Download presentation
Presentation is loading. Please wait.
Published byTerry Starling Modified over 9 years ago
1
Belle SVD status & upgrade plans O. Tajima (KEK) Belle SVD group
2
KEKB : the highest luminosity in the world 3.5 GeV e + 8.0 GeV e e + e (4S) with = 0.425 22 mrad crossing angle Located in Tsukuba, Japan L peak = (1.65 10 34 )/cm 2 /sec ~ 1M BB pairs/day integrated luminosity = 0.63 /ab _ Belle detector
4
Belle Detector K L detector 14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X 0 Aerogel Cherenkov Counter n = 1.015~1.030 TOF counter 3.5 GeV e + Central Drift Chamber momentum, dE/dx 50-layers + He/C 2 H 6 charged particle tracking K/ separation Si Vertex Detector ( SVD ) 4-layer DSSD B vertex Muon / K L identification , 0 reconstruction e +-, K L identification 8.0 GeV e -
5
SVD Group Frankfurt U., U. Hawaii, Jozef Stefan Inst., Kanagawa U., KEK, Krakow INP, U. Melbourne, National Taiwan U., Niigata U., Nihon Dental U., Nova Gorica U., Osaka U., Princeton U., U. Sydney, Tohoku U., U. Tokyo, Tokyo Inst. Tech., Tokyo Metropolitan U., Toyama NCMT, Vienna IHEP The Belle SVD Group ~100 people
6
SVD Past and Present SVD2 (Oct 2003 ~ ) SVD1 (1999 ~ 2003 ) Unresolved issues Rad. Hardness Small acceptance 3 layers 23 o < < 139 o r min = 3.0 cm 2 kGy (2M Rad) 4 layers 17 o < < 150 o r min = 2.0 cm 200 kGy (20M Rad)
7
SVD1 SVD2 : Larger Acceptance Coverage 84 91 % B 0 J/ K S 14.4 15.8 events/fb -1 +10 % Higher Efficiency Achieved !
8
SVD1 SVD2 : Smaller Radius ~30% improvement for z-Vertex Resolution
9
SVD1 SVD2 : Radiation Tolerance Layer 3 Layer 2 (1.2 m) Layer 1 Relative Gain SVD1 Readout VA1 (0.8 m) Rad. Tole. 2kGy SVD2 Readout VA1TA (0.35 m) Rad. Tole. 200kGy No longer afraid of Radiation Damage No replacement for SVD2 (>3 years) Gain of operation time is priceless Belle IR dose 0.2kGy/year Layer 1 Layer 3 Layer 4 Layer 2
10
SVD Past and Present SVD2 (Oct 2003 ~ ) SVD1 (1999 ~ 2003 ) Unresolved issues Rad. Hardness Small acceptance 3 layers 23 o < < 139 o r min = 3.0 cm 2 kGy (2M Rad) 4 layers 17 o < < 150 o r min = 2.0 cm 200 kGy (20M Rad) Higher efficiency Better resolution Stable operation efficiency Unresolved issues z trigger terminated Beam BG (non-phys) event suppression Performance in higher Beam BG
11
Future prospects of Beam-BG 2000 2002 20042006 Peak Luminosity (/nb/sec) Beam currents (A) Higher Luminosity is provided by Higher Beam current Higher Luminosity will be provided by the Higher beam currents Beam BG I 2 Beam BG may increase x(2~3) in 2008
12
SVD Past and Present SVD2 (Oct 2003 ~ ) SVD1 (1999 ~ 2003 ) Unresolved issues Rad. Hardness Small acceptance 3 layers 23 o < < 139 o r min = 3.0 cm 2 kGy (2M Rad) 4 layers 17 o < < 150 o r min = 2.0 cm 200 kGy (20M Rad) Higher efficiency Better resolution Stable operation efficiency Unresolved issues z trigger terminated Beam BG (non-phys) event suppression Performance in higher Beam BG
13
Layer1 Layer2 Layer3 Layer4 Occupancy Hit-finding Efficiency High occupancy Fake hits Cluster shape distortion Current BG level Future BG level ? Degradation of Hit-finding Efficiency Is there hit or not?
