Minutes-9-6-2012

September 6, 2012 FDC meeting

Agenda

1. Production Construction Tracking (Dave)
   • Grounding scheme (Vlad)
2. Cathode corrosion
   • Recent test results: [1]
   • Cathode foil coating
3. Engineering (Bill)
4. Electronics (Chris, Nick)
5. Third package tests FDC E-log (Beni)
6. TDR, pages 132-145 (Lubomir)
7. Other

Minutes

Participants: Eugene, Bill, Dave, Simon, Vlad, Beni, and Lubomir

Production

- Dave: Need to put the cards on another two cathodes and we will be ready with the first three cells that will go in package #1. Chris put the resistors on one PCB set and Casey started today making the PCB ring for wire frame #28. It will be laminated beginning of next week and Anatoly will put and test the HV caps before the end of the next week.

- Eugene: in order to expedite the solenoid testing, the plan so far is that three of our techs will be taken from us for two months, October and November. Dave and Anatoly will still work on the FDC. In case we need somebody for a short time, like half a shift, we should discuss this with Tim and Tom in advance.

- Just for the record: starting about Sunday evening or Monday morning (09/02-03) the humidity in the clean room was above 60%. On Tuesday it was 63% all day. A faulty fan was found that was replaced on Wednesday before lunch; in the afternoon the humidity returned back to normal for the season, 47-49%. In the clean room we have only the fourth package with four cell assembled being flushed with Nitrogen.

- Vlad updated the grounding scheme including the ~100 additional grounds, that is linked above.

Cathode corrosion

- Another test with Viton+Apiezon was done in the vacuum chamber, this time using a spacer ring to have the right pressure on the O-ring applied with a lead brick. This time the lamps were kept on continuously over the holiday weekend; one of them burned on Monday. The copper changed color (picture attached). Unlike the previous test (with higher pressure) we could see only tine holes through the copper using microscope and these are not clear if they are result of mechanical or chemical reaction.

- Olga analyzed the sample from the previous test, Viton+Apiezon at high pressure, and this time there's no sulfur visible, except at one place outside of the O-ring and Apiezon area, most likely pollution.

- We started several experiments coating the cathode foil below the O-ring:

1. Using Kapton film glued with Hysol: doesn't work due to many bubbles and wrinkles.
2. Coating only with Hysol: we used a "bad" cathode from package 1 and on the next day the Hysol spread away from the O-ring place that had some residue from the EPDM. The coated surface was also not very even, Trying to fix these problems we applied one more coating. Also we will try this on a cathode that has not been damaged.
3. Using Kapton film siting on Apiezon (Anatoly's proposal); not real gluing but should work. The problem is that it will be very messy and Apiezon may accidentally go on the wires.

- Vlad proposed