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The Making of ATLAS Muon chambers @NIKHEF

The Making of ATLAS Muon chambers @NIKHEF. The NIKHEF Muon Mission Drift tube wiring Chamber assembly X-ray scan of BOL-0 at CERN Status and Plans. 5m. 2m. NIKHEF Muon Mission. BOL=spacer+2x3 drift tube layers+ In-Plane alignment. Construct: 96 Barrel Outer Large (BOL) chambers

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The Making of ATLAS Muon chambers @NIKHEF

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  1. The Making of ATLAS Muon chambers@NIKHEF • The NIKHEF Muon Mission • Drift tube wiring • Chamber assembly • X-ray scan of BOL-0 at CERN • Status and Plans Marcel Vreeswijk (NIKHEF)

  2. 5m 2m NIKHEF Muon Mission BOL=spacer+2x3 drift tube layers+ In-Plane alignment • Construct: • 96 Barrel Outer Large (BOL) chambers • High Mechanical Precision: • 20mm RMS on wire positions • This talk: BOL-0 and Serial Production West side has expansion length o 0.1m in Xras Marcel Vreeswijk (NIKHEF) s

  3. Tube wiring + QC • Drift tubes: • Extruded aluminum drift tubes (3cm) • Wire (50mm gold-plated tungsten) positioned by two end-plugs Endplug • QC on drift tubes, specs: • Wire position: |Z,Y|<25mm • Wire tension=> • frequency 27.2+-1.4 Hz, RMS<0.3Hz • Leak rate: <2.5 10-8 bl/s • HV check: <20nA @3500V Marcel Vreeswijk (NIKHEF)

  4. Drift Tube Coil EndPlug RMS: ~6mm QC-Wire position • Wire position Spec: • |Y,Z|<25mm For BOL-1 All tubes checked In future: Fast pre-check endplug Rejection <<1%: 2 tubes with Z> 50um (1 checked: no twister) cut cut No twister to position wire Marcel Vreeswijk (NIKHEF) s

  5. QC-Wire tension • Quality Control on drift tubes, specs: • Wire Frequency: 27.2 (+-1.4)Hz, RMS<0.3Hz Principle: Lorentz force on current through wire causes vibration Drift tube Frequency RMS: 0.17 Hz Horse-shoe magnet Tension re-measured just before gluing on table (checks creep + broken wires) Rejection <<1%. Marcel Vreeswijk (NIKHEF) s

  6. QC-Leak Rate + HV • Quality Control • Leak rate: <2.5 10-8 bl/s • HV: < 20nA at 3400V Principle: HV Drift tube (1% He) Vacuum chamber He sniffer Automated ‘Matrix’ for 80 tubes Marcel Vreeswijk (NIKHEF) s

  7. QC-Leak Rate Leak-rate Leak rate is low: from 3bar to 2bar takes several years!! spec Rejection 1% (!) 10-6 bl/s • 3 tubes inspected: • 1 physical hole in aluminum • 2 ‘dust’ on O-ring Marcel Vreeswijk (NIKHEF) s

  8. QC-HV • A typical ‘Matrix’ fill Tube with excess<<spec. Measure 5hrs. Average last 3hrs Current (nA) Gauge Tube nr Marcel Vreeswijk (NIKHEF) s

  9. Chamber Assembly • Spacer monitored by RASAS Situation mid 2000 No Flexo In-plane lens NIKHEF Comb longbeam RASAS tower Xplate In-plane mask Frascati comb ‘Ear’ with sphere and RASAS-MASK Sphere tower with changeable block to adapt to tube layers West side has expansion length o 0.1m in Xras Marcel Vreeswijk (NIKHEF) s

  10. Block 3 Block 2 Ypitch 26.011mm Scatter 5um Block 1 ‘RASAS’ Monitors Monitor positioning during assembly by RASAS monitor: Support ‘ear’ which holds the mask xplate Changeable blocks The RASAS tower which holds the camera and lens Measured temperatures explain (small) drift Marcel Vreeswijk (NIKHEF) s

  11. tube tube tube tube tube Gluing BOL-0 Tube diameter 3cm Distance 65mm 2 x glue units 2x3 glue nozzles Side rope Central rope • Tube layer 1 central ropes • Spacer glued on layer 1 • Tube layer 2 central ropes • Spacer+1 glued on layer 2 • Tube layer 3 central+side ropes • Spacer+1+2 on layer 3 • etc…. Marcel Vreeswijk (NIKHEF) s

  12. Sagcompen-sation tower Additional weight for balance Sag Compensation Residue: order 10mm • Own weight leads to large sag of xplates • Compensate (at Bessel points) with pneumatic system • Need typical P=3bar (8 towers) to carry chamber (150kg) Marcel Vreeswijk (NIKHEF) s

