1. MICE Berkeley, Oct 2002 MICE Spectrometer Design Proposed Tracker Implementations A. Bross Fermilab

2. MICE Berkeley, Oct 2002 Spectrometer Requirements  Experimental goal is u Measure 6D emittance   n =  D  (x,y,t) and (x’,y’,t’)  (p x /p z,p y /p z,E/p z )  Single-particle experiment u Measures x i,y i position at z i s Plus possibly t u Resolution requirement  rms  10% of beam parameter rms u At least 3 planes   1 m long (2/3 turn @ 200 MeV/c and 3T  Beam with  30 MeV/c p 

3. MICE Berkeley, Oct 2002 Spectrometer Requirements  Rough transverse beam specs   x,y = 5 cm   x’,y’ = 100 mrad  Using the PSI LOI analysis u SCIFI option s 4 planes s 150 micron resolution  On the order of 1000 muons needed for 10  u Assumes   contamination < 10%   rejection 99% s e identification  Does not address problem of operating near RF cavities  Ionizing background (e,  ) u EM (rf) background Transverse cooling for 7, 14, and 28 MeV cooling channels

4. MICE Berkeley, Oct 2002 Spectrometer Requirements  6 D measurement   t  2 ns   E / E  10%  Approximately 3000 muons needed for 10  measurement

5. MICE Berkeley, Oct 2002 Detector Options  Two Options are currently under study for trackers u Scintillating Fiber s Based on D0 experience s Uses 350 micron diameter fiber s Visible Light Photon Detector Readout s 45,000 channels (in most aggressive configuration)! u GEM based Time Projection Chamber or TPG s Based on HARP design –Plan to use HARP electronics s But will use Gaseous-Electron-Multipliers (GEMs) instead of wires for gain region.

6. MICE Berkeley, Oct 2002 Fiber Tracker Option for MICE  Fiber Tracker Baseline Design u Assume s Backgrounds are extremely high! s Requires use of smallest fiber diameter possible –350 micron u u-v-t readout station s Doublet structure s 0.3 % X o per station u 5 stations/spectrometer u This yields a system with about 45k channels! s VLPC readout s <3 m light piping fibers from detector to VLPC

7. MICE Berkeley, Oct 2002 Fiber Tracker Channel Mirror Scintillating Fiber Optical connector Waveguide VLPC cassette Electronics Cryostat

8. MICE Berkeley, Oct 2002 Fiber Tracker Parameters  Mechanical u 300 mm active diameter u 5 stations in 1 m path u Material budget 0.8g/cm 2  Electrical/Readout u 45,000 channels u VLPC readout (1 mm pixel)  Tracking u Expect 8 pe signal/singlet   x =  y  40  m   p   0.2 MeV/c  Timing u 20 ns integration time s 2 ns time-stamp resolution +1

9. MICE Berkeley, Oct 2002 Scintillating Fiber Ribbons  Interlocking doublet  835  m 3HF scintillating fiber u Fluorescence 525 nm (peak) to 610 nm  Grooved substrate - machined Delrin  Pitch between 915 and 990  m  Optimal P/d  1.2  Substrate put into curved backbone u Fibers glued together with polyurethane adhesive  Ribbons is then QC’ed using scanning X-ray source  Technique is very fast  All MICE planes require  4 MM effort + Tooling

10. MICE Berkeley, Oct 2002 VLPC Readout Option  VLPC (Visible Light Photon Counter) u Cryogenic APD operating @ 9K  Characterization/test/sort Cassette Assignment u As shown

11. MICE Berkeley, Oct 2002 1024 Channel VLPC Cassettes  Engineering Design u 8 – 128 channel modules u Cassette carries two 512 ch readout boards s Front-end amp/discriminator s Analog – SVX IIe 3’

12. MICE Berkeley, Oct 2002 Lab 3 CRT (Singlet) Light Yield Lab 3 CRT Light Yield Summary Covers Waveguide lengths 7.7-11.4m

13. MICE Berkeley, Oct 2002 MICE Fiber Tracker  Conventional FT using MAPMT  With same length of readout fiber u If waveguides are used   430 nm = 1300 dB/km (1/e = 3.4m)   525  nm = 450 dB/km (1/e = 9.6m) –D0 measured 8.1m @ f p = 525 nm u QE = 20% u Yield = s 9 X 20/80 X exp(-5/3.4)/exp(- 5/8)   1 pe  Waveguide length would have to be limited to 2 to 3 meters Attenuation vs. wavelength of Kuraray clear fiber 3 HF Conventional Blue

14. MICE Berkeley, Oct 2002 TPG Concept for MICE  Basic TPG Design u 90% He – 10% iso- butane TPC with gain section consisting of 3 GEMs u Readout plane - strip geometry 5  m Cu on 50  m Kapton. 70  m holes with 140  m pitch

