belle svd status & upgrade plans
DESCRIPTION
Belle SVD status & upgrade plans. O. Tajima (KEK) Belle SVD group. KEKB : the highest luminosity in the world. Located in Tsukuba, Japan. Belle detector. 3.5 GeV e + 8.0 GeV e - e + e - (4S) with bg = 0.425 22 mrad crossing angle. L peak = (1.65 10 34 )/cm 2 /sec - PowerPoint PPT PresentationTRANSCRIPT
Belle SVD status & upgrade plans
O. Tajima (KEK)
Belle SVD group
KEKB KEKB : the highest luminosity in the world: the highest luminosity in the world
3.5 GeV e+ 8.0 GeV e
ee (4S)
with = 0.425
22 mrad crossing angle
Located in Tsukuba, Japan
Lpeak = (1.651034)/cm2/sec ~ 1M BB pairs/day
integrated luminosity = 0.63 /ab
_
Belle detector
Belle DetectorBelle Detector
KL detector14/15 layer RPC+Fe
Electromagnetic CalorimeterCsI(Tl) 16X0
Aerogel Cherenkov Counter n = 1.015~1.030
TOF counter
3.5 GeV e+
Central Drift Chamber momentum, dE/dx 50-layers + He/C2H6
charged particle tracking
K/ separation
K/ separation
Si Vertex Detector( SVD )
4-layer DSSD
B vertex Muon / KL identification
, 0 reconstructione+-, KL identification
8.0 GeV e-
SVD GroupFrankfurt 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
SVD Past and PresentSVD2 (Oct 2003 ～
)SVD1 (1999 ~ 2003 )
Unresolved issues• Rad. Hardness• Small acceptance
3 layers23o < < 139o
rmin = 3.0 cm2 kGy (2M Rad)
4 layers17o < < 150o
rmin = 2.0 cm200 kGy (20M Rad)
SVD1 SVD2 : Larger Acceptance
Coverage 84 91 %B0J/KS 14.4 15.8 events/fb-1
+10 % Higher Efficiency Achieved !
SVD1 SVD2 : Smaller Radius
~30% improvement for z-Vertex Resolution
SVD1 SVD2 : Radiation Tolerance
Layer 3
Layer 2
Layer 2(1.2m)Layer 1R
elat
ive
Gai
n
SVD1 ReadoutVA1 (0.8m)Rad. Tole. 2kGy
SVD2 Readout VA1TA (0.35m)Rad. Tole. 200kGy
No longer afraid of Radiation DamageNo replacement for SVD2 (>3 years)Gain of operation time is priceless
Belle IR dose0.2kGy/year
Layer 1
Layer 3
Layer 4
Layer 2
SVD Past and PresentSVD2 (Oct 2003 ～
)SVD1 (1999 ~ 2003 )
Unresolved issues• Rad. Hardness• Small acceptance
3 layers23o < < 139o
rmin = 3.0 cm2 kGy (2M Rad)
4 layers17o < < 150o
rmin = 2.0 cm200 kGy (20M Rad)
Higher efficiencyBetter resolutionStable operation efficiency
Unresolved issues• z trigger terminated
Beam BG (non-phys) event suppression
• Performance in higher Beam BG
Future prospects of Beam-BG
2000 2002 2004 2006
Peak Luminosity (/nb/sec)
Beam currents (A)
Higher Luminosity is providedby Higher Beam current
Higher Luminositywill be providedby the Higherbeam currents
Beam BG I2
Beam BG mayincrease x(2~3)
in 2008
SVD Past and PresentSVD2 (Oct 2003 ～
)SVD1 (1999 ~ 2003 )
Unresolved issues• Rad. Hardness• Small acceptance
3 layers23o < < 139o
rmin = 3.0 cm2 kGy (2M Rad)
4 layers17o < < 150o
rmin = 2.0 cm200 kGy (20M Rad)
Higher efficiencyBetter resolutionStable operation efficiency
Unresolved issues• z trigger terminated
Beam BG (non-phys) event suppression
• Performance in higher Beam BG
Layer1 Layer2
Layer3 Layer4
Occupancy
Hit
-fin
din
g E
fficie
ncy
High occupancyFake hitsCluster shape distortion
Current BG level Future BG level ?Degradation of Hit-finding Efficiency
Is there hitor not?
