Difference between revisions of "Minutes-9-3-2015"

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# Engineering
 
# Engineering
 
# Other
 
# Other
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= Minutes =
 
= Minutes =
  
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Participants: Curtis, Mike, Naomi (CMU), Fernando, Eugene, Luke, Beni, Dave, Chris, Nick, Simon, Sergey and Lubomir (JLab).
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Participants: Curtis, Naomi (CMU), Fernando, Eugene, Luke, Beni, Dave, Marc (Mcmullen), Chris, Nick, Simon, Sergey and Lubomir (JLab).
  
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== Electronics ==
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== CDC update ==
  
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- Fernando studied the noise on the CDC and FDC together using two differential probes: see scope pictures linked in the agenda. First picture shows the noise levels in the two detectors are similar; FDC looks better but not by a lot. The second and third pictures show typical cosmic signals with correct timing. Last plot discussions - occasionally there are long tails in the CDC signals (~5 usec).
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- Simon went trough half of the CDC layers: the deformations are not always in vertical direction, i.e. this may not be sagging. Need to make a map of all the measurements to make some conclusion.  
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The signals are still low enough (~100mV) so this is not a saturation effect (Fernando). Most likely it comes from ion tails (Lubomir), however it is not clear why it happens mostly in the CDC, is the ion-cancellation different in the two detectors?
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- Nick: all "noise-reducing" elements from the CDC were removed. Tim is informed about that but needs to decide about the installation of an additional Al-foil target before inserting the target back. Nick replaced one LV module in the CDC; it was giving high current without any load. This is the second problematic LV module, the first one had different issue.
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- Beni: CDC is working now with the new MFC (separated from the FDC) blending the same 50/50 mixture. Need to verify this with the CO2 sensor.
  
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- The PR for 100 spare pre-amps was approved.
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- Measurements over weekend in mode 7.
  
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== CDC update ==
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== FDC update ==
  
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- Simon continues to study the tube deformations using beam data. So far he checked rings 1 to 7 and 13. Ring 7 (stereo) looks worse and there's a straw with more than 1mm deformation.  
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- Lubomir showed cathode resolution results from the spring run with two different ST+FCAL triggers: run 3137 "standard" trigger and run 3200 excluding 4 additional layers of blocks in the center. The resolutions with the inner blocks excluded looks better and now very close to the one (~200 microns) in the fall run. This was achieved by using tighter cuts on the tracks used for the resolution studies; obviously the fact that we had half the energy in the spring explains this. Still, the offsets used for the fall and the spring runs are different and we don't understand why.  
  
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- Beni informed us that the Bryan's libraries on the hdcdcops account are the new ones, corresponding to the new f125 firmware.
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- Studies with 55Fe on the thick cell in the spare package: due to diffusion not all the charge is visible depending how far the photon interaction was from the wire. Expecting better results with 90/10 gas mixture where the drift times are much shorter.
  
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== FDC update ==
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== Electronics ==
  
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- Lubomir showed the change of the spring 2015 alignment offsets w,r.t. fall 2014 run (plot attached - black/red are x/y offsets for each cell given by the z-coordinate). The max deviations are for the first package +/- 200 microns. Most likely it has to do with the alignment procedure, that starts with package 3 then 4-2-1. The problem is however, that with the new alignments the resolutions in the spring runs are worse than in the fall run, like ~250 microns compared to ~200 microns in the fall. May have to do with the lower energies. 
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- The reason for the LV module failure not known yet.
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- Luke presented his latest results about the avalanche position studies with 55Fe. First plot shows the avalanche position in plane perpendicular to the wire - empty area around the wire is visible. Second plot: the two maximums in up/down direction vs gain - distance between them increases with decreasing the gain (no idea why!). Last plot is the same but for the maximums in left/right direction - no dependence on the gain as expected.  
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== Engineering ==
 
== Engineering ==
  
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- We have now two new MFC calibrated for 2 l/min max flow. Scot will replace the bad CDC CO2 MFC and we will separate the two gas systems. Scot is also installing additional relief valves at the high pressure lines.
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- Dave is planing to shut down the interlock systems on FDC and CDC whenever that is convenient.
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Latest revision as of 17:02, 9 September 2015

September 3, 2015 Drift Chamber meeting

Connection

  1. Instructions for Bluejeans meeting connection
  2. Meeting ID: 290664653
  3. To join via a Web Browser, go to the page [1] https://bluejeans.com/290664653.

Agenda

  1. CDC update (Mike, Simon, Beni)
  2. FDC update (Luke,Lubomir)
  3. Electronics
  4. Engineering
  5. Other

Minutes

Participants: Curtis, Naomi (CMU), Fernando, Eugene, Luke, Beni, Dave, Marc (Mcmullen), Chris, Nick, Simon, Sergey and Lubomir (JLab).

CDC update

- Simon went trough half of the CDC layers: the deformations are not always in vertical direction, i.e. this may not be sagging. Need to make a map of all the measurements to make some conclusion.

- Beni: CDC is working now with the new MFC (separated from the FDC) blending the same 50/50 mixture. Need to verify this with the CO2 sensor.

- Measurements over weekend in mode 7.

FDC update

- Lubomir showed cathode resolution results from the spring run with two different ST+FCAL triggers: run 3137 "standard" trigger and run 3200 excluding 4 additional layers of blocks in the center. The resolutions with the inner blocks excluded looks better and now very close to the one (~200 microns) in the fall run. This was achieved by using tighter cuts on the tracks used for the resolution studies; obviously the fact that we had half the energy in the spring explains this. Still, the offsets used for the fall and the spring runs are different and we don't understand why.

- Studies with 55Fe on the thick cell in the spare package: due to diffusion not all the charge is visible depending how far the photon interaction was from the wire. Expecting better results with 90/10 gas mixture where the drift times are much shorter.

Electronics

- The reason for the LV module failure not known yet.

Engineering

- Dave is planing to shut down the interlock systems on FDC and CDC whenever that is convenient.

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