaelJ: W2-B2Ghazi, H: T3-A2Ghosh, VJ: TP23Gibson, WM: T2-C2Giebultowicz, TM: M2-A4Gilardi, R: M4-A3Gilbert, EP: TP59, WP19Gilliam, DM: TP42Glanville, YJ: MP49Glinka, CJ: M2-B4, M2-C2, M2-C4, MP21, MP27, T2-C6, WP13, WP42Glyde, HR: WP61Gnaupel-Herold, T: T3-C3, W2-A3, WP55Gog, T: T1-B4Goka, H: M4-A2Goldberger, J: TP7Goldfarb, D: M2-B5Goossens, DJ: T3-A5, TP57Gopalakrishnan, V: M4-D5Gordon, J: WP55Goremychkin, EA: T2-D3Gorini, G: MP17, WP66Goukassov, A: TP60Gourieux, T: M2-A3Granroth, GE: TP66, W3-A7Gray, CP: WP70Greedan, JE: T3-A2, WP12Greenblatt, M: M2-D5Greene, GL: T1-D3, TP42Greenwald, BS: MP28, WP42Greer, SC: MP12Gregory, R: MP3Gregory, RB: M3-B4, MP50Gregurick, SK: MP11,T2-A2Grenier, B: W2-D4, TP53Greven, M: MP37, MP47Grohol, D: W2-D2Gschneidner Jr, KA: TP51


Gu, B: M4-D4Gudkov, V: M4-B4Gu, GD: M4-A2, W2-C4Guo, L: M2-B6, TP45, WP52Gupta, K: MP2Gurney, BA: M2-A5Guthrie, M: TP49Guttmann, M: MP40Gu, X: T3-B3

HHadzi, D: M3-D4Haese-Seiller, M: T2-C4, WP26Hagen, M: W3-A10Hagiwara, M: W2-D5Hamilton, WA: M4-D4, T1-B3, W2-B1, WP48Hammonds, JP: TP70, TP71,WP72, WP74Hammouda, B: MP27, TP58Hansen, FY: T3-B4Haravifard, S: MP46Harden, James: T3-B5Hardy, WN: TP56Harlow, RL: TP64Harpham, MR: MP25Harris, AB: T1-C1Harrison, N: MP35Harrison, NM: TP54Hartig, C: T2-C8, WP57Hartl, M: M3-D4, WP10Hartman, MR: T2-B3Hasan, ZM: TP63Head-Gordon, T: T2-A4He, B: T1-A3He, D: M2-D5Heffner, RH: M3-C7Hehlen, MP: WP71He, J: MP40Heller, WT: TP33, WP5, WP7, WP9Hemley, RJ: M2-D3, M2-D5Hennion, B: M3-C6Hennion, M: M2-A3Hersman, FW: M4-B1Herwig, KW: M4-C6, T3-B4, MP25Hettinger, JD: TP68Hiera, KJ: T2-C5Hilger, A: MP16Hinde, R: WP11Hinks, DG: W2-C3Hiraka, H: M3-C3Hjelm, RP: M2-B2Hobbie, EK: M2-B4Hodges, J: WP39Hodges, JP: TP34


Ho, DL: M2-B4, T3-B3, MP12, WP13, WP14Hoffmann, A: MP43Hoffmann, C: TP74, W3-A9Holden, TM: W2-A2Holderna-Natkaniec, K: WP31Holt, SA: M3-B2Homouz, D: MP45Honda, Z: TP53Hong, GP: TP29Hong, JH: WP56Hong, K: WP47Hong, KS: M3-C7Hormadaly, J: TP64Horsewill, AJ: M2-D2Horton, DJ: T3-C4Howard, CA: MP42Huang, C-Y: MP21Huang, JG: MP31Huang, JS: W2-B4Huang, JY: MP31Huang, Q: W2-C2, TP4, TP64Hubbard, CR: T3-C2, MP29, MP30, WP58Hudson, BS: MP5, MP9, W3-A8, TP16, TP40, WP23Huffman, PR: M4-B3, T1-D3Hundertmark, PK: WP38Huq, A: WP27Hura, G: T2-A4Hur, N: M3-C2Hu, Tengjiao: M2-B5Hu, Z: M2-B2Hwang, PJ: TP62Hwang, SR: MP18Häussler, W: W2-D1

