Minutes-9-1-2011
September 1, 2011 FDC meeting
Contents
Agenda
- Production Construction Tracking (Dave)
- Status
- Package configurations
- First package tests (Lubomir)
- Engineering update (Bill)
- First package flatness measurements
- Electronics update (Chris)
- Chamber testing at EEL126 (cell#2) (Beni, Lubomir)
- Other
Minutes
Participants: Bill, Eugene, Dave, Chris, Simon, Beni, Glenn, and Lubomir.
Production
- During Irene the power was always on and the humidity and particle counts were OK on Monday.
- Dave: wire frame #6 is out of the stringing table and now working on #7: it was strung yesterday by Casey and Al in ~4 hours (record). Then the wires were taped and now doing position measurements. Aanatoly finished replacing the caps on frame #7. Cathodes: Tina and Mike tensioned type-1 cathode from set#7 and put the daughter cards on type-2 from set#6. Anatoly finished testing all the 80 foil sets. Wire frame #6 will be populated by Chris tomorrow and then (possibly on Monday) the central wires will be deadened.
- In the construction tracking at the second page there's table about the wire frames explaining differences in the material/procedures used: Epon or Epo-lite, with or without Humi-seal, capacitors replaced/not replaced, and whether the wires were deadened. Starting from frame #6 and up (6 is the consecutive number, not the frame number that is labeled) on all the frames the caps were/will be replaced without Humi-seal and Epon was/will be used instead of Epo-lite. If we exclude the first four wire planes as spares, there's only one (#5) production frame on which the caps were not replaced, but still Epon was used. We discussed if we want to replace the caps on all the frames and how, or if we just want to build new wire frames using the latest technology. Bill: we need to replace the old caps everywhere. However it will be very difficult, time consuming and risky: one easily damage wires especially on the frames with Humi-seal on the caps. Eugene: it might be better just to make new wire frames, but it has to be evaluated. Lubomir will collect more information for the next meeting what needs to be purchased to produce extra wire frames.
- We started stacking the first production package. The first cell was installed yesterday and since then is being flushed with gas. The current between sense and field wires dropped by a factor of 10 in ~12 hours. It is explained by the fact that we used Epon; this is to be compared with more than one week for cell#2 when we used Epolite. In the moment the currents are of the same order (~700nA) as those that we have on cell#2 in 126. Before stringing we had 50-60nA on the capacitors only.
Engineering
- Flatness measurements were done on the first package and the results are attached above. The aluminum fixture was measured with a height gauge lifted with two precision blocks on the granite table. Then the flatness of the gusset ring was measured in the same way; the ring is sitting on the hubs and it was tightened also on the top with nuts. The overall variations of the height of the gusset ring is +/-6 mils or +/- 150 microns. This is so far acceptable but of course important is the flatness when the whole package is stacked.
Electronics
- HV cap problem: Chris contacted the procurement and sent a complaint letter with pictures to the company. The question is if we can ask the company about some sort of compensation if their product doesn't meet the technical requirements.
