1. Jan24-26, 2008BNM2008 Atami, Japan1 Belle upgrade: Tracking and Vertexing T.Kawasaki(Niigata-U)

2. Jan24-26, 2008BNM2008 Atami, Japan2 Introduction High luminosity B factory –High precision measurement with high statistics to search the new physics in B decays Many modes which are sensitive to new physics need –High Hermeticity –Good efficiency on Low momentum & Ks daughter tracking, (tCPV) Ks vertexing Hermeticity

3. Jan24-26, 2008BNM2008 Atami, Japan3 Requirements for sBelle Tracker Robust against high beam background We assume ×20 BG @2×10 35 Occ ~8% @the first layer of Belle SVD(r=2cm) Fine segmentation Fast pulse shaping & time slice information High trigger rate Need high speed & deadtime free readout More tracking efficiency –Hermeticity –Shallow angle tracking. Low momentum tracking –Ks reconstruction Better Resolution ( At least competitive performance as current SVD) –Thin sensor ( ⇒ refer the next talk for material effect) –Small BP radius Belle SVD Hit finding eff. vs. Occ. Occupancy 15% By Fujiyama(TIT)

4. Jan24-26, 2008BNM2008 Atami, Japan4 Super Belle detector (LoI ‘04) SC solenoid 1.5T New readout and computing systems Aerogel Cherenkov counter + TOF counter  / K L detection 14/15 lyr. RPC+Fe  tile scintillator CsI(Tl) 16X 0  pure CsI (endcap)  “TOP” + RICH Tracking + dE/dx small cell + He/C 2 H 6  remove inner lyrs. use fast gas Si vtx. det. 4 lyr. DSSD  2 pixel/striplet lyrs. + 4 lyr. DSSD

5. Jan24-26, 2008BNM2008 Atami, Japan5 Super Belle Vertex Tracker(LoI ‘04) (cm) r =150mm Aim 1cm radius beam pipe (cm) Two thin pixel layer Slanted layer to keep acceptance, optimize incident angle and save detector size 6 sensor layers to make low momentum tracking 17°

6. Jan24-26, 2008BNM2008 Atami, Japan6 Upgrade Schedule Stop Belle on the end of 2008 (JPY) Start sBelle operation from the beginning of 2012 Along to the current upgrade schedule We need REALISTIC upgrade plan for T=0 operation in 2012 ( with ~10 35 ) Further upgrade can be done after getting higher luminosity 2007 2008 2009 2010 2011 2012 Stop Belle Start sBelle Reconstruction of detector takes 3 years ⇒ We have only 1 year for R&D work!! KEKB&Belle upgrade R&D （ 1cm beampipe, Thin Monolithic Pixel sensor …… needs further R&D work ）

7. Jan24-26, 2008BNM2008 Atami, Japan7 Central Drift Chamber Large cover area in radius –88~863 mm ⇒ 172~1118 mm Inner part replaced by Si Tracker –50 ⇒ 58 layers Small cell to reduce occupancy – ⇒ 2.5mm –8k ⇒ 15k sense wires Same gas mixture :He + C 2 H 6 Fast FADC readout CDC Occupancy esitimation –Hit rate : ~100kHz  ~5kHz(current) x 20 –Maximum drift time : 80-300nsec  Shorter than the current one –Occupancy : 1-3%  100kHz X 80-300nsec = 0.01-0.03 Momentum resolution(SVD+CDC)  Pt /Pt = (0.11~0.19)Pt  0.30/  [%] :possible thanks to large cover in radius

8. Jan24-26, 2008BNM2008 Atami, Japan8 Silicon Vertex Tracker Occupancy estimation –Assuming Occ ∝ Tp, channel area, 1/r 2 –Current SVD VA1(Tp=800ns): ~8%@ 1 st layer L =2×10 35 ⇒ 8% × 20BG = 160%! Ex)APV25 (developed for CMS Si Tracker) –Tp=50ns ⇒ Factor 16 reduction is possible Shaper ・ 160 pipeline FIFO ⇒ pulse shape scan with 40MHz Clk Further BG reduction is possible by Pulse shape and timing information 32 step FIFO as event queues Deadtime free readout@ 10kHz trigger rate 0100200 ns ⇒ Standard rectangle DSSD is OK

