Minutes-11-17-2011

November 17, 2011 FDC meeting

Agenda

1. Production Construction Tracking (Dave)
   • Production update
   • Second package tests (Lubomir)
2. Engineering update (Bill)
3. Electronics update (Chris)
   • LV cabling
4. TDR (Lubomir)
5. Other

Minutes

Participants: Eugene, Bill, Dave, Chris, Simon, Vladimir, and Lubomir.

Production

- Dave: second cell of the second package was installed. Third wire plane will be populated tomorrow by Chris and we will try to install the third cell by the end of the day. Working on the fourth and fifth cell cathodes. The fourth wire frame on which Dave replaced the caps, is being tested with HV by Anatoly (see below). It delayed the wire stringing by one week so far. The fifth wire frames was laminated.

- Discussions about the noise coming from a HV trace initiated by Eugene. We know the noise is coming from a HV trace on the back of the PCB. The amplitude of the noise is close to that of the standard signals, but is random with a frequency of <3kHz and width of ~20ns. So, the probability for interfering with the signals is <0.3% say for 1us window, so negligible. Starting with the sixth wire frame we are going to apply additional conformal coating (like the green coating on the PCBs) on the four HV traces.

- Lubomir about the HV cap tests on the fourth wire frame: after replacing the caps last week and some conditioning we were able to get leakage current of 100-300nA initially but it later increased up to several uA. Anatoly replaced/fixed ~10 caps and the current went down to few tens of nA but still it was increasing after that. Normally, the initial current is high and then it goes down, opposite to what we see with this frame. This is the second frame on which we use 3kV rated caps and we had no issues like this with the first one. Also, Anatoly tested 37 of these 3kV caps separately and they didn't show such increase of the current with the time. Eugene: if the problem is in the 3kV caps we better wait for the 4kV capacitors (will have them hopefully in January!). We decided to continue with the HV tets: leave the frame under HV overnight and see if it will stabilize, then tomorrow morning will decide if we want to replace all the caps once more and then do more tests over the weekend. Then finally on Monday we should be in a position to decide if we will wait for the 4kV capacitors.

- Vladimir about the second cell tests: all channels working fine with a source. No noise on the second cell at the place where we found it on the other cells (as discussed above), but some kind of low frequency noise at a place close to another HV trace.

Engineering

- The scheme for the positions of the signal connectors in the package is linked above

- Bill: will look into the cooling system. Using Fluorinert (FC-72 made by 3M) instead of water require proper sealing. We discussed if we will need real cooling for the 126 tests, or just the tubing.

Electronics

- Chris is ready with the first 22 pre-amps that handed to us at the meeting. Cody will test the rest with a LabView system; working on the program now. Will install the pre-amps and the first cooling tube on the first package tomorrow.

- Based on the Bill's drawing of the pre-amp cards, Fernanda made a scheme for the low voltage cables, also linked above. Will have 4 cards per cable.

Chamber testing at 126

- Beni: working on the OSB and THA for the tests at 126 (latest version linked above). Some leakage on an Indiana chamber, made temporary fix. The materials for the translator boards are here, now writing PR for their assembly.

TDR

- Slow progress, current version is at the link above. Need drawings from Bill of the wire and cathode frames. Simon working on the tracking section. Eugene: the document should be self contained as much as possible, i.e. important info must be in the document not cited.

Other

- Beni setup a new logbook to be used for the FDC (see link above).

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