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Michigan B184 Update March 19, 2004 |
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1) Total 3 chambers "passed" CR test till today. These chambers are:
EML3C01, EMS5C16, EML4A15. they are still sitting in bldg184
platform.
2) Chambers are under CR test: EML3C03, EML4C09
EML3C03 has been HV=3100 V cooked for almost one week. CR data
taking twice (each ~15 hours). It was pretty hot in the beginning,
then -HV=2500 V was applied for 30 minutes. hot channels decreased
a lot. however, till this morning, there are still a few hot
channels. There is a low efficiency channel which disappeared
after replacing the corresponding SHH card.
EML4C09 also has a few hot channels.
Jeff is trying to get the correct information of the Mezz cards on
the chambers from the DB.
It's extremely time consuming to do the CR tests, particularly in
dealing with dead or hot channels. We will continue taking CR data
on these two chambers.
3) Chambers in progress:
EMS5C12: Epoxy applied. Cabling done. Survey target and B sensor
platform glued, T sensors and inplane system have been
tested. pressurized with AR+CO2 to 3 bar, past Q196 leak
detector test.
EMS5A02: Epoxy applied. cabling done. Survey target and B sensor
platform glued, T sensors and inplane system have been
tested.
EML4A11: T sensor test done. Alan is cabling the chamber.
4) Chamber in hospital:
EMS5A08: Cracks are found in 11 endplugs (one more found). Epoxy
have been applied to ALL tubes. After curing for three
days, we pressurized it slowly to 3 bar with Helium
(first 8 psi, then 25 when no leaks found to the location
with cracks, then to 45 psi). Both ML1 and ML2 have past
Q196 test. We will measure the leak rate over weekend.
T sensor and inplane systems tested. Cabling done.
A dent was found on ML1-2-64 (about 80 cm to RO end). No
leak yet. We don't know when it happened. We will apply
epoxy to the dent, just for to be safe.
We request everyone working on the chamber to be extremely careful
while passing, or dealing with chambers. No tools and any hard
materials should be put on the chamber directly. Also be caution while
moving around chamber with tools in hand.
We will add one more item on our check list, i.e. "vicious the
chamber, record anything abnormal found"
Problems and experiences:
1) SHH coated foam problem.
While working with EML4C09, we found at leak four SHH cards had bad
contacts while doing MECCA test. After inserting and pulling out the
cards a couple of times "dead" channels disappeared, except for one
card which kept most of the "dead" channels. I then used a magnifer to
look at the pins and found some while powder-like stuff around the
pins. Because of this, I think we do need to clean SHH card with
acetone. We may have to spend some time on doing so, but we do save
time for CR test, since replacing SHH cards with low efficiency
channels is pretty time consuming.
I wish Curtis could make at least one more wash basin for us.
2) Gas mixture.
The gas flow rate we have used so far has been found to be
incorrect. The volume of CO2 was not considered, and the calibration
data was not the right one. The original setting was from Paulo. I
asked Joerg to confirm the calibration and he found a right one from
his office. According to the information I have from him, I
recalculated the flow rate in order to have mixture Ar(93%)+CO2(7%).
A new table is attached on the gas control system.
Now we are using the new table to flush the two chambers for CR the
test. We will see how the drift time changes.
3) We forgot to measure the inplane system as Ed requested (rotate
chamber to a vertical position and PMO mount facing ground). This item
is in the last a few pages of the check list. We will have to do it
next Monday by move the chamber back to the transportation cart.
So when we put EMS5 chamber back into crate, we should remind each
other that one should check whether the chamber needs this special
measurement or not.
This week, temperature here goes up to nearly 20 C^0. Today we
switched off the heater in bldg184. The huge noise finally is gone.
Zhenngguo Zhao