Neil Jackson University of Liverpool Hiroshima Symposium 14-17 June 2004 1 THE ATLAS SEMICONDUCTOR...

Neil Jackson University of Liverpool

Hiroshima Symposium 14-17 June 2004

1

THE ATLAS SEMICONDUCTOR TRACKER (SCT)

A PRESENTATION ON BEHALF OF THE ATLAS

SCT COLLABORATION

•Overview of the ATLAS SCT

•Module production

•Engineering assembly and services

•Macro-assembly

•Current Status

•Summary



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Overview of the SCT• The SCT forms part of the ATLAS Inner Detector.• It is constructed using 4088 silicon micro-strip modules

arranged as 4 barrels in the central region and 2 x 9 annular wheels in the forward region

Inner Detector (ID)



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• The modules are arranged to provide 4 space points per track-2.5< < 2.5

• Each module measures two coordinates– Detector pitch is 80 m and +-20 mrad stereo



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• Modules consist of 4 (2) detectors mounted on a baseboard (barrel) or spine (forward) consisting of Thermal Pyrolytic Graphite + AlN and /or Be0– Ensures good thermal performance

• The kapton hybrids are mounted on carbon-carbon substrates

• Modules have 1526 binary readout channels per module

• Spatial resolutions r = 16 m, z (R) = 580m

Barrel Module Forward Module



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Support structures• All support structures, cylinders and discs,

are produced using a sandwich material constructed with carbon fibre skins and a Korex core in industry

• Cu/Ni cooling pipes, precision mounts for modules, power tapes, opto-fibre harnesses + DCS and alignment components are added



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MODULE PRODUCTION• Production of the 4088 modules occurs at several sites

worldwide

– Barrel modules in Japan, Scandinavia, UK and USA

– Forward modules in Australia, Germany, Netherlands, Spain, Switzerland and the UK

• Modules must satisfy many criteria and tolerances – e.g.

– A range of mechanical tolerances, some < 5 m

– Module leakage current < 80 A at 350V

– Noise per channel < 1500 ENC

– Average noise occupancy at 1 fC threshold < 5 x 10-4

– < 1% bad channels



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A forward module assembly station

Vertical scale is deviation from nominal in units of tolerance. Horizontal scale is module number.



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Bonding and testing

Module bonding Module in testing

Module metrology



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Threshold Scans Noise Occupancy



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MODULE YIELDSBARREL MODULES• ‘Good’ modules satisfy all specifications• ‘Pass’ modules allow for a small % of modules that just

fail a metrology specification – e.g. A deviation in the MIDYF parameter up to 8 m is

allowed (the tolerance is 5 m) • Current yield of Good + Pass modules is 87%

– Pass modules comprise 7.5% of the total• The main failure categories are

– Abnormal leakage current (54%)– Damaged sensors (16%)– Gross mechanical error (metrology out of specification

(14%)



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FORWARD MODULES

• ‘Good’ modules satisfy all specifications

• Current yield of Good modules is 84.3%

• ~50% of the ‘failures’ are just outside metrology specifications

• A ‘Pass’ category

may be defined as

for the barrel

– Should improve

Yield > 90%



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Lessons learned

• The progression from prototyping components to full production can introduce some problems and cause delays– e.g. Forward hybrid de-lamination problem

• Do not underestimate the time required to optimise techniques and commission equipment– e.g. Module assembly techniques

• Take care in defining specifications– Achieving the same quality in multiple sites is not straight forward

• Expect unexpected production problems and allow for the time required to solve them– Start with a proper contingency to allow for unexpected problems

– Rigorous prototyping and QA will minimise unexpected problems



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Engineering assembly and servicesPreparation of barrels

• Mounting pads and brackets are added to the cylinder

• Grounding foils are added• Services are added

– Cu/Ni cooling pipes– low mass tapes,– Fibre harnesses – alignment components– DCS

• The ‘dog leg’ tapes have the optical ASICs mounted – These are mounted on the hybrids for

forward modules



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Mounting services on barrels



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Preparation of discs

• Mounting pads and closeouts are glued onto the disc

• The pads are machined plane• Patch panels and grounding

foils are added• Services are added

– Low mass tapes – C-C mounting blocks

soldered onto Cu/Ni pipes are mounted with high precision

– Optical fibre harnesses, alignment components and DCS



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Metrology results for mounting pin positions for disc 9A

