marcel vreeswijk (nikhef) the assembly of atlas muon chambers @nikhef 2m 5m5m nikhef muon mission:...

Marcel Vreeswijk (NIKHEF)

The Assembly of ATLAS The Assembly of ATLAS Muon chambers @NIKHEFMuon chambers @NIKHEF

The Assembly of ATLAS The Assembly of ATLAS Muon chambers @NIKHEFMuon chambers @NIKHEF

2m

5m

NIKHEF Muon Mission: 96 Barrel Outer Large (BOL) chambers

NIKHEF Muon Mission: 96 Barrel Outer Large (BOL) chambers

• Tube Production

• Assembly Station

• Assembly: Tube placing & Gluing

• Tomograph@CERN + test stand@NIKHEF

• Summary: Status & Plans


Tube wiring + QC

•Drift tubes:•Extruded aluminum drift tubes (3cm)

•Wire (50m gold-plated tungsten) positioned by two end-plugs

QC on drift tubes, specs:•Wire position: |Z,Y|<25m •Wire tension=>frequency 27.2+-1.4 Hz, RMS<0.3Hz•Leak rate: <2.5 10-8 bl/s •HV check: <20nA @3500V•Tube Length +-0.5mm

Endplug


QC-Wire position

Wire position Spec: |Y,Z|<25m

s

EndPlug

Drift Tube

Coil

Rejection <<1%:2 tubes with Z> 50um (1 checked: no twister)

cut cut

For BOL-1All tubes checked

In future: Fast pre-check endplug

No twisterto positionwire

RMS: ~6m


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

FrequencyRMS: 0.17 Hz

Tension re-measured just before gluing on table(checks creep + broken wires)


QC-Leak Rate + HVQuality Control •Leak rate: <2.5 10-8 bl/s•HV: < 20nA at 3400V

s

Drift tube (1% He) Vacuum chamber

HV

He sniffer

Principle:

Automated ‘Matrix’ for 80 tubes


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 2bartakes several years!!

10-6 bl/s

Leak-rate

spec


QC-HV• A typical ‘Matrix’ fillA typical ‘Matrix’ fill

s

Tubbies: Leak current 30-5-2001, av. laatste 3 metingen

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

nA

Gauge

Tube withexcess<<spec.Measure 5hrs. Average last 3hrs

Tube nr

Cur

rent

(nA

)

Current as function of time

0

1

2

3

4

5

6

30-05-0118:00

30-05-0119:12

30-05-0120:24

30-05-0121:36

30-05-0122:48

31-05-010:00

Date & Time

tub

e c

urr

en

t (n

A)

Tube A1

Tube A2


Chamber Assembly

West side has expansion length o 0.1m in Xras

• Spacer monitored by RASASSituation mid 2000

Sphere tower with changeable block to adapt to tube layers

NIKHEF Comb

Frascati comb

RASAStower

‘Ear’ with sphere and RASAS-MASK

In-plane mask

In-plane lens

Xplate

longbeam

s

No Flexo


‘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 26.011mm

Scatter 5um

Measured temperatures explain (small) drift

RA

SA

S H

eigh

t (m

m)


Temperature Stability

s

•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

Xplate 2.4mfixed monitorgranite

Free toexpand

Raw: 50um

Correct for AL 24um/ oC/m

+ Correct for granite 7um/ oC/m


Precision Mechanics


• intrinsic accuracy better than 10um

The quantities which affect the wire positions are checked and found to be precise within 10umGranite table has sag of 25um + 10um light on/off

s

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)


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)

s


Tube Placing I

s

Place tubes (with clocking pins) on combs (Re-)Measure Wire FrequencyRun Final-OK programIF all tubes OK, follow placing scheme

FOK program ensures 72 tubes are OK

Tube numbers and positions stored in dbase

Specs:RMS< 0.3 HzBOL1: 27.2+-0.7 HzLater: 27.2+-1.4 Hz

Frequency

Small calibration problem


Tube Placing II

Fix gas jumpers-length differences get ‘neutralized’Spec=-+0.5mm (FE-cards+ground foil)

s


Tube Placing QC

s

Vacuum onRemove clocking pins, loosen gas jumpersCheck precision: Guido Laser (not automated yet)

Tube Position (South)

Tube Position (North)

Y d

evia

tion

(m


Sag Compensation

s

‘Dry’ CheckPosition spacer (+tube layers) on the tableCheck sag-compensation (not automated yet)

Sagcompen-sation tower

Additionalweight for balance

BOLP (bar) South Mid NorthL1 2 1.3 2L2 2.5 1.7 2.5L3 3 2.1 3L4 3.5 2.5 3.5L5 4 2.9 4L6 4.5 3.3 4.5

Gauge Actual Gluing:Chamber is pre-positioned: 1mm strips under sphere blocks+50% sag-comp.

