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25 Oct 2011
The Silicon Vertex Detector of the Belle II Experiment
IEEE NSS 2011
Thomas Bergauer (HEPHY Vienna)
Valencia
The Silicon Vertex Detector of the Belle II Experiment
2T. Bergauer (HEPHY Vienna)25 Oct 2011
Belle and Belle II SVD Double Sided SensorsReadout SystemChip-on-Sensor-ConceptSummary
The Silicon Vertex Detector of the Belle II Experiment
3T. Bergauer (HEPHY Vienna)25 Oct 2011
Linac
Belle
KEKB
KEKB and Belle @ KEK (1999-2010)• Asymmetric machine:
8 GeV e- on 3.5 GeV e+
• Center of mass energy: Y(4S) (10.58 GeV)• High intensity beams (1.6 A & 1.3 A)• Integrated luminosity of 1 ab-1 recorded in total• Belle mentioned explicitly in Physics Nobel Prize
announcement to Kobayashi and Maskawa
~1 km in diameter
KEKBBelle
Linac
About 60km northeast of Tokyo
The Silicon Vertex Detector of the Belle II Experiment
4T. Bergauer (HEPHY Vienna)25 Oct 2011
SuperKEKB and Belle II (2010–2014)
• Aim: super-high luminosity ~81035 cm-2s-1 11010 BB / year– Refurbishment of accelerator
and detector required
• Schedule:– LoI published in 2004– TDR was written in 2010
– Construction 2010-2014– Commissioning 2014-2015– Operation 2015 onwards
http://belle2.kek.jp
The Silicon Vertex Detector of the Belle II Experiment
5T. Bergauer (HEPHY Vienna)25 Oct 2011
Belle Silicon Vertex Detector (SVD)
• Present SVD limitations are– occupancy (currently ~10% in
innermost layer) need faster shaping
– dead time (currently ~3%) need faster readout and pipeline
• Belle II needs detector with– high background tolerance– pipelined readout– robust tracking– low material budget in active
volumeCurrent SVD is not suitable for Belle II
10%
L1
L2 L3 L4
The Silicon Vertex Detector of the Belle II Experiment
6T. Bergauer (HEPHY Vienna)25 Oct 2011
Previous SVD Layout (until 2010)
• 4 straight layers of 4" double-sided silicon detectors (DSSDs)• Outer radius of r~8.8 cm
• Up to three 4” sensors are daisy- chained and read out by one hybrid located outside of acceptance region
0
0
10
12
34
[cm]
layers
[cm]
20
-10-20-30 10 20 30 40
The Silicon Vertex Detector of the Belle II Experiment
7T. Bergauer (HEPHY Vienna)25 Oct 2011
0
0
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1+23
45
6[cm] layers
[cm]
20
-10-20-30 10 20 30 40
New Layout for Belle II SVD (2014-)
• New double-layer pixel detector using DEPFET technology
• Strip layers extend to r~14 cm– 6” sensors
• Every sensor is read out individually (no daisy-chaining) to maintain good S/N chip-on-sensor concept
Double-layer of DEPFET pixels
4 layers of double-sided strip sensors
The Silicon Vertex Detector of the Belle II Experiment
8T. Bergauer (HEPHY Vienna)25 Oct 2011
Belle and Belle II SVDDouble Sided SensorsReadout SystemChip-on-Sensor-ConceptSummary
The Silicon Vertex Detector of the Belle II Experiment
925 Oct 2011
Vendors of 6” DSSD
• Double sided strip silicon detectors with AC-coupled readout and poly-silicon resistor biasing from 6 inch wafers
• 6” prototypes ordered and delivered from – Hamamatsu (rectangular)– Micron (trapezoidal)
T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
Rectangular Sensors from Hamamatsu
• HPK re-started production of DSSDs on 6” wafers• Old 4” production line was
decommissioned
• We evaluated first three batches so far• Quality is constantly improving
• Technical details (layers 4,5,6):• Dimensions: 59.6 x 124.88 mm2
• p-side: 768 strips, pitch: 75 µm• n-side: 512 strips, pitch: 240 µm
25 Oct 2011 10T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
11T. Bergauer (HEPHY Vienna)25 Oct 2011
Trapezoidal Sensors from Micron
• Trapezoidal sensor for forward region
• Different p-stop layouts on test sensors
Atoll p-stop
Common p-stop
Combined p-stop
The Silicon Vertex Detector of the Belle II Experiment
12T. Bergauer (HEPHY Vienna)
Modules for Beam Test
• Read out by APV25 (CMS)• Baby Module used to verify p-stop
geometries
25 Oct 2011
Baby Module
Trapezoidal Module
The Silicon Vertex Detector of the Belle II Experiment
13T. Bergauer (HEPHY Vienna)25 Oct 2011
Signal-to-noise-ratios
• Dark colors: non-irradiated, Light colors: irradiated• Atoll pattern (half-wide) performs best, both irradiated and non-
irradiated • Charge accumulation in non-implanted regions after irradiation
narrow half-narrow half-wide wide
10
15
20
25
30
35
40
Atoll p-stop
Geometry
SN
R
narrow half-narrow half-wide wide
