SVD upgrade for sbelle

Transcription

1 SVD upgrade for sbelle T.Kawasaki(Niigata-U) Mar19-20, 2008 Super Belle Pre kick-off 1

2 Requirements for sbelle Tracker 1. More tracking efficiency High precision measurement with high statistics to search the new physics in B decays B B 0 0 φk K S 0, ηk 0 π γ 0, K S K S K (tcpv) B τν, μν, Dτν Hermeticity τ μγ S (tcpv) Ks vertexing High Hermeticity/Acceptance coverage Good efficiency on Low momentum & Ks daughter tracking, Mar19-20, 2008 Super Belle Pre kick-off 2

3 Requirements for sbelle Tracker 2. Robust against high beam background We assume Occ first layer of Belle SVD(r=2cm) Fine segmentation Fast pulse shaping & time slice information High trigger rate Need high speed & deadtime free readout Hit finding eff. Belle 34 15% Occupancy By Fujiyama(TIT) 3. Better Resolution (At least competitive performance as current SVD) Thin sensor Momentum resolution Small BP radius Impact parameter and vertex resolution Mar19-20, 2008 Super Belle Pre kick-off 3

4 Aim 1cm radius beam pipe Super Belle Vertex Tracker (LoI 04 for SuperB) (cm) Two thin pixel layers r =150mm 17 6 sensor layers to make low momentum tracking Slanted layer to keep acceptance, optimize incident angle and save detector size (cm) Mar19-20, 2008 Super Belle Pre kick-off 4

5 Upgrade Schedule Along to the current upgrade schedule Stop Belle R&D KEKB&Belle upgrade Start sbelle Stop Belle on the end of 2008 (JPY) Start sbelle operation from the beginning of 2012 Reconstruction of detector takes 3 years We have only 1 year for R&D work!! We need REALISTIC upgrade plan for T=0 operation in 2012 ( with ~10 35 ) Further upgrade can be done after getting higher luminosity (1cm beampipe, Thin Monolithic Pixel sensor needs further R&D work) Mar19-20, 2008 Super Belle Pre kick-off 5

6 Occupancy estimation Occupancy estimation (L=2x10^35, x20 BG, 10kHz trigger rate) Assuming Occ Tp, channel area, 1/r 2 Current SVD VA1(Tp=800ns): ~8%@ 1 st layer L = % 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 ns Standard rectangle DSSD is OK Mar19-20, 2008 Super Belle Pre kick-off 6

7 The current detector (SVD2) Size of DSSD R [mm] Z [mm] [mm 2 ] st x nd x rd x th x73.8 Beam Pipe DSSD in z ladde r in φ SVD3: Replace L1 (&L2) with similar ladders readout with APV25. Proposed as intermediate upgrade plan. We are the final stage of mass production. Postponed (?) if sbelle construction really start in Mar19-20, 2008 Super Belle Pre kick-off 7

8 Realistic deliberation for 2x10 35 SVD2 Nonsense! Performance SVD3 Minimal fallback 4layer, r=1.5cm(same as SVD2) Low Replace L1,2 of SVD2 with APV(fast shaping) Keep SVD2 L3,4(slow shaping~1μs, 30μs deadtime) Budget Cheap SVD3Mod Baseline (Day 0 for 2x10^35) 4~6 layer, r=1.5cm L5&6: Thick material; 500μm-t <=Chip on sensor, Slant (cone/disk) FW/BW All layer readout with fast shaping~50ns High SuperVTX Ideal (further upgrade ~2015 toward 10^36?) 6 layer, r=1cm, L5,6: FW L1,2: Thin Pixel(~50μm ) L3~6: DSSD with Short Tp Expensive Mar19-20, 2008 Super Belle Pre kick-off 8

9 SVD(SVT) upgrade Strategy T=0 option (2012) for L = ~ Keep beampipe radius of 1.5cm same as current one Current SVD configuration + 2 outer layers = 6 layers 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 Mar19-20, 2008 Super Belle Pre kick-off 9

10 x30bg ~10 36 Occupancy estimation Assuming SVD3 x15bg SVD3mod <1 2x10 35 SuperVTX <1 <1 3 1 <1 SVD3 SVD3mod SuperVTX L <1 L <1 L 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) 2 6 L L5 - - <1 1 L6 - <1 <1 - <1 1 Deadtime ~60% negligble negligble?? ~5%? ~5%? [%] 10kHz trigger rate Mar19-20, 2008 Super Belle Pre kick-off 10

