VCI, 13 February 2013
The Belle II Silicon Vertex Detector
Markus Friedl (HEPHY Vienna) for the Belle II SVD Group
Introduction
Front-End
Electronics
Performance
Summary
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
2
Introduction
Front-End
Electronics
Performance
Summary
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
3
KEKB and Belle @ KEK (1999-2010)
KEKB
~1 km in diameter
Belle
 Asymmetric machine:
8 GeV e- on 3.5 GeV e+
Belle
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
Masukawa
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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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
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Belle II Vertexing Subdetectors
Silicon Vertex Detector (SVD)
4 layers of DSSDs
Pixel Detector (PXD)
2 layers of DEPFET pixels
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Belle II Vertexing Environment
 Low energy machine (10.58 GeV) – multiple scattering
 Needs very low mass detector
 PXD DEPFET sensors are thinned to 75 µm
 SVD uses “Origami chip-on-sensor” concept
 High luminosity – occupancy/pile-up
 Need small sensitive area and/or fast readout
 PXD has small cell size (50 x 50 µm2)
 SVD has fast shaping (50 ns) and hit time reconstruction (~3 ns)
 Radiation –  100 kGy
 Magnetic field – 1.8 T
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Silicon Vertex Detector Concept
 Use largest possible (6”) double-sided sensors (DSSDs)
 Minimize relative amount of structural material
 Fast shaping readout
 Minimize occupancy
 Fast readout implies higher noise
 Noise is mainly determined by input capacitance
 Place readout chips as close as possible to sensor strips
 Minimize capacitive load by avoiding long fanouts
 Use efficient CO2 cooling
 Allows thin cooling pipes
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Belle II Vertex Detector
 Pixel Detector – 8M pixels
 2 DEPFET layers at r = 14, 22 mm
 Excellent and unambiguous
spatial resolution (~15 µm)
 Coarse time resolution (20 µs)
 Silicon Vertex Detector – 220k strips
 4 DSSD layers at r = 38, 80, 104, 135 mm
 Good spatial resolution (~12/25 µm)
but ambiguities due to ghosting
 Excellent time resolution (~3 ns)
 Combining both parts yields a very powerful device!
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Introduction
Front-End
Electronics
Performance
Summary
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Front-End Geometry
 4 layers arranged in ladders
 Outer 3 layers have slanted forward part
 Limited acceptance angle (17°…150°) allows to place services
outside (cyan cones) while minimizing material within
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Double-Sided Silicon Sensors
 3 different types required
 Large rectangular sensors – 123 x 58 mm2 (HPK)
 Small rectangular sensors – 123 x 38 mm2 (HPK)
 Trapezoidal sensors – 123 x 58…38 mm2 (Micron)
 Production is in progress
 Presently ~60% delivered
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
12
Origami Chip-on-Sensor Concept
 Low-mass double-sided readout
 Flex fanout pieces wrapped to opposite side
 All chips aligned on one side  single cooling pipe (D = 1.6 mm)
3-layer kapton hybrid
CF sandwich
ribs
APV25 chips
(thinned to 100µm)
cooling pipe
Side View
(below)
DSSD
fanout for n-side (z)
flex fanout wrapped
to p-side (r-phi)
wrapped
cooling pipe
flex fanout
APV25
(thinned to 100µm)
Kapton
Airex
Sensor
support ribs
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Origami Prototype Modules
 Single Origami module
 Double Origami module
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Sensor underneath flex circuit
End ring (support)
APV25 chips
Origami ladder
Pitch adapter bent
around sensor edge
Cooling pipe
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Introduction
Front-End
Electronics
Performance
Summary
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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General SVD Readout Scheme
 Based on existing prototype system
DATCON
ONSEN
(2007) verified in lab and beam tests
Finesse Transmitter
Board (FTB)
FADC
~2m Junction ~10m
copper
box
copper
cable
cable
Unified optical
data link (>20m)
COPPER
1748
APV25
chips
Front-end
hybrids
Rad-hard
DC/DC
converters
Analog level translation,
data sparsification and
hit time reconstruction
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
