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Status ATLAS SCT 2002. NIKHEF Contributions to ATLAS: Magnets – discussed by Frank Trigger DCS Muon MDT and alignment – Covered by next talk SCT Talk Outline: SCT Progress Past Year NIKHEF SCT Work Past Year Future NIKHEF Work. ATLAS Detector. SCT Progress – Barrel.

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Status ATLAS SCT 2002

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Status ATLAS SCT 2002

  • NIKHEF Contributions to ATLAS:

    • Magnets – discussed by Frank

    • Trigger

    • DCS

    • Muon MDT and alignment – Covered by next talk

    • SCT

  • Talk Outline:

    • SCT Progress Past Year

    • NIKHEF SCT Work Past Year

    • Future NIKHEF Work

N.P. Hessey NIKHEF

ATLAS Detector

N.P. Hessey NIKHEF

SCT Progress – Barrel

  • 1st Carbon Fibre Cylinder Delivered

    • Mostly in spec, some difficulties achieving the very high precision machining requirements they had

    • Ready to start mounting brackets

    • Some delay because of last minute change in layout for clearances

  • Modules

    • UK and Japan sites qualified for production

    • Nordic Group and USA have made modules but still not perfect

    • Japan in routine production since summer 2002 and now speeding up

    • UK started routine production

  • System Test

    • Many modules run simultaneously

    • With good grounding and shielding, no extra noise and good rejection of external noise

N.P. Hessey NIKHEF

Barrel System Test

N.P. Hessey NIKHEF

SCT Progress - Endcap

  • Modules

    • Hybrids: K4/K5/KB/Filters story

      • Mid 2001 realised K4 had serious problems

      • Started program to be sure of solving it

        • 1. Investigate/understand the problem: difficult with binary (hit-or-miss) readout

          • At NIKHEF we realised it is a feedback from Digital Power Supply to Analogue side

        • 2. Fix K4 (NIKHEF)

          • Filters in digital power supply

          • Worked well on NIKHEF modules, but could not rescue a Liverpool module

        • 3. New version: K5 (Freiburg)

          • 4 layer  6 layer + better AGND plane

          • Now working well

        • 4. Fit Barrel Hybrid on Endcap Module: KB (Geneva)

          • Worked as well as Barrel Modules (still some feedback)

          • Cooling finally worked well, but more material and ?cost?

          • Would have been a lot of extra engineering work

      • Decided early 2002 to go ahead with K5

N.P. Hessey NIKHEF

Feedback Model (S. Peeters simulation)

N.P. Hessey NIKHEF

Feedback Reduction with Filter Glued on Chip

S-curves Before Filter:

After Filter:

Filter Circuit glued to ABCD Chip

Joop Roverkamp/Henk Peek

N.P. Hessey NIKHEF

Radiation Hardness of Endcap Modules

  • June 2002:

    • Two Endcap Modules Irradiated

      • Very noisy, out of spec

      • Optimists: Maybe they got overcooked?

      • August 2002: Two more irradiated…behaviour much better, well inside spec

      • Pessimists: Maybe the August ones were undercooked

      • The Pessimists were right

    • Status now:

      • Some chips out of spec on irradiation; most OK/on the edge

      • Are Endcap modules worse than Barrel? (I.e., is K5 bad?)

        • Don’t know any mechanism why they should be

        • Hybrid power supply lines all OK after irradiation

        • Could be statistics? Barrel were lucky?

      • Fix: We can raise threshold from 1 fC to 1.2 fC

        • Fixes noise rate; little effect on efficiency or tracking

      • Raise bias to 450 or 500 V:

        • Regains full charge collectione efficiency; Modules hold this HV

N.P. Hessey NIKHEF


  • In addition to feedback also has calculated the fundamental noise limit

  • Many significant contributions

  • Many input parameters, some were unknown and had to be measured

  • End result:

    • Modules are 10-20 % noisier than predicted

    • Best quality chips are closer to prediction

  • Conclusion: we have a good hybrid, close to ideal

  • But…still some things not understood, e.g. anti-noise at low signals

Module Noise Model – Simon Peeters

Chip-0 Output Noise:

N.P. Hessey NIKHEF

Module Manufacture – 5 Inner K5 Modules Made

  • Aim was to test K5 and develop assembly techniques and QA

  • All are in specs; most important parameter within ~1 micron

  • Sent to test centres

    • 3 to system test

    • 1 for thermal tests

    • 1 for irradiation

N.P. Hessey NIKHEF


  • Order placed with PCI in July 2002

    • First 2 Discs Delivered Last Week

    • DU01: In Spec

    • DU02: Not flat enough

    • Needs work with PCI to see what can be done

  • Cylinder and Wings contract imminent

    • NIKHEF Cylinder due July 2003

  • Cheap-O Prototype

    • Torlon Inserts Succesful

      • ~300 per disc; low X0

    • Now glued to disc

    • Next: machine flat

    • Send to UK for Services tests

Flatness of DU01, side 1: ~0.4 mm

N.P. Hessey NIKHEF

Cheap-O – with inserts, ready for measurement

N.P. Hessey NIKHEF

Tooling to machine discs flat

  • Discs ~0.5 mm flat; Modules need better:

    • For placement; For Services Clearances

  • We machine inserts to 0.1 mm flatness

  • Stiff-back rohacell sandwich made

  • Most fittings made

  • Ready Feb 2003

N.P. Hessey NIKHEF

Future NIKHEF Work

  • NIKHEF Site Qualification

    • We make five more modules in Jan/Feb

    • If all OK, we are ready to receive components and start manufacture

    • These 5 modules can go into ATLAS

  • Endcap Module Production

    • Officially starts April

    • Hybrid delayed though…looks optimistic

  • Discs

    • Sort out flatness

    • Finalise disc layout details

    • Test services, inserts etc.; incorporate minor improvements

    • Start machining discs

N.P. Hessey NIKHEF

Disc Assmbly

  • H026:

    • Glue inserts

    • add services

N.P. Hessey NIKHEF

H023/24/25 Assembly

  • Module assembly

  • Modules-to-disc

  • Disc-to-Cylinder

  • Testing

  • C3F8 Evaporative Cooling

  • Whole disc readout

N.P. Hessey NIKHEF

The End – 2005 Ship One Endcap to CERN

N.P. Hessey NIKHEF

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