Difference between revisions of "Minutes-7-12-2012"

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# Test set-up in 126 (Beni)
 
# Test set-up in 126 (Beni)
 
# Other
 
# Other
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= Minutes =
 
= Minutes =
  
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Participants: Bill, Glen, Eugene, Chris, Nick, Simon, Vlad, Beni, and Lubomir
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Participants: Bill, Dave, Eugene, Nick, Simon, Vlad, and Lubomir
  
 
== Production ==
 
== Production ==
  
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- Dave was absent but he updated the production tracking linked above: last two spare cathodes are almost ready. Spare wire frames: third wire frame (#6) is being tested already for a week, the current is very high (~1100nA) which doesn't surprise anybody since the caps were not replaced. Bill wanted to know if we have to order additional g10 frames. We have one spare frame now that will be used to replace wire frame #1. First we will try to fix #6, if it doesn't work we have to order g10 frames. The problem with #6 is that the caps are covered with Himiseal. Bill suggested, first, removing the caps (say on one HV sector) and then cleaning the Humiseal. Chirs: aceton cleans Humiseal very well (we can't use it inside the chamber!), but one can also use alcohol; have to soak the Humiseal first and after 5min start cleaning. We will try that.  
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- Results of the tests of the last three cells of the fourth package: top cell #1 (wire frame #18) working fine, cell #2 (wire frame #28) and cell #3 (wire frame #27) had a problem, high dark currents, about 400-500nA for frame #28 and 1100-1300nA for #27. Both cells held HV for a long time (3-4 days) and all channels are OK.
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Still, we were not comfortable with that and disassembled the three cells on Monday. It turned out that the HV caps on all wire frames were indeed replaced, just Anatoly didn't have record for #28. On Wednesday we installed the third cell with wire frame #18, that was on the top.
  
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- Started  preparations of the first package (which is at Blue Crab) for refurbishment: HV cables from the PCBs were disconnected from the cables that are in turn connected to the two HV connectors. Later we may have problems to reconnect them since the cables were cut to the proper length, we have to route them exactly as they were before. Copper tubes (together with one part of the pre-amp brackets that is glued to the tube) and the pre-amps were removed from the package.   
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- From Monday till Wednesday we were testing #27 separately between the two Lexan sheets: the high current didn't change even after cleaning, or removing HV cap on the HV PCBs. There's no current through the field HV and looks like the current goes on the HV PCBs to ground. Most likely humidity plays a role here. We used a lamp for several hours to heat/dry the PCB; the current goes up by a factor of two almost immediately after turning it on. On Wednesday we gave up with #27 and started testing wire frame #28, the current there is much lower, ~400nA. The plan is to try clean it and if it's stable we will use it as
  
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- Fourth package tests: Vlad tested cell #4 which is OK. On cell #3 (with wire frame #27) the current was very high (~800-1000nA) and doesn't go down already four days, but never tripped: most likely the HV caps have problems. Other than that all the channels on #3 are fine. Vlad applied today HV on cell #2 (wire frame #28), the current was initially 500nA but then started going up. It turned out Anatoly doesn't have a record that he had replaced the HV caps on #28. We will finished with the tests on cell #2 and cell #1 and then decide what exactly we want to disassemble.
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== Engineering update ==  
 
== Engineering update ==  

Revision as of 17:35, 12 July 2012

July 12, 2012 FDC meeting

Agenda

  1. Production Construction Tracking (Dave)
    • Fourth package tests
    • Spare wire frames
    • Third package preparation
  2. Engineering update (Bill)
  3. Electronics update: PR for the spare PCBs, grounding, other (Chris, Nick)
  4. Gas system update (Beni)
  5. Test set-up in 126 (Beni)
  6. Other

Minutes

Participants: Bill, Dave, Eugene, Nick, Simon, Vlad, and Lubomir

Production

- Results of the tests of the last three cells of the fourth package: top cell #1 (wire frame #18) working fine, cell #2 (wire frame #28) and cell #3 (wire frame #27) had a problem, high dark currents, about 400-500nA for frame #28 and 1100-1300nA for #27. Both cells held HV for a long time (3-4 days) and all channels are OK. Still, we were not comfortable with that and disassembled the three cells on Monday. It turned out that the HV caps on all wire frames were indeed replaced, just Anatoly didn't have record for #28. On Wednesday we installed the third cell with wire frame #18, that was on the top.

- From Monday till Wednesday we were testing #27 separately between the two Lexan sheets: the high current didn't change even after cleaning, or removing HV cap on the HV PCBs. There's no current through the field HV and looks like the current goes on the HV PCBs to ground. Most likely humidity plays a role here. We used a lamp for several hours to heat/dry the PCB; the current goes up by a factor of two almost immediately after turning it on. On Wednesday we gave up with #27 and started testing wire frame #28, the current there is much lower, ~400nA. The plan is to try clean it and if it's stable we will use it as


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