The University of Chicago/ Argonne National Lab ICAR Activities

10 September 2003 Mark Oreglia/ICAR review 1

The University of Chicago/Argonne National Lab

ICAR Activities

• Who we are• Muon accelerator issues:

– Muon cooling theory– Profile monitoring of intense beams

• Smith-Purcell Free Electron Laser• Linear electron collider development:

– electron source design– LC machine design/administration/education– hadron calorimetry and energy flow technique


U of C/ANL Personnel

• University of Chicago:– Mark Oreglia (Professor, co-PI) … LC, muon/LC

instrumentation– Yau Wah (Professor) … Smith-Purcell; JHF development– Kara Hoffman (RA) … beam profile monitor; neutrino factory– Bud Kapp (RA) … Smith-Purcell– Yin-e Sun (Grad Student) … electron sources– Assorted undergraduate students (6, so far)

• Argonne National Laboratory– Kwang-Je Kim (Senior Scientist; Professor/UofC)

• … Smith-Purcell; accelerator theory and education• Chung-Xi Wang (RA) … muon cooling theory

• Future additions likely:– Ed Blucher (Assoc. Prof.) and Young-Kee Kim (Professor)


Kwang-Je Kim’s Group Activities

• Part A: Ionization cooling theory– K.-J. Kim and C.-x. Wang (ANL)

• Part. B: Smith-Purcell Laboratory– O. Kapp, A. Crewe,Y.-e Sun (student),Yau Wah

• Part C: Graduate Physics Course “ Accelerator Physics and Technologies for Linear Colliders”– Kwang-Je Kim

• Part D: Participation to flat beam generation experiment at FNPL– Y.-e Sun (student)


Part A: Ionization Cooling Theory

• Theoretical effort by K.-J. Kim and C.-x. Wang

• A comprehensive linear theory for ionization cooling taking into account– Transport in cooling lattice (Hamiltonian)– Dissipation and fluctuation in absorbers– Emittance exchange via dispersion and wedge absorbers– Beam angular momentum

• Moments expressed in terms of five invariant emittances


Emittance Exchange

Dipole (bend)

+p

0

-p

x xop/pDipole introduces dispersion

Wedge Absorber reduces energy spread

beam


Further Theoretical Topics

• Recursive evaluation of beam transport lattice consisting of extended elements ( such as solenoids used in ionization cooling channels)

• Rigorous treatment of magnetic field expansion for curved reference orbits…Provided bench-marking of ICOOL

• Extensive Publications including two PRLs


Selected papers on related developments

• C.-x. Wang and K.-J. Kim, COOL03, NIM A (2003)

Beam envelope theory of ionization cooling

• C.-x. Wang and K.-J. Kim, PRL 88(18) 184801 (2002)

Linear Theory of Ionization Cooling in 6D Phase Space

• C.-x. Wang and K.-J. Kim, NIM A503 401 (2001)

Linear theory of transverse and longitudinal cooling in a quad. channel

• C.-x. Wang and K.-J. Kim, PRE 63 056502 (2001)

Recursive solution for beam dynamics of periodic focusing channels

• C.-x. Wang, NIM A503 409 (2001)

Dispersions in a bent-solenoid channel

• C.-x. Wang and L.C. Teng, PAC’01(2001)

Magnetic Field Expansion in a Bent-Solenoid Channel

• K.-J. Kim and C.-x. Wang, NIM A472 561(2001)

Progress in the Linear Beam Dynamics Study of Ionization Cooling Channel

• K.-J. Kim and C.-x. Wang, PRL 85(4) 760 (2000)

Formulas for Transverse Ionization Cooling in Solenoidal Channels


Part B: Smith-Purcell Laboratory• An electron microscope–based Smith-Purcell generator for a

compact far IR source

• Retrofitted the sample chamber of a Cambridge S-200 scanning electron microscope with a grating

• Radiation transported via a polyethyene window to a bolometer

• Observed spontaneous Smith-Purcell radiation after carefully eliminating the effects due to blackbody radiation. (c.f., Dartmouth claim on high-gain behavior)

• We are evaluating:– Several options for electron sources (heated tungsten tip, Lab6,

Thermionic field emission)– Electron beam recovery system

• Preparing proposals for other funding agencies


IR detectorFEL

Bud’s lunch


Part C: A Graduate Physics Course “ Physics and Technologies for Linear Colliders

• Physics 575 during winter 2002

• Lectures by experts in the field– S. Holmes, K.J. Kim, T. Raubenheimer, J. Rosenzweig, L. Emery,

J. Wang, L. Lilje, F. Zimmermann, V. Shiltsev, W. Gai

• Lecture notes in the course web page– http://hep.uchicago.edu/~kwangje/phy575.html


Part D: Flat Beam Generation

• A novel beam manipulation technique proposed by Y.Derbenev

• A flat beam ratio (FBR) of 50 has been achieved at FNPL ( FNAL-NIU Photocathode Laboratory).

