1. 2004/12/04RICH2004 Workshop 1 Development of RICH Counters for Belle Upgrade Toru Iijima Nagoya University KEKB/Belle Plan Belle PID Upgrade Plan Status of TOP Counter Summary

2. RICH2004 Workshop2 2004/12/04 Carb cavity (2006) L peak = (3-5) x 10 34 cm -1 s - 1 L int = 1ab -1 by 2007? Super-KEKB +RF, ante-chamber etc. L peak = (3-5) x 10 35 cm -1 s -1 Present L peak = 1.4x10 34 cm -2 s -1 L int = 300+  fb -1 KEKB/Belle Plan Letter-Of-Intent available (KEK- Report 2004-4), Not decided yet

3. RICH2004 Workshop3 2004/12/04 Far precise CKM CPV in b  s penguin modes ex. B   Ks,  ’Ks, Xs  A FB in B  Kll, Xsll Charged Higgs (ex. B  D  ) LFV in  decay (ex.    ) Physics Objects sin2  1 (  ) (’04) = 0.73±0.04 for 0.41±0.07 for 3.8  deviation Discovery of CPV in B decays Precise test of SM and search for NP Study of NP effect in B and  decays Identification of SUSY breaking mechanism time or integrated luminosity Yes!! NP discovered at LHC (2010?) Now 300 fb -1 if NP=SUSY Present KEKB/Belle Super-KEKB/Belle

4. RICH2004 Workshop4 2004/12/04  / K L detection 14/15 lyr. RPC+Fe Tracking + dE/dx small cell + He/C 2 H 5 CsI(Tl) 16X 0 Aerogel Cherenkov counter + TOF counter Si vtx. det. 3 lyr. DSSD SC solenoid 1.5T 8GeV e  3.5GeV e   2 pixel lyrs. + 3 lyr. DSSD  tile scintillator  pure CsI (endcap)  remove inner lyrs.  “TOP” + RICH New readout and computing systems Belle Upgrade

5. RICH2004 Workshop5 2004/12/04 Particle ID in Belle fake(   K)<10% eff.(K  K) >90% Calibratiopn by D *+  D 0  +, D 0  K -  +

6. RICH2004 Workshop6 2004/12/04 Motivation of PID Upgrade Improve separation for K/ , and also for  hopefully. Extend momentum coverage in the forward endcap.  Endcap-ACC (n=1.03) functions only for flavor tagging Reduced material thickness, and more homogeneous distribution.  30% in total = 18% (ACC) + 12% (TOF)  PMTs dominate for ACC To cope with increasing background.  TOF may not survive  ACC seems to be OK @ x10 background W/ MQT. Physics Targets  B   /K  D  /DK  B   /K*  (b  d  /s  )  B  K ll, K   Full reconstruction  Less systematics for precise measurements

7. RICH2004 Workshop7 2004/12/04 Idea of PID Upgrade Baseline  Barrel  TOP Counter  Endcap  Aerogel RICH Other ideas  Focusing DIRC  TOF w/ finer segmentation  co-exist with the present Barrel-ACC to cover high momentum Prototype

8. RICH2004 Workshop8 2004/12/04 Proximity Focusing Aerogel-RICH Candidate for the forward endcap. Proof-of-principle w/ flat panel PMT. New idea of dual-(multi-) radiator for improvement.    = 14.6mr, N pe = 9.1 w/ focusing (n1/n2=1.047/1.057) K/  sep. = 4.8  at 4 GeV/c Development of 12x12 HAPD +electronics is underway The major remaining issue cf) Talks by P.Krizan, S.Korpar, T.Sumiyoshi, I.Adachi, A.Gorisek “Focusing” “Defocusing” n1 n2 n1<n2 n1 n2 n1>n2 “Multi-radiator”

9. RICH2004 Workshop9 2004/12/04 TOP Counter Concept Quartz-based RICH counter to detect internally reflected Cherenkov light (like DIRC at BaBar) But reconstruct the image in (X,TOP) instead of (X,Y). “TOP” = Time Of Propagation Possible if  TOP < 100ps for each arriving photon. TOP or NIM A453(2000)331 TOF from IP to quartz bar is also used.

