Ssgf Magazine 2013
Transcript of Ssgf Magazine 2013
-
7/23/2019 Ssgf Magazine 2013
1/28
STEWARDSHIP
SCIENCEThe SSGF Magazine 2013-2014
PRESSUREPREDICIONSHow Sandia is refining matter modelsby applying first principles
Los Alamos: Neutron
beam record-breaker
Livermore: At the edge
of the periodic table
Plus: Former fellow goes to Washington,
more juice for Z, bringing the big bang
down to size, fission and scission, and
SSGF on the road.
-
7/23/2019 Ssgf Magazine 2013
2/28
Department of Energy National Nuclear Security Administration
BENEFITS
$36,000 yearly stipend
Payment of full tuition and required fees
$1,000 yearly academic allowance
Yearly program review
12-week research practicum
Renewable up to four years
This is an equal opportunity program and is open to all qualified persons without regard to race, gender, religion, age, physical disability or national origin.
IMAGESLEFT: A metallic case
called a hohlraum holds the fuelcapsule for National Ignition Facility
experiments at LawrenceLivermore National Laboratory.
MIDDLE: At Sandia NationalLaboratories, high magnetic
fields on the aluminum side of thismagnetically launched aluminum/copper
flyer drive it into diamond targets attens of kilometers per second,
generating enormous pressures andshock waves in the diamond.
RIGHT: X-ray laser flashes generated inan undulator, an arrangement of magnets
that directs high-energy electrons. Imagecourtesy of Los AlamosNational Laboratory.
The Department of Energy National Nuclear Security Administration Stewardship Science
Graduate Fellowship (DOE NNSA SSGF) program provides outstanding benefits and
opportunities to students pursuing a Ph.D. in areas of interest to stewardship science,
such asproperties of materials under extreme conditions and hydrodynamics, nuclear science,
or high energy density physics. The fellowship includes a 12-week research experience
at Lawrence Livermore National Laboratory,
Los Alamos National Laboratory
or Sandia National Laboratories.
The DOE NNSA SSGF program is open to senior undergraduates or students in their first or second year of
graduate study. Access application materials and additional information at:
APPLY
ONLINE
www.krellinst.org/ssgf
Stewardship Science
Graduate Fellowship
Krell Institute | 1609 Golden Aspen Drive, Suite 101
Ames, IA 50010 | 515.956.3696
email: [email protected]
FOR MORE INFORMATION
APPLICATIONS DUE
MID JANUARY
-
7/23/2019 Ssgf Magazine 2013
3/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE PC
MUCH OFthe discussion in Washington these days revolves aroundfiscal restraint, doing more with less and the dreaded S word: sequestration.Even in this environment, there is a continuing understanding of the value
of science by NNSA leadership and the nations elected representatives.
This fourth edition of Stewardship Science: The SSGF Magazinerepresents a
milestone since the magazines publication now spans an entire class of
fellows! Our shared commitment to sustaining programs like the Stewardship
Science Graduate Fellowship represents the value we place on developing the
leaders of tomorrows scientific endeavors. The work highlighted in this issue
shows the return on those investments.
In missions that range from reducing the risks of nuclear terrorism or theproliferation of nuclear weapons technology to responding to nuclear accidents like the
one at Fukushima in Japan, NNSA relies on tools and technology based on a fundamental
understanding of nuclear science. The work of fellow Matthew Buckner at Lawrence
Livermore National Laboratory (page 4) on Accelerator Mass Spectrometry (AMS) advances
the state-of-the-art of a key diagnostic tool. AMS is used in several fields, including
detecting signatures of nuclear fuel reprocessing an important nonproliferation
function. Matthew used AutoCAD, along with simulation tools, to build a prototype
detector, install it and test it on a Livermore accelerator beamline.
At a more fundamental level, fellow Nicole Fields worked on calibrating a key material
during her research practicum at Los Alamos National Laboratory (page 7). Fieldsexamined germanium-76, an isotope researchers hope will find evidence of neutrinoless
double-beta decay. This rare interaction is key to understanding neutrinos and can
help in advancing our fundamental knowledge of the universe. She used neutron beams
from LANSCE, the Los Alamos Neutron Science Center, to simulate cosmic ray exposure
so she could calibrate the effects of this radiation for future experiments.
In related work, fellow Joshua Renner conducted his practicum at Livermore (page 7) on
the technology for time projection chambers (TPCs). These TPCs also are designed
to detect evidence of neutrinoless double-beta decay. Renner worked with physicist Adam
Bernstein on the negative ion TPC and used simulation tools to emulate ion drift behavior.
These tools provided clues to help maximize the efficiency of Livermores detector forthese rare interactions.
From fundamental exploration to prototype development, Stewardship Science fellows
are advancing the frontiers of nuclear science and helping NNSA build its future.
Christopher Deeney
L E T T E R F R O M N N S A
Investing in the Future
Christopher Deeney
Assistant Deputy Administrator
for Stockpile Stewardship
U.S. Department of Energy National
Nuclear Security Administration
With assistance from Mark Visosky
Senior Technical Advisor
TechSource, Inc., contractor to NNSA
-
7/23/2019 Ssgf Magazine 2013
4/28
P2STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
FEATURES LAB INITIO 10
By Jacob Berkowitz
Sandias Luke Shulenburger and colleagues are harnessing the power of quantum Monte
Carlo methods to boost matter models accuracy. Theyre already finding that elements
under extreme temperatures and pressures behave in unexpected ways.
IN THEIR ELEMENT 15By Karyn Hede
The newest, heaviest elements on the periodic table are difficult to produce and oftenquickly disappear, making it hard to quantify their properties. Livermore scientists are
finding new ways to separate and understand these strange substances.
THE BEAM COUNTERS 19By Thomas R. ODonnell
Los Alamos National Laboratorys Trident, a powerful laser that produces fleeting pulses,
has racked up a new neutron beam record. The experiment could lead to more precise
detectors and to compact neutron sources for science and nuclear forensics.
Stewardship Science: Te SSGF Magazine showcases researchers and graduate students at U.S.
Department of Energy National Nuclear Security Administration (DOE NNSA) national laboratories.
Stewardship Scienceis published annually by the Krell Institute for the NNSA Office of Defense
Sciences Stewardship Science Graduate Fellowship (SSGF) program, which Krell manages for NNSA
under cooperative agreement DE-FC52-08NA28752. Krell is a nonprofit organization serving the
science, technology and education communities.
Copyright 2013 by the Krell Institute. All rights reserved.
For additional information, please visit www.krellinst.org/ssgf or contact the Krell Institute 1609
Golden Aspen Dr., Suite 101 |Ames, IA 50010 |Attn: SSGF |(515) 956-3696
STEWARDSHIP
SCIENCEThe SSGF Magazine 2013 - 2014
I I I
I I I
FIRST-PRINCIPLE INVESTIGATO
This visualization by Sandia National LaboratLuke Shulenburger shows a charge densityfor FeO (iron oxide) calculated with quantuMonte Carlo methods. Iron oxide is of inteto geophysicists, but modeling its electronstructure is challenging. Shulenburger beloto a corps of young mathematicians whoinclude Miguel Morales of Lawrence LivermNational Laboratory, an alumnus of the NaNuclear Security Administration StewardshScience Graduate Fellowship working oufundamental properties of this and other mabased on first-principles physics. Read morstarting on page 10.
COVER
-
7/23/2019 Ssgf Magazine 2013
5/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P3
2 0 1 3 2 0 1 4
IMAGE CREDITS
Cover, Luke Shulenburger, SandiaNational Laboratories (SNL);page 1, National Nuclear SecurityAdministration; page 4, WalidYounes, Lawrence LivermoreNational Laboratory (LLNL);page 5, SNL; page 6, ATLASExperiment/CERN; page 9,Laura Berzak Hopkins; pages
10-12, Shulenburger/SNL; pages16-17, LLNL; pages 19-20,Markus Roth, TechnicalUniversity of Darmstadt;page 21, julsdesign (source:Los Alamos National Laboratory[LANL]); pages 22-23, LANL.
EDITOR
Bill Cannon
SR. SCIENCE EDITOR
Tomas R. ODonnell
DESIGN
julsdesign, inc.
COPY READERSRon WintherShelly Olsan
CONTRIBUTING WRITERS
Monte BasgallJacob Berkowitzony Fitzpatrick
Karyn HedeTomas R. ODonnell
Sarah Webb
SSGF STEERING COMMITTEE
Robert VoigtNuclear Security Division
SAIC
Darryl P. ButtDepartment of Materials Science and Engineering
Boise State University
Stephen M. SterbenzLos Alamos National Laboratory
Kimberly S. BudilLawrence Livermore National Laboratory
Ramon J. LeeperSandia National Laboratories
DEPARTMENTSFRONT LINES
4 FISSION UP CLOSE Deciphering the details of atom splitting.
FELLOWS ON LOCATION
The latest SSGF graduates design a detector, test elements for gamma
ray exposure, put tantalum under pressure, track some particles and
measure ion-stopping power.
5 Z, SUPERCHARGED Sandia plans to amp up the Z machine in the same space.
6 LITTLE BIG BANG Probing the properties of the quark-gluon plasma.
9 CONVERSATION: BRIDGINGSCIENCE, POLICY AND THE PUBLIC
Former fellow Laura Berzak Hopkins on providing science expertise to
Congress, fusions two varieties and her Why-Sci communications project.
