Difference between revisions of "Minutes-5-26-2011"

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= Minutes =
 
= Minutes =
  
Participants: Eugene, Bill, