Minutes-9-27-2012
September 27, 2012 FDC meeting
Agenda
- Production Construction Tracking (Dave)
- First package tests (Vlad)
- Cathode corrosion
- Recent SEM results Viton+Apiezon not cleaned, Viton+Apiezon cleaned with alcohol, Viton+Apiezon cleaned with xylene
- Engineering (Bill)
- Electronics (Chris, Nick)
- Third package tests FDC E-log (Beni)
- TDR, pages 132-143 (Lubomir)
- Other: plots for Eugene's talk
- packages: #1,#3, #4
- corrosion: damaged cathode, EPDM optical, EPDM spectrum, Viton+Apiezon spectrum
- oxygen issue: g10 coating, and Viton+Apiezon reduce O2 from ~10,000ppm to <100ppm.
- test results: Wire Resolution from the full-scale prototype 40/60% Ar/CO%, 5*10^4 gas gain
- Some pictures from the TDR: FDC system, one cell elements, cell section, wire frame lamination, and other in that directory
Minutes
Participants: Eugene, Bill, Dave, Chris, Nick, Vlad, Simon, Beni, and Lubomir.
Production
- Dave: Tina is soldering wire frame #29. Mike is working on the PCB ring for #30. Five new g10 wire frames (we asked for four) were made by Vision machine, then we laminated the Rohacel rings and sent them back to Vision for the fly cut.
- Vlad: testing the first three cells of package #1. The oxygen went down to 170ppm, we started flushing on Sunday. All the channels of the three cells were tested with a source and scope and are working fine. One pre-amp card was noisy, has to be replaced. Currents of the positive HV are higher in all the cells: 940nA, 82nA, and 350nA for cells 6,5, and 4 resp. This is to be compared to 149nA, 13nA, and 62nA we had in October 2011 when the same wire frames were in the second package: about a factor of 6! We will check the HV supply.
- Lubomir: on Sunday Vlad found the gas bottle at Blue Crab (supplying gas to the first package and the testing vacuum chamber) empty due to high consumption of the testing chamber. The vacuum pump connected to the oxygen sensor through rotameter (~200ccpm) started sucking the gas from the chamber. The mineral oil in the bubbler filled completely the thin vertical tube (55mm corresponding to ~500Pa) but didn't go up in the spherical section of the bubbler. The top end window (2mil Mylar) had spherical shape meaning it was not touching the ground below it. After replacing the bottle on the same day, everything recovered. Vlad tested for leakage <5*10^-5 ml/sec about what was before. Beni is afraid that bending inward may cut the window if you have some epoxy sticking out of the frame. Bill: we need to find a way to turn off the pump when the pressure in the chamber drops.
