Difference between revisions of "Minutes-5-5-2011"

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# Other
 
# Other
  
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= Minutes =
 
= Minutes =
  
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Participants: Eugene, Bill, Glenn, Chris, Roger, Simon, Beni, and Lubomir.
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Participants: Eugene, Bill, Dave, Roger, Beni, and Lubomir.
  
 
== Production ==
 
== Production ==
  
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- Problem again on Monday with the HVAC at Blue Crab: same transformer failed. It will be replaced with one with higher power, but the origin of the problem is not clear.  
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- Dave: Two cathode frames type 3 (with ground planes with holes) are assembled waiting for the rigid-flexes and ground wires to be glued on them. One wire frame was strung, the wires glued and now being soldered. Expect to be ready by the end of the day, then we will do position and tension measurements. We started also cutting foils for the third cathode plane and the second wire frame is also ready.
  
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- Two cathodes are glued to the frames, including the flaps. Next steps: tensioning/gluing the mylar and gluing the mylar flaps on top of the copper flaps. We have to decide what should be the tension on the mylar: it's not as critical as for the kapton foil. For gluing the mylar flaps Bill suggested using conductive epoxy only in the area overlapping with the copper flaps, and regular epoxy over the g10 frame. Mark made a template needed to make holes on the mylar.
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- We discussed the configuration needed to test the first chamber: end window, cathode type 3, wire plane, cathode type 3, end window, plus empty frames to make the same thickness as of the full package. We will use the plastic gussets. Bill wanted first to do gas leakage tests 
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- One wire frame was strung and now they are measuring the wire positions. The new laser sensor that was mounted on the system has higher resolution but there was not enough light reflecting from the wire. We replaced it with the old sensor that, after some tuning, is being used with the old software for position measurements. The CC wants us to give them the computer used with the wire stringing system for repairing the OS. Eugene: this is critical for the production and we don't want to spend even an hour on this now.
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- Lessons learned from the production so far: Lubomir will start collecting corrections to the existing procedures based on this experience. In particular we discussed the potential problem due to the extra epoxy on the inner edge of the cathode frame that can puncture the cathode. Bill suggested whipping with ethanol the epoxy from the katon right after gluing.
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- A report from Olga (linked above) about the discoloration spots on the cathodes: there's chlorine but also sulfur at some places. According to Roger Allflex doesn't use ferric chloride for etching. Therefore the origin of both Cl and S is not clear. Roger will ask Allflex for samples of water that is used there. We also got foil samples from Allflex not wrapped with paper that we are going to test to exclude the paper as a possible origin. In any case the resistivity is not affected by these spots and they are not reactive, so we decided to continue with the foil production.
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== Electronics ==
 
== Electronics ==

Revision as of 15:18, 5 May 2011

May 5, 2011 FDC meeting

Agenda

  1. Production
    • Status (Dave)
    • Wire position scanning logbook page 564 (Lubomir)
    • End window material (Bill)
  2. Electronics (Fernando, Chris)
    • Status
    • Rigid-flex stuffing
  3. Engineering status (Bill)
  4. Chamber testing (Beni)
  5. Other


Minutes

Participants: Eugene, Bill, Dave, Roger, Beni, and Lubomir.

Production

- Dave: Two cathode frames type 3 (with ground planes with holes) are assembled waiting for the rigid-flexes and ground wires to be glued on them. One wire frame was strung, the wires glued and now being soldered. Expect to be ready by the end of the day, then we will do position and tension measurements. We started also cutting foils for the third cathode plane and the second wire frame is also ready.

- We discussed the configuration needed to test the first chamber: end window, cathode type 3, wire plane, cathode type 3, end window, plus empty frames to make the same thickness as of the full package. We will use the plastic gussets. Bill wanted first to do gas leakage tests

Electronics

- Chris: got an answer from the company for the stuffing of the first 100 rigid-flexes. Bill and Lubomir: we need 18-20 for the first chamber next week; Chris will talk to them.

- Beni made pictures (pages 561-563) of the pre-amps that we use now on the prototype and then verified with Fernando the resistor settings. So we have for the cathodes 2.6mV/fC (high gain, RC=1, DR at 5% = 130fC or 338mV) and for the anodes (with and without discriminator) 0.77mV/fC (low gain, RC=0, DR at 5% 260fC or 200mV). The dynamic ranges we observe correspond to these values. Before, there was some confusion, we assumed we had 0.62mV/fC for the anode cards.

Engineering

- Bill can't find a good solution for storing the cathode foils. The jig plate for the package assembling is in the machine shop.

Chamber testing

- Simon reported his results about strip resolution and calibration. He used a new procedure (better pedestal subtraction), explained in pages 557-560 of the FDC logbook, that improved the strip resolution by ~20%. Eugene: such procedure may work in different ways on the central and side strips and one may use the sample range defined by the central strip also for the side strips. This however is difficult to implement within the fADC125 firmware.

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