9. Jan24-26, 2008BNM2008 Atami, Japan9 SVT upgrade Strategy T=0 option (2012) for L = ~10 35 –Keep beampipe radius of 1.5cm same as current one –Current SVD configuration + 2 outer layers = 6layers Improve Ks efficiency. Replace CDC inner layers Similar design DSSD can be used –Fast Shaping(~50ns) + Timeslice on FE chip Further upgrade for L >10 35 –Smaller beampipe radius (r =1cm or less) –Innermost (thin) Pixel layers Improve impact parameter resolution

10. Jan24-26, 2008BNM2008 Atami, Japan10 Study on Detector configuration CDC SVD SVD SVD L1-L4 @ r = 2.0, 4.35, 7.0, 8.8 cm CDC r= 8.8 ~ 86.3cm SVD Add L5&L6 @ r = (13), 14cm CDC r=16.0 ~ 112.0cm Put 5&6 layer Modify the current Belle simulator Use L4 ladder structure as L5&6 layer No sensor at forward region Belle sBelle Evaluate new detector configuration with TRACKERR calculation & GEANT3 full simulation

11. Jan24-26, 2008BNM2008 Atami, Japan11 Impact Parameter resolution r-   direction z direction Calculated by TRACKERR Occupancy effects. Degradation of intrinsic resolution is included. Efficiency loss is NOT included Beampipe radius is important Competitive performance as the current SVD LoI ‘04 sBelle SVD2(now) For   0.2GeV 0.5GeV 1.0GeV 2.0GeV sin  0 1.4 0.02 0.01 [cm] 0.03 [cm]

12. Jan24-26, 2008BNM2008 Atami, Japan12 Momentum resolution   resolution  resolution Calculated by TRACKERR Competitive performance as the current SVD More layer doesn’t worsen momentum resolution LoI ‘04 sBelle SVD2(now) For   0.2GeV 0.5GeV 1.0GeV 2.0GeV sin  0 1.4 0.02 0.01 [rad] [/MeV] 0.3 0.1 Refer the next talk about a material effect

13. Jan24-26, 2008BNM2008 Atami, Japan13 Ks reconstruction : 5 th layer position =0.68 Move 5 th layer to outer More Ks but poor B vtx resolution Eff. Ks Ks Vtx resolution GEANT3 Full simulation by Shinomiya (Osaka) Ks e-e- e+e+ Beam profile B vertex: Ks pseudo track + Beam profile Relative luminosity to measure Acp Require SVD hits on 2 layers

14. Jan24-26, 2008BNM2008 Atami, Japan14 Requirement on S/N ratio Noise performance depends on FE chip VA1 @ Tp = 1  s enc [e - ]= 180+ 7.5/Cd[pF] ⇒ Leakage current dominates APV25 @ Tp = 50ns enc [e - ]= 246 + 36/Cd[pF] ⇒ Detector capacitance is crucial ・ Assuming signal=MIP@300  m Si ・ Noise determined by Sensor Leakage current Detector Capacitance 3DSSDs are readouted via FLEX ⇒ Chain readout makes large detector capacitance 3DSSDs:~60pF 630e - ⇒ 2500e- sBelle Belle (calculate Cd component only)

15. Jan24-26, 2008BNM2008 Atami, Japan15 Effect of poor S/N ratio on the outer layers M.E. (Matching Efficiency) = Prob.(SVD hits are found on at least 2 SVD layers) Noise M.E. All Layers Only 5&6 Layers S/N degradation on the outer layer doesn’t affect to M.E. so much CDC M.E. SVT Kalman filtering Extrapolate track from CDC Noise 10 ×Typ. 10 ×Typ. But, In case of Ks daughter track… GEANT3 Full sim. Increase noise

16. Jan24-26, 2008BNM2008 Atami, Japan16 r of Ks decay vertex Matching efficiency for Ks Matching efficiency Noise x 2 Noise x 4 normal 0 1.0 0 10 20 [cm] SVD Matched track r of Ks decay vertex 0 10 20 [cm] M.E. for Ks daughters are affected by S/N degradation Lose 20% (SVT) events with 4 times worse S/N L3 L4 L5 L3 L4 L5 Noise x 4 normal GEANT3 Full sim By Nakagawa (Niigata) Increase Noise on L5&L6 only

