Minutes-2-17-2011

February 17, 2011 FDC meeting

Agenda

1. Production (David)
   • Blue Crab status
2. Electronics (Fernando, Chris, Roger)
   • Rigid-flex and foil production status
   • Other
3. Engineering (Bill, David, Lubomir)
   • Lessons learned from the test wire plane FDC Log Book, page 551
   • Wire stringing modifications
   • Other
4. Chamber testing
   • Plans for full package tests (Beni)
   • Tests with the middle chamber (Lubomir)
5. Other

Minutes

Participants: Bill, Mark, Dave, Chris, Simon, Beni, and Lubomir.

Production

- Dave: the stringing table and the cathode tensioning system are the only main items not yet moved to Blue Crab. The stringing table will be modified before moving there: 6 holes in the granite have to be drilled and different other new pieces mounted there. Will have three computers in the clean room, one new and another two used, all Windows. The temperature in the clean room is lower than the required one and the vendor will fix the problem tomorrow. It turned out the temperature control is not in the clean room and we are not supposed to use it.

- The plan for the next month work at Blue Crab includes: cathode frame inspection, building PCB rings, cutting, aligning, and gluing cathodes. We will start with old PCB and damaged cathode foils and then use the new/good ones. The ultimate plan is to build parts for one chamber that has to be tested before the mass production.

- Dave's working on the procedures/travelers, we can't start production without these documents.

Electronics

- Chris: 50 cables were reworked, but 13 of them came short by a foot. It turned out those are CDC type cables. Even if the length is not critical, we decided not to accept such cables for the FDC. Simon was concerned that we need a plan how to bundle, run the cables. Bill has some preliminary drawings, but everybody agrees that this is important.

- The rigid-flex will be produced as it was in the first article. We requested additional 140 flexes to be used for exercising and as spares in case of cathode foil failure. In total we will have 640 flexes.

Engineering

- There was a long discussion what we have learned from the stringing:

1. Bill questioned if the wire vibration (used in tension measurement) is the reason for the several broken wires between the epoxy and the solder. Suggested using computer to control the amplitude and frequency of the generator. Dave will try connecting to the generator with LabView. Lubomir thinks that the wires broke by the leads while trying to keep them on the solder. The use of conductive rubber (from Fernando) will prevent this because one can put them away from the soldering pad. Bill suggested using pogo pins so that fewer people can do the measurements.
2. To prevent wire brakes at that place we can put later additional epoxy to cover the wires at that region, but Bill wants to avoid having epoxy on the solder.
3. Bill wants to try soldering before gluing. Lubomir: without glue before soldering, it will be difficult to cover the wires to prevent from solder balls, without touching the wires.
4. We discussed again different types of solder we and other groups have used.
5. Bill wants to make tools for the wire taping.
6. Lubomir is concerned having magnets (for the weight shield) close to the weights because of the possibility for attracting the weights and wire braking.

- Bill wants to know if we can use aceton, it's need for the cathodes. Lubomir will study this issue.

- The CMU conductive epoxy will be tested soon. We can have more from CMU.

Full-scale prototype tests

- Lubomir showed few more plots (bottom two plots on page 550) demonstrating how the ratio top/bottom strip signals changes over the plane for the individual wires. On the bottom chamber the effect (if any) is much smaller. We discussed different ways of troubleshooting the problem: changing the flow in the chamber in different ways, measuring the pressure in the chambers, disassembling the ground/cathode plane package.

-->