15. MICE Berkeley, Oct 2002 Gaseous Electron Multiplier TPC

16. MICE Berkeley, Oct 2002 TPG Parameters  Mechanical u Active diameter = 300 mm u Active length = 1000 mm u Material budget s 0.01g/cm 2  Drift u 500 V/cm (50KV)  1.7 cm/  s  Electrical/Readout u 3 GEM amplification s Gain upwards of 10 4 -10 5 s Gated during RF pulse –[TPG readout between pulses] –  60  s max drift time –500  s exposure time u u,v,t hexagonal pads s Readout with u,v,t strips –450  m pitch   120 samples in z

17. MICE Berkeley, Oct 2002 Expected TPG Performance  Tracking   x =  y  150  m   p   0.2 MeV/c u With u,v,t readout expect to be able to readout 400 muons during a single time window  Timing  60  s readout time u The TPG requires a fine grained hodoscope in order to “tag” each muon so that its arrival time relative to the RF phase can be measured. s Possibly SCIFI layer + High resolution (50-100 ps) TOF

18. MICE Berkeley, Oct 2002 TPG Electronics  HARP electronics can be used for MICE TPGs

19. MICE Berkeley, Oct 2002 HARP TPC Electronics  Based on ALICE prototypes  ALTRO (Alice Tpc ReadOut) chip u Sophisticated zero-suppression and time-over-threshold logic  100  s depth @10 MHz sampling  Uses FEDC board version of ALTRO readout system  1 FEDC = 48 channels u 4 - 10 bit ADCs + ALTRO on daughter card (12/FEDC) s Fed by preamps on TPC pad plane  4000 channels available u 6 9U VME crates  MICE TPG  600X3X2 = 3600 ch  Can handle expected data rates

20. MICE Berkeley, Oct 2002 MICE Tracking Decision  In the absence of ionizing (e +  ) and electromagnetic radiation backgrounds from the cavities, and safety considerations because of the LH absorbers, both trackers can easily work.  Final decision will depend on u Actual background radiation environment s Includes EM interference concerns for TPG –To be tested at CERN in the near future s Tracking performance of each option in the expected rad field –Big uncertainties (or large extrapolation) until prototype 201 MHz cavity under test u Safety issues s Need to be studied for TPG option s Not an issue for fibers since detector passive u And eventually – COST s Fiber tracker is dominated by channel count (VLPCs) s TPG saves a great deal by reusing HARP electronics

21. MICE Berkeley, Oct 2002 Radiation Backgrounds  Snap-shot of background measurements. We are on a VERY steep (and slippery) slope!

22. MICE Berkeley, Oct 2002 Radiation Backgrounds  Question regarding equilibrium point e/  u E max = 10 MeV  e  brem    Compton  e

23. MICE Berkeley, Oct 2002 Strawman Background Hit comparison  Based on 1 MHz hit rate from 30 cm long, 835 mm diameter fiber located about 1.5 m from pill-box cavity in Lab G at Fermilab (B=2 T, 10 MV/m) [Assume from x-rays only – not correct] u This corresponds to an x-ray fluence of 6X10 7 /cm 2 -s s Assumes x-ray energy 50 keV u Hits/read s Fiber Tracker –6X10 7 X 20X10 -9 X[1-exp(-0.2cm 2 /g X.8g/cm 2 )]X707  125 s TPG –6X10 7 X 60X10 -6 X[1-exp(-0.17cm 2 /g X.01g/cm 2 )]X707  4300  But u TPG has 120/5 more “measurement stations” u Fiber Tracker also has possibility of 2 ns time-stamp u In both systems an x-ray interaction may produce more than one hit u Low energy x-rays (<10 keV) more of a problem for TPG than fiber tracker where they do not register a hit.  Need Measurements with Final Cavity to be sure!

24. MICE Berkeley, Oct 2002 Conclusions  In the absence of backgrounds, the choice of tracker for the spectrometers would likely only be based on cost and safety considerations. u Both TPG and SCIFI can easily meet the experiment requirements in terms of tracking performance (resolution) and pattern recognition (in zero BG conditions) and do so within an acceptable material budget  Radiation, ionizing +  from RF cavities still present a very difficult environment in which to operate, however  Sensitive electronics (front-end preamps) may also have problems due to EM leakage from cavities u Detailed shielding question  Constraints imposed by safety requirements will be severe for any active components within the 5 m safety-zone

25. MICE Berkeley, Oct 2002 Conclusions  Critical tasks u “Best-possible” measurement of ionization background s Preferably with 201 MHz cavity u Demonstration of prototype operation near cavity to determine effect of EM fields on sensitive front-end electronics for TPG u Conformation of light yield measurement for Fiber Tracker u Complete analysis of safety risks and constraints that will be imposed on the detectors u Operation of prototypes near RF cavity s Again 201 MHz cavity best  It is clear that getting the first 201 MHz cavity built is of critical importance to both MuCool and MICE.