• Yin-e Sun is investigating effects reducing FBR– Energy spread, space-charge effects, breaking of

cylindrical symmetry

• To improve the flat beam ratio to >100.


Schematic rendition of the layout at Fermilabfor flat beam experiment

x = A cos z

y = A sin z

A cos z

A sin (z+/2)

flat beamvortex beam


FermiLab/NICADD PhotoInjector

Layout taken from PAC01 paper of D. Edwards etc.


Flat electron beam profile at 9.6m from the cathode (XL6) and horizontal and vertical beamlets used for emittance measurements downstream at XL7 and XL8. The transverse emittance ratio is about 41 in the example shown here.

4195.0

85.38

mradmm

mradmmxn

yn


Mark Oreglia’s Group Activities

• Started out with muon cooling instrumentation R/D– Bolometric beam profiler

• Made progress, but Kara developed another idea …– Thin diamond beam profile monitor

• First time diamond used for intense beams• More versatile application than just muon channel

– FNAL machine groups very interested• Cheaper than single-particle application

• Then Oreglia got involved in the Linear Collider– Co-chair of American LC Physics Group; US Steering Ctte– Member of International LC parameters ctte– Working on hadron calorimetry; RPC

development/assessment + energy flow techniques


The challenge of The challenge of profiling beamprofiling beam in muon cooling in muon cooling channelchannel

•While disturbing the beam as little as possible measure:

• intensity

• size/profile (in 2 dimensions?)

• timing between bunches or pulses

• The detection medium must be radiation hard.

• The beam must be accurately measured in an environment with a lot of noise from rf cavities, etc.

• The profiler and associated readout/power cables must fit within the design of the cooling channel.

• Muons are difficult to detect.


IDEA IDEA #1#1


Bolometry: proof it Bolometry: proof it worksworks

0.8

V0

.8 V

10 ms10 ms

Carbon

0.8

V0

.8 V

20 ms20 ms

Nickel “bolometer”(actually a commercially made thin film nickel thermometer)

Xe flashlamp

lenses

cryostat

filter

electronics

Signal or background?

Look for thermal dependence(i.e. change in signal size, time constant).

Polarity: carbon’s electrical resistivity increases with

temperature while nickel’s decreases.

Signal or background?

Look for thermal dependence(i.e. change in signal size, time constant).

Polarity: carbon’s electrical resistivity increases with

temperature while nickel’s decreases.

(“homemade” from graphite foil or colloidal carbon)

@20@20KK


Materials Studies• We’ve researched traditional

and non-traditional materials– Measured properties

• Developed thin film techniques

• Constructed pulse simulators– Laser calorimetry

simulation– ANL e-beam tests

• Constructed temperature controller to simulate cooling channel– LHe cryostat +

temperature controller


Amplifier Development

• To match time constants and minimize noise, we have developed special purpose amplifiers in the Enrico Fermi Institute Electronic Design Group (Harold Sanders!)

• X600 amplification• Baseline

subtracting

• They work!


Beamtests at ANL: setupBeamtests at ANL: setup•copper block with 1/8” hole used to mask off beam and shield the thermometer

•Pulses nominally 10 nA in duration--we tried to reduce inductive noise by elongating pulses to lower instantaneous current

beampipe

cryostat

temperature controller

vacuum pump

LH2 tank

bolometric film

• /pulse

•840 nA @ 30 Hz

e11107.1


Beamtests at ANL: resultsBeamtests at ANL: results

• see opposite coefficient for Ni vs C … for a while

• learned that intense e-beam modifies graphite

• Some interesting results here

• minimizing inductive noise will need more design work

• … but, in principle, the technique shows some promise


0.30 - 0.35 K0.25 - 0.300.20 - 0.25

0.10 - 0.15 0.15 - 0.20

0.00 - 0.050.05 - 0.10

2 beam radius

Signal expectation: Signal expectation: the linac test facility the linac test facility (protons!) (protons!)