IIjiri, Y: M2-A1Imai, S: W2-D4Iniguez, J: M3-D6Iolin, E: WP25Islam, MF: WP14Isnard, O: TP6Itoh, K: TP17, WP60Iwase, H: WP60

JJacobson, DL: M4-B3, TP19James, M: T3-A5, WP32Jenkins, T: MP9, WP23Jeong, I-K: M3-C7Jeon, JW: T3-C2Jin, R: TP67Jones, CY: M2-D4, TP19, TP2, TP51, WP15Jones, GL: MP18


Jones, JL: WP43Jones, Ronald: M2-B5Jorgensen, JD: W2-C3

KKacman, P: M2-A4Kaiser, H: WP6Kakurai, K: TP57Kalus, J: WP31Kamaras, K: WP64Kamath, SK: M2-B3, M4-D2Kamitakahara, WA: WP20Kamiyama, T: TP17Kampmann, R: T2-C4, WP26Kanatzidis, MG: WP70Kang, H: MP39Karen, P: T3-A1, TP13, TP7Kartini, E: TP17, WP60Kastner, MA: TP55Katsaras, J: MP21Katsumata, K: TP53Keegan, N: M3-B2Keller, T: W2-A4Kelley, TM: T2-D5, MP44, TP73, WP75Kennedy, SJ: T1-D2, WP60Kent, MS: T1-B4Kenzelmann, M: M3-C4, W2-D6Kepa, H: M2-A4Keppens, V: TP66Kern, S: T2-D4Khaykovich, B: TP55Kienzle, PA: WP76Kim, HC: MP23Kim, HJ: WP70Kim, H-Ch: MP22Kim, JH: WP56Kim, M-H: M2-C4, T2-C6, WP49Kim, SB: M3-C4Kim, SJ: WP75Kim, YJ: TP29Kintzel, Jr, EJ: M4-C6Kirby, BJ: MP43Kiriluk, KG: M4-B2Kiryukhin, V: M3-C2Kisliuk, A: M3-B4, MP50Kitchens, CL: WP78Kjær, K: MP51Klann, RT: TP38Klarstrom, DL: M3-A5, MP32Kleinke, H: WP70Klose, F: W3-A3, WP35Klug, DD: TP49Klupp, Gy: WP64Kneller, LR: TP69


Koetzle, TF: T2-B6, W3-A9Kohlbrecher, J: M3-A4Kohn, J: W2-B4Kolesnikov, AI: M4-C3Koo, YM: WP56Kozlowski, P: TP16Kozlowski, T: T1-D4Kramer, D: T1-A4Kresch, M: WP68Kresch, MG: M3-A3, MP44Krishnamurthy, LN: M4-D3Krishnamurthy, VV: T1-A3, WP41Krist, Th: T2-C3Krueger, JK: WP3, WP7Krueger, S: M3-B1, T1-B2, T2-A2, MP11, MP2, TP46, WP4, WP50, WP8Kudryashov, V: T2-C4, WP26Kuhl, TL: T1-B3, MP51Kulkarni, A: T3-C5Kuo, RC: MP31Kurita, Y: MP39Kuzmanovic, DA: M3-B1Kwon, SC: WP56Kyratsi, T: WP70Kögerler, P: TP50

LLaakmann, J: WP57Ladanyi, BM: MP25Lago, J: W2-D1Lai, K-C: MP24Laine, RM: WP71Lakey, JH: M3-B2Lal, J: M2-C3, W2-B4Lamberty, A: TP42Landee, CP: TP48Lander, GH: T2-D4Langan, P: T2-A1Lang, E: TP38Lan, Y: WP23Larese, JZ: W3-A8, TP14, TP40, WP11LaRock, JG: WP38Lashley, JC: T2-D5Lavelle, C,: T1-D1Lawrence, JM: T2-D3Lawson, A: TP9Lawson, AC: T2-D5Lay, M: M2-B3, M4-D2Lay, MA: MP13Lea, C: WP6Leao, JB: TP18, TP22, WP24, WP30, WP64Lee, CH: TP29Lee, J-K: M3-C7Lee, JS: TP29Lee, MN: WP56