10
15
20
25
30
35
40
Common p-stop
Geometry
SN
R
narrow half-narrow half-wide wide
10
15
20
25
30
35
40
Combined p-stop
Geometry
SN
R
• Test sensors have been Gamma-irradiated with Co-60 (70 Mrad)• Tested before and after at CERN beam test (120 GeV hadrons)
The Silicon Vertex Detector of the Belle II Experiment
14T. Bergauer (HEPHY Vienna)25 Oct 2011
Belle and Belle II SVDDouble Sided SensorsReadout SystemChip-on-Sensor-ConceptSummary
The Silicon Vertex Detector of the Belle II Experiment
15T. Bergauer (HEPHY Vienna)25 Oct 2011
Readout System Concept• Prototype readout system exists• Verified in several beam tests• Scheme shown below
1902APV25chips
Front-end hybrids Rad-hardvoltage
regulators
Analog level translation, data sparsification andhit time reconstruction
Unified Belle IIDAQ system
~2mcoppercable
J unctionbox
~10mcoppercable
FADC+PROC
CO
PP
ER
Unified opticaldata link (>20m)
Finesse Transmitter Board (FTB)
The Silicon Vertex Detector of the Belle II Experiment
16T. Bergauer (HEPHY Vienna)
Readout Chip: APV25
• Developed for CMS (LHC) by Imperial College
London and Rutherford Appleton Lab – 70.000 chips installed
• 0.25 µm CMOS process (>100 MRad tolerant)
• 128 channels
• 192 cell analog pipeline
no dead time
• 50 ns shaping time low occupancy
• Noise: 250 e + 36 e/pF
must minimize capacitive load!!!
• Multi-peak mode (read out several
samples along shaping curve)
• Thinning to 100µm successful
25 Oct 2011
The Silicon Vertex Detector of the Belle II Experiment
17T. Bergauer (HEPHY Vienna)25 Oct 2011
Prototypes
Repeater BoxLevel translation, buffering
FADC+PROC (9U VME)Digitization, zero-suppression,
hit time reconstruction
The Silicon Vertex Detector of the Belle II Experiment
18T. Bergauer (HEPHY Vienna)25 Oct 2011
APV25 – Hit Time Reconstruction
• Possibility of recording multiple samples (x) along shaped waveform (feature of APV25)
• Reconstruction of peak time (and amplitude)by waveform fit– Offline now– Hardware later
• Is used toremove off-timebackground hits
0 50 100 150 200 250 300
0
5000
10000
15000
20000
25000
30000
S peak
tpeak
Measurement
The Silicon Vertex Detector of the Belle II Experiment
19
Occupancy Reduction
Threshold
Threshold
Tim e over threshold ~ 2000ns (m easured)
Tim e over threshold ~ 160ns (measured)
Sensitive tim e window ~ 20ns
VA1TATp~800ns
APV25Tp~50ns
Pulse shapeprocessingRM S(tm ax)~3ns
Gain ~12.5
Gain ~8
Total gain ~100
25 Oct 2011 T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
20T. Bergauer (HEPHY Vienna)25 Oct 2011
Belle and Belle II SVDDouble Sided SensorsReadout SystemChip-on-Sensor-ConceptSummary
The Silicon Vertex Detector of the Belle II Experiment
2125 Oct 2011
Chip-on-Sensor Concept• Chip-on-sensor concept for double-sided readout• Flex fan-out pieces wrapped to opposite side (hence “Origami“)• All chips aligned on one side single cooling pipe
Side View (below)
T. Bergauer (HEPHY Vienna)
APV25 chips(thinned to 100µm)
3-layer kapton hybrid
fanout for n-side (z)DSSD
double-layer flex wrapped to p-side (r-phi)
cooling pipeCF sandwich ribs
APV25(thinned to 100µm)
support ribs
cooling pipe
SensorAirex
Kaptonwrappedflex fanout
The Silicon Vertex Detector of the Belle II Experiment
2225 Oct 2011
Origami Module with 6” HPK DSSD
T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
23T. Bergauer (HEPHY Vienna)
Origami Module Assembly
Ingredients:
• DSSD sensors
• Kapton PCB and pitch-adapters
• APV Readout chips
Followed by complicated assembly
procedure
• currently verified by all groups
interested in ladder assembly
25 Oct 2011
The Silicon Vertex Detector of the Belle II Experiment
2425 Oct 2011
Sketch of the Outermost Ladder (Layer 6)
• Composed of 5 x 6” double-sided sensors• Center sensors have Origami structure• Averaged material budget over the full module: 0.55% X0
ca. 60cm
T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
2525 Oct 2011
Ladder Mechanics
• Carried by ribs made of carbon fiber and Airex foam
• Very stiff, yet lightweight thanks to the sandwich construction
Cooling Pipe Sensor
Support Ribs
T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
26T. Bergauer (HEPHY Vienna)
CO2 Cooling
• Closed CO2 cooling plant under development
• Collaboration with CERN• First step is to gain experience
with open (blow) system
25 Oct 2011
Control cabinet with touch screen Accumulator
Liquid pumps
1.3 m
1.6
m1.
