Transcript Document

P326 Gigatracker Pixel Detector
• Requirements
– material budget, time resolution, radiation hardness,...
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Hybrid pixels: sensor, readout chip, bump bonding
Electronics system
(Mechanics and) Cooling
Resources - Workplan
• Possible interest in R&D for CLIC
04/10/06
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P326 Proposal
• 10-11 branching ratio
• high intensity K beam
• high background rejection
• ≈ 5.1012 K decays/year
• ≈ 100 events by 2011
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P326 Beam
Tracking, momentum, time stamp
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modified NA48 K12 beam line
3.1012 protons on target (400GeV) ==> 60% pions, 20% protons, 14% electrons, 6% kaons
overall particle rate ≈ 0.8GHz ==> “Gigatracker”
beam cross-section ≈ 12cm2 at GTK
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GTK Si Pixels
P. Riedler
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Required Gigatracker time resolution
P(>1hit in Dt) =1-exp(-Dt*rate)
Dt ( ±2s) @0.8GHZ @1GHZ
400
27%
33%
500
33%
39%
600
38%
45%
K+ p+p0
Dependence of the signal to
background (from K+ p+p0 )
as a function of the gigatracker
time resolution
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Material Budget Requirements
• Full GEANT simulation
• Impact of GTK material budget
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beam momentum resolution
angular beam resolution
vertex resolution
missing mass
• No significant degradation at ≈ 0.5%Xo per plane
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Radiation Levels in Gigatracker (GTK)
• Calculated fluence
≈ 2. 1014 (1 MeV neq cm-2)
100 days
• For comparison:
• ATLAS SCT/CMS TK
≈ 1.5 1014 (1 MeV neq cm-2)
10 years
• Safety factors in estimates
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GTK Hybrid Pixel Design Parameters
(Preliminary)
hybrid pixels
• Pixel cell size
• Sensor thickness
300mm x 300mm
200mm
– charge collection time vs signal amplitude
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Pixel chip thickness
Bump bonding
Material budget
Operating temp.
Cooling
04/10/06
≤ 100mm
Pb-Sn
≈ 0.4% X0 (each station)
T ≤ 5 °C (in vacuum)
≈ 120mm CF radiator/support with
peripheral cooling
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Si Sensors
• Radiation effects
– type inversion (higher Vb required)
– leakage current increase
DIvol=a fne (a ≈ 5 x 10-17 A/cm)
Remedies
– M-CZ material (to be studied)
– operation at low(er) temp (in vacuum...)
I  exp(-Eg/2kT)
(up to ≈ 200mA/cm2 @ 25 °C )
DI reduction ≈ 16x @ 0 °C
– periodic replacement of station
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GTK Pixel ASIC
• Technology: CMOS8 (0.13mm)
– speed, density, power, (radiation
hardness)
– availability/obsolescence, MPW access
– cost (prototyping, engineering run)
– frame contract at CERN for applications
within the HEP community
• Conceptual study well advanced
– definition of system architecture
– noise (mixed-signal application)
– upcoming MPW submission of functional
blocks (amplifier, discriminator, TDC, ...)
ALICE pixel ASIC
(CMOS6 0.25mm)
8,192 pixel cells
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Bump Bonding
• Bump bonding of 150mm pixel chips to
200mm sensors: in volume production
(ALICE SPD 107 pixels)
– Pb-Sn (VTT/Finland)
• Thinning of pixel wafers (D=200mm) is
done after bump deposition
• Thinning/bb to 100mm (or less)
requires prototyping
• Preliminary test under way with ALICE
pixel dummy wafers
• Key issue: flatness of sensors
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Pb-Sn
~20-25µm
©VTT
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Readout Wafer Thinning
200mm Si wafer thinned to 150 mm
J. Salmi/VTT
BOND’03
CERN
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Chip Size - Power Management
• Power dissipation up to 2W/cm2 (preliminary estimate)
• Material budget constraints on coverage of beam area
• Lowest material budget with only pixel matrix in beam
– I/O pads and cooling at periphery
• This leads to power management problems
• Beam cross section adjusted (≈ rectangular) to ease
matching of optimized chip layout
– without degradation of beam quality
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Configuration I
• Highest rate
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Pads for
power supplies
and clock
(additional
material
budget)
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Configuration II
Max rate on
one chip, but
chip smaller
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
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A. Kluge
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Configuration IV
60 mm
6 mm
12 mm
Quic kTime™ and a
TIFF ( Unc ompres s ed) dec ompr es sor
are needed to s ee this pic ture.