Lee, PL: TP64, WP70Lee, S-H: M3-C2, M3-C3, M4-A4, W2-D2, W2-D3, MP46Lee, SL: M4-A3Lee, VY: MP22Lee, WT: M2-A2, WP39Lee, YS: W2-C1, W2-D2, TP55Leheny, R: T3-B5Lehmann, E: T1-A4Letzring, HF: MP30Leuschner, MB: T1-D1Levinger, NE: MP25Lewis, P: T1-D4Liang, L: M4-D4Liang, R: TP56Liaw, PK: M3-A5, T3-C2, T3-C4, MP29, MP30, MP31, MP32Lieutenant, K: T2-C7LI, JC: M3-D2, WP65Li, JF: M3-C5Li, L: MP34Lim, WL: MP43Lin-Gibson, S: MP10Lin, E: M2-B5Ling, CD: MP41Lin, J: WP68Lin, Z: MP23Lising, LJ: MP18Littrell, KC: M2-C3, TP44, WP34, WP40Liu, CT: WP69Liu, L: M4-C1Liu, X: MP43Livescu, V: TP12Livingston, RA: T2-B1, TP5, TP8Li, W-H: TP62Li, Y: TP63, WP27Llobet, A: T2-D2, TP11Lobanov, MV: M2-D5Lobo, RF: M2-D1, MP7, TP2Loesche, M: W3-A1Lofland, SE: TP68Lograsso, TA: M3-A2, TP51Loizou, E: MP10Lokshin, K: WP28Lokshin, KA: M2-D5Lone, MA: T1-D1Loong, C-K: M4-C3Lorenzo, JE: M4-A4Louca, D: T3-A6, W2-D3Loutfy, RO: M4-C3Lufaso, MW: TP10, TP13Lumsden, MD: TP67, WP73Lutterotti, L: T2-C8Luzin, V: T3-C6, W2-A3, MP34, WP55Lynn, GW: TP33, WP9Lynn, JW: M3-C4, T2-D2, T3-A6, TP58, TP63, W2-C2, MP47, TP30,

TP62, TP64, TP68, WP38, WP63


MMaat, S: M2-A5Majerz, I: WP31Majewski, J: T1-B3, T1-B4, W2-B3, TP47, MP51, WP51Majkrzak, CF: M2-A4, M3-B3, T2-C1, WP36, WP4Major, J: MP36Maliszewskyj, NC: TP72Malliakas, C: WP70Malwitz, M: MP10, MP6Mamontov, E: TP6Mancini, DC: M2-B6Mandrus, D: MP40, TP66, TP67Mandrus, DG: TP65Mangan, MA: WP43Mangin, Ph: M2-A3Mang, JT: WP71Mang, PK: MP37, MP47Mankey, GJ: T1-A3, WP41Manley, ME: WP43Mao, H-K: M2-D3, M2-D5Mao, WL: M2-D5Maple, MB: T2-D1Maranas, JK: T3-B1Margadant, N: W2-A4Marmotti, M: T2-C4Martin, JD: T2-B4Martínez-Iñesta, MM: M2-D1Mason, TE: W1-A3Masuda, T: W2-D4, W2-D5Matan, K: W2-D2Maxey, ER: T2-C2, T3-C4, WP27Mayers, J: M3-D2, WP65Mays, J: WP47McDaniel, SM: T3-C6McGillivray, DJ: WP4McGregor, DS: TP38McKerns, MM: TP73, WP68, WP75McLain, SE: MP15, TP49, WP18McLaughlin, JC: TP5McMorrow, DF: TP50McQueeney, RJ: T2-D4, T2-D5, WP43, WP62McQueen, T: WP51Mecking, H: WP57Medina, T: TP9, WP57Mehta, R: M2-B3, M4-D2, WP16Melnichenko, YB: M4-C2, WP47Mesecar, Andrew: WP39Mesot, J: M4-A3, W1-A2Metting, CJ: TP68Meyer, E: WP57Meyer, HO: T1-D1Meyer, O: WP57Mezei, F: T1-D4, T2-C3, T2-C7Micklich, BJ: TP21