11 To be discussed Configuration/Design To be discussed and fixed by the end of 2009 More MC study is needed Mentioned later Technology choice Depend on budget/time/man power What technology should be developed? Concentrate to the selected items Mentioned later Mar19-20, 2008 Super Belle Pre kick-off 11

12 Configuration/Design Layer positions in r IP resolution (beampipe and 1 st layer) Momentum resolution Tracking efficiency for low p track and Ks. Material budget Inner Layer IP resolution Outer Layer momentum resolution All items are not fixed yet Strip pitch on outer layer Fine pitch: Good resolution Wide Pitch: S/N, #readout Slant part Acceptance, hermeticity, optimize incident angle Reduce #readout Mar19-20, 2008 Super Belle Pre kick-off 12

13 Study on Detector configuration SVD r = 2.0, 4.35, 7.0, 8.8 cm CDC r= 8.8 ~ 86.3cm SVD Add r = (13), 14cm CDC r=16.0 ~ 112.0cm Belle CDC CDC sbelle Put 5&6 layer SVD SVD Evaluate new detector configuration with TRACKERR calculation & GEANT3 full simulation Modify the current Belle simulator Use L4 ladder structure as L5&6 layer No sensor at forward region Mar19-20, 2008 Super Belle Pre kick-off 13

14 Ks reconstruction : 5 th layer position 0 B * 0 K ( KSπ )γ GEANT3 Eff. Ks Ks Vtx resolution Full simulation by Shinomiya (Osaka) Require SVD hits on 2 layers sin 2φ eff 1 =0.68 Move 5 th layer to outer More Ks but poor B vtx resolution Ks B vertex: Ks pseudo track + Beam profile Relative luminosity to measure Acp e - e + Beam profile Mar19-20, 2008 Super Belle Pre kick-off 14

15 Impact Parameter resolution [cm] 0.02 r-φ direction [cm] 0.03 Calculated by TRACKERR z direction LoI 04 sbelle SVD2(now) 0.01 For π 0.2GeV 0.5GeV 1.0GeV 2.0GeV Beampipe radius is important Competitive performance as the current SVD sinθ Occupancy effects. Degradation of intrinsic resolution is included. Efficiency loss is NOT included Mar19-20, 2008 Super Belle Pre kick-off 15

16 Momentum IP [rad] 0.02 φ resolution [/MeV] 0.3 κ resolution Calculated by TRACKERR LoI 04 sbelle SVD2(now) For π 0.2GeV 0.5GeV 1.0GeV 2.0GeV sinθ Competitive performance as the current SVD More layer doesn t worsen momentum resolution Mar19-20, 2008 Super Belle Pre kick-off 16

17 T.Hara(Osaka) Res. Center value Mar19-20, 2008 Super Belle Pre kick-off 17

18 Requirement on S/N ratio Assuming Si Noise determined by Sensor Leakage current Detector Capacitance 3DSSDs are readouted via FLEX Chain readout makes large detector capacitance Noise performance depends on FE chip Belle Tp = 1μs enc [e - ]= /Cd[pF] Leakage current dominates 3DSSDs:~60pF 630e esBelle Tp = 50ns enc [e - ]= /Cd[pF] Detector capacitance is crucial (calculate Cd component only) Mar19-20, 2008 Super Belle Pre kick-off 18

19 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) GEANT3 Full sim. M.E. Increase noise M.E. CDC SVT All Layers Noise 10 Typ. Only 5&6 Layers Noise 10 Typ. Kalman filtering Extrapolate track from CDC S/N degradation on the outer layer doesn t affect to M.E. so much But, In case of Ks daughter track Mar19-20, 2008 Super Belle Pre kick-off 19

20 Matching efficiency for Ks + π + B K S SVD Matched track L3 L4 L5 Increase Noise on L5&L6 only L3 L4 GEANT3 Full sim By Nakagawa (Niigata) L5 r of Ks decay vertex r of Ks decay vertex M.E. for Ks daughters are affected by S/N degradation Lose 20% (SVT) events with 4 times worse S/N Mar19-20, 2008 Super Belle Pre kick-off 20