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A. Kluge
24 mm
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Time Stamp
• Fast discriminator with time walk compensation is key
element
• TDC bin size
100ps
• TDC options
– one TDC per pixel cell (linear discharge)
• cell area, power dissipation, dead time
– group multiplexed TDC
• efficiency loss (must be limited to <2%)
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Chip size/data rate
• With a beam of 24 x 60 mm -> 2 x 5 chips
• Assume chip matrix of 40 rows x 40 columns:
12 mm x 12 mm = 144 mm2
• Pixel size 300 um x 300 um
– => 40 x 40 pixels = 1600 pixels
• Avg Rate of center column: ~ 96 MHz/cm2
– => 86 kHz/pixel
– => 138 MHz/chip
– => 138 MHz/chip * ~ 32 bit = ~4.4 Gbit/s
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Cooling
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Power dissipation (pixel plane) ≈ 20W
Operating temperature < 5 °C (==> sensor leakage current)
CF radiator fins coupled to cooling circuit
Adhesive/filler (≈ 50mm) thermal conductivity ≈ 1 W/(m K)
Cooling system options
– fluid coolant
– evaporative cooling
• C4F10
• C4F8
– Peltier cell ?
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Carbon Fibre (CF) Composites
• CTE (ppm/K)
≈ -1.5/+12
• Th. conductivity (W/m K)
≈ 150
≈ 1,000
≈ 390
≈ 145
• Density (g/cm3 )
≈ 1.9/2.2
• X0 (g/cm2)
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• 2-ply radiator thickness
≈ 42
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≈ 120 mm
G. Stefanini/LC WG/P326/GTK
(M55J)
(K-1,100)
(Cu)
(Si @ T=300K)
(≈ 21 cm)
(≈ 9.36cm for Si)
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Initial Situation
• Case A: without cooling plane
• Case B: with cooling plane and with
different thermal contact resistances between
the solids
Case
Cooling plane
Thermal
conductivity
k [W/(cm K)]
B1
Toray M55J
1.5
B2
Carbon-Carbon
2.5
B3
Thornel 8000X
panels
8.0
B4
Thornel K-1100
10.0
• Total Heat Load of 2 W/cm²
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Results with ideal contact between materials
Case
A
B1
B2
B3
B4
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Temperature gradient of the Silicon Pixel detector in dependence of the
thermal conductivity of the cooling plane
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Temperature gradient [K]
40
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0
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Thermal conductivity, cooling plane [W/(cm K)]
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Results with thermal resistance between
materials
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Influence of the thermal resistance
• It is quite difficult to calculate the real thermal resistance of the
contact surfaces between the materials.
• Differences between hand calculation and CFD-Simulation, show
the influence of the bumps.
Case
A
B1
B2
B3
B4
ΔT, hand calculation
72.0
54.0
46.3
25.9
22.3
ΔT, CFD-Simulation
80.0
59.6
49.5
26.6
23.7
ΔT with thermal contact
resistance
Rt,c= 0.2 x 10-4 m2K/W
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33.9
28.4
ΔT with thermal contact
resistance
Rt,c= 0.9 x 10-4 m2K/W
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37.5
31.6
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Detector Development Team
(Very preliminary)
Sensors
Analog electronics
Electronic system & integration
CERN
INFN Ferrara
CERN
INFN Torino
CERN
INFN Ferrara
INFN Torino
1 Phys Staff, 1 Fellow
1 PostDoc (tbc)
1 Eng, 1 Fellow (but...)
2 Eng
1 Eng
(tbd)
(tbd)
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CERN staff (sensors and system) for the time being fully committed to
LHC activities (ALICE SPD)
==> 2 FELL/DOCT student required (1 already available)
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Mechanics & cooling
04/10/06
CERN), Ferrara
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Planning (Preliminary)
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System architecture def. & simulation
Small scale prototype submission
Engineering run 1 submission
Engineering run 2 submission
Production of final chip
Detector assembly
H1 YR1
≈ Q3 YR1
≈ Q2 YR2
≈ Q2 YR3
≈ Q1 YR4
≈ Q3 YR4
• YR1 start of PH support & funding
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