Then strips are removed + 80-90% sag-compensation

Strip


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

Understoodwithin +-10m

Marcel Vreeswijk (NIKHEF) s

Tube diameter 3cmDistance 65m

Central rope,Glu: 2019

Gluing2 x glue units2x3 glue nozzles

tube

tube tube

tubetube

Side rope,Glu: 2011

automated

50m tape on

Bessel points


Gluing BOL

s


Monitoring

s

3 systems monitor chamber during assembly:•RASAS system (include temperature check)•In-Plane system•RASNIKS on cross-plates (sag)

badly positioned -> action!

Compensation on

Monitoring system->actions not yet user friendly….time

Sag

0

50m


The BOL-0

s

The BOL-0 was mechanically

finished Dec 5th 2000

The BOL 1 was finished yesterday


Power Outage- BOL1

s

Power outage Amsterdam, during curing of layer 5Chamber immediately covered with foil (sag compensation remained on + vacuum probably okNo indications for damage


Gluing BOL-1• RASAS monitors

SE

NW

SW

NE

Global Z,RASAS X

Global X

s

Global Y (up)

Global Z

• Positioning spacer appears sufficiently accurate•However, differences with and without tubes (+glue) in combs --> touch•(Y pitch dangerously small)


The road to BOL-1Date Item Comment15/06 Glu Spacer Use sagcompensation26/06 Layer 1-half Problem glu-machine27/06 Layer 1-rest Ok27/06 Praxial Platforms No measurements…..

27/06 Spacer on 1st layer Ok28/06 Preparations29/06 2nd layer + spacer Spacer+1st+2nd layer ok01/07 Preparations02/07 Preparations03/07 3rd layer Spacer+3 layers ok04/07 4th layer Spacer+4 layers ok05/07 5th layer Spacer+5 layers ok06/07 Preparations09/07 6th layer Mechanically finishedJuly Gas manifolds +Protective covers>July Xray tomo@CERN>2001??? FE-Electronics

•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->

10 working-days/chamber


Test @CERN inTomograph (BOL0)

Wire positionsRMS 16m

Analysis of Martin Woudstra


Parameters BOL0

Zpitch wires: 30.0354m (30.0353 expected)

Ypitch wire-planes:

26.026m (26.011 expected). Especially between two inner layers we have a larger pitch. Inelastic deformation during gluing?

dY multilayers ~75m.Hard to understand. ALL chamber scanned at CERN have deviations in this parameter?!

dZ multilayers ~12m. We expected deviations of this order, based on Balmonitor measurements

•Relevant Parameters (goal 20m):

RO side =15.8m HV side =16.1m


Test stand

s

DATCHADATCHA

Like cosmic ray setup at CERN (shutdown in 2000)

Test of alignment principle with prototype muon sector,using cosmic tracks --> 10m on sagitta


Test stand @NIKHEF

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>1GeVExpected rate: 100Hz


Status & Plans

• Finished BOL-0 at NIKHEF (dec. 5th 2000) with high mechanical precision (16m RMS)

• Quality Control Tube Assembly automated

• Production of tubes started May 2001

• First chamber, BOL1, produced! Difficulties due to small Y pitch.

• Automate steps+QC chamber assembly

• Cosmic ray setup end 2001….


Expected shifts


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)


Gluing BOL-0• Guido laser test indicate tube

heights in combs <10um.

• Stability Xplates during gluing

Start glue

Start glue

Layer 2

Layer 3

Yrasnik=2 x Sag

Start glue

Layer 1

Layer 1: dSag=7um

Layer 2: dSag=10um

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

s


Gluing BOL-0• In-Plane and Xplate monitors

•X-inplane very stable•Y-inplane alternates with chamber orientation, because off granite sag of 30um

down down

up up

Cross-plate sag. For chamber up (down) positions, a negative (positive) sag points down.

s


BOL-0

•Tubes press glue away?•Tubes deform?

•Affects precision praxial platforms!

Thickness Multi-layers BOL0 has tape between tubes at one side

2 layers

3 layers

Much work..

s


BOL-0Heat Studies (No flexoos in BOL-0)

s

Inplane

Yrasnik= 2 x sag

The BOL-0 was covered with heat blankets, producing 50W/m2

Gradient between MLs: 2.5 to 4 oCSag of Chamber: 200um 50 to 80 um/oC= acceptableSag of xplate: 25um 6 to 10 um/oC = acceptable

400um

Yrasnik= 2 x sag

Xplate

50um

Chamber sag

Xplate

sag


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?)

tube

marcel vreeswijk (nikhef) the assembly of atlas muon chambers @nikhef 2m 5m5m nikhef muon mission:...

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