SAMPLINGS
24 BOTTLING THE SUNFellow Evan Davis probes the slim sliceof turbulence that has an outsized say
in fusion energys viability.
DIRECTORY
25 DOE NNSA SSGF FELLOWSWhere to find current fellows
and alumni.
-
7/23/2019 Ssgf Magazine 2013
6/28
P4STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
F R O N T L I N E S
DETECTOR UPGRADE
Matthew Bucknerspracticum at Lawrence
Livermore National Laboratory was a bit like a
high-tech physicists shop class. His plans for an
improved gas ionization chamber detector went
from computer modeling to fabrication
at a machine shop and testing.
Buckner worked with Scott Tumey at Livermores Center for Accelerator
Mass Spectrometry. Accelerator mass spectrometry, or AMS, speeds ions
to high energies, separating isotopes from surrounding material before
mass analysis. AMS is used in several fields, including detecting signatures
of nuclear fuel reprocessing an important nonproliferation function.
The device Buckner made uses AMS to measure transition metal
activation products. He simulated a previous design on a computer
and found that voltages were incorrectly applied for the detector
anodes to adequately collect electrons. After some research, he usedsimulations to tailor the new detector design to transition metal
activation products and modified grids, voltages and other aspects.
Using AutoCAD software, Buckner designed a detector enclosure
for fabrication at the labs machine shop, then built the detector and
installed it on the accelerator beam line. He and Tumey tested it
with relevant materials and Buckner compared its resolving power
with that of the original detector. The new detector is more sensitive
and bolsters the labs nuclear forensics capabilities, Tumey says.
The fellow, meanwhile, says the project was a contrast with his doctoral
work at the University of North Carolina at Chapel Hill. Under
Christian Iliadis, Buckner has studied proton capture by rare oxygen
isotopes thermonuclear reactions associated with nucleosynthesis
and energy generation in a class of stars and with explosive hydrogen
burning during classical novae. During the summer, he reports, it
was really interesting to participate in an application of the nuclear
and accelerator physics Im interested in.
Members of DOE National Nuclear Security Administration
Stewardship Science Graduate Fellowships 2013 outgoing
class share their national lab research experience.
continued on page 7
Fission Up Close
Although it releases vast amounts of energy, the processof splitting atomic nuclei is still difficult to understand
in detail. Nuclei are infinitesimally small and fission
happens incredibly quickly (within 10-20 seconds), so
its hard to study in a laboratory.
Undaunted, Lawrence Livermore National Laboratory researchers are
looking at fissions microscopic detail with the hope of improving
nuclear waste management and recycling and increasing nuclear power
production. Describing fission in detail also can help answer basic
science questions, such as how heavy elements formed in the universe.
Physicists started delving into fission theoretically 75 years ago by
simplifying the problem. Instead of looking at all the protons and
neutrons within the nucleus, they considered it as a liquid drop,
Livermores Walid
Younes says. During
fission, the drop would
stretch into an oblong
peanut shape. At
the scission point,
the narrow neck in
the peanut wouldbreak to form two
new atomic nuclei
and release energy.
Even today, with
high-performance
computers, the
data challenges for
understanding fission remain enormous. If you put all that information
into a computer, Younes says, youd quickly be looking at tens of millions
of processor hours as the simulation moves toward scission.
Despite the difficulty, Younes and his colleagues have extended the
traditional droplet model. Instead of considering the nucleus as a
single stretching blob, their calculation includes protons and neutrons
that arrange themselves within the droplet in a way thats energetically
favorable. Tey then stretch the theoretical nucleus until it breaks
naturally and probe how that force affects the individual particles.
We dont force it, he says. We dont take a knife and cut it in two.
continued on page 6
A schematic illustration of microscopic fission
calculations for plutonium-240. The arrows
epresent evolution of the nucleus in the calculation
across its energy surface toward its breaking
point. On the right are three examples of the
nuclear configuration near breaking.
F E L L O W S O N L O C A T I O N
-
7/23/2019 Ssgf Magazine 2013
7/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P5
Z, Supercharged
By far the worlds largest, most powerful and mostsuccessful pulsed-power accelerator, Sandia National
Laboratories Z machine is poised to become even
more powerful.
Te Z machine named for z-pinch, a type of plasma device driven by
pulsed-power accelerators generates an 80-terawatt electrical power
pulse. Its 33 meters in diameter and fills the high bay of Building
983 on the labs Albuquerque, N.M., campus. Tanks to LD technology,
for linear transformer driver, over time Z will become Z 300, a
300-terawatt machine that will fit the same space.
Te Z 300 will generate twice the current and four times the power that
Z now generates, says William Stygar, manager of the labs Advanced
Accelerator Physics Department, which specia lizes in pulsed-power
accelerator physics. With that capability, Z 300 will be able to perform
ultra-precise high energy density physics experiments in support of
various Department of Energy missions, including the Stockpile
Stewardship Program of the National Nuclear Security Administration.
Stygar is confident that Z 300 will quadruple pressures for conducting
material-physics experiments with plutonium, uranium and other
critical elements; achieve thermonuclear ignition in an inertially confineddeuterium-tritium plasma; quadruple the energy and power radiated
by non-thermal X-ray sources for weapon-physics and weapon-effects
experiments; and quadruple the energy and power radiated by thermal
X-ray sources for laboratory astrophysics, radiation opacity and
radiation transport experiments.
John Porter, senior manager of Sandias Z accelerator sciences group,
was the first to propose building a next-generation LD accelerator
that fits inside the same building.
Te High Current Electronics Institute (HCEI) at omsk, Russia, beganwork on LD technology about 10 years ago. Sandia has developed the
technology to its present state. Stygar, a Sandia researcher since 1982,
says Russia, Israel, France, England, China and other countries already
use LD technology to drive high energy density physics experiments.
LD technology dates back to 1920s, when Erwin Marx described his
self-named generator. Tirty-six Marx generator-driven pulsed-power
modules create the 26-megampere, 80-terawatt pulse that powers Z.
A Marx generator creates a 1 microsecond-long power pulse. Z
experiments, however, require a 100-nanosecond power pulse, so
four stages of pulse compression must reduce the span of the Marxpulse. Pulse-compression hardware introduces electrical impedance
mismatches, causing multiple internal reflections of the Z power pulse
and reducing Zs efficiency. In addition, Stygar says, pulse compression
hardware substantially complicates the design of a machine like Z,
increasing maintenance costs and ramping up the difficulty of
developing an accurate accelerator circuit model and conducting
accelerator simulations.
An LD generates a 100-nanosecond power pulse in a single step,
which eliminates the need for additional pulse-compression hardware,
Stygar says. As a result, an LD module is twice as efficient as aMarx-driven module, substantially more compact, less costly to
maintain and easier to simulate.
Te belly of the LD beast is a collection of 20 bricks arrayed in a
circle like the spokes of a wheel. Each shoebox-sized brick holds a
200-kilovolt switch and two 100-kilovolt capacitors. Te bricks are
inside an annular enclosed metal cavity that looks like a g iant Life
Savers candy, Stygar says.
Z 300 will be driven by 90 LD modules, each consisting of 33 LD
cavities (each cavity is 2 meters in diameter and .22 meters thick)stacked horizontally, like a Life Savers roll. Altogether, Z 300 will
have 2,970 cavities, each producing a 100-nanosecond-long,
105-gigawatt power pulse.
Each cavity converts, in a single step, the energy stored in its
capacitors to the 100-nanosecond pulse, Stygar says. Hence, Z 300
will not need any additional pulse compression hardware.
But it will need some work to upgrade LD cavities from a 79-gigawatt
electrical pulse, the current standard, to the labs 105-gigawatt pulse
goal. o get there, technicians will replace existing switches with new,more advanced ones now under development by researchers from
Kinetech Inc. and Sandia. Teyll also use upgraded capacitors from
technology company General Atomics. Voss Scientific also participates
in the project.
Stygar says the plan is to first operate an LD cavity at 105 gigawatts.
Ten the team of about 17 technicians and researchers will build an
LD module with 33 cavities that generates a 3.5-terawatt electrical
power pulse. After we demonstrate successful operation of this
module, we will be ready to build Z300.
Tony Fitzpatrick
-
7/23/2019 Ssgf Magazine 2013
8/28
P6STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
F R O N T L I N E S
Although scission the last part of fission is incredibly important,
its also the hardest to understand. Physicists would follow the
process up to this point of no return but didnt have the tools to
examine the nucleus as it fragments. Younes and his team now use their
framework to examine scission and have gotten as far as calculating
some properties of the resulting nuclear splinters.
Researchers can examine the pairs of nuclei that form as the nucleus
comes apart. Most break into a variety of combinations with different
energies, so Younes and colleagues are interested in which fragments
form and how frequently. Understanding scission is so challenging,
in part, because the breakup of a single nucleus into two doubles the
complexity: two sets of properties now, plus the nuclei are interacting,
introducing still another variable that can affect the system.
Little Big Bang
Equipped with particle accelerator-colliders, scientists areglimpsing conditions like those scant microseconds after the
Big Bang began our universe 13.8 billion years ago. By bashing
together energized heavy gold or lead ions accelerated to
near-light speed, they trigger so-called Little Bangs that help reveal
states of matter that are even odder than theyd anticipated.
Los Alamos National Laboratory physicist Ivan Vitev is among the
theorists attempting to understand these tiny-bang states, known as
quark-gluon plasmas, or QGPs. Tats because QGPs are by definition
not observable on the time scales at which detectors make experimental
measurements, Vitev says.