Unified Belle II
DAQ system
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APV25 Front-End Chip
MUX gain
128:1
Differential
MUX
current
output amp
inverter
pipeline
preamp
shaper
APSP
S/H
 Developed for CMS by IC London and RAL
 70,000 chips running in the CMS Tracker since 2008
 40 MHz clock; 128 channels; 192 cells deep analog pipeline
 50 ns (adjustable) shaping time
 0.25 µm CMOS process (>100 MRad tolerant)
 Low noise: 250 e + 36 e/pF
 Multi-peak mode (read out several samples along shaping curve)
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Junction Box
 CERN-made DC/DC
converters for
front-end powering
 Comparative
measurement:
no noise penalty
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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FADC Block Diagram
Jitter
Cleaner
Delay
CLK
Controls
V/I
Monitoring
Junction Box
FIR
ADCs
Signals
Level Translation
Controls
Central
FPGA
VME
FPGA
Slow
Controls
Data
Data
FADC Controller
VME bus
GbE
FTB
HV LV
 Analog & digital level translation between  bias and GND
 Digitization, signal conditioning (FIR filter), data processing
 Central FPGA is an Altera Stratix IV GX
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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FADC: Overall Concept
 9U VME
Indicator
LEDs
VME
Altera
P1
Delay
Analog
level
translation
Bus
ADCs
CLK
distribution
Stratix 4 GX
daughter board
Jitter
Cleaner
Hybrid
Connectors
P2
FE control
& monitoring
Digital
(controls)
level
translation
GbE
Delay
CLK
distribution
M.Friedl (Belle II SVD Group): The Belle II SVD
P3
module
(needs
much space
for level
translation
circuits)
 Circuit is
designed,
now PCB
layout is
made
13 February 2013
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The “Human” Touch…
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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FTB: Link to DAQ and PXD
 Firmware development ongoing
 Optical link tests at 2.54 and 3.175 Gb/s successful
 Second iteration of PCB for minor corrections underway
 SVD data are also streamed to PXD for online data reduction
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
23
Introduction
Front-End
Electronics
Performance
Summary
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Hit Time Reconstruction Benefits
Belle I SVD
VA1TA
Tp~800ns
Threshold
Time over threshold ~ 2000ns (measured)
APV25
Reduction ~12.5
Tp~50ns
Threshold
Time over threshold ~ 160ns (measured)
Pulse shape
processing
RMS(tmax)~3ns
Sensitive time window ~ 20ns
Belle II SVD
Reduction ~8
Total reduction ~100
 Sufficient to cope with a 40-fold increase in luminosity
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Achieved Hit Time Resolution
 Results achieved in beam tests with several different types
of Belle II prototype modules (covering a broad range of
SNR)
Peak time precision vs. SNR
10
 2...3 ns RMS
 Will be done
in FPGA (using
lookup tables) –
simulation
successful
KEK Nov 08 standard
KEK Nov 08 doubled IPRE
8
KEK Nov 08 31.8 Mhz
SPS Aug 09 run042
7
SPS Aug 09 run043
Trms [ns]
accuracy at
typical cluster SNR
(14...24)
SPS June 2008
9
SPS Aug 09 run6873
6
SPS Aug 09 run012
SPS Aug 09 run019
5
Theory
4
3
2
Close to theoretical limit
1
(G. De Geronimo, in “Medical Imaging” by K. Iniewski)
0
0
M.Friedl (Belle II SVD Group): The Belle II SVD
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10
15
20
25
30
Cluster SNR
13 February 2013
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Z Vertex Resolution
 Belle II (PXD & SVD) will be a factor 2 better than Belle (SVD
only)
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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Introduction
Front-End
Electronics
Performance
Summary
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
28
Summary
 Belle II Vertex Detector consists of
 Pixel Detector (PXD): unambiguous spatial resolution
 Silicon Vertex Detector (SVD): precise timing
 Silicon Vertex Detector
 4 layers of 6” double-sided silicon sensors
 APV25 front-end chip with 50 ns shaping time
 Origami chip-on-sensor readout concept for low mass
 Highly efficient CO2 cooling
 Schedule
 R&D completed, construction has started
 Now building final prototypes (pre-series)
M.Friedl (Belle II SVD Group): The Belle II SVD
13 February 2013
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