Minutes-9-8-2011

September 8, 2011 FDC meeting

Agenda

1. Production Construction Tracking (Dave)
   • Status
   • Additional testing procedures
   • First package tests (Lubomir)
2. Engineering update (Bill)
3. Electronics update (Chris)
   • New testing card for the cathodes
4. Chamber testing at EEL126 (cell#2) (Beni)
5. Other

Minutes

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

Production

- Dave: The capacitors were changed on all wire frames needed for the first production package. Wires frame #6 was populated, wires deadened and will be put in package today or tomorrow. Wire frame #7 is out of the stringing table and Chris will put the elements on it tomorrow. The last two cathodes for the first package: started putting the rigid-flexes on type-1; on type-2 the frame was glued and on Monday the Mylar foil will be glued.

- After testing the first cell of the production package we found the following problems:

• One wire was broken at the standard place, between the pad and the epoxy. Casey fixed it already. Beni asked if this is a "standard place", how we can mitigate the problem. Dave: before soldering we started putting additional epoxy at that place that reduced the number of broken wires, so after that this is the first wire that we found broken. Beni and Bill discussed if this was caused by a frame deformation.
• One cathode channel didn't have a good contact; it passed the test with the diode testing card, but when we checked it with a generator the signals were attenuated. Re-heating the conductive tape for 30 sec solved the problem. However, after finding this we checked all the channels with a generator and found another bad channel. In this case re-heating for 30 sec didn't help. Casey decided to try re-heating for 60 sec and this time it helped.
• On the two wire frames that will go in the first package we found several broken resistors, some at the signal and some at the HV side. These are 1MOhm current limiting resistors. Most likely they were broken during the ring lamination when putting lead bricks on the top to make the ring flat. We were using cork pads bellow them, but Bill suggested another (Teflon?) material. Also for the future we should try putting the bricks on ant elements on the boards.

- All the above findings suggested that we need to do more tests before stringing and before stacking the wire frames and the cathodes:

• testing the resistors on the wire frames (with an ohmmeter) before stringing.