21 Change thresholds on SVD hit finding Noise x 3 Threshold = 3 x σ Default setting Threshold = 2 x σ Lower thresholds save Matching efficiency. But lower thresholds make data size huge Mar19-20, 2008 Super Belle Pre kick-off 21

22 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 started by India/Korea group Mar19-20, 2008 Super Belle Pre kick-off 22

23 R&D activities We have been working to prepare Pipeline readout sensor module for SVD3 Hybrid card with 4 APV25 chips Operated with 40MHz clock (Princeton) FADC: 40MHz digitization Online sparsification with FPGA (Vienna) Beamtest done in KEK in Nov 2007 in KEK Fuji testbeam line 3GeV electron Confirm the capability of online sparsification algorithm The result will come soon Mar19-20, 2008 Super Belle Pre kick-off 23

24 Chip on sensor with FLEX hybrid Keep good S/N ratio at the outer layers Proposal by Vienna group Readout each DSSD by putting thinned FE chip on sensor Cooling with water through carbon fiber tube (low material and good thermal conduction) No Cooling Cooling with 13 water Mar19-20, 2008 Super Belle Pre kick-off 24

25 Schedule Assuming that all R&D items are performed and finished in time. It is too dangerous scenario. We should concentrate on selected items. Mar19-20, 2008 Super Belle Pre kick-off 25

26 Schedule for SVT upgrade Stop Belle We are here Start sbelle SVT Design R&D Sensor Production Endring &Beampipe Assembling Test Installation Final Test NOT official one Mar19-20, 2008 Super Belle Pre kick-off 26

27 Summary We start the activity for SVD upgrade for sbelle Any activities and contributions are welcome. Please join! Requirements on new SVD(SVT?) In my opinion, we should keep current resolution and improve acceptance and efficiency. Configuration/Design Please feel free to propose new idea. Nothing is decided yet. Technology Please propose your idea. But be aware on tight schedule and budget.. Mar19-20, 2008 Super Belle Pre kick-off 27

28 Extended meeting for SVD upgrade on Feb20 You need to know account for KEK indico page Mar19-20, 2008 Super Belle Pre kick-off 28

29 Backups Mar19-20, 2008 Super Belle Pre kick-off 29

30 Condition Start sbelle on 2012 Start Construction in 2009 Budget is limited (not determined yet) We should have some options Luminosity & Background L=2x10^35, x20 BG, 10kHz trigger rate. Keep current performance on resolution Improve efficiency Acceptance, hermeticity, Ks eff., Slow tracking. My own Mar19-20, 2008 Super Belle Pre kick-off 30

31 Online Sparsification at SVD readout Processing with 500~1kHz Online Offline SVD FADC Online PCFARM Storage Analysis Clustering Data sparsification for each strip. Threshold = 3.7 σ Noise is calculated as σ of pedestal Threshold = 3. x σ It is difficult to set low threshold since lower thre. Make data size huge. Mar19-20, 2008 Super Belle Pre kick-off 31

32 Other activity New DSSD company No longer HPK DSSD Micron sensor will be evaluated Will be delivered by the end of March. India/Korea group Working to develop high performance DSSD independently Development of FE Readout chip APV25 was designed 10 years ago. Hawaii group started the design of own FE readout chip Pipeline on each channel. Hopefully, short shaping time ~ 50ns and good noise performance Krakow has also interests Develop pipeline VA chip with IDEAS? Mar19-20, 2008 Super Belle Pre kick-off 32

33 Readout scheme Mar19-20, 2008 Super Belle Pre kick-off 33

34 Ladder structure/ Cabling.. Mar19-20, 2008 Super Belle Pre kick-off 34

35 Super Belle detector (LoI 04) SC solenoid 1.5T μ / K L detection 14/15 lyr. RPC+Fe tile scintillator CsI(Tl) 16X 0 pure CsI (endcap) Aerogel Cherenkov counte + TOF counter TOP + RICH New readout and computing systems Si vtx. det. 4 lyr. DSSD 2 pixel/striplet lyrs. + 4 lyr. DSSD Tracking + de/dx small cell + He/C 2 H 6 remove inner lyrs. use fast gas Mar19-20, 2008 Super Belle Pre kick-off 35

