Transcript Tooling for MWPC - Istituto Nazionale di Fisica Nucleare

Tooling / Test Stations for MWPC
(Meeting LNF, Roma1/Pz 8-4-2002)
Production rate :
408 chambers (Fe + LNF) :
192
144
48
24
R4 M1
R3 M1,M2,M3
R2 M4,M5
R1 M4,M5
Production rate/lab : 2–3 chambers / week
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OPERATIONS INSIDE CLEAN ROOM
(Responsibility of production centers)
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- Wiring
~ 2 hours / 2 gap
- Glueing / soldering.
- Control wire pitch
- cut in two mono-gap layers
- Wire tension test
< 1 hours / gap
(< 1 min / wire, 16-32 wires in parallel)
- HV test in air on single gap with open chamber
- assembling 4 gap chamber
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OPERATIONS OUTSIDE CLEAN ROOM
(Tools developed by Roma1)
1 - gas leakage test.
< 1 hour / chamber
Give over-pressure, close gas pipe, measure pressure
decrease with time. Record pressure and temperature.
2 - chamber conditioning (Gas mixture and HV)
~ 24 hours
(parallel operation for several chambers is needed)
3 - Gain uniformity measurement
with radioactive source
< 1 hour / chamber
Record source position, total current
4 - cosmic rays test
2 - 4 days/chamber
measure efficiency plateau, time resolution
(parallel operation for ≥ 4 chambers)
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1) - gas leakage test
2) - chamber conditioning
1) can be done in air/argon in a short time
2) require a long time and the right gas mixture
Tests outside the clean room need several working areas
(problems of space, number of gas subsystems).
Try to reduce working areas
- perform 1) and 2) on the same station (with final gas mixture?)
Digital manometers and readout cards are being ordered.
Three flow-meters are available…
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Tentative layout for test stations
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3 - Gain measurement with radioactive source
- We assume that a spot ~ 5cm diameter on the farthest gap is ok to
monitor gain uniformity
- a minimum current of >20-30 nA should be measured
(assumimg a maximum acceptable dark current of order of 10 nA)
- the most suitable source seems Ce137, 20-30 mCurie intensity.
According to Cern safety rules, 4-5 cm Pb screening is needed.
- Best solution: screen with a layer of 4 cm Pb below the chamber.
This implies about 500Kg Pb and a quite heavy table structure.
(second option: eliminate the lead plate and protect operators
from irradiation by closing the access to the table all around).
To be recorded : source position, total current
Current readout : digital nA 16 channels home made (G. Corradi)
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4 - cosmic rays test
Measure efficiency plateau, time resolution
- Trigger : two layers of scintillator counters
- Muon tracking with an hodoscope of 6 same-size chambers
(top and bottom chamber used as reference)
- Readout through DIALOG. Measure the efficiency of all
front-end channels running with two DIALOG configurations.
( 2 runs of > 24 hours) (test single gap switching off HV ?)
- A maximum of 96x6 channels must be readout.
- Multiplexing by a factor 6 with a delay of ~ 200ns/chamber
(home made V. Bocci) allows to use only one TDC (128 ch).
# Estimated cost of ReadOut : - with multiplexing 10-20 E / ch
- with more TDC modules 55 E / ch
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4 movable
chambers
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