Silicon Detectors the LHC

1
Silicon Detectors _at_ the LHC
Chris Parkes
TOTAL 287 m2 3.6 secs/m2
2
Contents

• Layouts
• x 4
• Then pick a few examples.
• Sensor Designs
• ALICE Si Drift Detector, LHCb VELO
• CMS Strip Optimisation
• FE Electronics / Mechanics / Cooling
• ATLAS Pixels
• Module Assembly
• CMS Strips
• Q/A
• ATLAS Strips

3
ALICE Silicon

• Double-sided Silicon Strips
• 2.7M 95 ?m pitch
• stereo twist p/n on n
  strips, analogue rad-tol 0.25 ?m
  CMOS readout,
• 1770 modules
• Silicon Drift Detectors
• 260 modules,
• 0.13M channels
• p/n on n see later
• Silicon Pixel Detectors
• 9.8M 50 x 425 ?m
• p on n pixels
• 240 modules

Occupancy 90 cm-2
R39-43cm
R15-24cm
R4-7cm
28 cm
102 cm
3 x 2 layers
4

• Tracker
• 4 all Si layers
• Strips close to beam, outside straw drift tubes
• 200?m pitch pon n , stereo twist, 16
  layers, 2300 sensors, 0.5M strips
• Vertex Locator
• n on n, 0.2M strips
• 8mm from beam, weird layout!!!
• see later

Forward geometry
1m
?Analogue DSM/DMILL readout
5
ATLAS Inner Detector
ICHEP Abstract 158
Pixels n on n, 50x400 ?m2 3 layers, 8 disks,
1500 modules r 4.8 - 16 cm, 140 M channels,
SemiConductor Tracker (SCT) 19,300 single sided
80 ?m pitch p-on-n strip detectors
6 sensor geometries Dmill BiCMOS
Binary readout r 27 - 52 cm, 6.3 M channels
Tracking and Vertex reconstruction Axial magnetic
field 2T Enclosed in a thermal envelope inside
the solenoid, -70C
7 m
2.3 m
4 Barrel cylinders (square), 2 x 9 End-cap disks
(wedge)
6
Two key differences of ATLAS/CMS strips Size
4,000 ? 15,000 modules Strip readout Analogue
DSM chip - APV
2 Pixel Layers R4cm layer to be replaced by
R11cm after low lumi. Period Due to radiation
damage ATLAS 5x more pixels
10 barrel layers, 3 inner disks, 9 outer
7
Design

• R/Phi Sensors
• 40-100um pitch
• 2nd metal readout
• 4um resolution

• Primary/ b decay Vertex reconstruction
• Stand alone Tracking
• Second Level Trigger
• Fast tracking
• Extreme Radiation Environment
• 8mm from beam,
• 1014 1 MeV n/cm2 / year

One set of half disks

• In vacuum
• Retract each fill
• Align each fill

8
Test-Beam Results
ICHEP Abstract 181

• blah

Opposite polarity signal observation at 40MHz
n/p on n Comparison

• 200?m read-out, floating strips
• ?16 strips , 3mm !!! Bi-polar

n-on-n fully efficient when 60 depleted
9
Si Drift Detector
segmented

• High particle multiplicity
• But low event rate
• Trade Speed for 2D
• Readout
• Rad. Tol. DSM ASIC
• 10-bit ADC
• 40 MHz sampling
• 4.5?s drift time
• Temp. sensitive
• Control to 0.1oC
• Monitor with implanted MOS charge injection

2 x 256 anodes
35mm
Built-in voltage dividers
R
e-
n
n
p
Constant E field
Collect e-
10
Drift Distortions
?x XSDD-Xtelescope
Residual doping inhomogeneity causes charge
clusters to deviate from their ideal trajectory
- NTD better than FZ Si
Uncorrected
Anodic resolution, z (mm)
Corrected
25(z)/33(r?) ?m
11
CMS Strip Design

• Width of the metal strip extending beyond
  implants to guarantee good HV stability and avoid
  high field regions at implant edges

with
without
Also capacitance work w/p ratios, lt100gt crystal
orientation.
12
ATLAS Pixels- Readout

• Rad-hard DSM chip success
• 8 Assemblies,
• bump-bonded,
• Irradiated 1015
• 1 MeV n/eq.
• 13?m resolution
• 98 efficiency
• 350e- noise
• Some final tweaking
• (e.g. high SEU rate)
• Final iteration
• end 2002
• Then production.

Electronics
Bump Bonding (In/SnPb)
Sensors
13
ATLAS Pixel Insertable Layout

• allows independent installation removal of
  pixels
• decouples ID / pixel schedule
• facilitates upgrades
• (e.g. replace R4cm B layer)

7m
Pixel Detector
Service and Beampipe Support

• Mechanic/Cooling integrated
• Position stability 10?m
• Remove 15KW (FE chips)
• Keep at 6oC
• Glassy carbon
• Tube between
• CC facings

14
9,648,128 strips, 75,376 APV chips, 15,232
modules .
The module assembly is fully automatic!!!!!
ICHEP Abstract 181
Glue dispensing syringe
Sensor pick up tool
Tool rack
Silicon sensors
Hybrid pick up tool
Assembly platform
Carbon fibre frames
Developed at CERN and exported to the 7
laboratories that assemble modules
Hybrids
Vacuum system
perugia
15
Gantry system locates automatically components
for assembly by visual search for a marker
Image found
First 10 endcap modules Readout tested with
automatic system
s DX3 mm
DF
s DF1.5 mrad
DX
lt20 mm
16
Quality Assurance - ATLAS Strips
On ALL modules

• Production Status
• 85 detectors delivered
• gt99 yield
• Some delays in forward but module construction is
  underway
• .
• .
• .
• .

• Metrology
• 100 pts per detector
• Leakage current
• IV to 500V
• I 24hr stability
• Electrical
• 99 strips efficient, low noise _at_ 1fC threshold
• Gain, discriminator offset
• Timewalk
• Thermal cycling
• -250C ? 400C x 10
• 24 hr with ASIC
• Clocked Triggered

Metal short
Detector Manufacture
100
achieved
schedule
0
2001
2002
On subsamples

• Irradiation Tests
• Beam Test
• Source Test
• Laser Test

Implant break
17

• Regulation Tennis Court Size
• 36x78 ft2 ? 261 m2