36 Mar19-20, 2008 Super Belle Pre kick-off 36

37 Material effect Mar19-20, 2008 Super Belle Pre kick-off 37

38 Sensor Configuration (SVD1 SVD2) SVD2) 45cm 22cm Z view 46cm Mar19-20, 2008 Super Belle Pre kick-off 38

39 BG effect on physics analysis J / ψ ( μμ) K Nominal 5 BG 20 BG 20 BG Preliminary S B Eff 56.8 % 56.0 % 49.0 % % With 40% shorter shaping 51.4 % ( π Total performance of CDC + SVD + π ) Ratio % -1.5 % -9.5 % ( D Dπ,D K 3π ) 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 D * D * Nominal 5 BG 20 BG 20 BG * B Eff 6.48% 5.69% 2.28% With 40% shorter shaping 3.86% s Ratio % % % % By Ozaki Mar19-20, 2008 Super Belle Pre kick-off 39

40 Intrinsic Resolution vs. Occupancy Intrinsic Resolution occupancy < 0.04 occupancy residual [ m[ residual residual [ m[ residual At high occupancy, cluster shape is 'distorted' reconstructed cluster energy to be off the residual distribution to be widened Occupancy S.Fratina Mar19-20, 2008 Super Belle Pre kick-off 40

41 Hit Efficiency vs. Occupancy Layer No. Efficiency hit or not? Layer1 2 Layer2 Higher Occupancy ~ Lower Hit Efficiency Signal + background hits wider 'distorted' cluster 0.6 Layer3 3 Layer4 4 0% 30% Occupancy Wrongly associated background cluster Mar19-20, 2008 Super Belle Pre kick-off 41 Y.Fujiyama

42 Occupancy problem at innermost layer Estimate occupancy at Super B Occupancy at SVD2 At most, 10% in r =20mm for /cm 2 /s Assuming Occ. = luminosity/r 2 r =15mm for /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? % 1 L=10 35 /cm 2 /s Occupancy (%) SVD1(1usec) SVD2(500nsec) SVD2(800nsec) Radius (cm) Mar19-20, 2008 Super Belle Pre kick-off 42

43 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 Z rφ Striplet can survive up to /cm 2 /s (10 36 needs pixel type sensor!) 10mm Occupancy (%) 70mm Mar19-20, 2008 Super Belle Pre kick-off % Dead region Striplet Tp=50ns SVD1(1usec) SVD2(500nsec) SVD2(800nsec) S-VTX(50nsec) S-VTX(100nsec) With striplet Radius (cm) mm U V

44 Prototype Striplet Sensor (HPK) 2.75mm 74.1mm 71.0 mm Thickness:300μm Double sided P and N strips on N-bulk Incline strip by 45 degree strips on each side 10.5mm 8.5mm Strip pitch = 51μm in U-V direction. (Pad spacing is 72μm 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. Mar19-20, 2008 Super Belle Pre kick-off 44

45 Scan strips with IR laser scan Results Striplet detector is functional. No signal on the triangle part The edge of active region is so sharp. Signal (normalized) P-side sum Signal (normalized) N-side End of active region sum Laser position[μm] Laser position[μm] Mar19-20, 2008 Super Belle Pre kick-off 45

46 全層の S/N を悪くしたとき Matching efficiency Normal S/N Noise x 4 Noise x 5 Mar19-20, 2008 Super Belle Pre kick-off 46

47 Matching efficiency for the various threshold. Default noise Noise = default x 2 Mar19-20, 2008 Super Belle Pre kick-off 47

48 Noise = default x 3 Noise = default x 4 Mar19-20, 2008 Super Belle Pre kick-off 48

49 Noise = default x 5 Mar19-20, 2008 Super Belle Pre kick-off 49

50 Mis-alignment effect Large VTX tracker makes difficulty on alignment. Ks eff. Ks VTX Resolution Red: Perfectly aligned Blue: 10um, 0.1mrad Green: 20um, 0.2mrad Pink: 30um, 0.3mrad Mis-alignment doesn t affect to efficiency Mar19-20, 2008 Super Belle Pre kick-off 50

51 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. Trigger Shaper Proven in beam tests: Resolution ~ 2 nsec. Reconstruction done in the FPGA chips in FADC board. (HEPHY Vienna) Mar19-20, 2008 Super Belle Pre kick-off 51 The silicon tracker development at KEK, Toru TSuboyama (KEK), 19 Dec SILC meeting at Torino, Italy 51

52 Mar19-20, 2008 Super Belle Pre kick-off 52

53 Mar19-20, 2008 Super Belle Pre kick-off 53