Middleton, CT: WP23Migliori, A: T2-D5Mignot, JM: T2-D2Mihailescu, M: M3-B3, W2-B4Mikkelson, DJ: TP70, TP71, W3-A4, WP72, WP74Mikkelson, RL: TP70, TP71, WP72, WP74Mikula, P: WP25Mildner, DFR: T2-C2Miller, CE: MP51Miller, M: WP72, WP74Miller, ME: T2-B6, T2-C2Miller, M: WP74Miller, RD: MP22, MP23Mitchell, JF: T3-A6, WP63Modi, N: WP7Mo, H: T3-B4Mojet, B: WP10Monkenbusch, M: W2-B4Moodenbaugh, AR: TP7Mook, HA: M4-A1, TP65Moravsky, AP: M4-C3Moreno, NO: T2-D2, T2-D3Moritomo, Y: W2-C4Morosan, E: T1-C3Morrison, I: M4-C4Morrison, MM: MP30Moss, SC: M3-A1, MP36Motahari, SM: MP33Moyer, J: M2-C4, WP38Mumm, HP: MP18Murbach, M: TP30Myles, DAA: TP33, WP9

NNaday, Istvan: TP38Nagler, SE: TP50, TP65, TP66, TP67, W2-D2, W3-A7Nair, S: M2-D2Nakajima, K: WP59Nakotte, H: T2-D4Nann, H: T1-D1Narayanan, RA: WP22Narehood, DG: M4-C5Natkaniec, I: WP31Necker, CT: T2-C8Neiser, R: MP34Nelson, A: WP32Nemes, NM: T2-B1, TP5, WP64Neumann, DA: M2-D2, M3-D3, T2-B1,T3-B4, MP36, TP18, TP22, TP5,

WP21Neumeier, JJ: MP41Nico, JS: M4-B2, MP18, TP42Niedermayer, C: , TP50Nieh, M-P: MP21Nikles, DE: T1-A3


Noakes, DR: T1-C4Nocera, D: W2-D2Nossal, R: TP46Notardonato, W: TP12NPDGamma Collaboration: M4-B1Nufris, S: WP66

OO Brien, CP: M2-B3O’Donovan, KV: M2-A5, T2-C1, MP43, WP36, WP76Ohwada, K: M3-C3Okorokov, A: WP26Oldfield, E: WP6Osborn, R: M2-C1, T3-A6Oszlanyi, G: WP64O’Connell, C: M3-B1

PPagliuso, PG: T2-D2, T2-D3Paliwal, A: MP1Palosz, B: WP43Palosz, W: WP43Pang, J: T3-C2Pantea, C: WP28Parikh, AN: W2-B3Parise, J M2-D3Parizzi, AA: WP35Park, DG: MP32, WP56Park, JS: M3-C7Park, SY: M3-C2, M4-A4, W2-D3, W2-D4, W2-D6, MP30, TP63Passell, L: TP23Paulaitis, ME: MP1, MP2, WP50Paul, DMcK: M4-A5Pauwels, J: TP42Payzant, EA: TP15, WP58Pecharsky, AO: TP51Pecharsky, VK: TP51Peets, D: TP56Pencer, J: T1-B2, MP2, TP1, WP50Penin, N: T3-A2Penttila, S: T1-D4Peral, I: M2-D1, M2-D4, M3-B4, M4-C6, T3-B1, MP3, TP2, MP50, WP15Perelli-Cippo, E: MP17, WP66Perez-Salas, UA: WP4, WP8, WP36Perring, TG: M4-A2, WP59Persechini, A: WP7Peters, J: T2-C7Peterson, EJ: WP43Peterson, P: WP74Peterson, PF: W3-A4, WP77Peterson, VK: MP4Phair, JW: TP8Pheiffer, S: TP72