17. Jan24-26, 2008BNM2008 Atami, Japan17 BG effect on physics analysis Major loss comes from low tracking efficiency for slow particles Efficiency loss on high multiplicity event is serious –Moreover a pulse shape information CDC by FADC readout can save efficiency –Gain by SVD standalone tracker is not included B Eff Ratio-1 Nominal56.8 %0.0 % ×5 BG56.0 %-1.5 % ×20 BG49.0 %-13.8 % With 40% shorter shaping ×20 BG51.4 %-9.5 % B Eff Ratio-1 Nominal6.48%0.0 % ×5 BG5.69%-12.2 % ×20 BG2.28%-64.9 % With 40% shorter shaping ×20 BG3.86%-40.5 % By Ozaki Preliminary Total performance of CDC + SVD

18. Jan24-26, 2008BNM2008 Atami, Japan18 Key technology for upgrade Timeslice Information/Full Pipeline readout –Pipeline in FE chip (APV25, VA-modified, own ASIC) Practical implementation scheme in a limited space –Ladder assembling. Mechanical Support structure –Cooling/Cabling scheme Save S/N for outer layer. –FLEX readout. Chip on sensor –Sensor development Low noise & Large area sensor is desirable Thin (less material)  Thick (more signal) Pixel sensor (Option for future upgrade) –Thin & Fast readout. Monolithic device? No more HPK DSSD. Micron? SINTEF? New activities in India, Korea

19. Jan24-26, 2008BNM2008 Atami, Japan19 Status of R&D Activity We have been working to prepare Pipeline readout sensor module Hybrid card with 4 APV25 chips Operated with 40MHz clock (Princeton) FADC: 40MHz digitization Online sparsification with FPGA Confirm the capability of online sparsification algorithm The result will come soon Beamtest done in KEK in Nov 2007 in KEK Fuji testbeam line 3GeV electron (Vienna)

20. Jan24-26, 2008BNM2008 Atami, Japan20 Chip on sensor with FLEX hybrid Proposal by Vienna group No Cooling Cooling with 13 ℃ water Readout each DSSD by putting thinned FE chip on sensor Cooling with water through carbon fiber tube ( low material and good thermal conduction )

21. Jan24-26, 2008BNM2008 Atami, Japan21 Schedule for CDC/SVT upgrade 2007 2008 2009 2010 2011 2012 Stop Belle Start sBelle Design NOT official one CDC SVT Test End Plate Machining Wire stringing Cosmic Test Installation &Final Test Cabling/Tubing Sensor Production Design Test Assembling Final Test Installation R&D Endring &Beampipe

22. Jan24-26, 2008BNM2008 Atami, Japan22 Summary We have started activity for the practical detector design for Belle upgrade –CDC Same gas mixture as Belle Better resolution with larger coverage in radius Reduce BG Occ. with small cell and time digitization –SVT R=1.5cm Beampipe + 6 DSSD layers Employ Standard DSSD with short shaping (=50ns) for T=0 Competitive resolution as the current SVD R&D of Pixel sensor should continue for the further upgrade Please join!! Any contributions are welcome!

23. Jan24-26, 2008BNM2008 Atami, Japan23 Pixel sensor R&D Items to be achieved for High luminosity B factory 1.Readout Speed 2.Radiation Hardness 3.Thin Detector 4.Full-sized detector ・ MAPS is the unique solution. ・ Development of MAPS (Monolithic Active Pixel sensor) is in world wide competition (ex: CAPS(Hawaii), SOIPIX (KEK) ) ・ It looks promising but needs more R&D for a few years Progresses in the coming a few years are very important. 2005 2.5mmx2.5mm 32x32 cells chip 2006 5mmx5mm 128x128 cells chip SOIPIX KEK-OKI

24. Jan24-26, 2008BNM2008 Atami, Japan24 Backups

25. Jan24-26, 2008BNM2008 Atami, Japan25 Bkg & TRG rate in future KEKBSuperB Luminosity (10 34 cm -2 sec -1 ) ~180 HER curr. (A) LER curr. (A) vacuum (10 -7 Pa) 1.2 1.6 ~1.5 4.1 9.4 5 Bkg increase-x 20 TRG rate (kHz) phys. origin Bkg origin 0.4 0.2 14 10 4 Synchrotron radiation Beam-gas scattering (inc. intra-beam scattering) Radiative Bhabha SVDCDCPID / ECLKLM KEKB Bkg x10 Bkg x20 Bkg

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27. Jan24-26, 2008BNM2008 Atami, Japan27 Hit rate 10KHz Apr.-5 th,2005 I HER = 1.24A I LER = 1.7A L peak = 1.5x10 34 cm -2 sec -1 I CDC = 1mA Main Inner Small cell

