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Michigan B184 Update March 4, 2005 |
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Definitions of the numbers listed in Summary table:
N(total) = number of chambers to be worked or reworked at CERN in phase I
N(finished) = number of chamber that have been finished
N(this week) = number of chamber finished this week
1. Summary table
N(total) N(finished) N(this week)
UM 80 80 0
BMC 80 12 4
UW 80 71 4
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Total 240 163 8
2. Chambers finished this week:
UW: EML1A13, EML1C05, EML1C09, EML2C13
BMC: EMS1C02, EMS1C08, EMS1C10, EMS1C14
3. Chambers in progress
UW chamber
EML1A11: taking cr data
EML1C15: flush gas and then dark current test
EML1A05: Dark current test, T sensors and inplane system tested
EML1A15: Dark current test. Dealing with tubes with higher dark current.
EIL4A03: Last week we reported:
"Tube ML1-3-54 has dark 30-150 nA, leading hot channel in CR
data. Delt with -HV=3200 V for over night, applied HV=3100 V for
three days, replace tubelets. DC stays. We will keep HV=3200 V
till sunday or monday, then retake cr data."
This tube was cured after applying HV=3200 V over
weekend. However, the second run of cr data show that this tube
is no longer hot. However, the other two tubes appeared to be
hot. Negative HV over night does not help reducing the dark
current of these two tubes. We now decide to apply HV=3200-3400 V
over weekend.
This chamber has been in hospital for over two weeks.
BMC chambers
EMS1C16: ready for taking cr data.
UM chamber
EML4A07: Test finished. Chamber is still keep on rotator. Curtis
is analyzing the data and doing some tests.
4. Problems and other issues
a) ML1-3 tripped at HV=1.6 kV, and the reason was found to be a
fiber bridging signal cap and ground pin. Problem was soon fixed
after tracing to the tube by opening FC.
b) EML1A15 has a few tubes with slightly high dark current (100-300
nA/tube), we are dealing with them.
c) EML1A05 has also unstable slight high dark current and we will
pin down to the tubes and then treat them.
d) According to our estimation, we will finish all UW chambers and
the 20 BMC chambers at CERN around the end of this month. We are
waiting for the 4 chambers from H8.
e) Its almost another 6 months I have been absent from USA and I
have to go back to Michigan so that my green card could be valid.
I'm leaving CERN for Ann Arbor tomorrow and will return to CERN
on March 18. During my absence,
- Paul and David will continue reporting you weekly.
- David will take care of chamber movement. In case he is not
available, Bingyun will take care of it, with Paul or Matt
around.
f) We once more call everybody's attention on the safety
issue. Please strictly follow our policy while working in
bldg184. We would like to emphases
- follow the traveler to work for your chamber
- don't box chamber alone
- while dealing with HV, MAKE clear sign "HV ON" around the
chamber
- while moving chamber in bldg184, help watch out safety.
- check HV, gas system before going home.
Zhengguo and David