Piao, M: T1-A3Pierce, DL: WP36, WP38Pietropaolo, A: MP17, WP66Pike, TD: TP19, WP38Pirling, T: W2-A4Pittman, Jr, C: MP14Pivovar, AM: T2-A3Plakhty, VP: TP60Platzman, P: M3-D2, MP45, WP65Podlesnyak, A: TP60Polachowski, S: M2-C2Porcar, L: M4-A5, M4-D4, T1-A3, W2-B1, MP10, MP28, MP6, WP42,

WP48Pozzo, DC: MP19Prabhakaran, D: WP59Prabhu, VM: M4-D1Prask, H: W2-A3Prask, H-J: T3-C3, MP34, WP55Prince, T: TP19Proffen, TE: M2-D1, M3-C7, MP38, W2-D3, TP11, TP15, WP18, WP33Prokes, K: T2-D2Prud’homme, RK: T1-A2, W2-B4, WP44Purwanto, A: TP17

QQian, J: WP28Qiu, X: MP38, WP15, WP70Qiu, Y: M4-A4, W2-D3, W2-D6, MP46, TP50, TP64, TP69

RRadaelli, PG: TP54Radulescu, A: WP44Raebiger, J: M2-C2Rajaram, R: T2-D4Rajewska, A: WP46Ramakrishnan, S: M4-D5Ramanujachary, KV: TP68Ramirez-Cuesta, AJ: M3-D5, WP11Ramirez-Cuesta, T: TP14Rangan, P: WP8Rappl, TJ: M2-B1, MP26Ratcliff II, W: M3-C2, TP54, TP63Rathod, CR: TP12, WP17Refson, K: TP54Regnault, LP: T3-A4, W2-D5, TP53Rehm, C: M2-C5, WP34, WP39Reich, DH: MP35, W2-D6Reichert, H: MP36Reiter, GF: M3-D2, MP45, WP65Ressouche, E: W2-D4Rhodes, N: MP17, WP66Rhyne, JJ: MP43, TP11, W3-A2Richardson, JW: T2-C2, T3-C4, WP27, WP53, WP69


Richter, D: W2-B4, WP44Rinckel, T: T1-D1Riseborough, PS: T2-D3Rix, JE: T2-C5, TP27Roberts, CB: WP78Roberts, J: TP9Robertson, JL: MP36, MP48, WP41, WP73Robertson, RGH: MP18Robinson, J: TP47Robinson, RA: T1-D2, TP57, TP59Rodriguez, E: TP11Rodriguez, JA: MP36Rodriguez, MA: WP43Rogan, RC: MP33Rogante, M: WP54Roh, JH: M3-B4, MP3, MP50Root, JH: W2-A1Rosenkranz, S: M2-C1, T3-A6Rosov, N: M3-B5, M4-D1, T3-B1, W2-D1Ross, DK: M4-C4Rowe, JM: M1-B2Rubatat, L: MP20Ruiz-Hervias, J: W2-A3Rusevich, L: WP25Rush, JJ: TP6Russell, TP: MP8Russel, WB: W2-B4Russina, M: T1-D4Russo, D: T2-A4

SSackett, DL: TP46Sackmann, E: WP26Saibal B, : TP32Sakuma, T: TP17Saleh, TA: M3-A5, T3-C2, MP31, MP32Sales, BC: TP65Sampath, S: MP34Sangaa, D: WP67Sankowski, P: M2-A4Santhosh, PN: TP7Santodonato, LJ: W3-A6, TP27, WP29Santoro, A: TP19Sarrao, J: M4-A4Sarrao, JL: T2-D2, T2-D3Sasaki, DY: T1-B4Satija, S: T1-B4Schadler, L: WP22Scharfstein, G: WP38Scherer, G: T1-A4Schiffer, P: WP63Schlagel, DL: TP51Schmidt, G: MP10, MP6Schmidt, M: TP54


