Difference between revisions of "Minutes-5-3-2012"

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== Production ==
 
== Production ==
  
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- Dave: for package #3: wire planes 4 & 13 were deadened, now all the elements for this packag are ready. Package #4: wire planes 24 and 25 read  
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- Dave: for package #3: wire planes 4 & 13 were deadened, now all the elements for this package are ready. Package #4: wire planes 24 and 25 ready for deadening, will be done on Monday. Chris will put components on wire plane 26 tomorrow. Anatoly is gluing daughter cards on cathode 47. Tina working on cathodes 49 and 50. Casey is filling the groove on the second type-1 cathode to be converted into type-2.
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- Now we have four cells in package #3 installed. After the first cell installed and tested we put the next three cells on Wednesday, Thursday and Friday at once without tightening the chamber in between. On Friday after starting the gas we found huge leakage from the top spacer ring. It turned out the O-ring was smashed at one place. We suspect it happened because of the grease and incorrect use of the installation metal pins. When you insert the pins up into the new holes during the next cell installation, the pin can lift some of the frames and create gaps in between them. When you have gap the O-ring can stick to the surface above the groove (due to the grease), and then get out of the groove. To exclude this from happening again, when inserting the metal pins we should always apply force from the top (by fingers) to avoid separation of the frames. In fact it is dangerous because you can damage an O-ring anywhere in the already installed cells which will require re-installation of the whole package. In case we have more problems Bill will consider designing a tool for pulling the pins. The damages O-ring was replaced on Friday and we started flushing the package with gas.
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- Withe four cells in the third package after 6 days flushing with gas we have 130ppm oxygen. A gas leakage that we had before was significantly reduced by putting a 5mil shim in between the bottom gusset ring and the end window. Now the leakage detector shows between upper 10^-4 and lower 10^-5.   
  
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- Two more cells were added to package #3 without tightening the package and tomorrow we will add another one, will have four in total. Then we will start flushing with gas and testing all four together. Normally we do the installation/testing cell by cell, but we want to save time on the flushing (5 days) and minimize the disassembling of the top end window and type-3 cathode that we have to do before each new cell installation. Bill: we take some risk with this, at least we can test the gas tightness by putting Lexan sheet on the top (after each cell installation). We will decide about this based on the experience  with the first four cells. Eugene: when we can expect the third package ready for tests; if everything is OK we will need two weeks flushing and testing the first four cells, then another 1.5 weeks for the remaining two cells and one more week for HV cabling, pre-amps and cooling tubes and grounding.
 
  
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- The first cell in package #3 was tested with a source. With low oxygen, the chamber is much more quite, very low noise (3-5mV), signals are higher and very uniform, and the working HV can be as low as 2050V where the chamber was stable for ~24 hours. Above that HV it was not possible to have it stable for a long time, the adverse effect of the low oxygen, which was helping before as a quencher. Also with the Viton the gas tightness is not as good as with EPDM: we have a leak (10^-4-10^-3 mL/sec) most likely due to a deformation in the gusset ring at that place. We found with Viton it's better to apply 100 in*oz torque on the rods, that's why we need them aluminum. Fernando pointed out that in this case we need to insulate them since we are closing the loops on the gusset rings. For that, we decided we better put the cuts on the top and bottom gusset rings at the same place.
 
  
 
== Engineering ==  
 
== Engineering ==  

Revision as of 17:11, 3 May 2012

May 3, 2012 FDC meeting

Agenda

  1. Production Construction Tracking (Dave)
    • Production status
    • Third package refurbishment status
    • Third package tests (Lubomir)
  2. Engineering update (Bill)
  3. Electronics update (Chris)
  4. Tests with first package at 126 FDC E-log (Beni)
  5. Other


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