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

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

Marcel Vreeswijk (NIKHEF) Tube wiring + QC Drift tubes: Extruded aluminum drift tubes (3cm) Wire (50  m gold-plated tungsten) positioned by two end-plugs QC on drift tubes, specs: Wire position: |Z,Y|<25  m Wire tension=> frequency Hz, RMS<0.3Hz Leak rate: < bl/s HV check: Endplug

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

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

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

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

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

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

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

Marcel Vreeswijk (NIKHEF) s Tube diameter 3cm Distance 65  m tube Side ropeCentral rope Gluing BOL-0 2 x glue units 2x3 glue nozzles 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) Sag Compensation Sagcompen- sation tower Additional weight for balance s 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) Residue: order 10  m

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

Marcel Vreeswijk (NIKHEF) s in Tomograph

Marcel Vreeswijk (NIKHEF) s in Tomograph Wire positions RMS 16  m Analysis of Martin Woudstra

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

Marcel Vreeswijk (NIKHEF) Test s 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) Status and Plans Finished BOL-0 at NIKHEF (dec. 5th 2000) with high mechanical precision (16  m 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) Sag Compensation Xplate sag before and after compensation s After sag adjustment we observe (almost) symmetric sags for chamber up and down positions-> no stress Chamber up Chamber (upside) down Understood within +-10  m

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

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

Marcel Vreeswijk (NIKHEF) Assembly Station West side has expansion length o 0.1m in Xras Granite table: 6m x 2.5m 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) Situation mid 99 North X East Z Up Y s

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

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

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

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

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