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Michigan B184 Update August 13, 2004 |
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1) Chambers passing CR test
a) Chambers passing CR test this week: EMS4A04, EMS5C10, EMS4C08
The tube with a blind tubelet has been repaired and it works fine
now, except the drift time is longer than the others due to insufficient
gas flushing.
b) Total number of chambers passing CR test at CERN: 49
2) Chambers in progress
EMS4A08: Ready for CR test this afternoon
EMS4A06: Epoxy done, survey target, B sensor platform glued. Will
move back to the station for leak test.
EMS4A10: Just arrived
3) Chambers in hospital.
EMS5A04 (5th Michigan chamber): [ from last report: leaks are
found in the location between Al ring and endplug for almost all
tubes of both RO and HV sides. Previously we had 4 such
chambers). This chamber failed long term gas leak tightness. We
decided to apply epoxy to the leak location for ALL tubes. We did
careful cleaning before applying epoxy]
The leak rate is still above 10mbar/day for helium, The leaks are
still from the location between AI ring and endplugs. We decided
to reapply epoxy to some tubes which have high leak rate (a few x
10^-5 ml/sec), though, by eye, the epoxy was well applied to the
location.
EMS5A06: Higher dark current found in bottom multilayer, as I have
specially reported one or two days ago. We have done a few rounds
of cleaning and measuring dark current. Now the dark current
dropped to about 2000 nA at RH=62%. Hopefully it will reach ATLAS
specification at RH=45%.
4) Problems and other issues
a) Parts. UW has been doing their inventory and some counts have
become clear. After returning what they borrowed from UM, both
sites feel now much more comfortable. Both sites are short of only
one piece of FC (82040602), and are not short of Mezz card
covers. This is completely different picture as compared to last
week, when they told us that they didn't use so many parts from UM,
which worried me a lot.
We are still waiting for survey targets, which have been sent from
Jim Bensiger. We have about 80 mezz cards left which will only keep
us going for only one week. so it's urgent to have mezz cards. We
received 256 mother board from Bernard. Claudio, please confirm
this number.
We got two DCS boxes from Matt which were mounted to chambers. I
keep requesting DCS boxes from Matt.
b) Problem with blocked tubelets. We found one blind ET (no hole on
ET), and one blind US stainless steel tubelet. It took lots of our
time to identify these two guys.
When changing the blind tubelets, the Mezz cables were swapped. We
found the error from the hitmap of CR data. Both mezz caps and mezz
cables are numbered, for the purpose of connecting them correctly.
I wish we all could pay great attention to each step, and check what
you did before moving to the next step.
c) Visiting Russians. Two Russian colleagues are working with us as
volunteers to get experience working on chamber integration and
testing. They will then work on their own chambers some time next
year at bldg184. They are actually quite experienced physicists, I
feel.
Zhengguo Zhao