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June 2, 2011 FDC meeting


  1. Production (Dave)
    • First chamber assembly
    • Cathodes
    • Wire planes
    • Other
  2. Engineering (Bill)
    • Rigid-flex gluing tool
    • Wire position measurements
    • Other
  3. Electronics update (Chris)
  4. Chamber testing (Beni)
  5. Other


Participants: Bill, Dave, Chris, Beni, Glenn, and Lubomir.

Short meeting since most of the people are at Blue Crab every day and know what's going on; still we discussed some issues in more detail. For the outside people I added more info about the current status. After the meeting we finished the assembly of the first chamber layer, important milestone.


- The first production chamber is being assembled right now. We have, from bottom to top on the assembly fixture: 9 empty cathode frames, end window (1mil mylar) with O-ring, cathode type 3 (0.5mil mylar with holes on the bottom and cathode foil on the top). Casey is putting now the O-ring on the wire plane that will be installed in the package right after the meeting. Then we will put the spacer ring (also ready except for O-rings) and then will put on the top the transparent lexan sheet. Later we will replace it with the second cathode (ready) and the second end window.

- Cathodes: we have the third (type 3) and fourth (type 1) cathodes mechanically ready, waiting for the rigid-flexes; on the fifth cathode (type 3) the mylar will be tensioned today. By tomorrow we will have also the second end window (2mil mylar) ready.

- Wire frames: the second wire frame is being prepared now for stringing. We have also the third wire frame laminated. On the test wire plane and on the first production wire plane we tried the new procedure, ultrasonic cleaning, and it worked fine. First the planes were cleaned with Vigon, then put in the ultrasonic tank filled with distilled water where they were rotated manually.


- Rigid-flex pressing tool: today Bill and Casey did tests using pressure indicator paper. It showed that the issues we had with the un-tinned flexes are due to pressure not being equally applied on all the contacts. With the tinned contacts, due to increased thickness, the pressure was OK for all the test configurations. For the un-tinned contacts they tried several configurations: kapton tape only at one side of the connector (first two cathodes were done in such configuration), kapton tape over the connector, and without kapton tape. The best results were obtained with the kapton tape over the connector. In addition they tested the flatness of the shoe and turned out there's a gap in the middle. Bill will take the tool and will modify it in couple of days. In addition to make it flat, he will also reduce the width of the shoe that is now ~6mm; the first tool had 4mm shoe.

- Wire sensing problem: at the end of last week we found by turning off all potentially vibrating devices, that the vibration is not causing this problem. As suspected before, the field wires are the problem: they are not seen by the sensor at some places. We have no problems with the old field wires. Caleb made several samples with wires marked in the problematic regions. It turned out Hall B is using exactly the same field wires but we are not aware if they had any problems with them. Important finding was that our field wires are only 2% of theirs, so if we need spare (since we have a little only) we may borrow from them.

- After the stringing of the second chamber Bill will make some improvements in the stringing table: the new encoder and monuments will be installed. The tooling for rotating the wire frames in the ultrasonic cleaner will be ready by that time, as well.


- Chris wanted to know if we have decided about the type of the rigid-flex connectors: tinned or un-tinned? As discussed above now the origin of the difference between the two is clear: just difference in the height of the contacts. After modifying the shoe of the tool we can claim for sure we understand the problem and will make a decision. As Chris pointed out in may take weeks to start the production, so we should decide soon. So far we have enough rigid-flexes for another two cathodes.

- Chris is working on the new testing card with LEDs on the top; he will have the parts next week.

Chamber testing

- Beni will come tomorrow at Blue Crab to install the gas system and start testing the first chamber there. He has all the parts/tools needed for the test.