Status of MWPC production in LNF

1
Status of MWPC production in LNF
April 1st chamber 21 assembled
C.Forti LHCb-Muon meeting CERN, April 6th, 2004
2
Gluing of HV bars

• the HV-bars arrive now in LNF with R,C already
  mounted
• and conformal coating on them
• 2 new gluing tables are operating, 1 has been
  ordered
• the manpower has increased a supplementary
  technician from Rome I
• the rate of 2 panels/(work day) has been reached
  easily

new
old
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Wire Tension Measurement (WTM)

• LabView software is completed measurement fully
  automatic (Emiliano)
• Tension measurement allowed to discover and
  solve problems (see next slides)

• 59 wires changed in chambers C6 ? C21
• 52 wires with T lt 50 g 1 wire with T gt 100 g
• 6 wires broken accidentally during construction

Fraction of substituted wires/1000 integrating
all wires from chamber 6
4
Wire tension random loose wires
Wires in green circles are loose because they
fell on the border of the groove. The effect is
bigger on the panel mounted on the machine side
with the comb with grooves perpendicular to the
machine axis by the spool side.
C12L1
The wires indicated by red arrows are looser
because at the end of pitch control the lights of
the soldering machine stopped for a long time
close to them
glue is still soft ?
C12L2
5
Glue is still soft when the wires are cut ?
C14L1
Wires of last 2 pads were glued with cyanoacrilic
glue this proves that the other wires are
looser because the ADEKIT glue is still soft
when they are cut.
C12L4
After soldering wires are 2 g looser
either because more time has passed between
wire cutting and WTM, or because the laser heats
the wire and the glue. In both cases, glue is
still soft.
6
Effect of heating the wire glue
C14L2
_at_ 23 C s(T) 2.6 g
Lights for heating 23 ? 30 C
C15L2
_at_ 30 C s(T) 1.4 g
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Sigma(tension) vs. Panel number (ch.6-21)
Our goal is to reach a stable sigma lt 2 grams.
20
Chamber 20 group of wires at higher tension due
to an accident.
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HV test in air
Chambers 6-21
Panel is switched on at 2 kV the day after gluing
the lateral bars. Current drops lt 60 nA always in
less than 1 hr (usually in few minutes). No
particular problem was observed.
9
Test of gas leakage
Dry air in the chamber with an overpressure DP
5 mbar. Then we measure DP as function of time.
The results obtained in 15 minutes are fitted
(with an exponential) and extrapolated
to evaluate the expected pressure drop in 2
hours.
Chamber 6
10
Test of gas leakage
At present we do not correct DP accounting for
external pressure variations, because we measure
external pressure with a big error ( 1 mbar). We
plan to perform a more precise measurement in the
future and will repeat measurements of all
produced chambers, if needed.
Chamber 9
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Schedule of M3R3 chambers produced in 2004
For last chambers (16-21) the elapsed time
between wiring of first panel and chamber
closing is 56 days. Chambers 16, 18 6 days (
3 3) 3 in parallel with previous
chamber) Chambers 17,19,20 5 days (2
3) Chamber 21 6days (1 5)
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Differential chamber production rate
Rate (ch/week)
Closing date
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Estimated end of M3R3 production
M3R3 will be completed in july, between 4th july
(_at_2.3 ch/week) and 19th july (_at_2.0 ch/week) We
can make up the 2 months delay during the
M1(bigap) production
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LNF production schedule
52 M3R3 52 M5R3 52 M1R4 120 M1R3 276
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Conclusions

• Gluing of HV-bars on the panels 2 panels/day ?
  OK
• Wiring machine mechanical instabilities have
  been solved
• Wire pitch never found a wire out of specs
  (lt1.9 or gt2.1 mm)
• Soldering machine very stable, right quantity
  of tin
• Panel preparation faster, several expert
  operators available
• WTM fully automatic, fast (1 hour) and
  reliable
• HV test fast and always OK (if glue is
  reasonably dry)
• Assembly faster than before, several expert
  operators
• Conditioning the cosmic ray stand, nearly
  ready, will allow
• soon to switch on 6 chambers together for a 2
  weeks conditioning
• Uniformity test with source see Pincis talk

Many thanks to Dubna colleagues Igor, Dimitri,
Sergei, Sasha for their precious help
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Spare transparencies follow
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Substitution of loose/broken wires
It is not easy to provide (by hand) a precise
tension to the wire. However, this is not
critical, if we are in the range 50ltTlt90 g
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Average wire tension vs. Panel number
The average tension is still not completely
stable. Our goal is to reach a stable value
around 70 g.
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M3R3 Production schedule
M3R3
20
Integral chamber production rate
21
Wire tension in Chamber 20