The Silicon Vertex Detector
of the Belle II Experiment
Thomas Bergauer (HEPHY Vienna)
EPS HEP 2013 Stockholm
19 July 2013
The Silicon Vertex Detector
of the Belle II Experiment
Belle and Belle II
SVD Components
Summary
19 July 2013
Thomas Bergauer (HEPHY Vienna)
2
The Silicon Vertex Detector
of the Belle II Experiment
KEKB and Belle @ KEK (1999-2010)
KEKB
• Asymmetric machine:
8 GeV e- on 3.5 GeV e+
Belle
Belle
~1 km in diameter
Linac
KEKB
About 60km northeast of Tokyo
• 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
Linac
• Belle mentioned explicitly in 2008 Physics Nobel
Prize announcement to Kobayashi and Maskawa
19 July 2013
Thomas Bergauer (HEPHY Vienna)
3
The Silicon Vertex Detector
of the Belle II Experiment
SuperKEKB/Belle II Upgrade: 2010–2015
•
•
•
Aim: super-high luminosity ~81035 cm-2s-1  11010 BB / year
LoI published in 2004; TDR published in 2010
Refurbishment of accelerator and detector required


nano-beams with cross-sections of ~10 µm x 60 nm
10 mm radius beam pipe at interaction region
http://belle2.kek.jp
19 July 2013
Thomas Bergauer (HEPHY Vienna)
4
The Silicon Vertex Detector
of the Belle II Experiment
Previous SVD Layout (until 2010)
20
[cm]
10
0
-30
layers 4
-20
3
2
1
-10
0
10
20
30
40
[cm]
• 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 (VA1 chip)
19 July 2013
Thomas Bergauer (HEPHY Vienna)
5
The Silicon Vertex Detector
of the Belle II Experiment
Belle Silicon Vertex Detector (SVD)
• Previous SVD limitations were
– occupancy (currently ~10% in
innermost layer)
 need faster shaping
– dead time (currently ~3%)
 need faster readout and
pipeline
L1
10%
• Belle II needs detector with
– high background tolerance
– pipelined readout
– robust tracking
– low material budget in active
volume
19 July 2013
Thomas Bergauer (HEPHY Vienna)
L2
L3
L4
Current SVD is not
suitable for Belle II
6
The Silicon Vertex Detector
of the Belle II Experiment
New Layout for Belle II SVD (2014-)
• New double-layer pixel
detector
using DEPFET
technology
• Four layers with 6”
double-sided strip
detectors at larger
radii and forward part
20
[cm]
10
4 layers of doublesided strip sensors
layers
6
5
4
3
0
-30
Two layers of
DEPFET pixels
1+2
-20
-10
0
10
20
30
40
[cm]
optimized for precision
vertex reconstruction of the
decays of short-lived Bmesons
19 July 2013
Thomas Bergauer (HEPHY Vienna)
7
The Silicon Vertex Detector
of the Belle II Experiment
Belle and Belle II
SVD Components
Summary
19 July 2013
Thomas Bergauer (HEPHY Vienna)
8
The Silicon Vertex Detector
of the Belle II Experiment
Double-sided strip sensors from 6” wafer
• Double sided strip silicon detectors
with AC-coupled readout
and poly-silicon resistor biasing
made of 6 inch wafers
– Size 12 x 6 cm
• After market survey, orders placed
at
– Hamamatsu (barrel)
– Micron (forward); trapezoidal
Sensor pitch
Layer 3
Layer 4-6
19 July 2013
barrel
160/50um
240/75um
forward
240/50-75um
Thomas Bergauer (HEPHY Vienna)
9
The Silicon Vertex Detector
of the Belle II Experiment
Trapezoidal Sensors for Forward Region
• Trapezoidal sensor for
forward region
• Different p-stop layouts
on test sensors
Atoll p-stop
Common p-stop
