June 21, 2012 FDC meeting
- Production Construction Tracking (Dave)
- Production status
- Spare wire frames (Lubomir)
- Engineering update
- Electronics update (Chris)
- Cable assignment (Vlad)
- Gas system (Beni)
- Test set-up in 126 (Beni)
Participants: Eugene, Dave, Nick, Vlad, Simon, Beni, and Lubomir.
- Dave: Fourth cell was installed yesterday in the fourth package. Working also on several spare cathodes. Right after the meeting we installed the fifth one. The plan was to install the last cell on Friday, however, after the meeting we found a bad channel (cut on copper trace) on one cathode that will require more time for fixing; therefore we will finish with the fourth package installation on Monday.
- The second production wire frame: there was a bad HV sector showing ~20MOhm field to sense wires resistance while the other three were OK. Two wires, which pads were covered by the copper sulfide spill there, were replaced by Casey including the epoxy around them that was most likely contaminated by the chemical. After that we measured the resistance: about 20-30 MOhm and 50-100 MOhm on the other sectors. We recalled that on the first four wire frames we used Epolite that is susceptible to humidity. After flushing the wire frame with gas since Monday today we were able to put 2100/-500V with ~800/-500nA currents, still high but we hope the epoxy will dry and the currents will go down. So far we have one wire frame that can't be used. Eugene suggested not to postpone too much the ordering of the four extra PCB sets.
- Without Bill we discussed the grounding hardware: if we want to use Rohacell or the rubber material suggested by Bill for filling the void between wire and cathode frames. Since we will have of the order of 100 such blocks per package, Simon said it's too much material and we better use Rohacell.
- Nick: no news, waiting for different parts, grounding clips, LV stuff, to come.
- Vlad showed the new scheme linked above. First, wire/strip pre-amp cards are classified according to their rate levels. Wires: level 1 for the side connectors 1 and 4, and level 2 for the central connectors 2 and 3. Every F1TDC module (two connectors) has always one level 1 and one level 2 card. Strips: level 1 for connectors 1 and 8, level 2 for 2 and 7, level 3 for 3 and 6 and level 4/4' for 4,5/9 (the three central sectors). Each fADC125 (three connectors) is connected to either 4-1-3 card levels or 4'-2-2. In addition cards from different packages are combined already on module level to equalize the rate difference in the different packages, the latter estimated to be ~20%.
- The presented scheme obviously confused many on the meeting since already on module/crate level you have mixture of crates, cells, sectors. Eugene insisted that if the package variation is relatively small we better have some order with respect to package/cell number when assigning modules/crates for them. The advantage of such scheme is also that we have better chances to keep the cables bundled up to the electronics, since cables from the different packages will end at different distances. Vlad will modify the scheme by assigning the cables from a package to a group of modules close together.
- Related to the cabling we discussed how the installation will be done in such a way that the cables will stay connected to the electronics. Without Tom, Tim or Bill our discussion was not very efficient. It was not clear for us how much extra cable will be needed during the installation and where will it go after that, how the installation carts will be removed minimazing the probability to damage the cables and so on. We will invite Tom/Tim for the next meeting to discuss this. What was clear for us is that mixing cables from different packages will make the installation even more difficult.
- Beni: Narciso is working on the system; expect specialized meeting soon soon.
Test set-up at 126
- Beni: Elliot is working on CODA-Light for the two-crate system.
- Vlad tested so far the cathodes of 3.5 cells on the first package. One bad pin on a LV connector found.