The University of Chicago Argonne National Lab ICAR
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 10 September 2003 Mark Oreglia/ICAR review 1
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/Uof. C) • … 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) 10 September 2003 Mark Oreglia/ICAR review 2
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) 10 September 2003 Mark Oreglia/ICAR review 3
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 10 September 2003 Mark Oreglia/ICAR review 4
Emittance Exchange 10 September 2003 Mark Oreglia/ICAR review 5
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 10 September 2003 Mark Oreglia/ICAR review 6
Selected papers on related developments • C. -x. Wang and K. -J. Kim, COOL 03, 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 6 D Phase Space • C. -x. Wang and K. -J. Kim, NIM A 503 401 (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 A 503 409 (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 A 472 561(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 inreview Solenoidal Channels 10 September 2003 Mark Oreglia/ICAR 7
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, Lab 6, Thermionic field emission) – Electron beam recovery system • Preparing proposals for other funding agencies 10 September 2003 Mark Oreglia/ICAR review 8
10 September 2003 Mark Oreglia/ICAR review 9
IR detector FEL Bud’s lunch 10 September 2003 Mark Oreglia/ICAR review 10
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/phy 575. html 10 September 2003 Mark Oreglia/ICAR review 11
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. 10 September 2003 Mark Oreglia/ICAR review 12
Schematic rendition of the layout at Fermilab for flat beam experiment x = A cos kz y = A sin kz A sin (kz+p/2) vortex beam 10 September 2003 flat beam Mark Oreglia/ICAR review 13
Fermi. Lab/NICADD Photo. Injector Layout taken from PAC 01 paper of D. Edwards etc. 10 September 2003 Mark Oreglia/ICAR review 14
Flat electron beam profile at 9. 6 m from the cathode (XL 6) and horizontal and vertical beamlets used for emittance measurements downstream at XL 7 and XL 8. The transverse emittance ratio is about 41 in the example shown here. 10 September 2003 Mark Oreglia/ICAR review 15
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 10 September 2003 Mark Oreglia/ICAR review 16
The challenge of profiling beam in muon cooling channel • 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. 10 September 2003 Mark Oreglia/ICAR review 17
IDEA #1 10 September 2003 Mark Oreglia/ICAR review 18
Bolometry: proof it works Nickel “bolometer” 0. 8 V cryostat filter (actually a commercially made thin film nickel thermometer) lenses electronics 20 ms Xe flashlamp 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. 10 September 2003 0. 8 V Carbon Mark Oreglia/ICAR review (“homemade” from graphite foil or colloidal carbon) @20 K 10 ms 19
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 10 September 2003 Mark Oreglia/ICAR review 20
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!) • X 600 amplification • Baseline subtracting • They work! 10 September 2003 Mark Oreglia/ICAR review 21
Beamtests at ANL: setup • copper block with 1/8” hole used to mask off beam and shield thermometer cryostat • Pulses nominally 10 n. A in duration--we tried to reduce inductive noise by elongating pulses to lower instantaneous current bolometric film • /pulse • 840 n. A @ 30 Hz temperature controller beampipe LH 2 tank 10 September 2003 Mark Oreglia/ICAR review vacuum pump 22
Beamtests at ANL: results • see opposite coefficient for Ni vs C … for a while • learned that intense ebeam modifies graphite • Some interesting results here • minimizing inductive noise will need more design work • … but, in principle, the technique shows some promise 10 September 2003 Mark Oreglia/ICAR review 23
Signal expectation: the linac test facility (protons!) 0. 30 - 0. 35 K 0. 25 - 0. 30 0. 20 - 0. 25 0. 15 - 0. 20 0. 10 - 0. 15 0. 05 - 0. 10 0. 00 - 0. 05 2 s beam radius Platinum TCR curve Corresponding % resistivity change in bolometer strip Mark Oreglia/ICAR review GEANT 3 simulation 10 September 2003 24
Bolometry findings 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 Future Plans: NIM publication in preparation … sort of … we still have a number of measurements to perform 10 September 2003 Mark Oreglia/ICAR review 25
New Idea (Kara, of course!): Diamond is prized for more than just its sparkle (high refractive index)… low leakage I very fast readout no p-n junction needed low capacitance no cooling Makes a great particle detector! 10 September 2003 Mark Oreglia/ICAR review hard rad hard, strong insensitive to g’s l>220 nm 26