28. Jan24-26, 2008BNM2008 Atami, Japan28 Simulation Study for Higher Beam Background by K.Senyo. MC +BGx1MC+BGx20

29. Jan24-26, 2008BNM2008 Atami, Japan29 Hit rate at layer 35 I HER = 4.1A Hit rate = 13kHz I LER = 9.4A Hit rate = 70kHz Dec., 2003 : ~5kHz Now : ~4kHz Dec.,2003 In total 83kHz HER LER

30. Jan24-26, 2008BNM2008 Atami, Japan30 CDC : Main parameters Present Future Radius of inner boundary (mm) 77160 Radius of outer boundary (mm) 8801140 Radius of inner most sense wire (mm) 88172 Radius of outer most sense wire (mm) 8631120 Number of layers 5058 Number of total sense wires 840015104 Effective radius of dE/dx measurement (mm) 752978 Gas He-C 2 H 6 Diameter of sense wire (  m) 30

31. Jan24-26, 2008BNM2008 Atami, Japan31 Intrinsic Resolution vs. Occupancy Intrinsic Resolution  Occupancy residual occupancy < 0.04 occupancy  0.3 At high occupancy,  cluster shape is 'distorted'  reconstructed cluster energy to be off  the residual distribution to be widened S.Fratina

32. Jan24-26, 2008BNM2008 Atami, Japan32 Hit Efficiency vs. Occupancy Layer1 Layer2 Layer3 Layer4 hit or not? 21 34 Layer No. 0%  30% Occupancy 1.0  0.6 Efficiency Higher Occupancy ~ Lower Hit Efficiency Signal + background hits  wider 'distorted' cluster Wrongly associated background cluster Y.Fujiyama

33. Jan24-26, 2008BNM2008 Atami, Japan33 Occupancy problem at innermost layer Estimate occupancy at Super B – Occupancy at SVD2 At most, 10% in r =20mm for 10 34 /cm 2 /s –Assuming Occ. = luminosity/r 2 r =15mm for 10 35 /cm 2 /s  occupancy = 200% Factor 40 of reduction is needed!! How can we reduce Occ.? –Assuming Occ. = sensitive area* shaping time –Short shaping time Tp=100ns is possible (Factor 8) (SVD2:VA1TA, Tp=800ns) –Strip area should be small. Area=pitch*length  short strip How to shorten a strip length by 1/5? 5% L=10 35 /cm 2 /s SVD2(800nsec)

34. Jan24-26, 2008BNM2008 Atami, Japan34 70mm Striplet design To shorten strip length, we propose new type of DSSD –Arrange strips in 45 degrees. Strip length is shortened –Small triangle dead region exists. About 7 % in Layer1 –Striplet can survive up to 2×10 35 /cm 2 /s (10 36 needs pixel type sensor!) Z rφ Tp=50ns Striplet 5% Dead region 14mm 10mm SVD2(800nsec) S-VTX(100nsec) U V

35. Jan24-26, 2008BNM2008 Atami, Japan35 Prototype Striplet Sensor (HPK) 2.75mm 74.1mm 10.5mm 8.5mm 71.0 mm Thickness:300  m Double sided –P and N strips on N-bulk –Incline strip by 45 degree. –1024 strips on each side Strip pitch = 51  m in U-V direction. (Pad spacing is 72  m along sensor edge) Since sensor size is small, inactive region can’t be ignored How to reduce dead region Check behavior near inactive region carefully.

36. Jan24-26, 2008BNM2008 Atami, Japan36 Scan strips with IR laser Laser position[  m] Signal (normalized) sum Laser position[  m] Signal (normalized) sum scan P-side N-side Results –Striplet detector is functional. –No signal on the triangle part The edge of active region is so sharp. End of active region

37. Jan24-26, 2008BNM2008 Atami, Japan37 Matching efficiency Normal S/N 全層の S/N を悪くしたとき Noise x 5 Noise x 4

38. Jan24-26, 2008BNM2008 Atami, Japan38 Ks vertex の分布

39. Jan24-26, 2008BNM2008 Atami, Japan39 Ks イベントでの Matching efficiency の変化 Noise x 2 Noise x 4 normal r of Ks vertex

40. Jan24-26, 2008BNM2008 Atami, Japan40 normalNoise x 2Noise x 4 Noise x 10

41. Jan24-26, 2008BNM2008 Atami, Japan41 Mis-alignment effect Large VTX tracker makes difficulty on alignment. Red: Perfectly aligned Blue: 10um, 0.1mrad Green: 20um, 0.2mrad Pink: 30um, 0.3mrad Ks VTX Resolution Ks eff. Mis-alignment doesn’t affect to efficiency

