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Michigan B184 Update November 26, 2004 |
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UM Chambers
1) Chambers re-working
a) Total number of chambers need to be reworked: 34
b) Total number of chambers that have been re-worked: 34
c) Chambers re-worked this week: EMS5C04, EMS4C12
2) Chambers reworked (install/change DCS box, grounding HV connector)
in bldg180: EMS5C14, EMS5A10, EMS5C06, EMS5A16, EML3A13, EML3A01
UW Chambers
1. Chamber passing CR test (from leak rate certification, painting
epoxy to CR test): none
2. Chambers in progress
EMS3A04: Cosmic ray test shows that one tube has about 100 ns longer
maximum drift time. After flushing 8 volume gas, the maximum drift
time decresed about 50 ns. In this case we decide not to replace the
two tubelets on this tube. One hot tube appeared in the second
run. After treating this tube, we are retaking CR data.
EMS3C06: Ready for CR test. Since the two dropped chambers blocked
the way of moving the chamber to the location where crane can
access, we have to put this chamber aside for a couple of days.
3. Chamber to be reworked for UW
EML2C09: Almost ready for CR test.
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1. Problems and other issues
a) MB test status: Since about two weeks ago, one full time manpower
is used for testing motherboard. This may last to another one or
two weeks, depending the quality of the mother boards. We still have
about 250 MB to be tested.
b) ACCIDENT IN BLDG 180!!!: Unfortunately to two of our chambers
(EML4A07, EML4C07). Details about it haven been reported by Bing,
Curtis and me.
These two chambers are now sitting on the floor of bldg184. what we
know so far is:
EML4A07.
- Top multilayer (ML1) no damage. Pressure is about 28.56 psi. (it
should be 3 bar after CR test, but some pressure will be lost when
we put the plugs on the ETs). We conclude at this point that there
is no leak in ML1
- No broken wires found for both ML by simply applied 500 V
HV. More detailed check will be done late.
- Three broken tubes have to be disconnected at this moment.
- 9 #3 (shortest) tubelets in short tube and HV side are dented.
One can see clearly the dent on the gas pannel from the
tubelets. To be safe, we think we should replace all of them no
matter whether the tubelet leaks or not since they are old HEIM
tubelets.
- We are now trying to pressurize the ML2 slowly and would like to
know the leak rate.
EML4C07:
- Top multilayer (ML1) pressure is 28 psi, no leak. 1 kV applied
to both ML, and no HV trip. There might be no broken wires.
However, bottom ML (ML2) has no gas at all! We then found that the
gas pannel at the RO side has been distorted. It seems that the
foam we put on the FC aginst the box wall was pressed under the
gas pannel, and gas pannel pressed the tubelets. We will only know
the detail after mounting the chamber to the transportation cart.
c) About 2 days ago, I was told by Paul that we need to check
whether the T sensor ground wire touched chamber (tube or spacer
frame) by measuring the resistor between DCS box ground and spacer
frame. Paul says they realized this problem only recently.
We checked 13 chambers and found 9 chambers have this
problem(~70%!). The solution to this problem is to reglue the T
sensor that has the problem. Paul and Matt agreed they have to take
care of this problem in phase II. In phase I, whenever we have
chance to access and test, we will do it, but we won't transport
chambers specially for working on this problem.
d) Reza left our team this afternoon. I wish him have a safe trip
back to USA. Bing and I are appreciate very much his contribution
to our work done at bldg184, and would like to express our thanks to
him here.
Zhengguo Zhao