IDEA #2 Anatomy of a diamond substrate microstrip detector… Ionizing radiation (36 e-h pairs per mm per mip) sputtered metal strips/pixels (400 angstroms of titanium or chromium coated with 4000 angstroms of gold) diamond substrate ~500 mm thick (when used as a microvertex detector) E - + - (>1 V/mm) + + solid electrode Essentially a very compact solid-state ionization chamber. 10 September 2003 Mark Oreglia/ICAR review 27
Diamond as a beam profiler? 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. • sensitive (2 coordinate? ) measurement • fast (subnanosecond ~40 ps) 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? ? ) 10 September 2003 Mark Oreglia/ICAR review 28
Polycrystalline CVD Diamond induced charge: dx= distance e-holes drift apart m = carrier mobility, t = carrier lifetime growth side Carrier lifetime effected by: • size of individual crystalsgrain boundaries • in grain defects and impurities substrate side 10 September 2003 Mark Oreglia/ICAR review 29
What kind of diamond is best suited as a beam profiler? “black” diamond We want to minimize the signal while exploiting the timing information. unpolished diamond • signal size could be limited by decreasing the electric field • this approach is destructive to timing information • diamond with short carrier lifetime • small t gives faster response at the expense of efficiency • much cheaper polished high purity diamond membrane (with person peeping through) • as thin as possible • less charge produced per mip • voltage required for maximum carrier velocity is proportional to thickness • easier to dissipate heat 10 September 2003 Mark Oreglia/ICAR • diamond “membranes” can be made 1 mm review thick 30
Detector fabrication: sputtering electrodes • We have fabricated our first prototype from a piece of 500 mm x 11 mm detector grade CVD diamond that was manufactured by De. Beers. • Leads were sputtered at OSU using a shadow mask—finer segmentation could be achieved with a lithographic mask. 10 September 2003 Mark Oreglia/ICAR review 31
Towards a diamond testing program… 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: • 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. 10 September 2003 Mark Oreglia/ICAR review 32
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 10 September 2003 Mark Oreglia/ICAR review 33
University of Chicago RPC Studies Development of a Digital Hadron Calorimeter for the LC based on Resistive Plate Chambers Work in conjunction with ANL (Jose Repond) Abigail Kaboth … undergrad! Ed Blucher Mark Oreglia Sasha Glazov 10 September 2003 Mark Oreglia/ICAR review 34
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! 10 September 2003 Mark Oreglia/ICAR review 35
Uo. C Data Acquisition Setup Trigger Counters RPC Drift Chamber z y x 10 September 2003 Drift Chamber Track, 250 m resolution Mark Oreglia/ICAR review 36
Photographs RPC Abby 10 September 2003 Mark Oreglia/ICAR review 37
• 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. Efficienc y Spacer Inefficiencies 7400 V Half width is 1. 8 mm Efficienc y Position (mm) 10 September 2003 7600 V Half width is 1. 8 mm Mark Oreglia/ICAR review Position (mm) 38
Efficienc y Finding Current Paths High Voltage on this side Position (mm) 10 September 2003 Mark Oreglia/ICAR review 39
Calculating Apparent Voltage Drop Voltage (V) • 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) 10 September 2003 Mark Oreglia/ICAR review 40
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 10 September 2003 Mark Oreglia/ICAR review 41
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 1 m 2 prototype for beam testing – Just starting studies of energy-flow analysis and optimisation of LC detector systems 10 September 2003 Mark Oreglia/ICAR review 42
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 m) – 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 10 September 2003 Mark Oreglia/ICAR review 43
Extra Slides 10 September 2003 Mark Oreglia/ICAR review 44
Equation of Motion • Phase space vector • • 10 September 2003 Mark Oreglia/ICAR review 45
Hamiltonian of the Focusing System solenoid + dipole + quadrupole + RF + absorber q Lab frame solenoid quadrupole dipole r. f. q Rotating frame , 10 September 2003 , , Mark Oreglia/ICAR review , 46
Emittance Evolution Near Equilibrium Parametrized by Five Invarients Guidance for developing cooling channel with emittance-exchange 10 September 2003 Mark Oreglia/ICAR review 47
Diagram of the RPC 10 September 2003 Mark Oreglia/ICAR review 48
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 10 September 2003 Mark Oreglia/ICAR review 49
Charge collection efficiency is a product of: • ud-carrier drift velocity- a function of the applied electric field up to a saturation velocity • t-carrier lifetime-a function of diamond qualitycommercially available diamond improving with time tails due to carrier lifetimes 10 September 2003 Mark Oreglia/ICAR review 50
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