14
Degradation of Resolution Occupancy (%) Intrinsic resolution ( m) BG overlay MC B 0 J/ K S Intrinsic Resolution BGx3 residual ( m)
15
SVD Past, Present and Future SVD2 (Oct 2003 ~ ) SVD1 (1999 ~ 2003 ) Unresolved issues Rad. Hardness Small acceptance 3 layers 23 o < < 139 o r min = 3.0 cm 2 kGy (2M Rad) 4 layers 17 o < < 150 o r min = 2.0 cm 200 kGy (20M Rad) Software Efforts in progress Almost saturated Unresolved issues z trigger terminated Beam BG (non-phys) event suppression Performance in higher Beam BG SVD3 from ’07
16
Threshold Shorter shaping time gives less occupancy Occupancy Reduction in SVD3 ~2000ns VA1TA Tp~800ns Threshold ~160ns APV25 Tp~50ns APV25 x 4chip VA1TA x 4chip Occupancy shaping time of readout chip Occupancy ~ 1/13 Performance degradation is not serious for outer layers Quick upgrade is necessary (~2007) Replace only for Layer 1 & 2 Layer 3 & 4 are same as SVD2
17
APV25 VA1TAAPV25 Peaking time [ns]80040~200 Pulse width [ns]~2000~160 Pipeline memory---192depths Clock [MHz]540 Sensor Preamp + CRRC Shaper Multiplexing Pipeline memory FADC Developed for CMS Si Tracker waveform sampling Time window ~20ns Further BG reduction
18
DSSD should be optimized for APV25 Capacitive noise will be serious because of short T p 800ns 50ns (C : detector capacitance) Reduction of Capacitance is Essential VA1TA (T p =800ns) APV25 (T p =50ns) Noise (enc) Detector Capacitance (pF) 203010 500 1500 1000 Capacitance of SVD2 DSSD(r- )
19
DSSD optimization for APV25 SVD2 DSSDSVD3 DSSD z (p) r- (n) z (n) r- (p) strip length (mm)25.676.826.177.7 strip/readout pitch ( m) 75/15050/5076/15225.5/51 implant width ( m) 5024 10 capacitance (pF) 3.8 22.54.79.4 S/N (VA1TA)1025610083 S/N (APV25) 1 st layer 52 17 48 33 S/N (APV25) 2 nd layer 38 10 34 21 Floating Strips for r- side (flip p n strip) Reduction of strip width Test sensors by HPK: DSSD x20 (2006), SSD(n-strip) (2005)
20
Beam Test (4GeV/c ) with APV25 + VA1TA system APV25+SSD(n-side) Dec, 2005 SVD2 spare ladders x3
21
SVD2 ladder APV25 ladder Simultaneous operation succeeded for APV25 system with SVD2 system
22
S/N of SSD towards SVD3 S/N=34 Readout strip Floating strip Charge Collection Eff. = 81% Beam test results 28.4mm ( DSSD 26.1mm)
23
Laser Scan test for SVD3 DSSD Laser 980nm Sep, 2006 Double sided assembly Poor bonding due to Kapton flex in R&D z (n strip) r- (p strip)
24
Laser scan results (n-strip) SSD DSSD for SVD3 Charge Collection Eff. = 85% Sep, 2006
25
Laser Scan results (p-strip) Sep, 2006 Due to poor bonding
26
Test in High BG area Plan to start from Oct, 2006 Operation with SVD2 spare ladder Check performances Occupancy reduction, etc.
27
SVD3 mockup test Sufficient clearance is confirmed for the larger Hybrid
28
NovOct Schedule DSSD Hybrid SepAugJulJunMayAprMarFebJanDec 20062007 full production Production / test Assembly Jig prod. / test Layer 1Layer 2mount Repeater prod. / test Test w/ ladders SYSTEM TEST INSTALLATION FADC Prod. / test DAQ Prod. / test Design Finalized soon
29
Summary The Belle SVD operated smoothly for the past year Degradation of performance due to high BG Hit finding Efficiency (layer 1 & 2), Vertex Resolution Might be serious ~2008 Upgrade plan (SVD3) to replace readout chip VA1TA APV25 (occupancy < 1/10) Replace only in Layer 1 and 2 (Layer 3 & 4 will be kept) DSSD is optimized for APV25 Short strip width to reduce capacitance noise Test sensors (DSSD & SSD) Beam test for SSD S/N~34 Simultaneous operation of APV25 system with SVD2 system Laser test full production was ordered from HPK We would like to upgrade SVD3 next year
30
backup
31
SVD3 mechanical issues connector APV25 65.3 31.0 3.0 4.0 Modifications are necessary because APV25 chip is wider than VA1TA
32
= 0.425 Requirements from Physics High Efficiency ( ~90% ) Good Resolution ( z ~ 100 m ) electron (8GeV) positron (3.5GeV) (4S) resonance ++ -- K+K+ -- ++ -- K S/L J/ z ~ 200 m B0B0 B0B0 _ B 0 tag _ Asym. = - CP sin2 1 sin m t
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.