2 m
The Silicon Vertex Detector of the Belle II Experiment
27T. Bergauer (HEPHY Vienna)25 Oct 2011
Belle and Belle II SVDDouble Sided SensorsReadout SystemChip-on-Sensor-ConceptSummary
The Silicon Vertex Detector of the Belle II Experiment
28T. Bergauer (HEPHY Vienna)25 Oct 2011
Summary• KEKB is the highest luminosity machine in the world
• Upgrade of KEKB and Belle (2010-2014)– 40-fold increase in luminosity– Needs upgrades of all sub-detectors
• New, enlarged Silicon Vertex Detector– DEPFET pixel double-layer– Four double-sided strip layers
• Strip Detector R&D– 6 inch Double Sided Strip Detectors by HPK and Micron
• Optimal p-stop geometry identified by SNR measurements before and after irradiation
– Readout with hit time reconstruction for improved background tolerance– Origami chip-on-sensor concept for low-mass DSSD readout
The Silicon Vertex Detector of the Belle II Experiment
29
Backup Slides follow
25 Oct 2011 T. Bergauer (HEPHY Vienna)
The End.
Beam Parameters
KEKB Design
KEKB Achieved: with crab
SuperKEKBHigh-Current
SuperKEKB Nano-Beam
Energy (GeV) (LER/HER) 3.5/8.0 3.5/8.0 3.5/8.0 4.0/7.0
by* (mm) 10/10 5.9/5.9 3/6 0.27/0.42
ex (nm) 18/18 18/24 24/18 3.2/2.4
sy(mm) 1.9 0.94 0.85/0.73 0.059
xy 0.052 0.129/0.090 0.3/0.51 0.09/0.09
sz (mm) 4 ~ 6 5/3 6/5
Ibeam (A) 2.6/1.1 1.64/1.19 9.4/4.1 3.6/2.6
Nbunches 5000 1584 5000 2503
Luminosity (1034 cm-2 s-1) 1 2.11 53 80
25 Oct 2011
The Silicon Vertex Detector of the Belle II Experiment
31T. Bergauer (HEPHY Vienna)
KEKB accelerator upgrade
25 Oct 2011
Crab cavity
3.5GeV e+
8GeV e-
New beam-pipeswith ante-chamber
Dampingring for e+
New IR with crabcrossing and
smaller by*
More RF for higherbeam current
SRbeam
The Silicon Vertex Detector of the Belle II Experiment
32
New dead-time-free pipelined readout and
high speed computing systems
Faster calorimeter with waveform sampling and pure CsI (endcap)
New particle identifier with precise Cherenkov device:
(i)TOP or fDIRC.Endcap: Aerogel RICH
Si vertex detector withhigh background tolerance
(+2 layers, pixels)
Background tolerant super small celltracking detector
KL/m detectionwith scintillator
and next generationphoton sensors
Belle-II
25 Oct 2011 T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
33T. Bergauer (HEPHY Vienna)25 Oct 2011
Sensor Types and Vendors
Rect (122.8 x 38.4 mm , 160 / 50 um pitch)2
Rect (122.8 x 57.6 mm , 240 / 75 um pitch)2
W e dge (122.8 x 57 .6-3 8.4 m m , 240 / 75..50 um p itch)2
0
0
10
3
45
6[cm] layers
[cm]
20
-10-20-30 10 20 30 40
6
z APVs
z APVs
z APVs
64
4
4 4
46
6
6
rphi APVs
rphi APVs
rphi APVs
6
64
4
4 4
4
4
46
666 6
6 6 6
6
Layer # of Ladders
Rect. Sensors[narrow]
Rect. Sensors[wide]
Wedge Sensors
APVs
6 17 0 68 17 850
5 14 0 42 14 560
4 10 0 20 10 300
3 8 16 0 0 192
Sum: 49 16 130 41 1902
The Silicon Vertex Detector of the Belle II Experiment
34T. Bergauer (HEPHY Vienna)
Micron Wafer Layout
Teststructuresfor p-side
Teststructuresfor n-side(no GCD)
Baby sensor 1p-side: 512 strips 50 µm pitch 1 interm. stripn-side: 512 strips 100 µm pitch 1 interm. strip atoll p-stop
3 different GCDsfor the n-side