Combined p-stop
19 July 2013
Thomas Bergauer (HEPHY Vienna)
10
The Silicon Vertex Detector
of the Belle II Experiment
Signal-to-noise-ratios
• Test sensors have been Gamma-irradiated
with Co-60 (70 Mrad)
• Tested before and after at CERN beam test
(120 GeV hadrons)
Common p-stop
Combined p-stop
40
40
35
35
35
30
30
30
25
20
15
10
SNR
40
SNR
SNR
Atoll p-stop
25
20
20
15
15
10
10
narrow
•
•
•
half-narrow
half-wide
25
wide
narrow
Geometry
half-narrow
half-wide
wide
Geometry
narrow
half-narrow
half-wide
wide
Geometry
Dark colors: non-irradiated, Light colors: irradiated
Four geometries: width of „virtual“ strip defined by p-stop
Atoll pattern (half-wide) performs best, both irradiated and nonirradiated
– Chosen for final sensor
19 July 2013
Thomas Bergauer (HEPHY Vienna)
11
The Silicon Vertex Detector
of the Belle II Experiment
Readout System Concept
• Analog data transmission up to FADC by copper cable
– Signal conditioning using FIR (Finite Impulse Response) filter
• Prototype readout system exists
– Verified in several beam tests
• Final system to be ready for beam test at DESY in January 2014
FADC+PROC
~2m Junction ~10m
copper
box
copper
cable
cable
Unified optical
data link (>20m)
COPPER
1748
APV25
chips
Front-end
hybrids
19 July 2013
Rad-hard
DC/DC
converters
Analog level translation,
data sparsification and
hit time reconstruction
Thomas Bergauer (HEPHY Vienna)
Unified Belle II
DAQ system
12
The Silicon Vertex Detector
of the Belle II Experiment
Prototypes
4A DC/DC converter prototype
(developed at CERN)
19 July 2013
FADC+PROC (9U VME)
Digitization, zero-suppression,
hit time reconstruction
Thomas Bergauer (HEPHY Vienna)
13
The Silicon Vertex Detector
of the Belle II Experiment
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
•
Multi-peak mode (read out several
samples along shaping curve)
•
Noise: 250 e + 36 e/pF
 must minimize capacitive load!!!
•
Thinning to 100µm successful
19 July 2013
Thomas Bergauer (HEPHY Vienna)
14
The Silicon Vertex Detector
of the Belle II Experiment
APV25 – Hit Time Reconstruction
• Possibility of recording multiple samples (x) along shaped waveform
(feature of APV25)
Peak time precision vs. SNR
• Reconstruction of
peak time (and
amplitude)
by waveform fit
• Is used to
remove off-time
background hits
• 2...3 ns RMS
accuracy at
typical S/N
19 July 2013
6
KEK Nov 08 standard
KEK Nov 08 doubled IPRE
30000
SPS June 2008
5
25000
KEK Nov 08 31.8 Mhz
420000
Trms [ns]
– Offline now
– Hardware later
Speak
Measurement
315000
10000
2
5000
1
0
0
0
0
50
5
100
10tpeak
150
15
200
20
250
25
300
30
Cluster SNR
Thomas Bergauer (HEPHY Vienna)
15
The Silicon Vertex Detector
of the Belle II Experiment
Occupancy Reduction Belle -> Belle II
VA1TA
Tp~800ns
Threshold
Time over threshold ~ 2000ns (measured)
APV25
Gain ~12.5
Tp~50ns
Threshold
Time over threshold ~ 160ns (measured)
Gain ~8
Pulse shape
processing
RMS(tmax)~3ns
Sensitive time window ~ 20ns
19 July 2013
Total gain ~100
Thomas Bergauer (HEPHY Vienna)
16
The Silicon Vertex Detector
of the Belle II Experiment
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
Material Budget cross secion:
3-layer kapton hybrid