Degradation of Resolution
Occupancy (%)
Intr
insic
resolu
tion
(m
)
BG overlay MCB0J/KS
Intrinsic Resolution
BGx3residual (m)
residual (m)
SVD Past, Present and FutureSVD2 (Oct 2003 ～
)SVD1 (1999 ~ 2003 )
Unresolved issues• Rad. Hardness• Small acceptance
3 layers23o < < 139o
rmin = 3.0 cm2 kGy (2M Rad)
4 layers17o < < 150o
rmin = 2.0 cm200 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
SVD3from ’07
ThresholdShorter shaping timegives less occupancy
Occupancy Reduction in SVD3
~2000ns
VA1TATp~800ns
Threshold
~160ns
APV25Tp~50ns APV25 x4chip
VA1TA x4chip
Occupancy
shaping time ofreadout chip
Occupancy
~ 1/13
• Performance degradation is not serious for outer layers• Quick upgrade is necessary (~2007)Replace only for Layer 1 & 2Layer 3 & 4 are same as SVD2
APV25
VA1TA APV25Peaking time [ns] 800 40~200
Pulse width [ns] ~2000 ~160
Pipeline memory --- 192depths
Clock [MHz] 5 40
Sensor
Preamp + CRRC Shaper Multiplexing
Pipeline memory
FADC
Developed for CMS Si Tracker
waveform samplingTime window ~20ns
Further BG reduction
DSSD should be optimized for APV25
pTCNoise
Capacitive noise will be serious because of short Tp 800ns 50ns
(C : detector capacitance)
Reduction of Capacitance is Essential
VA1TA (Tp=800ns)
APV25 (Tp=50ns)
Nois
e (
en
c)
Detector Capacitance (pF)20 3010
500
1500
1000
Capacitance of SVD2 DSSD(r-)
DSSD optimization for APV25
SVD2 DSSD SVD3 DSSDz (p) r- (n) z (n) r- (p)
strip length (mm) 25.6 76.8 26.1 77.7strip/readout pitch (m) 75/150 50/50 76/152 25.5/51implant width (m) 50 24 24 10capacitance (pF) 3.8 22.5 4.7 9.4
S/N (VA1TA) 102 56 100 83S/N (APV25) 1st layer 52 17 48 33
S/N (APV25) 2nd layer 38 10 34 21
Floating Strips for r- side (flip pn strip)Reduction of strip width
Test sensors by HPK: DSSD x20 (2006), SSD(n-strip) (2005)
Beam Test (4GeV/c ) withAPV25 + VA1TA system
APV25+SSD(n-side)
Dec, 2005
SVD2 spare ladders x3
SVD2 ladder
SVD2 ladder
SVD2 ladder
APV25 ladder
Simultaneous operation succeededfor
APV25 system with SVD2 system
S/N of SSDtowards SVD3
S/N=34
Readout strip
Floating stripCharge Collection
Eff. = 81%
Beam test results 28.4mm( DSSD 26.1mm)
Laser Scan test for SVD3 DSSD
Laser 980nm
Sep, 2006
Double sided assemblyPoor bonding due to Kapton flex in R&D
z (n strip)
r- (p strip)
Laser scanresults (n-strip)
SSD
DSSD for SVD3
Charge CollectionEff. = 85%
Sep, 2006
Laser Scan results (p-strip)Sep, 2006
Due to poor bonding
Test in High BG area
Plan to start from Oct, 2006Operation with SVD2 spare ladderCheck performances Occupancy reduction, etc.
SVD3 mockup testSufficient clearance
is confirmed forthe larger Hybrid
NovOct
Schedule
DSSD
Hybrid
SepAugJulJunMayAprMarFebJanDec
2006 2007
full production
Production / test
Assembly
Jig prod. / test Layer 1 Layer 2 mount
Repeater
prod. / test Test w/ ladders
SY
STEM
TES
TIN
STALLATION
FADC Prod. / test
DAQ Prod. / testDesign
Finalizedsoon
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
backup
SVD3 mechanical issues
con
necto
rAPV25
65.3
31.0
3.0
4.0
Modifications are necessary because APV25 chip is wider than VA1TA
= 0.425
Requirements from PhysicsRequirements from Physics
t z c
High Efficiency ( ~90% )Good Resolution ( z ~ 100m )
electron(8GeV)
positron(3.5GeV)
(4S)resonance
+
-K+
-
0D
+
-
KS/L
J/
z ~ 200m
B0
B0_
B0 tag_B
0 tag
Asym. = -CPsin21sinmt