Main sensorp-side: 768 strips 75-50 µm pitch 1 interm. stripn-side: 512 strips 240 µm pitch 1 interm. strip combined p-stop
Quadratic baby sensors 2,3,4p-side: 512 strips 50 µm pitch 1 interm. stripn-side: 256 strips 100 µm pitch 0 interm. strip different p-stop patterns
1) atoll p-stopvarying distance from strip
2) conventional p-stopvarying width
3) combined p-stopvarying distance from strip
1)
2)
3)
25 Oct 2011
The Silicon Vertex Detector of the Belle II Experiment
narrowhalf-
narrowhalf-wide wide
Common
Combined
Atoll35T. Bergauer (HEPHY Vienna)25 Oct 2011
p-stop layouts of the test sensors
• Three different p-stop patterns• Per pattern, four zones with different geometry• Green: strip implant (n), Red: p-stop
The Silicon Vertex Detector of the Belle II Experiment
36T. Bergauer (HEPHY Vienna)25 Oct 2011
eta distribution for atoll p-stop
Charge accumulation in unimplanted region
The Silicon Vertex Detector of the Belle II Experiment
37
Current Barrel Layout
Slanted Sensors
Origami
Cooling Tubes
Hybrid Boards
Layer Sensors/Ladder
Origamis/Ladder Ladders Length [mm] Radius [mm] Slant Angle [°]
3 2 0 7/8 262 38 0
4 3 1 10 390 80 11.9
5 4 2 14 515 115 17.2
6 5 3 17 645 140 21.1
25 Oct 2011 T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
38
Comparison VA1TA – APV25
VA1TA (SVD)• Commercial product (IDEAS)
• Tp = 800ns (300 ns – 1000 ns)• no pipeline• <10 MHz readout• 20 Mrad radiation tolerance• noise: ENC = 180 e + 7.5 e/pF• time over threshold: ~2000 ns• single sample per trigger
APV25 (Belle-II SVD)• Developed for CMS by IC
London and RAL• Tp = 50 ns (30 ns – 200 ns)• 192 cells analog pipeline• 40 MHz readout• >100 Mrad radiation tolerance• noise: ENC = 250 e + 36 e/pF• time over threshold: ~160 ns• multiple samples per trigger
possible (Multi-Peak-Mode)
25 Oct 2011 T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
39T. Bergauer (HEPHY Vienna)25 Oct 2011
Measured Hit Time Precision
• Results achieved in beam tests with several different types of Belle DSSD prototype modules (covering a broad range of SNR)
• 2...3 ns RMSaccuracy at typical cluster SNR(15...25)
• Working onimplementationin FPGA (using lookup tables) – simulationsuccessful
Time Resolution vs. Cluster SNR
0
1
2
3
4
5
6
7
5 10 15 20 25 30
Cluster SNR [1]
trm
s [n
s]
Previous beam tests
SPS 09 beam test
Log-Log Fit
(TDC error subtracted)
Origami Module
The Silicon Vertex Detector of the Belle II Experiment
40
Maximum Radiation Length Distribution
Kapton
0 10 20 30 40 50 600
0.5
1
1.5
2
2.5
3
3.5
Profile [mm]
Radi
atio
nLe
ngth
[%]
Rib Design
CFRP Rohacell
Pipe APVCoolant
Sensor
25 Oct 2011 T. Bergauer (HEPHY Vienna)
The Silicon Vertex Detector of the Belle II Experiment
Cooling Boundary Conditions
• Power dissipation per APV: 0.35 W• 1 Origami sensor features 10 APVs
• Total Origami power dissipation: 312 W• 354 W dissipated at the hybrid boards • Total SVD power dissipation: 666 W
Origamis/Ladder
Ladders APVs Origami
APVs Hybrid
Layer 6 3 17 510 340
Layer 5 2 14 280 280
Layer 4 1 10 100 200
Layer 3 0 8 0 192
25 Oct 2011 41T. Bergauer (HEPHY Vienna)
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