1. Belle Upgrade Plan - An Overview - M.Yamauchi KEK January 2004 Super B Factory Workshop University of Hawaii, Honolulu

2. Outline Introduction: motivation of the SuperKEKB project Introduction: motivation of the SuperKEKB project Can we continue to use DC with L>10 35 ? Can we continue to use DC with L>10 35 ? Belle upgrade plan Belle upgrade plan Summary and conclusion Summary and conclusion

3. 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!! sin2  1, CPV in B  ,  3, V ub, V cb, b  s , b  s ll, new states etc. Anomalous CPV in b  sss NP discovered at LHC (2010?) Now 150 fb -1 Grand scenario of B physics if NP=SUSY

4. Penguin CPV - A Smoking Gun Anomaly?

5. CPV in penguin decays Belle (July 2003) A CP (  K S )=  0.96±0.50 A CP (  ’ K S )=  0.43±0.27 A CP (J/  K S )=  0.731±0.057 Expected errors in A CP ’s A CP (  K S,  ’K S ) = A CP (J/  K S ) In SM, New phase in penguin loop may change this relation. KEKB PEPII Next B factory

6. Bd- unitarity    m(Bs)B->  KsB->Ms  indirect CP b->s  direct CP mSUGRA closedsmall SU(5)SUSY GUT + R (degenerate) closedlargesmall SU(5)SUSY GUT + R (non- degenerate) closedsmalllarge small U(2) Flavor symmetry large sizable Unitarity triangleRare decay Pattern of the deviation from the SM prediction Y.Okada

7. KEKB upgrade strategy Present KEKB L=10 34 2002030405080706091011 L=2x10 35 L~5x10 35 ∫Ldt =350fb -1 I LER =1.5A I LER =9.4A Constraint:  8GeV x 3.5GeV  wall plug pwr.<100MW  crossing angle<30mrad L=2x10 34 I LER =1.5A Crab crossing One year shutdown to:  install ante chamber  increase RF  modify IR Increase RF

8. Higher luminosity collider will lead to:  Higher background  Higher event rate  Require special features to the detector. - low p  identification  s  reconstruction eff. - hermeticity  “reconstruction” Detector upgrade - radiation damage and occupancy in the detectors - fake hits and pile-up noise in the EM calorimeter - higher rate trigger, DAQ and computing

9. Expected background SR and HOM Particle background Soft photons Neutrons and muons Vertex meas. Tracking and PID devices EM calorimeter K L  detector SR and HOM  Simulation works ok. Particle bkgnd. and soft  ~ vac. pressure at IR  beam current Increase by a factor of 20 is assumed.

10. Q1: Does DC work with L>10 35 ? If NO, –Need Si tracker. –EM cal, solenoid and iron structure have to be rebuilt!! If YES, –Upgrade the present Belle detector. New detector

11. Does CDC work with L>10 35 ? r = 15cm Layer Hit rate/wire(kHz) Exp 27 Run 206 HER 1.1A LER 1.5A L=9.6x10 33 cm -1 s -1 Main Inner Cathode Charge-up of the gas

12. Layer Number of hits Bhabha ev. 2000 2002 Layer 49 Layer 1 Layer 3 Radiation damage to the present CDC Efficiency for Bhabha tracks Gain drift No rad. damage has been observed after 0.2C/cm irradiation.

13. Track Reconstruction under High Background 51015200 Background factor 51015200 Background factor 0 20 40 60 80 100 Reconstruction eff. (%) High p T ( B      )Low p T ( B  D  (  D  s )   ) will be improved by replacing the inner part by Si. MC + real background at Belle

14. Tentative conclusion Drift chamber can be used in L >10 35 at r >15cm. The detector is designed as an upgrade of Belle detector.

15. Vertex detector upgrade Issues: ● Occupancy < ~5% ● Better vertex resolution with wider coverage ● Low p T tracking  Pixel or striplet DSSD at the inner layers + 4-5 layers of conventional DSSD

16. L=46cm, R=8.8cm Beampipe rad.=15mm 17º<  <150º (=CDC) SVD2 Present Belle SVD2 Installed in October, 2003

17. Occupancy vs. R Pixel for R < 3cm Pipeline for R < 10cm Based on 7.3MRad annual dose (estimation by Karim) for 1cm BP x ~27 at the same radius

18. DSSD w/ analog pipeline readout (~4 layers) to cope with high occupancy. APV25 for CMS as the best candidates CDC Possible configuration of the inner detector 1cm 13mm beampipe and 2-layer pixel sensors striplet as an alternative option 15cm Fast z trigger from APV25 3cm

19. Drift chamber upgrade To reduce the occupancy, –Smaller cell chamber –New gas with faster drift velocity  CH 4 To improve the 3D tracking efficiency, – Charge division method using normal Au-plated W wire Lorentz angle?