QGPs themselves refute normal rules of the strong interaction, a
fundamental force that keeps matters core components quarks and
gluons bound in an unbreakable embrace. Scientists think the Big
Bangs stupendous energy burst let quarks and gluons very briefly roam
free. But within a few microseconds, they cooled enough to rejoin as
the building blocks of protons, neutrons and other contemporary
fundamental particles.
Little Bang experiments artificial ly boost particle energy levels just
enough to recreate those last moments when quarks and gluons werestill approximately free, Vitev says. Tese semi-liberated QGPs were
expected to be gaseous. But when the Relativistic Heavy Ion Collider
(RHIC) at Brookhaven National Laboratory began producing them in
the summer of 2000, puzzled scientists instead found them acting
like perfect liquids, flowing with practically no viscosity.
Such discoveries, also observed at CERN accelerators in Europe, have to
be interpreted by theory to extract the information, Vitev says. We
have only a very short time about a millionth of a bill ionth of a second
when this plasma state lives and develops features we are looking
for in experimental data. Tats too fleeting for accelerator detector
measurements, so theorists must instead conduct thought experiments.
Tose reconstruct QGP qualities by using particles formed after the
quarks and gluons recombine. Tats what makes the field exciting
and at the same time difficult.
Vitevs contributions began with a paper published in 2002, the year
he received his doctoral degree from Columbia University. It laid the
theoretical foundation for jet tomography, which can be used once in a
blue moon, he says, whenever a comparatively rare heavy ion collision
creates especially energetic quarks or gluons. One quark or gluon maycollide with another and bounce apart like billiard balls at azimuths
roughly 180 degrees apart. After ricocheting, one of the resulting
particles continues on at a high speed and energy. Te other rapidly
loses both in a shower of fragments the jet while passing through
and interacting with the detectors plasma medium.
Experimentalists can then study the measurable byproducts. For
example, if one of the particles is a rare Z boson or a photon, the data
can be tagged for comparison with the final byproduct of its counterpart.
Researchers know those fragments are spaced by a predictable azimuth
and that one has interacted with the plasma medium, whereas theother hasnt. Tey can reliably use this information to recreate details
about the immeasurable QGP itself, such as its density and temperature.
Vitev compares this method to positron emission tomography and
radiography because both those medical techniques create images by
processing signals from particle behavior within a medium.
His theoretical work is part analytic and part computational, he
says, and his codes run on local computer clusters at Los Alamos,
where he started in 2004 as a J. Robert Oppenheimer Fellow and
now works in the Teoretical Division.
Monte Basgall
continued from page 4
-
7/23/2019 Ssgf Magazine 2013
9/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P7
continued from page 4
ISOTOPE HOPES
It will take some sensitive detectors to answer
basic questions about the nature of matter
in the universe. Fellow Nicole Fields
project during her Los Alamos National
Laboratorypracticum will help researchers
calibrate properties of a key material that
could do the job.
Working with Steve Elliott and the Neutron Science and TechnologyGroups weak interactions team, Fields examined germanium-76, an
isotope researchers hope will find evidence of neutrinoless double-beta
decay. This rare particle interaction is key to understanding neutrinos
the chargeless, nearly massless byproducts of nuclear reactions and
advance knowledge of the universe.
But germanium-76, when above ground, may interact with naturally
occurring cosmic rays, creating radioactive contaminants that could
interfere with experiments. The Los Alamos researchers wanted to test
other elements that produce similar radioactivity at much higher rates.
By counting gamma rays from those other materials, the researcherscould estimate how much cosmic ray exposure the germanium
received and account for that in their measurements.
Fields exposed foils comprised of the other elements cadmium, zinc
and niobium to neutron beams at the Los Alamos Neutron Science
Center to simulate cosmic ray exposure, but at higher levels. Then she
used a detector to count gamma rays and determine which and how
many radioactive isotopes resulted. With the neutron flux that hit the
foils and the measured cosmic ray neutron flux, Fields could predict
which radioactive isotopes would be good indicators of neutron
exposure from space.
Fields and her advisor, Juan Collar at the University of Chicago,
and Elliott are all collaborators on Majorana, an international
experiment that will use germanium-76 to seek signs of neutrinoless
double-beta decay.
PARTICLE TRACKER
Joshua Rennerspracticum project at Livermorewas the same as his
doctoral research at the University of California, Berkeley, only different.
In both, Renner worked on technology for time projection chambers, or TPCs,
designed to detect evidence of neutrinoless double-beta decay. Its key to
understanding neutrinos and to advance knowledge of the universe.
TPCs track charged particles released when two larger particles collide
or, in some cases, when atoms of fissionable materials split. In essence,
the energetic particles scientists seek knock loose electrons from atoms of
a gaseous material (the detector medium) in the TPC. The number of
freed electrons characterizes the particles energy.
At UC Berkeley and Lawrence Berkeley National Laboratory, Rennerworked under James Siegrist, now associate director of the Department
of Energy Office of Science for the High Energy Physics program. The
group collaborates with other institutions to develop a prototype
detector using xenon as a detector medium thus the acronym
NEXT, for Neutrino Experiment with a Xenon TPC.
At Livermore, Renner worked with physicist Adam
Bernstein on the negative ion TPC. It uses negative ion
drift, in which freed electrons attach to gas particles,
forming negative ions. The ions drift through an electric
Although the LLNL scientists are beginning to get a picture of what
scission looks like, questions remain. For example, physicists continue to
discuss the role of certain neutrons in the fission process. Tese scission
neutrons, in the neck of that splitting peanut, sometimes are emitted
as the nucleus breaks. We would like to be able to calculate what those
neutrons are doing from a microscopic point of view, Younes says. On
the atomic scale, this fundamental science also could help researchers
understand a variety of scientific problems that come up with multiple
particles. Scission is such an extreme example of the quantum
many-body problem.
Fission is the most computationally challenging problem in nuclear
physics, Younes says, partly because it incorporates so many complex
dynamic phenomena. It produces a lot of different kinds of observables
and is incredibly rich in the type of phenomena that you can study.
Sarah Webb
his visualizes jet quenching in a lead-lead collision in the Large Hadron Colliders ATLAS detector at a center of
mass energy of 2.76 TeV per nucleon-nucleon pair. Green and yellow bars represent particle tracks and energyeposition into the detector subsystems. An energetic jet is clearly visible at 1 oclock. The gray cone shows
heres a jet (a large energy deposition in a narrow cone) in this direction. Its away-side partner at 7 oclock
s completely missing, having dissipated its energy into the plasma.
-
7/23/2019 Ssgf Magazine 2013
10/28
-
7/23/2019 Ssgf Magazine 2013
11/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P9
As a 2010-11 American Physical
Society Congressional Science
Fellow, you got an inside look at
how science policy develops in
Washington. What did you take
away from your year in D.C.?
I think the general public has this idea
that if you are a scientist you know all
kinds of science. I was working in Congresswhen the Fukushima disaster unfolded. I
was asked to write a memo explaining
the different features and factors involved
in the [Japanese] nuclear power plant
and contrasting that to what the media
were reporting. I also would get questions
because someone thought: This is
science. You give it to the scientist. For
example, I did research on poppy growing
in Afghanistan and how it affects the opium
trade. Thats certainly outside my sphere
of knowledge. But as scientists, we are
trained in research skills.Although we
apply them to our specific fields, I learned
you also can apply those research skills
to a variety of topics. There was a general
comfort with getting research questions
that you dont know the answer to and
figuring out how to answer them.
Certainly, working in Congress really drove
that point home. I learned that there is a critical
role for scientists to play in policy. There doesnt
have to be this barrier between the policymakersand scientists.
After that year, you could have stayed
in Washington and pursued a career in
science policy, but you chose to return
to a research position at Lawrence
Livermore National Laboratory. How
did you make that decision?
I am still excited about science and research,
so I wasnt certain I was ready to completelystep away from research. Livermore provides a
lot of opportunities as far as career advancement
merging with science policy, so that was
definitely a big draw for me.
What are you working on now?
My graduate research was in magnetic fusion.
Now Im part of the research staff at the National
Ignition Facility, so Im working in inertial fusion,
which to anyone outside the field is exactlythe same. But its completely different. Im
studying different types of high energy density
implosions driven by NIF, which is an enormous
laser facility. The goal is to reach ignition,
which is a self-sustaining burn of light fuel
deuterium and tritium. Im in the design
physics group, so I work on the type of target
the laser hits and on shaping the laser pulse
both in power and in time, which is an
important part of how the implosion performs.
How did your time as an SSGF Fellow
inform your career choices?
During my practicum I worked at Sandia National
Laboratories, where I focused on developing
advanced materials for plasma-facing
components in magnetic fusion reactors. That
was an interesting and important introduction
to the national lab system and opened my
eyes to the career opportunities there. Also,
my initial introduction to science policy came
through the fellowship. At our annual
gatherings there always are opportunities
for connections to policymakers in D.C.
You recently co-founded a forum called
Why-Sci.com to connect nonscientists
with scientists and research. Why should
scientists communicate directly with
the public?
The reason its so important to build that
bridge is two-fold. In times of fiscal constraint
like we are in and will likely continue to be in,
its important to explain why peoples tax
dollars should fund what scientists are workingon. Second, its important for the public
to understand that from their new, quiet
refrigerator to their iPod, science goes into all
of that. Its important for people to understand
that scientific research really does affect them
and those investments can improve their lives.