GEANT3 simulation

Corresponding % resistivity change in bolometer strip

Platinum TCR curve

Platinum TCR curve


Advantages:

• doesn’t disturb the beam; inexpensive; robust

Drawbacks:• must be applied to absorber window for heat sinking – could be an issue mechanically/safetywise and cannot be removed or replaced

• small signal, particularly for more diffuse beams

• metal strips provide challenge in large electromagnetic noise environment

• large thermal time constants do not allow for measurement of timing information

Bolometry findingsBolometry findings

Future Plans: NIM publication in preparation … sort of… we still have a number of measurements to perform


New Idea (Kara, of course!):New Idea (Kara, of course!):Diamond is prized for more Diamond is prized for more than just its sparkle (high than just its sparkle (high refractive index)…refractive index)…

low leakage Ivery fast readout

no p-n junction neededlow capacitance

rad hard, strong

no cooling

hard

insensitive to ’s >220nm

Makes a great particle detector!


-

-

-

-

+

+

+

+

diamond substrate~500 m thick (when used as a

microvertex detector)

E (>1 V/m)

sputtered metal strips/pixels(400 angstroms of titanium or chromium coated with 4000 angstroms of gold)

solid electrode

Ionizing radiation (36 e-h pairs per m per mip)

Anatomy of a diamond substrate Anatomy of a diamond substrate microstrip detector… microstrip detector…

Essentially a very compact solid-state ionization chamber.

IDEA IDEA #2#2


Diamond as a beam Diamond as a beam profiler? profiler?

•sensitive (2 coordinate?) measurement

•fast (subnanosecond ~40ps) intrinsic response might allow temporal beam profiling, in addition to current and position measurements

•free standing-accessible

•low Z- very little beam loss

•has been demonstrated to be rad hard to a proton fluence of at least

•relatively huge signal (too huge??)

Diamond has not yet been realized as a microvertex detector because the signal size is small compared with silicon and single particle detection efficiency is required. However, single particle efficiency is NOT required for a beam profiler.

215 /105 cm


Polycrystalline CVD Polycrystalline CVD Diamond Diamond

growth sidegrowth side

substrate sidesubstrate side

L

dxedq induced charge:

Edx )(

dx= distance e-holes drift apart

= carrier mobility, = carrier lifetime

Carrier lifetime effected by:

•size of individual crystals-grain boundaries

•in grain defects and impurities

ddx


“black” diamond

polishedhigh purity diamond

unpolished diamond

diamond membrane(with person peeping through)

What kind of diamond is best What kind of diamond is best suited as a beam profiler?suited as a beam profiler?

• signal size could be limited by decreasing the electric field

•this approach is destructive to timing information

• diamond with short carrier lifetime• small gives faster response at the expense of efficiency• much cheaper

• as thin as possible•less charge produced per mip • voltage required for maximum carrier velocity is proportional to thickness• easier to dissipate heat•diamond “membranes” can be made 1m thick

We want to minimize the signal while exploiting the timing information.


Detector fabrication: Detector fabrication: sputtering sputtering electrodes electrodes •We have fabricated our first prototype from a piece of 500m x 11mm x 11mm detector grade CVD diamond that was manufactured by DeBeers.

•Leads were sputtered at OSU using a shadow mask—finer segmentation could be achieved with a lithographic mask.


Towards a diamond testing Towards a diamond testing program…program…

R&D areas:R&D areas:

•Application specific material will need to be developed, along with fast electronics.

•Over what range of intensity measurements could diamond be useful? (space charge effects?)

•How radiation hard is it?

Near term plans:Near term plans:

•We are in the process of obtaining some diamond with shorter carrier lifetimes.

•We plan to study the behavior of our prototype in a beam test at Argonne this summer.

R&D areas:R&D areas:

•Application specific material will need to be developed, along with fast electronics.

•Over what range of intensity measurements could diamond be useful? (space charge effects?)

•How radiation hard is it?

Near term plans:Near term plans:

•We are in the process of obtaining some diamond with shorter carrier lifetimes.

•We plan to study the behavior of our prototype in a beam test at Argonne this summer.


Linear Collider Activities

• We moved into this area when HEPAP announced this would be the next US accelerator project

• An important US LC workshop was hosted by the University of Chicago in January 2001 … ICAR-sponsored

• Oreglia, Blucher, Y.K. Kim sit on LC organizational groups• LC scope: Oreglia edited the US “scope paper” defining

required machine parameters; now participating in the international ctte

• ICAR funds have been essential in supporting this activity• Physics+Detector work:

– Focusing on hadron calorimetry:• Fits in with ATLAS-related activity• Working on RPC development with ANL (Jose Repond)

– This preliminary work will likely leverage some NSF support


University of Chicago RPC StudiesDevelopment of a Digital Hadron

Calorimeter for the LC

based on Resistive Plate ChambersWork in conjunction with ANL (Jose

Repond)Abigail Kaboth … undergrad!

