The University of Chicago/ Argonne National Lab ICAR Activities

1. The University of Chicago/Argonne National LabICAR 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 Mark Oreglia/ICAR review

2. 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) Mark Oreglia/ICAR review

3. 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) Mark Oreglia/ICAR review

4. 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 Mark Oreglia/ICAR review

5. Emittance Exchange Mark Oreglia/ICAR review

6. 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 Mark Oreglia/ICAR review

7. 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 Mark Oreglia/ICAR review

8. 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 Mark Oreglia/ICAR review

9. Mark Oreglia/ICAR review

10. IR detector FEL Bud’slunch Mark Oreglia/ICAR review

11. 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 Mark Oreglia/ICAR review

12. 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. Mark Oreglia/ICAR review

13. x = A coskz y = A sinkz Schematic rendition of the layout at Fermilabfor flat beam experiment A coskz A sin (kz+p/2) flat beam vortex beam Mark Oreglia/ICAR review

14. FermiLab/NICADD PhotoInjector Layout taken from PAC01 paper of D. Edwards etc. Mark Oreglia/ICAR review

15. 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. Mark Oreglia/ICAR review

16. 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 Mark Oreglia/ICAR review

17. 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. Mark Oreglia/ICAR review

18. IDEA #1 Mark Oreglia/ICAR review

19. Nickel “bolometer” Carbon (actually a commercially made thin film nickel thermometer) 0.8 V 0.8 V 10 ms 20 ms Bolometry: proof it works cryostat filter lenses Xe flashlamp electronics (“homemade” from graphite foil or colloidal carbon) 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. @20K Mark Oreglia/ICAR review

20. 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 Mark Oreglia/ICAR review

21. 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! Mark Oreglia/ICAR review

22. Beamtests 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 cryostat bolometric film • /pulse • 840 nA @ 30 Hz temperature controller beampipe LH2 tank vacuum pump Mark Oreglia/ICAR review

23. Beamtests 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 Mark Oreglia/ICAR review

24. 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 2s beam radius Signal expectation: the linac test facility (protons!) Platinum TCR curve Corresponding % resistivity change in bolometer strip GEANT3 simulation Mark Oreglia/ICAR review

25. 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 Mark Oreglia/ICAR review

26. 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 hard rad hard, strong insensitive to g’s l>220nm Makes a great particle detector! Mark Oreglia/ICAR review

27. Anatomy of a diamond substrate microstrip detector… IDEA #2 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) E (>1 V/mm) diamond substrate ~500 mm thick (when used as a microvertex detector) - + - + - + - + solid electrode Essentially a very compact solid-state ionization chamber. Mark Oreglia/ICAR review

28. 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 ~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??) Mark Oreglia/ICAR review

29. 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 crystals-grain boundaries • in grain defects and impurities substrate side Mark Oreglia/ICAR review

30. diamond membrane (with person peeping through) “black” diamond unpolished diamond polished high purity diamond What kind of diamond is best suited as a beam profiler? We want to minimize the signal while exploiting the timing information. • 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 • 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 1mm thick Mark Oreglia/ICAR review

31. Detector fabrication: sputtering electrodes • We have fabricated our first prototype from a piece of 500mm 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. Mark Oreglia/ICAR review

32. 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. Mark Oreglia/ICAR review

33. 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 Mark Oreglia/ICAR review

34. 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 Blucher Mark Oreglia Sasha Glazov Mark Oreglia/ICAR review

35. 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! Mark Oreglia/ICAR review

36. UoC Data Acquisition Setup Trigger Counters RPC Drift Chamber z y x Drift Chamber Track, 250 m resolution Mark Oreglia/ICAR review

37. Photographs RPC Abby Mark Oreglia/ICAR review

38. Spacer Inefficiencies • 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. Efficiency 7400 V Half width is 1.8 mm Position (mm) Efficiency 7600 V Half width is 1.8 mm Mark Oreglia/ICAR review Position (mm)

39. High Voltage on this side Finding Current Paths Efficiency Position (mm) Mark Oreglia/ICAR review

40. 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%. Voltage (V) Position (mm) Mark Oreglia/ICAR review

41. 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 Mark Oreglia/ICAR review

42. 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 Mark Oreglia/ICAR review

43. 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 Mark Oreglia/ICAR review

44. Extra Slides Mark Oreglia/ICAR review

45. Equation of Motion • Phase space vector Mark Oreglia/ICAR review

46. solenoid + dipole + quadrupole + RF + absorber Hamiltonian of the Focusing System • Lab frame solenoid quadrupole r.f. dipole • Rotating frame , , , , Mark Oreglia/ICAR review

47. Emittance Evolution Near Equilibrium Parametrized by Five Invarients Guidance for developing cooling channel with emittance-exchange Mark Oreglia/ICAR review

48. Diagram of the RPC Mark Oreglia/ICAR review

49. 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 Mark Oreglia/ICAR review

50. Charge collection efficiency • 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 quality-commercially available diamond improving with time tails due to carrier lifetimes Mark Oreglia/ICAR review