10. RICH2004 Workshop10 2004/12/04 “Bar TOP” Counter Proximity focusing in X measurement  Simplified structure and easier installation.  Loose requirement for  X (~5mm) Well polished quartz radiator Photodetection by linear-anode PMT Flipped images can be resolved by widening the bar width (>20cm). KK Simulation 2GeV/c,  =90 deg.  -ray, had. int.

11. RICH2004 Workshop11 2004/12/04 TOP Counter Design (LoI) Quartz radiator: 40cm x 255cm x 2cm  18 segmentation in r-  Photodetection: MCP-PMT w/ linear anode (5mm)  Good time resolution: < 40ps/photon  Single photon sensitive up to 1.5T Number of PMTs (channels)  15 pcs. (60ch) /module  270 pcs. (1080ch) / total for 1 read-out plane (LoI design)  810 pcs. (3240cn) / total for 3 read-out planes (present baseline) R=115~125cm Z=-72.5~182.5cm 16% x X 0

12. RICH2004 Workshop12 2004/12/04 Beam Test w/ Prototype Test counter @ KEK PS  2 line 3 GeV/c   beam  in =  in =90 degree Clear ring image Reasonable time resolution Enough bar quality Demonstration of principle w/  1m(L)x20cm(W)x2cm(T)  R5900-00-L16

13. RICH2004 Workshop13 2004/12/04 Performance of TOP Separation power in two particle species Single photon resolution Npe Group velocity v g =c/n g ( )

14. RICH2004 Workshop14 2004/12/04 Synthetic fused silica  Long transmission  Good polishability  Radiation hardness Shin-etsu, “SUPRASIL-P30”  T~90% at = 250nm Polishing accuracy at Okamoto Kogaku Co. (Yokohama) Quartz Radiator Quartz polishing accuracy OK  time) measured w/ beam (“Butterfly TOP” w/ R5900-L16) Bar#1 Bar#2

15. RICH2004 Workshop15 2004/12/04 MCP-PMT (SL10) 1x4 linear-anode MCP-PMT newly developed for TOP readout. #MCP stage2 Gain (HV)2x10 6 (-3.5KV) MCP hole dia. 10  m Geometrical collection eff. 50% #pixel /size1x4 / 5mmx22mm Effective area/ Total area 64% Confirmed gain > 10 6 and TTS = 30ps(  ) In B=1.5T magnetic field. ※ Remaining issues: cross talk, life, deadtime etc. Under Development cf) My talk on Tuesday

16. RICH2004 Workshop16 2004/12/04 Expected Performance (1) Design optimization Long propagation distance  Large chromatic error. Read-out at both ends  better performance in  >90deg. Another read-out at  =46deg.  better performance in  <90deg. 4GeV/c,bialkali photocathode Geometrical acceptance loss = 6.3% for 5cm gap. forward

17. RICH2004 Workshop17 2004/12/04 Performance w/ 3 read-out planes Target: >4  K/  @ 4GeV/c over  =35-135deg. TOP performance (base design) D* decay events DIRC performance (from RICH2002) Want improvement to achieve the target ! ~2.5   @ 0.6GeV/c

18. RICH2004 Workshop18 2004/12/04 MCP-PMT with GaAsP Further reduction of chromatic dispersion → GaAsP photo-cathode  Higher Q.E. (~40%@540nm)  at longer wave length → less chromatic error Light propagation velocity inside quartz Photon sensitivity at longer wave length shows the smaller velocity fluctuation. cf) My talk on Tuesday

19. RICH2004 Workshop19 2004/12/04 Performance with GaAsP >4  K/  achievable almost everywhere. σ ～ 30ps HPK:R3809UGAAP TDC distribution Measured time response For MCP-PMT w/ GaAsP Input of MC

20. RICH2004 Workshop20 2004/12/04 Robustness against Beam BG Efficiency and fake rate for KID  Bialkali photo-cathode option Estimated background rate  Based on a simulation w/ spent electron generator (cross checked by the present TOF rate)  Dominated by    e+e- conversion   hit rate = 44kHz/counter at L=10 34 6.8photons/hit/counter  ~900kHz-hit/counter at BG x 20  ~80kHz/ch Stable performance even for 10 times more BG rate of our estimate Our estimate (/counter)

