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February 24, 2011 FDC meeting


  1. Production (David)
    • Blue Crab status
    • Readiness review
  2. Electronics (Fernando, Roger)
  3. Engineering (Bill, David, Lubomir)
  4. Chamber testing
    • Tests with the middle chamber (Lubomir)
  5. Other


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


- Dave: everything moved to Blue Crab (stringing table was moved there right after the meeting). We have there office with computers connected to network. Preparing for the PCB gluing. There was a problem with the lights again. Bill regarding the stringing table: the pin rail was modified at the machine shop, ready together with the other parts to be mounted on the table at Blue Crab.

- We will have a readiness review in a month from now. Dave and Bill will work on the procedures/travelers/QA documents that are needed for the review. Beni will set up a page with the agenda, similar to that for the CDC review, where we will link all the documents. According to Eugene the review will be more technical than administrative.


- The answer from Allflex regarding the first article inspection is linked above. Bill suggested using better (printer) paper for packing. Roger will contact Allflex to coordinate the rate of the production. They will have to re-adjust their equipment every time they switch to the production of our cathodes. Most likely we will not be able to inspect the foils with the same rate. Therefore we will do only partial inspection during the acceptance and 100% inspection later whenever possible before the use of the foils. We may use summer students for this inspection.

- Interesting discussion about the solder type (see the above link), but without Fernando we didn't make decisions. Important features of the solder: how reactive (corrosive) is it, wire diameter, how easy is to clean the flux. Bill: no-clean solder means also difficult to clean. Roger: there were some issues with no-clean solder for some applications at the accelerator and they decided not to use it. Paste vs wire: flux fully evaporates when using wire; paste can create solder balls. Bill: the wires will be covered during soldering. We will do more investigations but the best is to used something proven to work. We will ask UVA for a solder roll they have used for the Hall A chambers, it turned out they had several rolls remaining, although the wire diameter is bigger than what we want. After the meeting Beni found the Japanese company (http://www.almit.co.jp/eng/product/sold.html#pb) that made the UVA solder, but they no longer produce the exact same solder type.


- The test wire frame was taken out of the strongback and mounted (relatively loose) on the template jig with lead blocks on the sides to make it flat. The tension went down (page 552) by 10-30%. This is still acceptable but it doesn't represent the real tension when the frames will be mounted in the package. To investigate the flatness of the package Bill is going to use the cathode frames and the gas spacers to mount them as a package and measure the height of this assembly.

- Different epoxy types are linked above where Bill added outgassing parameters as rated by NASA. Again the rule will be to use something that was proven to work. The Epolite epoxy has higher viscosity (important advantage to control the glue spreading) but higher outgassing, although it is important what kind of gas is outgassing. Before making decisions we need more investigations. Still, unlike the solder type, we will be able to identify ougassing problems relatively fast if they exist with the first chamber and change the epoxy if needed.

Chamber testing

- Lubomir continues with the scan of the middle chamber. In the recent runs, the time difference between strip and wire signals, as extracted from fADC125, appeared to have two peaks separated by about one sample. That was not the case before and requires further investigations.