Ed BlucherMark OregliaSasha Glazov


RPC R/D• First built by Argonne … we are building our own prototypes

– Want to look for material damage; investigate chamber performance

• They are a very cost-effective technology for LC application, but

• The technology has a very checkered past• Useful technology for other experiments too (neutrino,…)

– Double gap RPC– Three fishing line spacers in each gap

• We are mixing our own gases– permits us to optimise for avalanche mode (new-ish application)

• Electronics Design Group is developing DAQ electronics

• … all supported exclusively by ICAR!

• …… and this “redundant” work is learning new things about RPCs!


UoC Data Acquisition Setup

Trigger Counters

RPC

Drift Chamb

er

Drift Chamber Track, 250 m resolution

x

z

y


Photographs

Abby

RPC


• We saw significant dips in the efficiency of the RPC around the fishing wire spacers.

• Bin size is .375 mm.• Dip is wider than

spacer.

Eff

icie

ncy

Eff

icie

ncy

Position (mm)

Position (mm)

7400 V

7600 V

Half width is 1.8 mm

Half width is 1.8 mm

Spacer Inefficiencies


Eff

icie

ncy

Position (mm)

High Voltage on this side

Finding Current Paths


Calculating Apparent Voltage Drop• Using drift chamber data,

we calculated apparent voltage as a function of position from the tanh curve.

• We see a variation of about 100 V, about 1%.

Position (mm)

Volt

ag

e

(V)


Possible Causes• Variations in internal geometry and construction

– Plates not being exactly parallel– Damage on glass from experimentation

• Actual voltage drop due to current flow– Through fishing line spacer– Because of moisture in gas


Epilogue

• ICAR funds have permitted us to move into exciting new directions and take important roles in the Muon Collaboration, the Linear Collider project, and new accelerator development

• We have been able to support 2 postdocs and students only because of the ICAR funding

• We plan to continue research on the original projects, with some additions and redirections:– Advanced accelerator theory beyond just muon now

• KJK working to establish a center for accel research– Beamline instrumentation has taken a new, more

promising direction … thin diamond detectors– Development of RPC calorimeters now fully underway

• Working to build a 1m2 prototype for beam testing– Just starting studies of energy-flow analysis and

optimisation of LC detector systems


Mutual Benefits from ICAR Funding• ICAR funding has permitted us to address problems which, in the

majority of cases, our traditional funding agencies denied• This results in novel developments; in our case:

– New beamline instrumentation• New knowledge of material properties and participation by

new people (materials scientists, nano centers, …)– New tools for materials research (Smith-Purcell instrument)– New tools for accelerator builders (theory, e-injector, cold )– New tools for HEP experimenters (next-generation calorimetry)

• Facilitates new types of student training• And benefits Illinois:

– Local industry participates or gets business – Illinois is a candidate site for LC

• And if not the site, our work helps ensure FNAL major player– Illinois students and teachers participate: learn and contribute


Extra Slides


Equation of Motion

• Phase space vector

•

•

0

0Tyx p

pp;),z,p,y,p,x(

X

motionnHamiltonia;JH,XdsdX

H H

HXX21 TH

MH dsdX

dsdX

dsdX

0100

1000

0001

0010

J


Hamiltonian of the Focusing System

solenoid + dipole + quadrupole + RF + absorber

dipole quadrupole r.f.

solenoid

,

Lab frame

Rotating frame

, ,,


Emittance Evolution Near Equilibrium Parametrized by Five Invarients

Guidance for developing cooling channel with emittance-exchange


Diagram of the RPC


Major Budget Items

• Part A… Fund transfer to ANL to support C.-x. Wang

• Part B …Partial (40-50%) salary support for O. Kapp, equipments and supplies, technician charges

• Part C…Travel support for lecturers

• Part D…Stipend for a graduate student

• Domestic and international travels

• Equipment for Smith-Purcell project


mLQ

Qd

induced

collectedcollection 100 mL

Q

Qd

induced

collectedcollection 100

tails due to tails due to carrier lifetimescarrier lifetimes

Charge collection Charge collection efficiency efficiency Charge collection efficiency is a product of:

• d-carrier drift velocity- a function of the applied electric field up to a saturation velocity

• -carrier lifetime-a function of diamond quality-commercially available diamond improving with time

The University of Chicago/ Argonne National Lab ICAR Activities

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