Rib Design
3.5
3
Radiation Length [%]
CF sandwich
ribs
APV25 chips
(thinned to 100µm)
cooling pipe
2.5
2
1.5
1
0.5
0
DSSD
0
10
20
30
Profile [mm]
40
50
60
fanout for n-side (z)
wrapped
cooling pipe
flex fanout
double-layer flex
wrapped to p-side (r-phi)
APV25
(thinned to 100µm)
Kapton
Airex
Sensor
support ribs
• Average Material Budget: 0.55%X0
19 July 2013
Thomas Bergauer (HEPHY Vienna)
17
The Silicon Vertex Detector
of the Belle II Experiment
Ladder Mechanics
CO2 Cooling Pipe
Sensor
• Carried by ribs made of carbon fiber
and Airex foam
• Very stiff, yet lightweight thanks to
the sandwich construction
Support Ribs
19 July 2013
Thomas Bergauer (HEPHY Vienna)
18
The Silicon Vertex Detector
of the Belle II Experiment
Origami Module Assembly
Ingredients:
• DSSD sensors
• Kapton PCB and pitchadapters
• APV Readout chips
Followed by complicated
assembly procedure
• Jigs for “mass production”
currently being fabricated
• “mass production” starts this
fall (~50 ladders)
19 July 2013
Assembly Plan:
•
Layer 3: Melbourne
•
Layer 4: Tata@IPMU (Tokyo U)
•
Layer 5: HEPHY Vienna
•
Layer 6: IPMU (Tokyo U)
•
FW/BW Parts of L4-6: INFN Pisa/Trieste
Thomas Bergauer (HEPHY Vienna)
19
The Silicon Vertex Detector
of the Belle II Experiment
Origami Module with 6” HPK DSSD
19 July 2013
Thomas Bergauer (HEPHY Vienna)
20
The Silicon Vertex Detector
of the Belle II Experiment
Building Ladders
•
•
•
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
19 July 2013
Thomas Bergauer (HEPHY Vienna)
21
The Silicon Vertex Detector
of the Belle II Experiment
Going real!
19 July 2013
Thomas Bergauer (HEPHY Vienna)
22
The Silicon Vertex Detector
of the Belle II Experiment
Belle and Belle II
SVD Components
Summary
19 July 2013
Thomas Bergauer (HEPHY Vienna)
23
The Silicon Vertex Detector
of the Belle II Experiment
Summary
•
•
KEKB is the highest luminosity machine in the world
Upgrade of KEKB and Belle (2010-2015)
– 40-fold increase in luminosity
– Needs upgrades of all sub-detectors
•
New, enlarged Silicon Vertex Detector
– DEPFET Pixels and
Four double-sided strip layers
•
Strip Detector R&D
– 6 inch Double Sided Strip Detectors
• 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
– Mass production of ~50 ladders starts this fall, SVD ready by 2015
19 July 2013
Thomas Bergauer (HEPHY Vienna)
24
The Silicon Vertex Detector
of the Belle II Experiment
The End.
Backup Slides follow
19 July 2013
Thomas Bergauer (HEPHY Vienna)
25
The Silicon Vertex Detector
of the Belle II Experiment
Belle Detector (1999–2010)
Aerogel Cherenkov counter
n=1.015~1.030
SC solenoid
1.5 T
3.5 GeV e+
CsI(Tl)
16 X0
TOF counter
8 GeV e-
Central Drift Chamber
small cell +He/C2H5
Si vertex detector
4 layers DSSD
19 July 2013
µ / KL detection
14/15 lyr. RPC+Fe
Thomas Bergauer (HEPHY Vienna)
26
The Silicon Vertex Detector
of the Belle II Experiment
Belle-II
Faster calorimeter with
waveform sampling and
pure CsI (endcap)
KL/m detection
with scintillator
and next generation
photon sensors
New dead-time-free
pipelined readout and
high speed
computing systems
19 July 2013
New particle identifier with
precise Cherenkov device:
(i)TOP or fDIRC.
