Minutes-8-4-2011

August 4, 2011 FDC meeting

Agenda

1. Production Construction Tracking (Dave)
   • Status
   • Wire deadening
   • Other
2. Engineering update (Bill)
3. Electronics update (Chris)
4. Chamber testing at EEL126
   • Cell#1 status (Beni)
   • Testing prototype again (Lubomir)
5. Other

Minutes

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

Production

- Dave: The construction tracking attached above has different structure now; it has the spare package with the first four wire frames (new epoxy used there) ready. Lubomir: as demonstrated with cell#2 just drying them for a week with nitrogen and/or Ar/CO2 would be enough to have them operational. Outside in the dirty area techs are laminating now the wire frames for the first package. After that (according to Dave) it will take less than a week per wire frame to finish the first package. Wire frame #5 was strung, wires taped and will be glued with the old Epoxy.

- Dave: we tested the electro-plating procedure this time on a full-scale wire frame, the one that was built at IUCF and shown on the open houses. Before that the frame was cleaned and HV applied to it in air. We were able to put on the two middle sectors 2200V with low current (~80 nA). After electroplating the current on one HV sector at 2200V in air was almost the same as before, but we could not apply even 10V on the second sector, most likely not related to the electroplating. Two issues related to the procedure were discussed:

• First, how to bypass the 1MOhm resistors on each wire and the 10KOhm on the HV sector; this is needed to use the HV paths to connect to the sense wires. Since we are plating only 6 or 8 wires this is not a big deal. Lubomir: the problem is that if by some reasons you had a bad connection to a wire and you don't know what was the current there, you can't repeat the electroplating to fix that wire. One way would be to unsolder the resistors and shorten the pads (as Dave did in this test) or simply to solder a wire on the top of the resistors. Bill proposed another option: after stringing not to cut these wires at the soldering pad, but to leave some length and use it to apply the voltage there. Related to that Beni figured out that actually the current trough each individual wire is different, proportional the wire length that touches the chemical and that's why we have the same thickening on all the wires (Dave confirmed it by measurements with micrometer on the small prototype frames).
• Second, how to check the results of the wire deadening. So far, with the full-scale frame, we were not able to look at the wires with good enough magnification. Using microscope in the middle of the wires is not practical. We will try to use the position measurement system to see if the laser sensor can measure the thickness of the wires, at least relatively.