One of the biggest take-home messages I
learned in D.C. is that people are excited
about science. So many people I met in D.C.
who dont know about science were excited
to learn more. My office [former Sen. Kent
Conrad, D-N.D.] asked me to give a lunchtime
mini-lecture on fusion and ongoing plasma
physics experiments. It was exciting to see
the interest, and I think part of it was the
direct interaction with a scientist who was
willing to explain what they do. Thats the
model for Why-Sci.com.
BRIDGING SCIENCE,POLICY AND HE PUBLIC
C O N V E R S A T I O N
Laura Berzak Hopkins
Physicist, Lawrence Livermore
National Laboratory
DOE NNSA SSGF Class of 2010
Its important to explain
why peoples tax dollars
should fund what scientis
are working on.
-
7/23/2019 Ssgf Magazine 2013
12/28
P10STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
Title image: Snapshot from a simulation of xenon in
which liquid atoms (red) are solidifying (green) at a
high temperature and pressure.
Jacob Berkowitz is a science writer and, most recently,
author of The Stardust Revolution: The New Story of
Our Origin in the Stars(Prometheus Books, 2012).
C O V E R S T O R Y
Lab iniioBY JACOB BERKOWITZ
-
7/23/2019 Ssgf Magazine 2013
13/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P1
While in high school in Lawrence, Luke Shulenburger would bike or walk up he hil l
o he Universiy o Kansas, where proessors menored he precocious een in
mah, physics, chemisry and compuer science.
By his senior year, his exracurricular educaion had led him o he Naional
Junior Science a nd Humaniies Symposium and his fi rs paper in Physics Leters A,
co-auhored wih his menors and published when he was an undergraduae a he
Massachusets Ins iue o echnology.
I also led him o a career-defining conundrum. While sudying organic chemisry
and sruggl ing o memorize reacion rules, he wondered why chemiss didn work
like physiciss: mahemaically, rom undamenal firs principles.
Why couldn you jus solve he equaions behind everyhing? says Shulenburger,
now a saff scienis in he high energy densiy physics heory group a Sandia Naional
Laboraories in New Mexico. Ive been playing around wih ha ever since.
Scientists at Sandia National Laboratories
are out to make first-principles chemical
models, hoping to reduce error and
illuminate experiments on materials
under extreme conditions.
Luke Shulenburger
W
-
7/23/2019 Ssgf Magazine 2013
14/28
P12STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
oday, Shulenburger has ound his inellecual home. Hes par o a new generaion
o young Sockpile Sewardship program researchers a Naional Nuclear Securiy
Adminisraion laboraories who are driven o creae models o mater based no
primarily on experimenal daa, bu on firs-principles physics equaions ab iniio,
lierally rom he beginning, models.
A he hear o his vision is Quanum Mone Carlo (QMC), a compuaional modelingechnique ha grew rom work a Los Alamos Naional Laboraory in he early
1950s. Sixy years laer, QMC is finding is greaes expression in exreme parallel
compuing applicaions on DOEs high-end supercompuers.
As a resul, wo decades since he las U.S. underground nuclear es, Shulenburger
and colleagues are aking sewardship science ino a new era. Tey are harnessing
he combinaion o QMC echniques, dramaic new insighs ino maerials a he
exreme and v isions o ever more powerul compuing o creae a new race or
accuracy beween experimenaliss and heoriss.
Experimenal resuls w ill a lways be needed o ground our research, bu our goal iso provide a more complee picure, says Shulenburger, who presened his laes
QMC work a he American Physical Sociey meeing in Ma rch 2013.
BEYOND APPROXIMATIONSShulenburger wasn he firs o dream o heoreically predicing he physical and
chemical properies o mater rom firs principles. Te pioneers o quanum heory
long shared ha vision. Te ormulaion o he Schrdinger equaion describing he
quanum behavior o elecrons held he promise o heoreically solving any chemical
ineracion. In pracice, however, he equaion his a compuaional Moun Everes.
Problems scale exponenially wih he number o paricles. Tus, even wih enormous
compuing power, exac soluions are obainable only or molecules wih jus aew elecrons.
o vaul his quanum mulibody hurdle, compuaional scieniss have developed
ways o approximae soluions o he Schrdinger equaion. Each approximaion
incorporaing a mix o experimenal
daa and wha physiciss call physics
inuiion makes he equaion more
compuaionally racable.
Te problem is ha every approximaion
also disors realiy o some exen.Tus, approximaions are erile
ground or improvemen or he
Sockpile Sewardship Programs
Predicive Capabiliy Framework,
which a ims o sig nificanly reduce
modeling uncerainies.
Te common hread ha links all
o my research is he eliminaion o
approximaions o develop a more
precise abiliy o simulae maerialsunder exreme condiions,
Shulenburger says.
Since joining Sandia in 2010, Shulenburger
has aken a wo-pronged approach o
reduce approximaions in models o
elemens across he periodic able
under exreme pressure.
Firs is adaping and applying QMCPACK,
a new QMC code opimized or use onDOEs massively parallel leadership-class
compuers. (See sidebar, New Code
esed Agains he Elemens.)
Te workhorse o quanum compuaional
approximaion is densiy uncional
heory, or DF. Te echnique was
developed several decades ago and now
has housands o users and applicaions
agile enough o run on smarphones.
Bu DF alers in describing how materbehaves under exreme condiions,
paricularly or heavy aoms.
Tis is where QMCPACK eners he
picure. QMC uses a sochasic, random
sep-sampling echnique o solve wave
equaions, an approach wih a compleely
differen and poenial ly inier class o
approximaions han DF.
A visualization of a charge
density for solid argon,calculated with quantum
Monte Carlo methods.
-
7/23/2019 Ssgf Magazine 2013
15/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P13
Miguel Morales
Apair of young DOE scientists is confident that anew first-principles quantum simulation codewill provide unprecedented predictive accuracy in
modeling elements across the periodic table under
sun-like extremes of temperature and pressure.
Their optimism is based on QMCPACK, for
Quantum Monte Carlo Package. Quantum Monte
Carlo isnt a widespread method yet, says Miguel
Morales, a staff scientist in the Condensed Matter
and Materials Division at Lawrence Livermore National
Laboratory. In terms of stockpile stewardship, the
challenge for us is to develop QMCPACK to the
point at which theres trust in its predictive capabilities.
QMCPACK was created under the leadership ofthe University of Illinois David Ceperley, a pioneer
in developing the quantum Monte Carlo family
of methods.
Ceperley, also a staff scientist at the universitys
National Center for Supercomputing Applications,
worked with fellow professor and physicist Richard
Martin to mentor a talented group of graduate
students. Many of those students now are Department
of Energy staff scientists applying QMCPACK to the
most challenging stockpile stewardship problems.
Jeongnim Kim, a scientist in the Computational
Chemistry and Materials Division at Oak Ridge
National Laboratory, leads QMCPACKs
ongoing development.
QMCPACK is completely designed with extreme
parallelism in mind, Morales says. Test runs on
Oak Ridges petaflops-capable supercomputer
showed the code could be scaled up to the entire
machine with little loss in efficiency. In a discipline
in which modeling a dozen individual electrons is
considered an admirable feat, QMCPACK has
demonstrated its capable of modeling thousands
of particles in a computationally cost-effective way.
Morales and Sandia National Laboratories Luke
Shulenburger both of whom, along with Kim,
worked with Ceperley on QMCPACK are testing
the code in a benchmarking program to predictively
model elements under extreme conditions. Were
going to touch on elements across the periodic table
and identify those areas where we do well and those
where we need to work harder, Morales says. Last
year, with Ceperley and colleagues, he co-wrote a
paper on hydrogen and helium under extreme
conditions for Reviews of Modern Physics.
Probably for the light elements, were there, sa
Shulenburger, who recently used QMCPACK to
reveal a possible new beryllium solid-solid phase
transition under high pressure. But as you get to
the heavier elements, its much more difficult from
the computational point of view.
In a 2010 Proceedings of the National Academy
of Sciencespaper, Morales used QMC ab initio
simulations to confirm and pinpoint a liquid-liquid
transition in high-pressure hydrogen of interest to
planetary scientists considering giant gas planetslike Jupiter.
Morales and Shulenburger are working with Sand
and Livermore colleagues to extend the QMCPAC
benchmarking to other elements, including gold,
silver and molybdenum. Applying QMCPACK inclu
porting the code to other supercomputers, includ
Cielo at Los Alamos and Sequoia, the IBM Blue
Gene/Q at Livermore.
The effort also has involved porting QMCPACK to
run on graphics processing units, or GPUs. These
massively parallel, energy-efficient chips develop
for video games are giving a low-cost, high-efficienc
boost to high-performance computing. Notes
Shulenburger, With GPUs you almost have to thi
of your problem in a whole different way about
how to decouple everything into parallel tasks to
extent thats previously unheard of. The approac
ideal for QMC, a naturally parallelizable techniqu
Titan, a world-leading computer at Oak Ridge, alrea
gets most of its processing power from GPUs. Kenn
Esler of Stone Ridge Technologies, another of
Ceperleys University of Illinois disciples, recently
ported QMCPACK to run on them.
