Difference between revisions of "Minutes-2-24-2011"

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- 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.  
 
- 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.  
  
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== Engineering ==
 
== Engineering ==
  
- There was a long discussion what we have learned from the stringing:
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- 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 still 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. 
  
# Bill questioned whether the wire vibration (used in tension measurement) is the reason for the several broken wires between the epoxy and the solder. Suggested using computer to control the amplitude and frequency of the generator. Dave will try connecting to the generator with LabView. Lubomir thinks the wires were broken by the leads while trying to keep them on the solder. The use of conductive rubber (from Fernando) will prevent this because one can put the leads away from the soldering pad. Bill suggested using pogo pins so that fewer people can do the measurements.
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- Different epoxy types are linked above where Bill added outgassing parameters as rated by NASA.  
# To prevent wire breaks at that place we can put later additional epoxy to cover the wires at that region, but Bill wants to avoid having epoxy on the solder.
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# Bill wants to try soldering before gluing. Lubomir: in this case it will be difficult to cover the wires to prevent from solder balls, without touching the wires.
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# We discussed again different types of solder and epoxy we and other groups have used.
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# Bill wants to make tools for the wire taping.
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# Lubomir is concerned having magnets (for the weight shield) close to the weights because of the possibility for attracting the weights and wire breaking.
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- Bill wants to know if we can use aceton, it's need for the cathodes. Lubomir will study this issue.
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- The CMU conductive epoxy will be tested soon. We can have more from CMU.
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== Chamber testing ==
 
== Chamber testing ==

Revision as of 19:50, 24 February 2011

February 24, 2011 FDC meeting

Agenda

  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

Minutes

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

Production

- 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 there 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.

Electronics

- 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.


Engineering

- 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 still 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.