Title: The LHCb Vertex Detector
1The LHCb Vertex Detector
- T. Bowcock
- University of Liverpool
2Overview
- Detector Design
- LHCb Components and Status
- Physics
- Vertex Detector
- Summary
3Detector Design(1)Goals
- A CP violation experiment
- Simultaneous measurements of ?,?,?, and ??
- Exploration of Bs sector
- Access to rare b-decays
4Detector Design(2)
a
g
b
5Detector Design(3)
- O(1012)bbpairs/year
- ?bb500?b
- ?bb/ ?inelastic510-3
- Pairs produced at small angles
- Modest luminosity
6LHCb(1)Components
Reversible field
7LHCb(2)Particle ID
- RICH system divided into 2 detectors and 3
radiators aerogel, C4F10, CF4
8LHCb(3)RICH
- Acceptance
- 300 mrad RICH 1
- 120 mrad RICH 2
- Radiators thickness L, refractive index n, angle
?c, ?/K threshold - Aerogel C4F10 CF4
- L 5 85 167 cm
- n 1.03 1.0014 1.0005
- qc 242 53 32 mrad
- p 0.6 2.6 4.4 GeV
- K 2.0 9.3 15.6 GeV
9LHCb(4)Particle ID
- 3s separation pK 3-80GeV/c
- 2s separation pK 1-150GeV/c
- of detected photons
- 7 Aerogel 33 C4F10 18 CF4
10LHCb(5)Particle ID
Bd ? ?? ? (a)
Bs ? Ds?K? (g)
11LHCb(6)Vertex Detector - VELO
Series of disks
12LHCb(7)Status
- LHCb Experiment Approved Sep 1998
- Technical Design Reports
- Magnet
- Calorimeter
- Muon
- RICH
- VELO
- Outer Tracker
13LHCb(8)Improving Performance
- Reducing Material Budgets
- VELO 0.19X0 0.04?
- RICH1 0.14X0 0.05?
- Tracking 0.27X0 0.11?
- Beam Pipe
- VELO material, stations
- RICH Mirror
- Tracking Stations
- Trigger efficiencies
14Physics(1)2005
15Physics(2)LHCb 200x
16Physics(4)LHCb Performance
17Physics(5)LHCb Performance
18Vertex Detector
Bs ? Ds K
- Precision tracking that
- B vertices
- lifetime (40fs)
19Vertex Detector
- Radiation Hard Sensors
- Analogue Electronics
- Precise Alignment
- Level 1 Trigger
20Geometry
Positioning and movement to 5mm
10cm
21UK
- Responsible for
- Sensors
- Hybrids
- Modules
- Cooling
- Alignment
22Operating Parameters
- Voltage
- Details of sensor technology
- Efficiency
- Temperature
- Mechanical construction
- Minimize cooling requirements
- Thickness
- Signal
23Damage
24LHC prediction (p-type)
25Depletion Voltages
26Depletion Voltages
27Operating Temp
28Sensor Design
29Sensors
Al
30Testbeam
UK Purchased Hamamatsu prototypes-1998 to present
31Laboratory
- Irradiation of n-in-n and p-in-n Comparison with
simulations - Comparison of charge collection efficiency vs
voltage curves obtained with beta particles
(106Ru source) and 1060 nm laser - Signal to noise with SCT128-VG
- Comparison of CCE with n and p read out strips
(n-in-n vs p-in-n diode geometry)
32Technical Choices
- p bulk on n-bulk
- Isolation techniques (n-bulk)
- Individual p-stops (Hamamatsu)
- P-spray (Micron)
- Do these work in case of intense non-uniform
irradiation?(PPESP)
33n-strip in n-bulk
34Non-uniform irradiation
ISE simulation of the electric field (120 V
applied bias) in the high gradient area of an
irradiated (gt6.1014 cm-2) n-in-n silicon detector
and signal of two neighbour strips generated by a
MIP crossing mid way of the two strips. The
difference in signal height corresponds to the
one obtained by moving the impact point of the
MIP off centre by half a micron.
35ISE simulation of the electric field (300 V
applied bias) in the high gradient area of an
irradiated (gt4.1014 cm-2) p-in-n silicon detector
and signal of two neighbour strips generated by a
MIP crossing mid way of the two strips
36Laser Injector
37Laser
- 2µm step which allows the intermediate
positioning with 1 µm precision. The light spot
has a FWHM of about 7µm. - The metalisation on the backside of the detector
has holes to avoid reflections of the laser
light.
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39Irradiation
- n-in-n and a p-in-n phi detectors have been
irradiated
40The effective doping concentration as measured by
the CCE curves in correspondence of laser
illumination of different strips. The high
gradient region is about from strip 550 to 600.
41Measure ?
R
L
?R/(RL)
x
42Distortions-low gradient
Measurement of the h function in differently
irradiated area of the detector low gradient
area (irradiation about at type inversion
fluence)
43Distortions-high gradient
Measurement of the h function in differently
irradiated area of the detector high gradient
area
44Distortions-high dose
Measurement of the h function in differently
irradiated area of the detector most irradiated
area
45Laser versus MIPS
Comparison between CCE obtained with 1060 nm
laser and 106Ru source
46nn v pn
Preliminary comparison of CCE between n-in-n and
p-in-n detectors highly irradiated region. The
signal was induced by 1060 nm laser. The
detectors were irradiated together. Thickness of
both types 200 µm.
47Noise
- S/N with SCT128VG(LHC speed)on 200 micron thick
n-bulk detectors - 161 (uncorrected) unirradiated
- 141 highly irradiated
- Noise independent of bias 50-500V
- Operated up to 1000V
48Conclusions on Lab tests
- Distortion of the resolution due to
non-homogeneous irradiation does not need
correction - CCE with n-strip read-out superior at low
voltages after irradiation - No evidence of microdischarges up to 500 V in
n-in-n (p-spray) detectors - 200 micron thick
- pn detectors(300micron) operated at 1000V
49Hybrid-SC128a
- IDEAS
- ?-detector
- Irradiated
- 1968-19-1
- 300?m Oxy
50Results with populated (12 chips) IDE hybrid and
irradiated 200µm p-in-n detector
51Kapton-SCT128a (IDEAS)
K-01
52Module(4)
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54Curvature of Sensors
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56Curvature
57Prototype Module
Pipe slides through paddle
58Prototype Module
- Base simplified(?)
- Production in CF
59Prototype Module
- Single (asymmetric) Cooling Pipe
60VELO Module
Hybrid(SCT-VELO)
Base
Paddle
61VELO Sensor Support
- Substrate
- Hybrid(K-02)
- Fanins
- Sensor(200?m)
- Chips
- Adhesives
- Connectors
62Material Table
63Material Traversed
Tracks with uniform density in ?
Average
average
64Average
RL 2.87 0.00 0.00 0.19 0.06 0.01 0.09 0.01
0.06 0.16 0.25 0.00 0.01 0.32 0.02 0.11
0.01 Tot 4.18
65Hardware Module(1)
- Thermal models for TDR
- Cooling system
- Safety issues addressed
66Module
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68Cooling System
- Safety compliant (factor 10!)
- certified
- Leak tested
- CO2 monitor
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70Summary
- Second generation b-physics experiment
- day-one operation
- UK RD sensor development a success
- Vital to keep lead
- Superb instrument for exploring possible
deviations from SM in B sector - Preparation progressing well