  13. Gluing BOL-0 Glue: Days needed 1 Glue Spacer 1 1st layer+platforms 1 spacer on 1st 1 2nd layer+spacer 4 layers Total <10 days Marcel Vreeswijk (NIKHEF) s

  14. The BOL-0 • The BOL-0 was mechanically • finished Dec 5th 2000 • Next, studies: • X-ray scan Marcel Vreeswijk (NIKHEF) s

  15. Test @CERN inTomograph Marcel Vreeswijk (NIKHEF) s

  16. Test @CERN inTomograph Analysis of Martin Woudstra Wire positions RMS 16mm Marcel Vreeswijk (NIKHEF) s

  17. Test stand DATCHA Like cosmic ray setup at CERN (shutdown in 2000) Test of alignment principle with prototype muon sector, using cosmic tracks --> 10mm on sagitta Marcel Vreeswijk (NIKHEF) s

  18. Test stand @NIKHEF • Tests five chambers using cosmic rays (end 2001) • Checks wire positions • Checks DCS + DAQ Trigger modules, consisting of 50cm iron, with two layers scintillator. Ecut>1GeV Expected rate: 100Hz Marcel Vreeswijk (NIKHEF) s

  19. Status and Plans • Finished BOL-0 at NIKHEF (dec. 5th 2000) with high mechanical precision (16mm RMS) • Quality Control automated • Production of tubes started May 2001 • Now: Produce first chamber • Expect to finalize 10 chambers by end 2001 • Produce 1chamber/2weeks: 24 chambers/year -> finish summer 2005 • Late 2002, evaluate need to speed up chamber production (work weekends and/or two gluing steps/day) • Cosmic ray setup operational end 2001 Marcel Vreeswijk (NIKHEF)

  20. Sag Compensation • Xplate sag before and after compensation Chamber up Chamber (upside) down Understood within +-10mm After sag adjustment we observe (almost) symmetric sags for chamber up and down positions-> no stress Marcel Vreeswijk (NIKHEF) s

  21. NW NE Global X Global Z, RASAS X SW SE Gluing BOL-0 • RASAS monitors Global Z • Relatively large Z movement layer 6 (spacer floats on glue?) Lever arm in stacking block Global Y (up) • Stability in Y appears good Marcel Vreeswijk (NIKHEF) s

  22. Xplate 2.4m fixed Temperature Stability • Aluminum expands 24um/ oC/m, Granite 7um/ oC/m • Under normal conditions, temperature stable within +-0.4 oC • Test case: increase temp. by 1 oC: check RASAS monitors Free to expand monitor granite Raw: 50um Correct for AL 24um/ oC/m + Correct for granite 7um/ oC/m Marcel Vreeswijk (NIKHEF) s

  23. Assembly Station • Granite table: 6m x 2.5m Situation mid 99 East Z Up Y North X • Three bare Cross-Plates are positioned on the station, carried by sphere holders • The combs which will support the tubes are also visible • In the background: wiring station, Quality Control setup(s) West side has expansion length o 0.1m in Xras Marcel Vreeswijk (NIKHEF) s

  24. In-Plane Relative measurement of three points. Accuracy 1 um Projective alignment Alignment the coded mask ~ 100um block size • Alignment scheme: West side has expansion length o 0.1m in Xras Marcel Vreeswijk (NIKHEF) s

  25. RASNIK • Components provided by NIKHEF Image sensor Light source + mask Lens + holder Marcel Vreeswijk (NIKHEF) s

  26. 0.02% |BHall| - |Bcoil| calibration ATLAS-Muon • Magnet system: air core toroid, • End cap toroid constructed in the Netherlands B field measurement by Hall probes (on CAN bus) designed and provided by NIKHEF West side has expansion length o 0.1m in Xras Marcel Vreeswijk (NIKHEF) s

  27. QC-Leak Rate • Quality Control on drift tubes, specs: • Leak rate: He (4 bar) 2.5 x 10-8 bl/s HV (future) Drift tube (1% He) Vacuum chamber He sniffer Leak rate is low: from 4bar to 2bar takes several years!! cut Rejection 4% Marcel Vreeswijk (NIKHEF) s

  28. Xplate 50um 400um Yrasnik= 2 x sag Chamber sag Xplate sag BOL-0 Heat Studies (No flexoos in BOL-0) The BOL-0 was covered with heat blankets, producing 50W/m2 Inplane Yrasnik= 2 x sag Gradient between MLs: 2.5 to 4 oC Sag of Chamber: 200um  50 to 80 um/oC= acceptable Sag of xplate: 25um  6 to 10 um/oC = acceptable Marcel Vreeswijk (NIKHEF) s

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