p i x e l 2 0 0 2 - c a r m e l sept. 9, 2002m. garcia-sciveres - the atlas pixel detector1 the...

Sept. 9, 2002 M. Garcia-Sciveres - The ATLAS Pixel Detector 1

P i x e l 2 0 0 2 - C a r m e l

The ATLAS Pixel Detector

Pixel 2002 WorkshopM. Garcia-Sciveres

Lawrence Berkeley National Lab


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Aerial View of the LHC Site

Circumference of 27 km

Main CERN Site


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A Toroidal LHC ApparatuS

Calorimeters

Inner Tracking

SuperconductingToroids

Muon Detectors

Tall person

SuperconductingSolenoid

LHC beampipe


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ATLAS Inner Detector


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Pixel Detector

1.3m

3 hit design


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ATLAS Pixel Collaboration

• University of Toronto, Canada

• Academy of Sciences of the Czech Republic

• Czech Technical University

• Charles University, Czech Republic

• CPPM, France

• U. of Bonn, Germany

• U. of Dortmund, Germany

• MPI, Germany

• U. of Siegen, Germany

• U. of Wuppertal, Germany

• INFN Genova, Italy

• INFN Milano, Italy

• INFN Udine, Italy

• Academia Sinica, Taiwan

• SUNY Albany, USA

• LBNL, USA

• Iowa State U., USA

• U. of New Mexico, USA

• Ohio State U., USA

• U. of Oklahoma, USA

• UC Santa Cruz, USA

• U. of Wisconsin Madison. USA


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Detector Parameters• 3 Barrel layers, 3+3 Disks covering ||<2.5• Inner radius: ~5cm Outer radius: ~12cm • n+ on n oxygenated sensors, 400m (z,R) x 50m (phi) pixels.• Number of channels 67M (barrel) + 13M (disks).• Readout type: zero-suppressed time over threshold.• Lifetime Dose, 1015 neq/cm2, 50MRad.• LHC Interaction rate: 40MHz.• Max readout rate: 160Gb/sec => 7KHz trigger at 1% occupancy.• ASICs: 0.25m CMOS with rad. Tolerant layout .• AC signal protocol: LVDS in active volume, optical outside.• Active volume operating power: 6.5kW at 2V• Silicon operating temperature: <0oC• Cooling system: evaporative C3F8.• Radiation length at normal incidence: ~10% R.L.


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Performance

=9m =13m Test beam measurement of single Front End chip bump bonded assembly. For single hits expect =sqrt(12) x pitch ~ 14m.

Test beam measurement of hit efficiency unirradiated and fully irradiated assemblies.

Time (10ns/div.) Time (10ns/div.)0

1

Eff

icie

ncy


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Sensors

Simulation of 70% depletion voltage at innermost layer. 150% LHC nominal fluence.

• 2 Manufacturers: CIS and Tesla• Basic Requirements:

– Leakage current after 1015 neq/cm2: <50nA / pixel– Total input capacitance: <400fF– Inter-pixel capacitance: small– Signal after irradiation: >10Ke-


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Sensors (cont.)

Charge collection efficiency (meas) n+ implants and bias grid

100mm wafer with 3 “tiles”, n sideDetail of p-side multi guard ring structure


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Custom ASIC Electronics

• Suite of chips all fabricated in 0.25m commercial bulk CMOS.

• Use circuit library with special layout rules for radiation tolerance (based on RD49 library)

Doric(from PIN diode to decoded LVDS)

VDC array(from LVDS to laser diodes)

Front End Chip2880 channels

Module Control ChipManages data & control between module’s 16 chips

Optical interface chips


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Readout architecture

FE chip

sens

or FE chip

FE chip

ModuleControlChip

Optical driver

Opticalreceiver

power

HV bias

bump bonds

LVDS control

LVDS data out

1m 100m

optical


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Xray of bumps16 chips. 46,080 bump bonds

Solder Bumps

Sensor ICs

The “Bare” Module

50m

Indium Bumps

OR

6.3cm

2cm


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Pixel Module

Schematic Cross Section(through here)

Bumps

Flex Hybrid (green)

Sensor

Wirebonds

ASICs

Pigtail (beyond)


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Interconnection

Flex hybrid. Interconnects 16 Front End chips to 1 Module Control. Distributes power to all chips and bias

to sensor. All connections wirebonded.

Flex pigtail + Al/Cu wire bundle connect flex hybrid to patch panels at either end of

pixel detector.

Transition to optical at ends of pixel detector. Power continues on Al/Cu wires to end or inner detector.


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Production line oriented design

• Flex hybrids mounted on frames immediately after fabrication.

• All module assembly proceeds on frame.

• Allows safe shipping & handling, testing, bar-code tracking, storage.

• Modules are removed from frame (by cutting sacrificial ends of flex) only at the time of attaching to a local support.

Bar code

Fully assembled module on frame


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Detector building blocks

Bi-stave assemblyIs replicated to formBarrel layers. 2x13 modules

Sector is replicated to form disks. 3+3 modules (back side looks the same)

Same unit repeated many times for production line assembly, uniformity of work at different sites


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Mechanics and services• In the detector volume:

– high power density

– minimum material (=> no thermal mass)

– cold operation

– <10m alignment maintained between room and operating temperatures

– Remain cold & dry even during down times

• Outside detector volume:– Supply 2V power from 100m away with acceptable voltage drop

– Supply adequate cooling with minimal plumbing

– Meet overall detector geometry and installation constraints

– Minimize material in front of calorimeters at low angles


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Module support

Exploded view of sector

Stave


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1st mode515.6 Hz1st mode546 Hz

Global Support

F.E.A.Real life prototypeDisk section of frame

Solid computer model of frame (cutaway view)

TV Holograph image

Need very stiff low mass structures with near zero CTE (build at room temperature- operate down to –25C). Use carbon composites, intense computer modeling & simulation barrel

disks

disks


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Pixel and Beam Pipe Assembly

Service and Beampipe Support

Service and Beampipe Support

Pixel Detector

A “package” that can be inserted in place into the inner detector (and removed also)

Fits into a support tube that provides mechanical support,

but also electrical and environmental isolation from the outside. Cold inside & dry inside & out no

matter outside conditions


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Construction Timeline

• Sensor production: started

• Pre-production chip submission: Dec. 2002

• Production chip submission: Summer 2003

• End Production Module assembly: Dec. 2004

• Start integration at CERN: Jan. 2005

• Start lowering detector into cavern: Fall 2005

• Begin commissioning: Spring 2006

• First collisions: 2007

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