42. Jan24-26, 2008BNM2008 Atami, Japan42 FLEX hybrid/Chip on sensor Flex Hybrid APV25Connector M.Pernicka, M.Friedl, C.Irmler (HEPHY Vienna)

43. Jan24-26, 2008BNM2008 Atami, Japan43 22cm 46cm Sensor Configuration (SVD1→SVD2) Z view 45cm

44. Jan24-26, 2008BNM2008 Atami, Japan44 SVD2: Ladder Structure DSSD FLEX Hybrid Rib Bridge Lyr# in z # in  BWFW 1116 22112 33218 433 VA1TA chip 4 VA1TAs on a hybrid 4analog signals read out in parallel 128 channels/chip 4 mW/channel Number of channel: 128ch × 4 chips ×2 hybrid(  /z)×2 hybrids(F/B) ×(6+12+18+18) Ladders = 110,592 Analog signals

45. Jan24-26, 2008BNM2008 Atami, Japan45 Readout with APV25 ASIC APV25 is chosen –Originally developed for CMS Silicon tracker Operated with 40MHz clock –192 stage pipeline (~4 µsec trigger latency) –Up to 32 readout queues –128 ch analog multiplexing (3 µsec@40 MHz) –Dead time: negligible at expected trigger rate of 10 kHz 45 Shaper Inverter preamp 192 stageAnalog Pipeline (4 µsec) Analog output Trigger 128 channel Multiplexer (3 µsec) Noise= (246 + 36/pF) @50nsec The silicon tracker development at KEK, Toru TSuboyama (KEK), 19 Dec. 2007 SILC meeting at Torino, Italy

46. Jan24-26, 2008BNM2008 Atami, Japan46 Hit timing reconstruction B-Factory --> 2 nsec bunch crossing –APV25 deconvolution filter can not be used. Hit time reconstruction –Proposed by Vienna group –Read out 3, 6 … slices in the pipeline for one trigger. –Extract the hit timing information from wave form. Proven in beam tests: Resolution ~ 2 nsec. Reconstruction done in the FPGA chips in FADC board. 46 (HEPHY Vienna) Shaper Trigger The silicon tracker development at KEK, Toru TSuboyama (KEK), 19 Dec. 2007 SILC meeting at Torino, Italy

47. Jan24-26, 2008BNM2008 Atami, Japan47 Occupancy estimation Int res= x1.5(1.2) for 30%(10%) occupancy Occupancy ∝ 1/r 2 × sensor aread Hit efficiency loss is not considered. (-10% for 30% Occ) L1L2L3L4L5L6 x15BG 2x10^3 5 SVD3 10(%)315 -- SVD3mod 10311<1 SuperB <1 31 x30BG 10^36 SVD3 20630 -- SVD3mod 20622<1 SuperB <1 6211 Assuming factor 3 for safety margin, in order to calculate helix resolution. Assuming x15BG@2x10^35, x30BG@10^36

48. Jan24-26, 2008BNM2008 Atami, Japan48 dr resolution New CDC conf. TRACKERR V2.18 dr resolutoin SuperB SVD3mod SVD3 For  0.2GeV 0.5GeV 1.0GeV 2.0GeV dr

49. Jan24-26, 2008BNM2008 Atami, Japan49 dz resolution dz resolutoin SuperB SVD3mod SVD3 For  0.2GeV 0.5GeV 1.0GeV 2.0GeV dz

50. Jan24-26, 2008BNM2008 Atami, Japan50  resolution phi resolutoin SuperB SVD3mod SVD3 For  0.2GeV 0.5GeV 1.0GeV 2.0GeV 

51. Jan24-26, 2008BNM2008 Atami, Japan51 tan resolution tanl resolutoin SuperB SVD3mod SVD3 For  0.2GeV 0.5GeV 1.0GeV 2.0GeV tan

52. Jan24-26, 2008BNM2008 Atami, Japan52  resolution kappa resolutoin SuperB SVD3mod SVD3 For 0.2GeV 0.5GeV 1.0GeV 2.0GeV 

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