Schneibel, JH: WP53Schoenborn, BP: T2-A1Schoen, K: M4-B3Schoen, KP: TP35Schooneveld, EM: MP17, WP66Schreyer, A: WP26Schultz, AJ: T2-B6, T2-C2, W3-A9, WP39, WP74Schulz, JC: WP19, WP32, WP42Schwahn, D: WP44Schwartz, F: T2-A2Schweizer, K: M4-D5Scierka, S: T3-B3Seeger, PA: TP40Senesi, R: MP17, WP66Seong, BS: TP29Serum, B: WP72Shannon, N: T3-A4Shapiro, SM: M3-C6, TP23, TP53, W3-A10Shaw, WJ: WP4Sherstobitova, E: TP52Shim, CM: TP29Shin, EJ: TP29Shirane, G: M3-C1, M3-C3, M3-C5Shiryaev, SV: TP60Shmalo, S: TP12Short, S: W2-C3, WP15Shreve, AP: W2-B3Siewenie, JE: T2-C5, MP15Sipatov, AY: M2-A4Skipper, NT: MP42Skomorokhov, AN: WP67Smee, SA: WP38Smeibidl, P: TP55Smirnov, L: WP67Smith, GS: T1-B3, TP74, W2-B1, WP51Snow, WM: M4-B3, T1-D1, T1-D3, TP42Sokolov, AP: M3-B4, MP3, MP50Sokolov, D: TP58Sokol, PE: M4-C5, MP49Soles, CL: T3-B2Somasundaran, P: MP27Soriano, S: M2-A3Speakman, SA: TP15Spooner, S: WP58Stare, J: M3-D4Stassis, C: M3-A2, T1-C3, TP50, TP51Sternstein, SS: WP22Stevens, RW: TP64Stock, C: M3-C1, M3-C5, TP56Stoica, A: WP34, WP58Stoica, AD: M3-A5, T3-C4, WP53, WP69Stone, MB: MP35, WP63Streule, S: TP60Strobl, M: MP16, WP25Strzalka, J: T1-B1


Stuhr, U: TP31Stull, JT: WP7Stunault, A: M2-A3Sung, L: T3-B3Sun, JR: TP62Sun, Y: MP31Surendra S, : TP32Svitelskiy, O: M3-C6Swainson, IP: T3-A2, WP12Swan-Wood, TL: M3-A3, WP68

TTakata, S: T2-A3Tangeman, JA: T2-C5Tan, J: WP51Tao, J: WP72Tao, JZ: TP70Tardocchi, M: MP17, WP66Taub, H: T3-B4Taylor, GB: WP29Taylor, SS: WP5te Velthuis, SGE: MP43Teller, R: W3-A2Terashita, H: MP41Thirumalai, D: WP8Thiyagarajan, P: M2-B6, M4-C3, TP38, TP45, WP22, WP34, WP39, WP52Thomas, JJ: T2-B2Thompson, AK: M4-B2, MP18Thompson, H: MP42Thompson, J: W2-D3Thompson, JD: T2-D3Tian, H: T3-C4Tirumala, VR: M2-B6Tobias, DJ: W3-A1, WP21Toby, BH: TP19, W2-C2Toghiani, H: MP14Tokura, Y: T3-A3Tome, CN: W2-A2Tomioka, Y: T3-A3Toomey, RG: T1-B3Toperverg, B: WP26Torbet, J: WP6Torikachvili, MS: TP57Toulouse, J: M3-C6Tranquada, JM: M4-A2, W2-C4, WP59Treimer, W: MP16, WP25Trewhella, J: WP5, WP7Trouw, FR: T2-D3, TP47, WP62, WP71Trull, C: MP18Tsao, FC: TP62Tulk, CA: M2-D3, TP49Tung, C-S: WP7Turnbull, MM: TP48


Turner, J: WP18Turner, JFC: MP15, TP49

UUchinokura, K: W2-D4Udovic, TJ: M3-D3, TP18, TP22, TP4, TP6Uefuji, T: M4-A3Urban, VS: TP33, WP9Urquidi, J: TP49Ustundag, E: T3-C1, MP33

