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Michigan B184 Update July 23, 2004 |
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1) Chambers passing CR test
a) Chambers passing CR test this week: EML3C11, EML4C11, EML4C07
b) Total number of chamber passed CR test at CERN: 41
2) Chambers in progress
EMS4A14: Has being doing CR tests for almost one week. The hit map
is imbalanced and most likely due to electronics logic. We
are still trying to find out the exact reason.
EMS4C08: Survey targets and B sensor platforms glued. T sensor and
inplane system tested.
EML4C01: Dealing with tubes with high dark current.
EMS4C14: Just arrived
3) Chambers in hospital
EMS5C14: After applying the epoxy around the Al ring and endplug
location, the leak rate is now about 1 mbar and 4 mbar/day
for helium at 3 bars (for the 2 ML). Another problem then
occurred to this chamber, i.e. some of the tubes had VERY
high dark current, at the level of a 1000-6000 nA/tube.
Before applying epoxy, we cleaned the endplug and the half
jumper location.
I know there was a time Scott used snoop to find leaking
tubelets at ISR. when I saw this, I stopped him. (I
allowed him to use it only for BU chamber which had over
100 leaking tubelets in one chamber and we had no other way
to certify the chamber with even Q196). I asked him how
long he used it, he said for a few chambers (may be 2-3). I
didn't know who put the snoop there. Maybe was left there
by the people who set up the gas system.
This thing is always in my mind, and this was why before
applying epoxy to this chamber, I requested the tubes be
cleaned.
We then did further cleaning with alcohol on the location
around half jumper. It reduced the dark current to the
level of 100 nA/tube - till high but much improved. Helmut
and Curtis, do you remember what BU used to clean the snoop?
Bing reminded me that BU used something I cannot remember to
clean snoop effectively.
4) Problems and other issues
These days both UW and UM are doing inventory, which is necessary
and important since we should try to avoid having nothing to do but
just waiting for parts. We are close to have "final" numbers.
Yesterday's video conference was devoted to this topic. I will work
with Dave to do make use of the extra parts with each other, then we
should have requested numbers to ask for (mainly for UW).
CR test is still our bottleneck. This is also true for UW. We need
to make more effort to optimize this piece of work. Once we receive
the third DAQ system, the situation should become better.
I'm thinking of reporting UW progress together, but not this time
since I need to work with Dave and know their situation in detail.
Maybe I can try next time.
Generally speaking, UW has CR tested 4 chambers. One is taking
data, and another 3 are waiting for CR test.
Zhengguo Zhao