Difference between revisions of "Minutes-3-1-2012"

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# Other
 
# Other
  
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= Minutes =
 
= Minutes =
  
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Participants: Bill, Dave, Nick, Elton, Mark, Simon, Beni, and Lubomir.   
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Participants: Simon, Nick, Eugene, Beni, Chris, Bill, Dave, and Lubomir.   
  
 
== Production ==
 
== Production ==
  
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- Dave: Deadened the first wire plane of package 3 with the larger diameter using the procedure with increased current and the same time as for the smaller diameter, but adding extra polishing cycle. Working on four cathodes now and on the last wire frame for the third package. One more cathode to finish the package. There's not much space to start the fourth package. Testing the chambers of the third package will be the bottleneck since it takes time to flush the chambers with gas. We will try to use weekends for that if possible. Third package was started partially end of November, so less than three months ago. Still we need to work on the subsystems for both package 2 and 3.
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- Dave: Chris will come tomorrow to install the elements on the next wire frame; we decided it will be #23 and will have #13 (with the glued HV caps!) at the top of the package in case we have to fix it. Dave will do the electroplating tomorrow, as well. So, the wire frame and the cathodes for the next cell will be ready by Monday. Working on the rest of the cathodes for package #3 and started working also on the first cathode for package #4.
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- First cell of the third package was assembled yesterday, flushed with gas over night and today we were able to apply HV which by now is already the nominal one. The dark currents are very low. If it holds over the night we will assume that the wire deadening procedure works and we will continue tomorrow with the deadening of the next wire plane. Tomorrow also we will test the first cell and if everything is OK will try to assemble the second cell so that we can use the weekend to flush it.  
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- Lubomir: first two cells of package #3 were installed, flushed with gas, conditioned and tested without problems within one week (~3 days for each). Yesterday we installed the third cell and started flushing with gas. Today after applying HV we found high dark current between the field and sense wires. We had similar problems before and we knew it is related to the epoxy used to glue the wires. It turned out that this is the first frame on which Casey used a new epoxy batch, both resin and hardener. Same epoxy was used on another three wire frames that will go next in the package. We will stop using this batch till we figure out if this is a problem. 
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== First package testing ==
 
== First package testing ==
  
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- Beni showed results posted in the new FDC Elog linked above. After all the gas problems have been fixed/identified, now the main concern is the chamber efficiency. The only time we had full efficiency was in cell#3 when it was leaking through the hole in the exhaust tube and was taking most of the gas flaw, but not clear what fraction of the total 200ccpm at that time. There are also two groups of 4 channels not working, but the problem is not in the chamber; Beni will investigate it.
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- Obviously this is a gas problem and we discussed different ways to approach it. Beni: wanted to install the two new mass flow controllers that allow to have 500ccpm each, but before that we will install the oxygen sensor. Lubomir: we have to make sure there are no air bubbles between the cathode and ground planes; for that we will incline the package so that the supply is at the lowest and the exhaust at the highest point. For the electrons to be attached to the oxygen a third molecule is needed, it could be CO2 but water is 10 times more efficient than CO2. Water may come inside from the kapton that may have 1-2% water due to
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to foil aligning procedure. The foils stay in direct contact with water for at least 16 hours. Depending on the results for the oxygen content we will decide if we need moisture measurements (to 0.1% precision).   
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== Engineering ==
 
== Engineering ==

Revision as of 18:51, 1 March 2012

March 1, 2012 FDC meeting

Agenda

  1. Production Construction Tracking (Dave)
    • Production status
    • Testing at Blue Crab (Lubomir)
  2. Oxygen contamination in the first package: monitoring results, possible explanation and options to reduce it FDC ELOG (Beni, Bill, Lubomir)
  3. Engineering update (Bill)
  4. Electronics update (Chris)
  5. Other


Minutes

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

Production

- Dave: Chris will come tomorrow to install the elements on the next wire frame; we decided it will be #23 and will have #13 (with the glued HV caps!) at the top of the package in case we have to fix it. Dave will do the electroplating tomorrow, as well. So, the wire frame and the cathodes for the next cell will be ready by Monday. Working on the rest of the cathodes for package #3 and started working also on the first cathode for package #4.

- Lubomir: first two cells of package #3 were installed, flushed with gas, conditioned and tested without problems within one week (~3 days for each). Yesterday we installed the third cell and started flushing with gas. Today after applying HV we found high dark current between the field and sense wires. We had similar problems before and we knew it is related to the epoxy used to glue the wires. It turned out that this is the first frame on which Casey used a new epoxy batch, both resin and hardener. Same epoxy was used on another three wire frames that will go next in the package. We will stop using this batch till we figure out if this is a problem.

First package testing

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