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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
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)

nikhef muon mission

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

tube wiring qc
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)

qc wire position

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

qc wire tension
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

qc leak rate hv
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

qc leak rate
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

qc hv
QC-HV
  • A typical ‘Matrix’ fill

Tube with

excess<<spec.

Measure 5hrs. Average last 3hrs

Current (nA)

Gauge

Tube nr

Marcel Vreeswijk (NIKHEF)

s

chamber assembly
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

rasas monitors

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

gluing bol 0

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

sag compensation

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

gluing bol 01
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

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

Marcel Vreeswijk (NIKHEF)

s

test @cern in tomograph
Test @CERN inTomograph

Marcel Vreeswijk (NIKHEF)

s

test @cern in tomograph1
Test @CERN inTomograph

Analysis of

Martin Woudstra

Wire positions

RMS 16mm

Marcel Vreeswijk (NIKHEF)

s

test stand
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

test stand @nikhef
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

status and plans
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)

sag compensation1
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

gluing bol 02

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

temperature stability

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

assembly station
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

alignment

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

rasnik
RASNIK
  • Components provided by NIKHEF

Image sensor

Light source + mask

Lens + holder

Marcel Vreeswijk (NIKHEF)

s

atlas muon

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

qc leak rate1
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

bol 0

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