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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
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
ATLAS Detector

N.P. Hessey NIKHEF

Sct progress barrel
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
Barrel System Test

N.P. Hessey NIKHEF

Sct progress endcap
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 reduction with filter glued on chip
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
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

Nikhef sct progress

  • 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
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

Tooling to machine discs flat
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
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
Disc Assmbly

  • H026:

    • Glue inserts

    • add services

N.P. Hessey NIKHEF

H023 24 25 assembly
H023/24/25 Assembly

  • Module assembly

  • Modules-to-disc

  • Disc-to-Cylinder

  • Testing

  • C3F8 Evaporative Cooling

  • Whole disc readout

N.P. Hessey NIKHEF