March 3, 2011 FDC meeting
- Blue Crab status (David)
- Readiness review program (Beni, Dave, Bill)
- Electronics (Fernando, Roger)
- Foil production
- Other: solder for wires
- Engineering (Bill, David)
- New mounting template
- Chamber testing
- "Upside-down" tests (Lubomir)
Participants: Bill, Dave, Simon, Chris, Glenn, Eugene, Beni, and Lubomir.
- Dave: There was safety walk-through at Blue Crab; no issues. All the tables needed are inside the clean room except the stringing table. A test PCB ring was glued using old boards and Bill is happy with it. Important is to fill the gaps at the joints where the O-ring is positioned to avoid gas leakage. Test were made with the conductive epoxy we got from CMU and it worked well. So we will use this epoxy to connect the cathode to the ground plane. Will need ~20g (~$80) per plane. Next to be done: checking cathode frame height and the depth of the O-ring grooves.
- Beni created a web page (linked above) for the readiness review. The first part contains a checklist for the review. Eugene commented on the recovery procedures that they have to be in parallel with the acceptance tests. Beni: since we can't anticipate all the problems there must be also a common part explaining in general what we should do in case of unexpected problems. Lubomir: regarding the package assembling and package testing we don't have clear procedures yet. The testing will depend on the results from the first new design chamber. The idea is to build first one chamber with two end windows, to mount it to empty cathode/spacer frames as if it is in the package and to test it. Eugene: the review will be for the production only up to the point of the package assembling. Later we will add the documents for the rest of the procedures.
- As of now Allflex plans to produce one set (three panels) per week starting 03/25/11. Eugene: the rate is too low and it will take almost two years. Bill: we would like to have 3 sets per week. We may use students for the foil inspection. We will ask Allflex to increase the production rate.
- Chris is working on the PR for the rigid-flex stuffing. We want to have all the flexes (615) populated. Thus we will have ~100 extra flexes in case of cathode soldering failure. We discussed once more the possibility to use one-direction-conductive tape.
- Beni/Bill contacted the Japanese company (http://www.almit.co.jp/eng/product/sold.html#pb) that made the UVA solder. They don't have the exact same solder but something very similar: KR-19 SHRMA QQ-S-571F Type RMA. UVA used the same except KR-18 that indicates difference in the flux but nobody knows exactly what that number means. This is a "no-clean" type and Chris suggested to ask what cleaners can be used for the flux.
- Bill is going to design a new template for the package mounting and wanted to collect ideas how to improve the old design. We want to have it opened inside, to have legs so that we don't have to put it on a table and have an easy access from the sides and bottom.
- We turned the prototype chamber upside-down to investigate the problem with the top/bottom signal ratio. The HV had to be increased by ~250V to get measurable signal from the chamber. In this position the signals from the top strips are bigger than from the bottom, as it was the case before, but now the these are different cathodes. This can be explained by cathode sagging or frame deformation. Most likely the drop in the gas gain can't be explained by geometry changes and we suspect gas problems. Right after the meeting Beni measured the oxygen contamination at the exhaust tube and it was ~0.5% as before. Glenn suggested measurements in vertical position. Eugene suggested to look at the width of the 55Fe peak and compare it with what it was before.