Minutes-3-25-2010
March 25, 2010 FDC meeting
Contents
Tentative Agenda
- Production space update off-site floor plans
- Electronics
- threshold variations in the discriminator section of the pre-amps (Fernando) Fernando's pdf
- PCB status
- Frame modification
- cathode sandwich and wire frame
- ground plane tests (leakage, tension)
- Wire winding update
- IUCF phase 3 contract phase 3 budget
- plans for wire winding upgrades in the summer
- tension specs
- Full scale prototype tests
- lessons learned from the HV tests cope-shots1, cope-shots2, HV issues
- plans for tests in the tend
- some results from the tests with Sr source FDC Log Book (Lubomir)
- Cathode frame redesign
- Other
- wire sample measurements wire sample reports
- updated FDC naming convention naming convention
Minutes
Participants: Lubomir, Eugene, Bill, Daniel, Glenn, Casey, Mark, Beni, Simon, Fernando
Production space update
Two options are being considered: properties behind Office Depot (preferably "Minuteman Press"), and properties around Middle Ground Blvd (at Blue Crab) . The rent price of the latter is half the one at Office Depot, but requires building a room inside the bay area. Our position is that he most promising for FDC construction that needs only minimal modifications is the "Minuteman press". We can share the bay area with SRF (John Hogan).
Electronics
- Fernando presented measurements about the discriminator part of the pre-amp cards. The worst card so far is showing ~30% variations (min - max range) in the effective thresholds, among the 24 channels. The question was whether this is acceptable. We all agreed that we don't want to modify the present design of the cards. The variations of the detector response are expected to be compatible if not bigger than 30%. The only procedure that may be considered if possible, is sorting the ASICs before putting them on the cards.
- Next week the design of the PCBs will be finalized (Fernando, Kim, Dan) and posted on the web. We discussed also the option of having checking points on the sense wire resistors at the readout side, related to the problems with the resistors discussed later.
Wire winding update
- Dan informed us about the latest IUCF budget estimate for phase 3 including the wire winding upgrades. This and other topics related to the transfer of responsibilities from Dan will be discussed in a separate meeting on Monday.
- the specifications for the wire tension will be revisited at the next meeting (Lubomir)
Full scale prototype tests
- several sources of the HV problems we had during the testing were identified:
1. We found inside layer 1 some metal pieces, like a wire piece, probably from the green cables used for grounding. Bill and Mark discussed how to avoid this.
2. The corona discharge we observed on the PCBs (at readout side) were obviously causing some of the problems. It turned out that cleaning of the boards with alcohol helped. Probable explanation is that there are impurities in the epoxy (from the wire frame production) which combined with some impurities on the surface of the boards would create the discharge.
3. On one of the boards we found sparking at the card connector. By looking at the pins that were sparking (in dark) we identified the corresponding channels. Replacing the sense wire resistors solved the problem. Likely explanation is that the resistor contacts were damaged when handling the frames.
- After fixing the above problems on layer 1 we were able to set the HV at 2200V with 40/60 Ar/C02 gas mixture on all sectors.
- Beni informed us about the tests he performed inside the tend. Using a scope he looked channel by channel at the signals from the pre-amps on the wires mostly using cosmics only. He found that about 10% of the channels show high rate signals with amplitude up to 300mV.
- The plan is to perform such tests in the tend layer by layer as being more efficient, possible also using DAQ. We also plan to open later 1 and try to clean the corresponding wires.
