Minutes-11-29-2012
November 29, 2012 FDC meeting
Contents
Agenda
- Production Construction Tracking (Dave)
- Package #1 subsystems
- Package #2 production
- Package #4 testing (Vlad)
- Corrosion tests (Vlad)
- Engineering
- Electronics (Chris, Nick)
- Tests at EEL126 (Lubomir)
- Third package wire resolution FDC E-log
- Plans for testing packages #1 and #4
- Other
Minutes
Participants: Eugene, Dave, Chris, Nick, Vlad, Simon, Beni, Glenn, and Lubomir.
Production
- Dave: now the techs are back and we are working on package #2. Tina and Mike are cutting/gluing new foils; Anatoly tested already the six new foil sets that we have received. Anatoly started gluing the daughter cards on the cathodes that were done before. Priority is to finish the two type-3 cathodes that will be needed in any package configuration.
- On package #1 Vlad installed the ground connections before Thanksgiving, then this week we installed the cooling loops and yesterday Chris and Nick started working on the HV cabling. The package will be ready at the beginning of the next week. We decided not to install the cooling manifolds so far: we don't need them now and in case we need to open the package we will not be able to re-use the cooling tubes. On package #3 it turned out the splittings of the cooling tubes are in wrong places due to misinterpreting the drawings. Correcting this will take ~2 days but will do it later.
- Package #4 was assembled (the two missing cells) just before Thanksgiving and flushed with gas over the holidays: now oxygen is 151ppm. Vlad tested all the cells, not only the last two. Currents on cells from #6 to #2: 21/-3, 44/-4, 42/-3, 50/-3, 110/-100 nA. On cell#1 HV could be applied only to several HV sectors +/-HV1, +/-HV4, and +HV3. On the rest of the HV sectors we found shorts between the HV and the lower cathode and therefore we opened it today: as expected we found a broken wire, field 47. It is not clear when and how the wire broke. Certainly it was in place when the wire frame was installed in the package, but later after closing the package somehow it broke in the middle, the only explanation so far that it may have had a kink in this place (Casey). Also some wire frame deformation must be involved, say even on the pins it stayed deformed but after tightening the package got flat and the wire broke? The tension of the wire was 122g very close to its neighbors. Casey is replacing already the wire; the plan is to finish it by tomorrow so that we can put the package together before the weekend.
Cathode corrosion test
- Vlad: test #3 (Ar/CO2 gas, at ~70degC). Two samples failed at the beginning of the week.
Engineering
- Without Bill not much to say.
Electronics
- Chris: no news about the daughter cards, it was three days delivery and we are waiting already a month. Will get the grounding clips right after Thanksgiving.
Third package tests
- As explained in FDC-Elog #96, the wire resolution was estimated. In addition to the wire TDC information, six cathode cards were used on cells #1,3, and 4. Using only cathode information from cells #1 and #4 that have parallel wires and strips, one finds a line on cell #3. Using the cathode information from cell #3 defines another line and their crossing gives you the hit point (even the angle is not completely defined) and the distance to the nearest wire can be calculated. This distance is compared with the distance obtained from the timing information for that wire using some initial time-to-distance conversion. The difference between to the distances has sigma of ~320microns for drift times between 30 and 160 ns. After correcting for the cathode resolution one obtains ~190 microns wire resolution, finally! This method can be used to extract the time-to-distance function experimentally.
- There's still some noise on cells #1 and #2. Beni thinks it requires better grounding. Chris will make additional ground that will connect to the fast-ons on the wire frames. After the meeting Beni and Lubomir looked at the noise. Swapping the translation boards didn't affect the noise position, however swapping the cables at the chamber also didn't change the noise. Therefore, the main suspects are the TDCs or a combination of the TDCs and the other elements. Beni will look again tomorrow.
Other
- No FDC meetings next two weeks: on Thanksgiving and the week after that. Will meet again on December 6.
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