Difference between revisions of "Minutes-9-6-2012"

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- Eugene: in order to expedite the solenoid testing, the plan so far is that three of our techs will be taken from us for two months, October and November. Dave and Anatoly will still work on the FDC. In case we need somebody for a short time, like half a shift, we should discuss this with Tim and Tom in advance.
 
- Eugene: in order to expedite the solenoid testing, the plan so far is that three of our techs will be taken from us for two months, October and November. Dave and Anatoly will still work on the FDC. In case we need somebody for a short time, like half a shift, we should discuss this with Tim and Tom in advance.
 +
 +
- Just for the record: starting about Sunday evening or Monday morning (09/02-03) the humidity in the clean room was above 60%. On Tuesday it was 63% all day. A faulty fan was found that was replaced on Wednesday before lunch; in the afternoon the humidity returned back to normal for the season, 47-49%. In the clean room we have only the fourth package with four cell assembled being flushed with Nitrogen.
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- Vlad updated the grounding scheme including the ~100 additional grounds, that is linked above.
  
 
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== Cathode corrosion ==
 
== Cathode corrosion ==
  
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- The last test with the vacuum chamber: we had a sample with Viton+Apiezon, three O-ring pieces across a strip using the strong (red) clamp and keeping it for one week at high temperature and humidity, the longest time so far. The picture of the sample is linked above: copper changed color everywhere except at the place where the Apiezon was applied. Several dark lines are visible at the O-ring positions. Two on the sides are darker, probably they took the main pressure from the clamp. Only in the middle we see some very small holes through the copper, visible only with a good back-light. Olga will do SEM analyses.
+
- Another test with Viton+Apiezon was done in the vacuum chamber, this time using a spacer ring to have the right pressure on the O-ring applied with a lead brick. This time the lamps were kept on continuously over the holiday weekend; one of them burned on Monday. The copper changed color (picture attached). Unlike the previous test (with higher pressure) we could see only tine holes through the copper using microscope and these are not clear if they are result of mechanical or chemical reaction.  
  
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- This is the first time we had dark traces under the Vition+Apiezon O-rings, though the conditions of the above test were extreme and we see corrosion/oxidation everywhere on the sample. To make sure we have the right pressure on the Viton we started a new test with a real spacer ring "inserted" through the vacuum chamber and applying pressure on it with a lead brick.
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- Olga analyzed the sample from the previous test, Viton+Apiezon at high pressure, and this time there's no sulfur visible, except at one place outside of the O-ring and Apiezon area, most likely pollution.
  
−
== Conductive tape studies ==
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- We started several experiments coating the cathode foil below the O-ring:
 +
# Using Kapton film glued with Hysol: doesn't work due to many bubbles and wrinkles.
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# Coating only with Hysol: we used a "bad" cathode from package 1 and on the next day it turned out the Hysol spread away from the O-ring place that had some residue from the EPDM. The coated surface was also not very even, Trying to fix these problems we applied one more coating. Also we will try this on a cathode that has not been damaged.
 +
# Using Kapton film siting on Apiezon (Anatoly's proposal); not real gluing but should work. The problem is that it will be very messy and Apiezon may accidentally go on the wires.
  
−
- Vlad did the same ball counting studies as before, but with another cathode (#4, one of the worst: top of former package #1) this time using improved technique in removing the conductive tape and measuring the resistances. The correlation between the resistances and the ball numbers is much more evident now (profile plot above). Again we have about 0.5-2 Ohms per ball and all the resistances above several Ohms (~10-15%) can be explained by loose contacts between the balls and the cathode traces. The highest resistance on this cathode was 50 Ohms.
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- Vlad proposed     
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== Engineering ==
 
== Engineering ==

Revision as of 18:23, 6 September 2012

September 6, 2012 FDC meeting

Agenda

  1. Production Construction Tracking (Dave)
  2. Cathode corrosion
    • Recent test results: [1]
    • Cathode foil coating
  3. Engineering (Bill)
  4. Electronics (Chris, Nick)
  5. Third package tests FDC E-log (Beni)
  6. TDR, pages 132-145 (Lubomir)
  7. Other


Minutes

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

Production

- Dave: Need to put the cards on another two cathodes and we will be ready with the first three cells that will go in package #1. Chris put the resistors on one PCB set and Casey started today making the PCB ring for wire frame #28. It will be laminated beginning of next week and Anatoly will put and test the HV caps before the end of the next week.

- Eugene: in order to expedite the solenoid testing, the plan so far is that three of our techs will be taken from us for two months, October and November. Dave and Anatoly will still work on the FDC. In case we need somebody for a short time, like half a shift, we should discuss this with Tim and Tom in advance.

- Just for the record: starting about Sunday evening or Monday morning (09/02-03) the humidity in the clean room was above 60%. On Tuesday it was 63% all day. A faulty fan was found that was replaced on Wednesday before lunch; in the afternoon the humidity returned back to normal for the season, 47-49%. In the clean room we have only the fourth package with four cell assembled being flushed with Nitrogen.

- Vlad updated the grounding scheme including the ~100 additional grounds, that is linked above.


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