Morales says the challenge QMCPACKs advocate
face is to build a series of success stories, convinc
others of its accuracy and utility. To the extent th
we can start using correct first-principle predictio
of materials at high density, we will start to identify
problems in stockpile stewardship models curren
being used. There are still many hurdles to cross,
I think its just a matter of time.
NEW CODE TESTED AGAINST THE ELEMENT
QMC is an excellen fi wih sockpile
sewardship because i has he poenialo deermine maerials properies
wih exremely small uncerainies,
Shulenburger says. Tis is criical o
verificaion and valida ion proving
models ac as inended and reducing
uncerainy. Wih QMC you have he
opporuniy o ge he physics righ
even where your inuiion ai ls you.
QMC algorihms also are naurally
parallelizable on several levels, providinghe ideal models or peascale compuers
ha can do quadril lions o scienific
calculaions a second and exascale
machines a leas a housand imes
more powerul han hose. I you give
me a bigger compuer o run on and
orunaely he DOE has los o big
compuers I can make he saisical
approximaion error as small as I wan.
Alhough QMC provides one avenueor reducing approximaions, anoher
approach quanifies how much each o
hose approximaions poenially
skews simulaions.
Many researchers working o i mprove
QMCs accuracy have ocused on
reducing he fixed-node approximaion,
known o limi ab iniiocalculaions o
-
7/23/2019 Ssgf Magazine 2013
16/28
P14STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
condensed mater and nuclear reacions. Te approximaion is a compuaional
compromise ha addresses he ermion sign problem, one o he major unsolvedproblems in modeling he physics o many-paricle quanum sysems.
In a sysem wih wo or more elecrons, he wave uncion has regions wih opposie
signs: one posiive, he oher negaive. However, or efficiency, QMC ypically
calculaes only in an approximaion o he posiive space. Tis fixed-node approximaion
is he mos difficul o eli minae and is a undamenal uncerainy in QMC
calculaions oday.
Shulenburger and colleagues are pursuing a comprehensive soluion o he sign
problem. Hes already made significan progress by showing ha, in pracice, i
migh be less imporan han previously hough in solving imporan sockpilesewardship problems. My work has ound ha i is rarely he deermining acor
or high-accuracy simulaions, Shulenburger says. Te way we pariion he
problem ino ighly bound and chemically acive pieces is ar more imporan
han his more heoreically undamenal quesion.
QMC INSIGHTS TO MATTER AT THE EXTREMEApproximaions nowihsanding, QMC already has proven is wor h in revealing
a dramaical ly new map o maters errain a exreme emperaures and pressures.
From firs principles, says Lawrence Livermore Naional Laboraorys Miguel
Morales, weve idenified a compleely new se o saes o mater ha appearwhen you compress maerials, and many o hese were compleely unexpeced.
Morales is a Livermore saff scienis and an alumnus o he DOE Naional Nuclear
Securiy Adminisraion Sewardship Science Graduae Fellowship. Hes collaboraing
wih Shulenburger o sysemaically apply QMCPACK a code hey boh helped
develop as graduae sudens a he Universiy o Ill inois o predic he equaions
o sae or elemens a high emperaures and pressures.
Teyve boh winessed he power o ab iniiomodels o redefine our undersanding
o maerial behaviors a he exreme condiions criical o sockpile sewardship
and fields such as planeary geophysics.
For example, previous models assumed ha delocalized elecrons ones a high
pressure, sripped rom heir nuclei orm a uniorm elecron curain ions inerac
agains. In pracice has no always wha happens, Morales says. Insead, in aoms
rom such elemens as aluminum and sodium under exreme pressure, delocalized
elecrons congregae in he voids o he ionic latice, creaing sable elecride srucures.
Similarly, Shulenburger says, scieniss now are reassessing models o large aoms
ha ignored inner elecrons. One o he ascinaing hings abou high-pressure
science is you can ge o he poin where
hese previously chemically iner innerelecrons sar o mater, because he
energy scales go up and up as you bring
he ions closer and closer ogeher, and
acoring his in undamenally changes
he properies o maerials a hese
exreme condiions.
Shulenburger was inroduced o
real-world high-pressure maerials
problems as a pos-docoral researcher
a he Carnegie Insiuions GeophysicalLaboraory in Washingon, D.C. Tere,
researchers sudy he behavior o minerals
squeezed a enormous pressures and
emperaures inside he Earh.
In his ime a Sandia, Shulenburgers
come ull circle in his desire o ge down
o ab iniiobasics. Working closely wih
Sandias engineers and experimenaliss,
his QMC fine-uning ocuses on making
his firs-principles echnique useul inhe Sockpile Sewardship Programs
applied big picure.
When I was a grad suden a Illinois, i I
could ell you abou he phenomenon
o a solid under pressure, ha i mealizes
and heres why, you probably wouldn
have cared as much abou exacly a
wha emperaure a nd pressure ha
happened, he says. Bu a Sandia, where
an engineer may acually incorporaehose daa ino plans or a device, you
care a lo more abou he deails. So
Ive goten a lo more ocused in erms
o how o produce a high-precision
quaniaive resul raher han jus
geting a qualiaive sense o he
physics o a problem.
Shulenburgers come full circle in his
desire to get down to ab initiobasics.
-
7/23/2019 Ssgf Magazine 2013
17/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P15
IN THEIR
ELEMENTBY KARYN HEDELawrence LivermoreNational Laboratory
scientists are probing
properties of atoms on
the edge of the periodic
table. Their rapid
separation techniques
could have ramifications
for nuclear forensics.
For yearshe periodic ablehas exised in limbo, is oherwise orderlysacks and rows o elemens peering ou ahe botom wih a series o elemens haseemed o signal chemiss had exhausedheir ideas. Running across he lower righrow, he elemens rom No. 113 o No. 118
read as a series o Us.One migh guesshese sood or unknown.
A leas some o hese orphans final ly
now have names ha acknowledge heir
discovery. Elemen 114 is flerovium, afer
-
7/23/2019 Ssgf Magazine 2013
18/28
P16STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
he Flerov Laboraory o Nuclear Reacions in Dubna, Russia, where i was firs
creaed. Likewise, No. 116 now is livermorium, a fer Lawrence Livermore Naional
Laboraory. Te labs collaboraed on he discoveries and sill cooperae on pushing
he edge o he periodic able, seeking he ouer limi o possible elemens.
Perhaps no living scienis is more associaed wih elemen discovery han Livermores
Ken Moody, a radiochemis and member o Livermores super heavy elemen group.Moody, who was involved in discovering elemens 113 o 118, has spen years rying o
undersand he cenral issue o how aomic nuclei balance he repulsion beween
proons wih he nuclear glue ha binds hem. Jus how heavy can an elemen ge,
he wonders, beore clusers o posiively charged proons promp nuclear fission?
Tis lingering issue moivaes nuclear chemiss in he super heavy elemen group.
Bu he ools and echnology required o address his undamenal quesion also
have ound applicaions in nuclear orensics, acinide chemisr y and oher fields.
Once a new elemen is discovered, group
leader Dawn Shaughnessy says, he nexquesion is wha are (is) chemical properies and
how does i relae o is neighboring elemens in
he periodic able? Doing hose experimens is
challenging because you are lierally doing
chemisry on a single aom o somehing
ha only lass a shor amoun o ime.
Teir fleeing exisence means we have scan
or,in some cases, no inormaion abou he
chemical properies o he heavy elemens
occupying he las ew blocks in period 7, helas row on he periodic able. For example,
we know ha elemen 118 exised only by
measuring alpha paricles released in is nearly immediae decay o livermorium
and hen o flerovium. Is he same or nearly al l he ma n-made elemens: Scieniss
only know heyve been here by couning radioacive emissions as hey decay.
Years ago, Moody descr ibed his work o his elemenary school-aged daugher.
Her incredulous response You mean you don acually know wheher you have
anyhing unil i goes away? encapsulaes he difficulies o working wih such
ephemeral species.
CHEMISTRY BY ANALOGYMos super heavy elemens can be sudied only a he ew places ha have colliders
capable o firing ions calcium, generally a one o he acinide elemens, such
as curium or cal iornium, a speeds approaching 30,000 kilomeers per second.
Experimens using hese rares o elemens are boh pracically and financially
difficul, so he Livermore eam wans
o probe he chemisry o analogous
elemens in he same verical group,
whose bonding and chemical behavior
should be similar. Te idea is o perec
analyical mehods using elemens ha
can reliably be made in a sandard ion
acceleraor, hen ranser hose mehods o
sudy he super heavy elemens.
Given he challenge o undersandinghe chemical behavior o an aom wih
a hal-lie o less han a minue, he
Livermore researchers mus develop swif
chemical mehods and ways o auomae
ofen-repeiive experimens. Dubnium,
or example, exiss in several isoopes
ha have hal-lives rom 35 seconds o
up o one day. Te problem wih he
more sable orm o he elemen, which
is named or he Flerov Laboraorys
locaion, is ha generally is possible ogenerae only one aom o i per day.
We need a chemisry where he kineics
are really as, Shaughnessy says.I
may be ha wih a sandard chemisry
on a sable elemen you can le your
experimen si and equil ibrae or a
long ime. We don have ha luxury.
Livermore uses an auomaed device ha
inroduces a sample as a gas-borne aerosolo a esing cha mber, deposis i on a
porous glass ri, adds acids o conver
he sample ino a liquid and roaes i
or subsequen chemical separaion and
measuremen. Te device hen moves
o a cleaning posiion and roaes back
o collec anoher sample. Te device
allows he chemiss o repea an experimen
abou once a minue or days or weeks,Karyn Hede is a freelance journalist whose work has appeared in Science,
Scientific American, New Scientist, Technology Review and elsewhere.