VVaidyanathan, R: TP12, WP17Vajk, OP: M3-C4, MP47Vaknin, D: T1-C2, TP50Van Gestel, J: TP42Varkey, SP: TP2Verdal, N: TP16Viehland, D: M3-C5Vigil, D: WP5Visinoiu, A: W2-D3Vlachos, D: MP7Vogel, SC: T2-C8, T2-B5, TP9, W2-A2, WP28, WP43, WP57Vokhmyanin, AP: TP52Volin, KJ: W3-A6Volkmann, UG: T3-B4Volksen, W: MP23Volz, H: TP9Von Dreele, RB: T2-C8Vorderwisch, P: MP35, TP55

WWada, N: WP20Waddington, ED: T3-C6Wagner, NJ: M4-D3, MP28, WP42Wagner, W: M3-A4, W2-A4, TP31Wakimoto, S: M3-C1, TP55Walker, LM: MP19Walker, LM: W2-B2Wang, H: M2-B4, TP47, WP14Wang, W: M4-D4Wang, X: T2-B6Wang, X-L: M3-A5, T3-C4, W3-A5, WP53, WP69Wang, YD: T3-C4, WP53Wasse, JC: MP42Watkins, EB: TP47, W2-B3Weber, JKR: T2-C5, TP27Wenk, HR: T2-C8Werner, SA: M4-B3, TP35Weygand, M: MP51White, SH: M3-B3, W3-A1Wick, C: M3-B1


Wiebe, CR: T3-A2Wiest, JM: T1-A3Wietfeldt, FE: M4-B2, MP18Wignall, GD: M4-C2, TP33, WP47, WP9Wilemsk, G: T1-A1Wilkerson, JF: MP18Williams, DJ: T2-B5, T2-C8, TP9, WP28, WP43, WP57Willumeit, R: TP37Wilson, C: MP40Wilson, S: TP67Winey, KI: M2-B4, WP14Withers, RL: T3-A5Withnall, R: WP23Wietfeldt, FE: TP42Wojowicz, T: MP43Woodfield, BF: TP64Woodruff, T: TP12Woodson, SA: WP8Woodward, FM: TP48, WP63Woodward, PM: T3-A1, TP13, TP7Woodward, R: TP59Woo, H: M4-A2, WP59Woo, W: MP29Worcester, D: WP6Worlton, TG: W3-A4, TP70, TP71, WP72, WP74Wozniak, Denis: TP38Wrenn, C: TP30Wright, MC: WP58Wu, J: M2-B2Wu, W-l: M2-B5, T3-B2Wyslouzil, BE: T1-A1

XXia, X: M2-B2Xu, G: M3-C5, M4-A2Xu, GY: M3-C3Xu, J: WP10Xu, Ting: MP8

YYamada, K: M4-A2, M4-A3, M4-A6, TP55, WP59Yang, B: MP30, MP31Yang, B-S: W2-B4Yang, CC: TP62Yang, FY: M2-A2Yang, L: WP69Yardimci, Hasan: T3-B5Yaron, PN: TP14Ye, F: T3-A3Ye, S: T1-B1Yethiraj, M: M4-A5, TP65, WP73Yildirim, T: M3-D3Yim, H: T1-B4


Yodh, AG: WP14Yong, G: M3-C6Yoonessi, Mitra: MP14Youngman, R: T2-C2Yu, DH: TP59Yue, B: MP21Yun, Seok-Il: MP24Yun, SI: WP47

ZZaliznyak, IA: MP35, W2-C4, TP23, W3-A10Zandbergen, HW: W2-C2Zanotti, J-M: M4-C3Zarestky, JL: M3-A2, T1-C2, T1-C3, TP50, TP51Zhang, J: T1-A4, WP28Zhang, R: MP27Zhang, Y: TP64Zhang, Z: W2-D3Zhao, JK: TP37Zhao, Y: M2-D5, WP28Zheludev, A: W2-D4, W2-D5, TP53Zhong, Z: M3-C5Zhou, J: T2-A2, MP11Zhou, Q: MP27Zhou, W: M2-B4, WP14Zhu, AJ: WP22Zhu, F: M2-A2Zoto, I: WP41Zukoski, C: M4-D5

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