Rphi (meas - nom)

-60

-40

-20

0

20

40

60

80

0 50 100 150 200 250 300 350 400

angular position

De

lta

r-p

hi (

mic

ron

s)

Radius (meas - nom)

-100

-80

-60

-40

-20

0

20

40

60

80

0 50 100 150 200 250 300 350 400

angular position

De

lta

Ra

diu

s (

mic

ron

s)

The measurements are repeatable (to ± 5 m) after thermal cycling

The disc is within specifications



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Lessons learned

• Developing new solutions is time consuming

– e.g. bending and soldering Cu/Ni pipes and developing C-C cooling blocks

• Take care with design of kapton components

– Design of tracks, attachment of connectors and stiffening where required

• The end-cap support cylinders when delivered were not up to specification and needed modifications involving delays



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Macro-assemblyGeneral infrastructure

• The macro-assembly is performed in clean conditions

(typically class 10000) • Evaporative cooling plants based on C3F8 and C4F10 are

required to cool large numbers of modules

• Special tooling is required to mount modules– A robot for the barrel

– A manual mounting jig for the end-cap

• Special tooling is required to mount discs into the support

• Testing must be done at –7C– Requires final power supplies, DCS and DAQ



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Mounting modules onto a barrel

• The barrel modules are mounted from one side and tilted at an angle of 10o which allows an overlap between adjacent rows– The clearance between adjacent

rows is 1 mm – The cooling block is coated with

thermal grease– The mounting procedure requires

the module to slide into position– A robot is programmed to

perform this delicate manoeuvre

• The ‘dog-leg’ is connected to the module



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Which button do I press??



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Mounting modules onto discs

• Thermal grease is applied to the cooling blocks• The module is extracted from its frame• The frame is removed and the module is lined up with the

mounting blocks– Using the x/y/ stages monitored with cameras

• The module is positioned and attached

• Lower modules are added first and then tested electronically and thermally at –7C. Upper modules next.



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Mounting discs into the support cylinder

• The disc is extracted from the test frame frame and attached to the tooling to insert it into the cylinder

• After insertion the services are added to the end-cap which is then moved to the cold room for testing.

• The cooling pipes, fibres, low mass tapes and DCS are connected and the disc is readout at –7C.

It will be possible to readout

two discs simultaneously to

check for cross talk



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CURRENT STATUS

MODULE PRODUCTION

Barrel Modules Forward Modules

Barrel Module Production

0

500

1000

1500

2000

2500

3000

Date [yymm]

SB startedGOOD+PASS ModulesSB targetGOOD+PASS target



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Structures• Barrels

– All 4 cylinders are delivered – B3 and B6 are having services attached

• Discs– All Discs have been delivered to NIKHEF– Preparatory work is 59% complete– Disc 9C is ready for module mounting– Discs 8C , 7C and 9A are having services added – Disc 6C has arrived at RAL and 5C and 4C arrive soon

• End-cap support cylinders and ‘wings’– One has been received with ‘wings’ but needed

modification– The second is completed but awaiting modification



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Macro - assembly

• Barrels– Oxford is awaiting the arrival of barrel 3 to commence module

mounting

– Assembly of last barrel is due to be completed in Spring 2005

• Discs– Module mounting on Disc 9C is now due to start

• End-cap support cylinders and ‘wings’– Expect to mount Disc 9C in end-cap C in July

– End-cap C to be ready to ship to CERN in mid-Summer 2005

– End-cap A to be ready to ship to CERN in late 2005



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SUMMARY

• The ATLAS SCT is in full production– Module production is well advanced (13% forward and ~75%

barrel completed)

– Most of the support structures have been delivered

– Population with services is underway

– The macro-assembly of completed barrels and discs is beginning

• Several problems have been solved– No show stoppers

• The schedule for completion is very tight but the collaboration is making every effort to achieve it.

Neil Jackson University of Liverpool Hiroshima Symposium 14-17 June 2004 1 THE ATLAS SEMICONDUCTOR...

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Transcript of Neil Jackson University of Liverpool Hiroshima Symposium 14-17 June 2004 1 THE ATLAS SEMICONDUCTOR...