In this artists conception, calcium
ions travel down an accelerator at
a high velocity, about 30,000
kilometers per second, towarda rotating californium target.
-
7/23/2019 Ssgf Magazine 2013
19/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P17
gahering enough daa o undersand how
heavy elemens such as Nos. 104, 105
and 106 adsorb or desorb rom a surace.
Following he periodic able would
lead scieniss o expec ha dubnium
(elemen 105) shares properies wih
analum (No. 73, jus above dubnium
in period 6) and niobium (No. 41, wo
rows up in period 5), Moody says.
Te good news is ha i does. Buhe ineresing hing is ha you would
expec i o be more similar o analum
han niobium, jus because i is c loser
in aomic weigh, bu in some sysems
we have ound i is closer o niobium.
In some ways, he research pis periodic
able aher Dmiri Mendeleev agains
Alber Einsein. When a nucleus
becomes large enough, is posiive
charge causes elecrons orbiing io spin so as ha relaivisic effecs
make predicing is behavior difficul.
I you jus pu elemen 114 in he periodic
able i should si under lead, Shaughnessy
says. Bu here are nuclear orbial
models ha say i should no behave
Narek Gharibyan, a postdoctoral researcher,
works on chemical separations of heavy
lements at Lawrence Livermore National
aboratory. The lab is known for its skill at
eparation methods, which are useful to
dentify uranium sources.
The new element 118 travels through
the accelerator to a detector. Quicklyseparating and observing the new atom
is key to understanding its properties.
like lead.I should behave like a noble gas, somehing iner ha doesn reac.
And ha would be a big deal in erms o how we undersand he periodic able.
Te research groups goal is o undersand how elemen 114, flerovium, behaves. o ge
here, hey are developing very as chemisry using some o he l igher elemens in
group 14, such as lead and in. Te researchers are sudying ligands, binding agens
ha can pull lead or in ou o a mixure. Tey also collaborae wih exas A&MUniversiy and he Universiy o Nevada, Las Vegas (UNLV) o sudy new maerials
ha wil l separae super heavy elemens quickly and efficienly rom inerering
background producs. Several docoral sudens have conduced heir hesis research
on chemical exracion and on analyzing behavior down a specific group in he
periodic able.
FINDING AN ATOM IN A HAYSTACKLivermore scieniss masered isoopic separaion mehods in an era o open-air
nuclear ess beore 1962. For example, he labs Cener or Acceleraor Mass
Specromery can separae and coun a handul o uranium-236 aoms rom a
sample o several grams. Such exacing separaions are essenial when rying oideniy he source o uranium aken rom one o dozens o sies where mined
ore is processed and enriched or energy producion or weapons.
Te challenge, Moody says, is aking decades o separaions and analyical experise and
applying i o he needs o modern nuclear orensics. In he 1960s, he research eam had
ime o careu lly scruinize a es s producs. oday, he goal is o supply answers
ha quickly locae he source o, or example, illegally obained uranium. Perhaps
jus as imporan, he researchers wan o rack he maerial sources should a erroris
organizaion succeed in deonaing a diry bomb or oher nuclear weapon. In a blas
scenario, he nuclear orensics group would analyze debris and reverse-engineer
wha device was used and how i was buil.
Te problems you have doing he heavy elemen chemisry are ofen similar o he
problems you would have in a (nuclear) orensics ype o scenario, Shaughnessy says.
You are looking or a very small amoun o somehing in a large marix o background
maerial. You wan o separae i quickly because every hing is radioacive, and you
wan o ge he answer as soon as possible. We are always look ing or new mehods
o very rapid separaion echniques.
In recen years, Livermore also has culivaed experise in developing chemical
signaures ha le he scieniss ideniy where and how a paricular sample o
uranium was produced. Now heyre working on parsing how i ges o where isseized. o ha end, Livermore has eamed wih UNLV researchers o rapidly
ideniy uranium samples. Graduae sudens and pos-docoral researchers
ofen spli heir ime beween he wo locaions.
Jonahan Plaue, one such docoral suden, recenly discovered ha differen
uranium samples precipiaed ino unique and reproducible crysal line shapes
depending on heir origin. Tis projec, which ormed an imporan par o his
disseraion, could help o rapidly ideniy inerdiced samples rom a specific
locaion or produced hrough a similar process.
-
7/23/2019 Ssgf Magazine 2013
20/28
P18STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
I we had a real-world sample, we now believe ha simply by looking a he shape
or shapes o he paricles we may be able o iner he process or processes ha were
used o produce hose paricles, says Ian Hucheon, a physicis and leader o he
chemical & isoopic signaures group in Livermores Chemical Sciences Division.
Par o Hucheons group specializes in he exacing work o measuring he
abundances o uranium isoopes in
surprisingly complex, small samples.
(See sidebar, Rare Earh.)
Looking ahead, he research eam aims
o avoid he chemical separaion sep
alogeher. Insead, he researchers in
Hucheons group are poining lasers aallou samples o aomize hem. An
ionizing laser fired a he cloud would
ransorm only he aoms o ineres,
usually uranium or pluonium, ino an
ionized sae. Ideally, he uranium or
pluonium would absorb he phoons,
wih all oher elemens invisible, hen
would be drawn ino a mass specromeer
or couning. Te mehod also would be
applicable o all he ac inide elemens,
bu o make i pracica l much moreinormaion abou he aomic energy
levels o hese elemens mus be colleced.
oward ha end, he group collaboraes
wih researchers a he Naval Pos Graduae
School in Monerey, Cali ., o sudy he
aomic energy levels o he heavy elemens
in he acinide period he 15 elemens
beween Nos. 89 and 103. Ta includes
uranium o curium, he mos ineresing
ones or nuclear orensics.
We hink ha his new echnique,
called resonance ionizaion mass
specromery, gives us he abiliy o do
analyses on he ime scale o much less
han a day, Hucheon says. Te
required mass specromeer will be
buil a Livermore while he basic
research projec is underway.
Ulimaely, Shaughnessy envisions a
mobile sysem ha would make nuclearorensics field-deployable.
We really should be hinking o
compleely new echnology, she says.
I could hink o probably five projecs
omorrow ha a suden could go
launch on. Ta could make a huge
difference in nuclear orensics.
The rare appearance of a meteor streaking over Russia in 2013 shocked localobservers but offered scientists another chance to learn more about the origins ofthe universe. For inside each slice of meteorite debris are some of the earliest building
blocks of solid matter once-molten droplets produced by high-temperature processes
at the birth of the solar system.
Few opportunities exist to study the remnants of such phenomena here on Earth, but
a recent discovery at Lawrence Livermore National Laboratory may have opened up a
new possibility.
Ian Hutcheon, a physicist who studies heterogeneous materials in the nanometer to
micrometer scales, was examining some of the glassy debris created during outdoor
nuclear testing in the 1950s and 60s. He realized that microscopic patterns in the
glassy spherules created moments after a powerful nuclear blast resemble those in
chondrules, the glassy spheres found in primitive meteorites.
It turns out that these fallout particles, even
though they are made of glass, are not
homogeneous, Hutcheon says. You find
large variations in both the elementalcomposition and, even more intriguing,
in the isotopic composition. Hutcheons
research team found that within a single
marble-like spherule, pockets of uranium-235
(the isotope found in a nuclear device) and
uranium-238 (the uranium form found in the
environment) exist side-by-side and unmixed,
along with various blends of the two.
What this tells us is that these spherules
were made in the aftermath of the detonation
by a process or processes that had to mix
materials coming from the device with
material coming from the environment.
Hutcheons nearly 40 years of experience studying meteorite inclusions may provide
clues to the mixing processes that occur in the seconds after a nuclear blast. His
research could offer a new avenue for combining nuclear forensics with the physics
of early solar system formation.
RARE EARTH
Cross section of a 2 milimeter-diameter
glassy spherule produced during a nuclear
test, mounted in epoxy. On the left, an
optical micrograph shows a large central
cavity surrounded by many smaller
bubbles. On the right, a scanning electron
microscopic image shows variations in
chemical composition that reveal cluesto the rate of cooling and solidification.
The light band at the perimeter is
enriched in calcium and iron.
-
7/23/2019 Ssgf Magazine 2013
21/28
RESEARCHERS USING LOS ALAMOS
NATIONAL LABORATORYS TRIDENT
LASER HAVE GENERATED POTENT
NEUTRON PULSES, OPENING NEW
AVENUES FOR SCIENCE.
A Trident laser shot,
delivering as much as 200
quintillion watts of energy
per square centimeter to a
deuterium-carbon target.
THE INTERCOM ECHOES THROUGH THE TRIDENT LASER
FACILITY AT LOS ALAMOS NATIONAL LABORATORY. A echnician
speaks. We are preparing or a sysem sho o he norh arge area. She warns saff
o avoid high-volage hardware and he laser bay. Do no break any inerlocks .
T he
BY THOMAS R. ODONNELL
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINEP19
BEAM COUNTERS
-
7/23/2019 Ssgf Magazine 2013
22/28
P20STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
Scieniss Juan Fernndez and Markus Roh lisen rom a nearby office. Fernndez
leads Los Alamos experimenal plasma physics group. Roh is a laser plasma
physicis rom Germanys echnical Universiy o Darmsad. Shos are always
a litle bi like a rocke launch, Roh says. Bu insead o sending off saellies,
riden is firing oodles o high-energy neurons.
