The NIKHEF Muon Mission

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The Assembly of ATLAS Muon chambers_at_NIKHEF

• The NIKHEF Muon Mission
• Chamber assembly
• Assembly QA
• Assembly QC
• Summary, Status and Plans

2
NIKHEF Muon Mission

BOLspacer2x3 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, BOL-1 and
Serial Production
West side has expansion length o 0.1m in Xras
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3
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
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4
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
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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
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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
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Tube Placing
Start with QC tubes Procedure Place tubes on
combs (Re-)Measure Wire Frequency Run Final-OK
program IF all tubes OK, follow placing scheme
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Glu Preparation
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Glu Preparation
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Glu Preparation
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Glu Preparation
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Glu Preparation
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Glu Preparation
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Glu Preparation
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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
• Spacer1 glued on layer 2
• Tube layer 3 centralside ropes
• Spacer12 on layer 3
• etc.

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Sag Compensation

Residue order 10mm

• Own weight leads to large sag of xplates
• Compensate (at Bessel points) with pneumatic
  system
• Need typical P3bar (8 towers) to carry chamber
  (150kg)

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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-gt no stress
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The road to BOL-0
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Gluing BOL-0
Glue Days needed 1 Glue Spacer 1 1st
layerplatforms 1 spacer on 1st 1 2nd
layerspacer 4 layers Total lt10 days
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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

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Gluing BOL-0

• Guido laser test indicate tube heights in combs
  lt10um.
• Stability Xplates during gluing

Layer 1
Yrasnik2 x Sag
Layer 1 dSag7um
Layer 2
Start glue
Layer 3
Layer 2 dSag10um

• The sag of the xplates in layer 1 and 2 change in
  time. Glue crimp? Temperature?
• Layer 3,4,5,6 Sag stable

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The BOL-0

• The BOL-0 was mechanically
• finished Dec 5th 2000
• Next, studies
• X-ray scan

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The road to BOL-0
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The road to BOL-1

• From 1st tube layer to 6th tube layer took 14
  days (spacer not counted)
• With optimal/parallel preparation the present
  scheme would allow a 7 day production cycle
• Infrastructure and manpower-gt
• 10 working-days/chamber

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Test _at_CERN inTomograph
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Test _at_CERN inTomograph
Analysis of Martin Woudstra
Wire positions RMS 16mm
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Test stand
Like cosmic ray setup at CERN (shutdown in 2000)

• DATCHA

Test of alignment principle with prototype muon
sector, using cosmic tracks --gt 10mm on
sagitta
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Test stand _at_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. Ecutgt1GeV Expected rate
100Hz
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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
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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 -gt
  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

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RASNIK

• Components provided by NIKHEF

Image sensor
Light source mask
Lens holder
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Precision Mechanics

• intrinsic accuracy better than 10um

• Positioning combs and sphere holders
• Tools
• Laser optics (straightness combs),
• silicon sensor (to line up combs),
• Slof (height-meter),
• tilt-meters (check Torque),
• Balmonitor (dZ between multilayers)

The quantities which affect the wire positions
are checked and found to be precise within
10um Granite table has sag of 25um 10um light
on/off
West side has expansion length o 0.1m in Xras
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Assembly Station

• The Balmonitor is a Cross-Plate equipped with
  lenses. Each lens is combined with a fork on
  the combs to form a RASNIK system

• The Balmonitor measures the Z and Y difference
  between Sphere tower and Comb between North and
  South. (Z difference between Multilayers)
• Additionally the Balmonitor is used to check for
  height difference between sphere towers at the
  reference and non-reference side (West/East)

West side has expansion length o 0.1m in Xras
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Gluing BOL-0

• Result for side (106) and central (103) ropes

Central rope
Central rope
Central rope
Central rope
Central rope, sometimes bad (stability glue unit?)