20. Small Cell Chamber

21. Drift Velocity Two candidate gases were tested. –CH 4 and He-CF 4 In case of He-CF 4, higher electric field is necessary to get fast drift velocity. In case of CH 4, faster drift velocity by factor two or more can be obtained, even in rather lower electric field.

22. dE/dx Resolution The pulse heights for electron tracks from 90 Sr were measured for various gases. The resolutions for CH 4 and He(50%)- C 2 H 6 (50%) are same. The resolution for He- CF 4 is worse than Ar- based gas(P-10).

23. Expected performance Occupancy –Hit rate : ~140kHz  ~7kHz X 20 –Maximum drift time : ~150nsec  300nsec/2 –Occupancy : 2%  140kHz X 150nsec = 0.02 Momemtum resolution (SVD+CDC)  Pt /Pt = 0.11Pt  0.30/  [%]  0.19*(863/1118) 2 Energy loss measurement –6.4%  6.9*(752/869) 1/2

24. PID device Issues: ● High background immunity ● >3   K separation up to 4GeV ● Thinner device, volume and X 0

25. PID detector Present Belle: Aerogel Cherenkov counter both for barrel and endcap. TOP counter for barrel & Aerogel RICH for endcap Requirements: - Thin detector with high rate immunity. - >3  /K separation up to 4GeV/c. - low p  /  separation. or finer segmentation TOF ~10ps

26. TOP (Time-of-Propagation) Counter TOP Quart bar Concept Prototype Beam Test Result Ring image can be reconstructed with X and TOP Multianode PMT R5900-L16 Quartz bar (20×100×2 cm 3 )

27. MCP-PMT(R3809U-50) TTS ~50psec @1.5T Gain~ 3 x 10 6 @1.5TGain~ 3 x 10 6 @1.5T Preliminary result. Appears at JPS Spring. 1p.e 2p.e 3p.e

28. Separability with TTS=50ps, photo cathode = bi-alkali @ r=1130mm. readout : Forward, Backward and  = 45 o

29. EM calorimeter upgrade Issues: - Radiation damage of CsI crystals - Pile-up noise of the counters - Fake 

30. Radiation damage of CsI crystals BarrelEndcap Expected dose 10-20% loss of the light output is not critical for the calorimeter performance.

31. Pile-up noise @ 10 35 /10 36 Backward Barrel Forward (Noise per crystal) Improvement by 1.5 Is obtained from 0.5-1  s sampling 0.5-1  s shaping time Green: current det./ electronics Red: future det./ electronics Kuzmin(BINP)

32. Upgrade plan and expected performance Now –CsI(Tl) + PD + Preamp –Shaper&QT module + FB TDC SuperKEKB Barrel (*) –CsI(Tl) + PD + Preamp  ~1000ns –Shaper&ADC +CoPPER Endcap –Pure CsI + tetrode  ~30ns ( 1/30 of CsI(Tl) ) –Shaper&ADC + CoPPER  noise : better 1/sqrt(30)~6 (*) If PID system becomes thiner,  det. eff. will be improved.

35. K L  upgrade Issue: High rate immunity

36. K L  Detector - scintillator strip geometry -

37. K L  Detector - scintillatior tile geometry - Light collection uniformityGeiger mode photodiode

38.  / 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  Detector upgrade: baseline design  2 pixel lyrs. + 3 lyr. DSSD  tile scintillator  pure CsI (endcap)  remove inner lyrs.  “TOP” + RICH New readout and computing systems

39. Summary SuperKEKB with L~10 35 -10 36 is considered. - Precision test of KM unitarity - Search for new physics in B and  decays - Study flavor structure of new physics Detector design is in progress for all the detector components of Belle, assuming that drift chamber is usable as a central tracking device. –Vertexing detector: “striplet” + APV25 or pixel –Central drift chamber: small cell + faster gas –PID device: TOP(B) + Aerogel RICH(E) –EM calorimeter: Pure CsI + tetrode (E) –Scintillator KLM –Pipelined DAQ and computing system