Is February, and Roh is aking a break beween sho seups on his second
riden visi in under a year. In spring and summer 2012, he was a Rosen Scholar,serving a research ellowship a LANSCE, he Los A lamos Neuron Science Cener.
LANSCE includes he Lujan Cener, where a kilomeer-long acceleraor generaes
neuron beams or invesigaing maerials, proein srucures, nanomaerials and
oher subjecs.
Some o wha he Lujan Cener does in a kilomeer, riden now does in a ew
mill imeers, hanks o a collaboraion involving Roh, Fernndez and oher
researchers rom Germany and rom Los Alamos and Sandia Naional Laboraories.
Te 2012 experimens produced he larges neuron beams a shor-pulse laser has
ever made: An objec placed a cenimeer rom he source would ge a burs o
neurons a a densiy o 4 quinillion 1018 per square cenimeer per second.Tose neurons also move as, wih energies as high as 150 megaelecron vols
(MeV, or a million elecron vols). Convenional acceleraor echnology like ha
a he Lujan Cener delivers many more neurons bu over a long period. Ta
makes he wo echniques complemenary, Fernndez says.
Te sheer number o energeic neurons,delivered in incredibly shor burss,
makes he riden beams suiable or
muliple uses, rom deciphering he
undamenals o radiaion damage o
ideniying il lici nuclear maerials. Te
echnology also may advance neuron
research as insiuions wihou he space
and money or linear acceleraors embrace
compac neuron-generaing lasers.
Tas probably he mos exciingaspec, says Frank Merril l, a neuron
scienis and eam leader or he
advanced imaging group in Los
Alamos Physics Division. Is his
novel way o generaing neurons
ha may open applicaions nobody
has hough abou because (neuron
beams) were so expensive o generae
and build.
ridens unusual properies and somephysics wizardry make i possible.
LASER JOCKSTe voice on he inercom indicaes he
power level o capaciors ha soon will
discharge in ridens high-inensiy
beam. Tweny-five percen charge.
Fernndez and Roh, Merrill says, are
laser jocks: physiciss who know how
o use shor-pulse lasers o do all k indso ascinaing hings. Alhough he
wo collaboraors are unsure abou he
nickname No sel-respecing laser
scienis would call us laser jocks,
Fernndez jokes hey agree lasers are
key o heir research. Juan and I are
more he users, Roh says. We really
are he ex perimenal side.Thomas R. ODonnell, senior science editor, has written extensively about
research at the DOE national laboratories. He is a former science reporter
at The Des Moines Register.
Researcher Markus Roth at work in the target
chamber at Los Alamos National LaboratorysTrident laser, where scientists often join lab
technicians in preparing shots.
-
7/23/2019 Ssgf Magazine 2013
23/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P2
ON TARGETFify percen charge.
Compared o larger laser aciliies, li ke NIF and he Universiy o Rochesers
Omega, research a riden is more hands-on, Fernndez and Roh say. Los Alamos
echnicians are involved, bu he scieniss hemselves ofen work ogeher o seup arges and insrumens, geting heir hands dir y, Fernndez says. Graduae
sudens work alongside hem o make as many shos as possible in a day. Roh
adds, o sum i up, we are having a pary here. He laughs. Is really a grea
eam, bu o course we are working hard.
For he neuron beam experimen, riden arges a super-hin plasic oil. Few
big lasers can use such oils because o prepulse a weak bu sign ifican burs o
ligh ha heas or desroys he arge beore he main pulse can hi i. riden is
known or is high conras, meaning he prepulse is negligible. You can shoo
arges ha are very hin, Fernndez says, so you can move he whole oil a
once, as opposed o a racion. Ta helps o accelerae he resuling plasmaions o unprecedened energies.
Te oils oher key propery is is composiion: carbon and deuerium, a hydrogen
isoope ha pairs a neuron wih each aoms lone proon. Te researchers ocus
ridens beam ighly and fire i in jus rill ionhs o a second, hiting he oil wih
200 quinil lion wats o energy per square cenimeer, equivalen o ocusing all he
suns ligh ino a spo he size o a pencils ip. Te arge is reduced o a plasma o
elecrons and deuerons deuerium nuclei, comprised o one neuron and one proon.
Te physics legerdemain ha occurs nex is vial o creaing a powerul neuron
beam wihou a gian linear acceleraor. Mos plasmas are opaque o lasers; heyreflec he beam like a mirror. Bu under ridens high inensiy, plasma generaed
rom he oil becomes relaivisically ransparen, Roh and Fernndez say. I
Merrill s specialy is deecors o coun
neurons and measure heir energies. He
and his colleagues develop sensiive
diagnosics or he Naional Igniion
Faciliy, or NIF, he gian laser buil a
Lawrence Livermore Naional Laboraoryo implode iny hydrogen-filled capsules
and, i successul, rigger nuclear usion.
NIF is in demand and shos are difficul
and expensive, so rouinely using he
laser o es diagnosics isn easible.
Merrill and his collaboraors need a
NIF sand-in: someplace ha readily
generaes copious neurons in a
shor pulse.
riden, a neodymium glass laser, can
deliver 200 ril lion wats o energy in
pulses as shor as hal a picosecond,
a ril lionh o a second. Roh says is
repuaion as one o he worlds bes
shor-pulse laser sysems drew him o
Los Ala mos. Alhough hes a plasma
physicis, I had neurons always on
my mind and worked on previous
atemps o produce hem wih lasers.
Older sysems, however, werenpowerul enough o yield significan
numbers or energies.
Merrill, o course, also had neurons on
his mind. Roh, afer arr iving a he lab
las year, gave a seminar on his plans.
Merrill caugh hi m laer in a hallway.
Te Los Ala mos deecor researcher
needed a source or brigh neuron
pulses. Te German visior waned o
show lasers could provide hem. A eamassembled o find a soluion.
Experiments at the Trident laser hit a thin,
carbon-deuterium foil with an intense laser pulse,
driving deuterium nuclei into a beryllium rod. The
nuclei displace beryllium neutrons and also break
apart, generating an intense neutron beam.
-
7/23/2019 Ssgf Magazine 2013
24/28
P22STEWARDSHIP SC IENCE 12/13 THE SSGF MAGAZINE
sars when elecromagneic waves rom he laser ligh push elecrons ino he
arge. Te number o elecrons available seadily decreases as heyre pushed
o he back o he oil.
A he same ime, he laser inensiy ramps up, Roh says. Te elecrons have
o oscillae in ha elecromagneic wave. Because he inensiy is so high, he
elecrons are acceleraed o he speed o ligh, sop, acceleraed o he speed
o ligh, sop, a every cycle o he laser pulse. Ta means mos o he ime
elecrons are acceleraed o near ligh speed.
Heres where Einsein seps in. Under relaiviy, elecrons become heavy as hey
accelerae. Wih laser inensiy increasing, heyre no longer able o ollow he
beam because o sop a very heavy elecron akes a longer ime han o sop a ligh
elecron, Roh says. In quadri llionhs o a second, he elecrons ca n no longer
ollow he elecromagneic waves, he oil becomes ransparen and he beam
passes. Suddenly, he laser breaks hrough ha oil a nd caches up wih he
elecrons ha are already pulling on he ions on he oher side. Te laser couples
efficienly o all elecrons in he volume, no jus hose on he plasma surace.
Te researchers call his effec breakou aferburner he laser breaks hrough
he oil and ransers energy hrough he elecrons o he deuerons, accelerainghem in a burs. Te linked proon and neuron slam ino a shielded beryllium
rod placed jus 5 mill imeers beyond he oil.
Beryll ium aoms have a large cross secion, meaning heir neurons have a high
probabiliy o ineracing wih incoming proons and neurons. Like a cue bal l
hiting a clump o bil liard balls, he deuerons send beryllium neurons flying.
Meanwhile, some deuerons break apar, generaing addiional neurons, Merril l
says. You ge some added oomph. Wha we ound is you ge higher-energy
neurons rom ha piece o he process.
Te neuron beam could be even bigger, Fernndez says, i he oils were pure ornearly pure rozen deuerium an idea Roh plans o ry laer his year.
For Merrill and his deecor-developing colleagues, he ough par was finding he
neurons amid he noise X-ray and elecromagneic radiaion byproducs. Tey
sifed hem wih a ime-gaed sysem, essenially a high-speed shuter ha opens
afer X-rays pass bu beore neurons arrive. We could find he swee spo,
admiting he neurons o ineres while in essence, everyhing else was quie.
I anyhing, he laser researchers
did heir jobs oo well, Merrill says,
producing neurons a energies greaer
han he and his colleagues need or
NIF neuron deecors. (See sidebar,
Capuring Neurons.)
ON THE PHYSICS EDGESeveny-five percen charge.
Beore hese experimens, riden had
never acceleraed deuerium ions. Tis
whole relaivisic regime is really he
edge o he known physics, Roh says.
Bu he researchers had some guidance:
Teoriss a Los Alamos Compuaional
Physics Division, including Brian Albrigh,
Chengkun Huang, Lin Yin and Huichun
Wu, prediced opimum arge hicknesses
or a given laser inensiy. Ta helped he
experimenaliss generae neurons onhe firs sho, no couning wo ohers
done o check alignmen. I knew riden
A Trident shot as seen through a t
chamber port. The laser is known f
high contrast, meaning it has little
prepulse a short, weak burst of
before the main laser p
Like a cue ball hitting a clump of billiard balls,
the deuterons send beryllium neutrons flying.