Endcap: Aerogel RICH
Background tolerant
super small cell
tracking detector
Si vertex detector with
high background tolerance
(+2 layers, pixels)
Thomas Bergauer (HEPHY Vienna)
27
The Silicon Vertex Detector
of the Belle II Experiment
Spatial Resolution of the Belle II Detector
MC simulation for 50 and 75 mm thick silicon: intrinsic resolution in R-F and Z
Extensive simulation
study (ILC software
framework):
• To determine the
expected Belle II
PXD resolution
75 mm thick silicon in R-F
50 mm thick silicon in R-F
better resolution
• Cluster sizes
• A/D conversion
• Signal processing
• Impact parameter
• Vertex resolutions
19 July 2013
75 mm thick silicon in Z
50 mm thick silicon in Z
shift of the best
resolution to 50 deg
Thomas Bergauer (HEPHY Vienna)
28
The Silicon Vertex Detector
of the Belle II Experiment
Sensor Types and Vendors
20
[cm]
layers
4
6
6
5
4
10
4
6
4
6
Layer
-20
z APVs
# of
rphi APVs
z APVs
Ladders
rphi APVs
z APVs
rphi APVs
4
6
4
6
-10
4
6
4
6
4
6
6
6
3
0
-30
4
6
4
6
4
6
4
6
6
6
0
10
20
30
40
[cm]
2
Rect. Sensors
Rect.
Sensors
Wedge
Rect
(122.8 x 38.4
mm
, 160 / 50 um
pitch) APVs
2
[narrow]
[wide]
Rect
(122.8 x 57.6 mm
, 240 / 75Sensors
um pitch)
2
Wedge0(122.8 x 57.6-38.4 64
mm , 240 / 75..5016um pitch) 800
6
16
5
12
0
36
12
480
4
10
0
20
10
300
3
7
14
0
0
168
Sum:
45
14
120
38
1748
19 July 2013
Thomas Bergauer (HEPHY Vienna)
29
The Silicon Vertex Detector
of the Belle II Experiment
Sensor Parameters
Rectangular Sensors
19 July 2013
Trapezoidal Sensors
Thomas Bergauer (HEPHY Vienna)
30
The Silicon Vertex Detector
of the Belle II Experiment
Current Barrel Layout
Layer
Sensors/
Ladder
3
2
4
Origamis/
Ladder
Ladders
Length [mm]
Radius [mm] Slant Angle [°]
0
7
262
38
0
3
1
10
390
80
11.9
5
4
2
12
515
105
16
6
5
3
16
645
135
21.1
Origami
Cooling Tubes
Slanted
Sensors
19 July 2013
Hybrid
Boards
Thomas Bergauer (HEPHY Vienna)
31
The Silicon Vertex Detector
of the Belle II Experiment
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
19 July 2013
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)
Thomas Bergauer (HEPHY Vienna)
32
The Silicon Vertex Detector
of the Belle II Experiment
Cooling Boundary Conditions
• Power dissipation per APV: 0.40 W
• 1 Origami sensor features 10 APVs
Origamis
/Ladder
Ladders
# APVs
Origami
# APVs
Hybrid
Power/
Layer
[W]
Power
Origami
[W]
Layer 6
3
16
480
320
320
192
Layer 5
2
14
240
240
192
96
Layer 4
1
10
100
200
120
40
Layer 3
0
7
0
140
56
0
47
820
900
688
328
Sum
• Total Origami power dissipation: 328 W
• 360 W dissipated at the hybrid boards
• Total SVD power dissipation: 688 W
19 July 2013
Thomas Bergauer (HEPHY Vienna)
33
The Silicon Vertex Detector
of the Belle II Experiment
CO2 Cooling
Control cabinet
with touch screen
Accumulator
1.6 m
• Closed CO2 cooling plant
under development
• Collaboration with CERN
• First step is to gain experience
with open (blow) system
Liquid pumps
19 July 2013
Thomas Bergauer (HEPHY Vienna)
34
The Silicon Vertex Detector
of the Belle II Experiment
Acceptance Region
19 July 2013
Thomas Bergauer (HEPHY Vienna)
35