Revision as of 17:59, 30 June 2011

June 30, 2011 FDC meeting

Agenda

1. Production (Dave)
   • Status Construction Tracking
   • Second cell HV tests
   • Radioactive source usage at Blue Crab
   • Other
2. Engineering (Bill)
   • Package flatness measurements
   • FDC cabling
   • Other: gusset rings, lifting frame
3. Electronics update (Fernando, Chris)
4. Chamber testing at EEL126 (Beni, Lubomir)
   • First cell status top/bottom asymmetry
   • Future plans
5. Other

Minutes

Participants: Eugene, Bill, Dave, Chris, Mark, Roger, Simon, Beni, and Lubomir.

Production

- Dave (see the Construction Tracking link above): cell#3: cathode type-2 needs three rigid-flexes (they were glued but Casey found they had solder bridges on the connectors), cathode type-1: the rigid-flexes to be glued. Since Monday we stopped working on the wire frame that was strung, due to possible tension problems discussed later. cell#4: first cathode tensioned, gluing foils for the second one. In addition techs are laminating wire frames, 6 ready so far. Beni asked if we cover the wires while soldering; not yet but we have the cover ready and will try it for the next wire plane. So far we have seen one solder ball on the wires, and Casey removed it.

- Lubomir on second cell HV tests: the cell is assembled as a package, now with lexan sheet on the top. The gas is runinng since Tuesday evening and since Wednesday we are conditioning the chamber. Today we are at 1800V/-500V with a current of 120-130nA for the whole chamber, which is at least 10 times smaller than the first cell. So, most likely the HV problems we had with the first cell are due to the ultrasonic cleaning in water (nobody was surprised).

- Thanks to Bert Manzlak and RadCon people there's a signficant progress with the source usage at Blue Crab. Keth Welch proposed using 25 micro-Curie 55Fe source which is bellow all regulation limits, but according to JLab rules they will most likely require creating RCA at Blue Crab and some additional restriction. Yesterday Bert and Vashek Vylet (RadCon) were at Blue Crab and didn't see any problems for having a source there. Now it's up to Rusty Sprouse to decide and see if there's something in the lease explicitly saying that we can't have a source there.

Engineering

- Based on the results with the first cell, it looks like we have some kind of frame deformation that Bill wants to investigate. The plan is to put the first cell package on a flat surface (like granite table) and measure the deformation of the frame. There were different ideas how to do it, but we expect deviation of 1-2mm which is measurable. Maybe related to that Casey noticed that the strong-back was sagging and asked for help people from the survey group. By the end of the meating we learned the results of their measurements: the strong-back is sagiing in the middle by 2mm. After meeting discussions: we will ask them to do also a survey of the first package in situ at 126 using the same tool.

- On Tuesday there was another engineering meeting about detector cabling. Here, we started talking about the FDC cabling but since it interferes with the other detectors the discussions became more general and conceptual, also some ideas came out, but not clear at all how realistic they are. Beni: CDC and FDC must be in one skeleton together with the cables. Bill developed further that idea showing also how the cables would run out of the detectors. As Eugene mentioned yesterday on the collaboration meeting, just to channge one pre-amp card on the FDC it will be a major operation. Lubomir: what if we pre-install all the four spare chambers in the four packages (making them packages of 7 chambers) connected them with cables that will not be connected at the electronics side and use them if needed. Bill says from construction point of view these are minor changes, there might be problems running 4x22 additional signal cables and also this is additional material.