-
7/23/2019 Ssgf Magazine 2013
25/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P23
was a grea laser, bu I never would have
dreamed ha wed ge resuls on he
hird sho on he firs day, Roh says.
Alhough ar smaller han a linea r
acceleraor, riden sill isn porablebecause is a mulipurpose research aciliy.
A sysem designed specifically o generae
neurons could fi on a ruck, making
he echnology available or a range o
research and pracical uses, i ncluding
sockpile sewardship experimens.
One use is flash radiography o assemble
deailed movies o mass evoluion over
iny ime incremens. Wih a neuron
source firing 60-nanosecond pulses,Merrill says, researchers could sring
ogeher reeze-rames o as, dynamic
evens like how meal deorms under
an explosive orce. Because maerials
absorb neurons a differen energies,
beams a lso could peer inside maerials
in ways X-rays can. Neuron radiography
ells researchers no only how much o
a maerial is presen he mass bu
also wha kind o maerial i is perhaps
aluminum in one par and seel in anoher.
In a simi lar way, he high-inensiy,
high-energy beams riden produces
are suied or acive inerrogaion
scanning conainers o spo hidden
nuclear maerials, perhaps a pors and
border crossings. Deecors could rack
paricles and radiaion emited when a
neuron beam passes hrough a conainer,
providing invesigaors signaures o
maerials inside, says research eammember Andrea Favalli, a scienis in
Los Ala mos Nuclear Engineering and
Nonprolieraion Division. Hes sudying
he riden beam or acive inerrogaion
applicaions. Oher such sysems have
been esed, says Favalli, a naive Ialian,
including one he helped develop a he
Join Research Cenre o he European
Commission. Tose, however, ofen relied on muliple measuremens or measuremens
over long periods. Te laser-driven beam could generae neuron signaures wih a
single rapid burs. Tere are many, many possible applicaions and more are
coming, Favalli says.
Te curren round o shos, in ac, is sudying acive inerrogaion. Te eam ound
ha passing he beam hrough a depleed uranium sample clearly delayed many o
he neurons. Delayed neurons is a signaure o fission, indicaing he presence o a
nuclear maerial.
***One hundred percent.
Shot 23-73 is complete. All areas are clear.
Wih ha and many oher shos, research on he riden neuron beam coninues.
Many are par o Favalli s acive inerrogaion projec, bu scieniss also wi ll sudy
opimizing he pulse o produce neurons wih a specific range o peak energies,
Merrill says. Te researchers also w ill address flucuaions in he number o
neurons each pulse generaes.
CAPTURING NEUTRONS
There already are neutron detectors at NIF, the National Ignition Facility,Frank Merrill says, but researchers need better ones.In a sense, the instruments are like digital cameras. A camera with more pixels captures a finer
image. A detector with better resolution provides a more accurate picture of neutron generation
and distribution in NIF shots.
NIF implosions are little tiny things, involving capsules of about 100 microns in diameter, says
Merrill, team leader for the Advanced Imaging Group in Los Alamos National Laboratorys Physics
Division. You dont want to just see theres a neutron source 100 microns in diameter. You want to
see some of the details inside. Top resolution now is about 10 microns and researchers are
constantly investigating ways to improve it. It would be wonderful if we got to 1 micron, but thats
a fairly significant technical challenge, he adds.
With bright neutron sources like the one Merrill and other researchers developed at Los Alamos
Trident laser, detector scientists will have greater access to testing. But in some ways, Trident is too
good. NIF typically produces neutrons with energies of around 14 megaelectron volts (MeV). Thelaser-driven neutrons at Los Alamos are up to 150 MeV. Its nice to have the higher energies,
Merrill says, but we were interested in the sweet spot, kind of zero to 30 MeV.
Never fear: The scientists use a high-tech gating system essentially a precise shutter to filter
out the speediest neutrons. Since they move faster, they arrive at the detectors first. Neutrons the
scientists seek come a hair later only after theshutter opens. That gated system is how we
were able to only look at the energy range we were interested in, Merrill adds.
-
7/23/2019 Ssgf Magazine 2013
26/28
P24STEWARDSHIP SC IENCE 13/14 THE SSGF MAGAZINE
S A M P L I N G S
Bottling the Sun
BY EVAN DAVIS
A metall ic feminine voice rings out through the control room:
Tree. wo. One. Zero. Entering pulse. Dozens of scientists and engineers
hold their breath and fix their eyes on the large computer display at the
front of the room. A warm, guttural hum fills the air, the ground
softly vibrates, and a flash of light appears on monitors throughout
the room.
In fractions of a second, millions of watts of power heat dilute gas to
200 mill ion degrees Fahrenheit, 10 times the temperature of the suns
core. At this temperature, the gas atoms are stripped of their electronsand their positively charged nuclei whiz by at 1 million miles per
hour. Some of these nuclei smash into each other with just the right
orientation and speed to fuse, forming an altogether different nucleus
and releasing an enormous amount of energy.
Te pulse ends almost as soon as it began. Te gas cools, the glow fades
from the monitors, and scientists scramble to analyze the data. en
minutes until next shot, the voice states, reminding the researchers
they must work quickly so theyre ready to coax every last bit of
performance out of their machine in the next experiment.
Its a typical day of operation at the Massachusetts Institute of
echnologys Alcator C-Mod reactor, located down a humble side street
in urban Cambridge, Mass. C-Mod is a compact nuclear fusion reactor
designed to study the scientific and engineering challenges that must
be overcome to make this technology a viable energy source.
Fusion is the energy of the sun and stars. Many scientists and engineers,
including my MI colleagues and me, want to bottle the sun for power
generation on Earth. When fully developed, fusion will provide
continuous power from abundant, virtually inexhaustible fuels, such
as deuterium, a hydrogen isotope harvested from seawater. Fusionpower plants will not directly produce any greenhouse gases. Tey
also would produce no long-lived nuclear waste, and there is no risk
of a meltdown or nuclear materials spreading for use in weapons.
okamaks like C-Mod are the leading candidates for successful fusion
reactor designs. Tese doughnut-shaped vacuum vessels use powerful
magnetic fields (2 to 3 esla, about the strength used in typical magnetic
resonance imaging (MRI) medical devices) to suspend a plasma in space,
preventing the hot core from touching any material walls. o prevent The author is a third-year fellow at the Massachusetts Institute of
Technology and this his winning entry in the 2013 SSGF Essay Slam.
melting the walls, the plasma temperature must drop from hundreds
of millions of degrees in the core to a few thousand at the reactor
wall, creating one of the largest thermal gradients in the universe.
Unfortunately, small-scale turbulence allows the plasma to leak through
the tokamaks magnetic fields. Indeed, Nobel laureate Richard Feynman
once described confining plasma within a tokamak as trying to hold Jell-O
with rubber bands: its possible, but its taxing and youl l probably lose at
least part of the Jell-O. A dozen or so scientists work on C-Mod with the
express purpose of understanding and controlling this turbulence.
Researchers at C-Mod and several other tokamaks over the past two
decades have identified several desirable operating modes that suppress
these detrimental turbulent fluctuations. In particular, weve discovered
that the potential fusion gain in tokamaks is strongly controlled by
parameters in the last inch or so of the plasmas edge.
My colleagues and I are working to develop and test a first-principles
computer model of this edge turbulence so that we can predict and
optimize a devices performance before its even built. Developing such a
model requires a strong coupling between experiment, computation,and theory. Tat means youll find me scrambling to set-up C-Mods
phase contrast interferometer before the days experiments begin
and fervently analyzing the measured turbulent density fluctuations
between shots. In the evenings, I run edge turbulence simulations on
the worlds most powerful supercomputers, aiming to validate the
code by comparing it with my experimental measurements. Its a
long, arduous process, but this crucial element of physics must be
understood if were to advance to a viable reactor.
Fusion science has progressed exponentially since its inception, and
we now stand poised to make a viable reactor for the first time. Aninternational collaboration is constructing IER, the first device
expected to reach and exceed fusion breakeven the point at which
energy put into the reaction equals the energy it produces.
C-Mod is the only tokamak that operates at the same densities and
heat fluxes as those expected in IER, so its thrilling to be here
and extremely important that our research continue.
Evan Davis
-
7/23/2019 Ssgf Magazine 2013
27/28
STEWARDSHIP SC IENCE 13/14THE SSGF MAGAZINE P25
CLASS OF 2013
MATTHEW BUCKNERSchool: University of North Carolina,
Chapel HillDiscipline: Nuclear AstrophysicsAdvisors: Tomas Clegg and Christian Iliadis
Practicum: Lawrence LivermoreNational LaboratoryContact: [email protected]
NICOLE FIELDSSchool: University of ChicagoDiscipline: Astroparticle PhysicsAdvisor: Juan CollarPracticum: Los Alamos National LaboratoryContact: [email protected]
KRISTEN JOHNSchool: California Institute of echnologyDiscipline: Aerospace EngineeringAdvisor: Guruswami RavichandranPracticum: Lawrence Livermore
National LaboratoryContact: [email protected]
JOSHUA RENNERSchool: University of California, BerkeleyDiscipline: Nuclear/Part