Difference between revisions of "Minutes-6-27-2013"

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- Bill: two spacers are ready, the last one will be glued right after the meeting. Pictures of the spacers, the fixture and the gluing are attached above. The carbon fiber rods are glued to the g10 cylinder. The two gusset rings needed for this procedure were taken from the spare package which is sitting now on a granite table with two Lexan sheets on both sides. Tomorrow after the last spacer is ready, we will put the gussets back. This operation requires at least 4 people, since we use metal pins inserted in the six places when lifting the Lexan sheets. As in happened already when taking the gusset ring in the same way, the pin can lift some of the planes/cells up.     
 
- Bill: two spacers are ready, the last one will be glued right after the meeting. Pictures of the spacers, the fixture and the gluing are attached above. The carbon fiber rods are glued to the g10 cylinder. The two gusset rings needed for this procedure were taken from the spare package which is sitting now on a granite table with two Lexan sheets on both sides. Tomorrow after the last spacer is ready, we will put the gussets back. This operation requires at least 4 people, since we use metal pins inserted in the six places when lifting the Lexan sheets. As in happened already when taking the gusset ring in the same way, the pin can lift some of the planes/cells up.     
  
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- Lubomir and Vlad showed some results from the thick cell study with a scope. We used two differential probes connected to wires from the two top cells. We used the scope as a trigger and fADC: we triggered on coincidences from the two wires, thus selecting almost vertical MIP that crossed the whole volume above the the wires. We recorded manually about a thousand events and plots linked above represent the results from their analysis.
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- Lubomir and Vlad showed some results from the thick cell study with a scope. We used two differential probes connected to wires from the two top cells. We used a scope as a trigger and fADC: we triggered on coincidences from the two wires, thus selecting almost vertical MIP that crossed the whole volume above the wires. We recorded manually about a thousand events and the plots linked above represent the results from their analysis. We increased the HV to +2450/-500V which corresponds to about 2-3*10^5 and it was stable for the whole weekend. With such high gain and very low noise (threshold of 5mV) we were able to see individual electrons with about 80% efficiency. There was 30-40 % loss of electrons (somehow different for the two cells) due to recombination (oxygen was 90-100 ppm) over the very long drift time of >20usec. Increasing the flow will reduce this effect. One can see the correlation in the cluster number counted by the two cells. The width of the difference agrees with the statistics. Interesting studies of the amplitudes of the single electrons
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show a nice exponential distribution of the gas gain with a slope that agrees to the average gas gain.
  
 
== Engineering ==
 
== Engineering ==
  
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- Bill started working on the fixture for the scintillators needed at the Hall for triggering: it is not a problem at all and will consists of unistruts along the cart attached to the cart frame.  
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- Bill explained how to install the trigger scintillators on the FDC installation cart as shown in the 3D models above.  
  
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- Bill was asked by Bruce Lenzer (suggested by Glen) to include the mock-up cabling in their QA plan, since this will verify that the cable density is correct and that there's enough space to the CDC and BCAL. Bill will write a short report after this exercise.  
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- We discussed the plan for the coming two months: finish with the spacers (end of this week) and the installation of the manifolds (next week) ; wait for the fiducial holders (end of next week) and then start installation of packages #1 and #2 on the cart with a spacer in between. After the third package is back from testing continue with the installation of packages #3 and #4; install the fiducials; make the gas connections between the packages (Bill still needs to find the right manifolds for the gas). At about middle of July, after all four packages are connected move them outside of the clean room and start practicing with the mock-up, connecting with cables one quadrant. Then, beginning of August move the packages to 126 and do the tests with the HV.
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- At the same time we should start moving the equipment out of Blue Crab. According to Dave Tim is working to find some space for us in the TDEF building. Eugene: Rolf Ent stated that physics wants to keep the clean room. There are rumors that Hall C wants to disassemble (Walter is coordinating this) it and store it somewhere for later use, but nothing official. In any case we would like to have the right to use some area of the clean room if we need to do something on the FDC.
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== Electronics ==
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- Chris and Nick will collect all the signal cables for each package together: some of the cables are with Tom, that's why the cables at Blue Crab to be used for the mock-up are mixed.
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- We may need contact cleaner for fixing the cathode pre-amp contacts; Chris will look for such cleaner.  
 
   
 
   
 
== Full electronics tests ==
 
== Full electronics tests ==
  
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- Beni now has the software to sparsify the data from the fADC in the ROC processors. Now he is taking long runs over the night and some results are shown in the E-log entries 110, 111. There you can see the raw signals (one plot per fADC), the profiles of the strips from all the planes connected (4 cells so far), and the wire positions as reconstructed from the strips. The reconstruction method is simplified so far, that's why you see a lot of noise in between the wire positions.  
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- Now the whole package is equipped with electronics and all the cables connected.
  
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- Two fADC channels are not working properly and there are four strips where the problem is in the FDC. In the previous version of these plots there were ~10 missing strips. Vlad and Lubomir fixed all of them by unplugging/plugging the cards and sometimes releasing a little bit the screws on the clamps. Several of the channels were next to a manifold, but those were fixed.  After that two strips re-appeared as problematic and two new strips showed problems. Beni suggested to spray the connectors with a cleaner to see if this will help. 
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- Beni showed results the 4 cell tests
  
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- Plans: the new VXS crate is in 126 and Chris and Nick will install it soon. Next week when Cody is back Beni will take 12 more fADC125s. Then we will connect the last two cells with signal cables and will be able to take data from all the channels.
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== Other ==
  
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- No meeting next week: 4th of July.

Revision as of 17:50, 28 June 2013

June 27, 2013 FDC meeting

Agenda

  1. Production
  2. Engineering [9], [10] (Bill)
  3. Electronics (Chris, Nick)
  4. Full electronics test FDC E-log (Beni)
  5. Other


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