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Michigan B184 Update November 19, 2004 |
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1) Chambers re-working
a) Total number of chambers need to be reworked: 34
b) Total number of chambers that have been re-worked: 4
c) Chambers re-worked this week: EML4A07, EML4C07, EML4A05, EMS4A02,
EML3C15, EML3A05
2) Chambers in progress
EMS3A02: Painted epoxy, survey targets and B sensor platform glued
EMS3C06: Gas leak certified
(These 2 chamber are the last 2 EMS3 chambers made in UW)
3) Problems and other issues
i. EML1A01 has passed CR test. The major work to be done for this
chamber is:
- measure the long term leak rate
- test t sensors
- mount the mask and test inplane system.
- measure dark current
- modify HV connectors (grounding)
- replace mezz cards
- perform CR test
However, 8 more T sensors from Boston need to be glued to the
chamber. UW has the T sensors but they are not calibrated yet.
ii. EMS3C12 (UW chamber) has over 10 hot tubes. All have been
treated by -HV and they are no longer hot. It's very painful to
deal with hot tubes at the stage of taking CR data since one has to
open cards and FC to access to the tubes.
CSM1 and DCS box on this chamber were damaged, according to Jeff.
No reason was found yet. This chamber was handled by Ried.
iii. When testing DCS box for one UM chamber, we failed all the
time. Then Matt was called and he found the low voltage power supply
was 5.5 V (it should be 5.0 V). In principle no one should not tune
it and the knobs actually are fix by epoxy. However, Matt touched
the knob and the voltage went to 10 v. Then Jeff found that 6 mezz
cards were burned.
I have informed and emphasized to all people, including UW people, to
be extremely careful, and strictly follow our rules announced for
working in bldg184. even though I jumped around 10 chambers working
in parallel everyday, this still happening.
iv. EML4C07 has a tube with long maximum drift time. Usually this
problem is attributed to tubelet blockage. We replaced the tubelets
at both tube ends and found that the tubelets were fine. However,
the drift time decreased from over 1000 ns to about 860ns, still
about 100 ns longer than average. The reason of decreasing of the
drift time might be this time we flushed enough. So it might be that
the threads on the endplug has blockage, or the tube is
contaminated.
This also happened to one UW chamber.
v. Otherwise, we are making good progress. We are trying to finish
UW EMS chambers by the end of this month. This week we should be
able to finish all UM chambers that need to be re-worked, except the
33 chambers in bld180, which will be re-worked there intensively for
about one week.
Also, as you have seen, we already started re-work UW chambers.
Zhengguo Zhao