21. RICH2004 Workshop21 2004/12/04 Issues Photodetection by MCP-PMT Cross talk, lifetime, deadtime Photocathode selection (bialkali or GaAsP) Readout electronics (TAC-IC) Further evaluation of performance Geant4 based simulation Reconstruction Analytic likelihood approach Multi-track capability, boundary effects… Beam BG effects Overall performance for physics processes Mechanical consideration Glue joint of 40cm wide quartz bars… cf) My talk on Tuesday

22. RICH2004 Workshop22 2004/12/04 Summary For improving the Belle PID performance in future, we are developing RICH counters based on new ideas.  TOP counter  TOP counter for barrel Detect internally reflected Cherenkov light with precise time measurement; (X,T) readout.  Aerogel-RICH  Aerogel-RICH for endcap Proximity focusing w/ novel “dual-(multi-) radiator” technique. Target performance: >4  for the whole B decay region. Target year for upgrade: 2008-9 The major remaining issue is photodetection for both  MCP-PMT  MCP-PMT for TOP  H(A)PD  H(A)PD for Aerogel-RICH Many Challenges ! Stay Tuned !

23. RICH2004 Workshop23 2004/12/04 Beam Test Results of Multi-Radiator Aerogel-RICH

24. RICH2004 Workshop24 2004/12/04 Butterfly TOP Cf) Talk by T.Ohshima at RICH2002

25. RICH2004 Workshop25 2004/12/04 TOP Simulation Evaluate TOP performance and optimize design  Located at current TOF position  GEANT base, 1.5T magnetic field  Readout (MCP-PMT)  ~30ps, 5mm ch. width 80% dead space QE~25%, CE~50% Use only 1 st arriving hit in each ch. Reference design Efficiency and fake rate : by log likelihood-ratio cut Measured TDC dist. including the tail is used as a response function.

26. RICH2004 Workshop26 2004/12/04 Efficiency/fake (LoI design) Large drop around  =70~80 degree, due to chromaticity. Need to optimize TOP design (Bar length, width, ch. division, etc.) PBelleBaBar Eff.(K  K) Fake(   K ) Eff.(K  K) Fake(   K ) 2 GeV/c85%10%99%2% 3 GeV/c85%7%92%10% 4 GeV/c85%6%87%11% cf.) Preset Belle/BaBar

27. RICH2004 Workshop27 2004/12/04 Segmented TOP For long path length,   TOP is increased, but  Error due to chromaticity is increased.  Optimal path length should exist. Segmented TOP  Various version is tested.  For example, 3 times more readout But no need for gluing (much easier construction)

28. RICH2004 Workshop28 2004/12/04 “Focusing TOP” 3D information  t, x and vertical angle Focusing block attached to forward edge. Matrix readout For example,  1cm x 2mm size with 0.5mm dead space  MCP-PMT (TTS~40ps) at x=0cm Similar concept to “Ultimate FDIRC” by B.Ratcliff, NIM A502(2003) 211

29. RICH2004 Workshop29 2004/12/04 Fake/Efficiency w/ Focusing Very good separation (= ultimate performance)! Require additional development of  Photodetectors w/ matrix anode ~10mm(X) x ~2mm(Y)  High density high resolution timing readout O(10 5 ) 98 % 2%

30. RICH2004 Workshop30 2004/12/04 Multi-anode MCP-PMT w/ GaAsP ? The timing performance has been checked with single channel MCP-PMT sample. According to HPK,  Can be made.  Effecive area ratio (cathode area/package) may be smaller. Need clarify  Life.  Dark counts  Cost ? HPK Data

31. RICH2004 Workshop31 2004/12/04 R&D for Readout ASIC Time-to-Analog Converter  Time resolution <~20ps. Double overlap gates  Less dead time (~100ns). 0.35  CMOS process. H.Nakano, T.Iijima (Nagoya) H.Ikeda, I.Adachi, S.Nishida (KEK) T.Sumiyoshi (TMU) 40MHz CLOCK INPUT GATE1 GATE2 AOUT1 AOUT2 75ps 125ps T1 T2 V1 = K x T1 V2 = K x T2 “TAC-IC” Concept

32. RICH2004 Workshop32 2004/12/04 Focusing DIRC cf) Talk by A.Drutskoy At Hawaii WS

33. RICH2004 Workshop33 2004/12/04 50ps TOF Finer segmentation faster electronics to cope with the increasing rate.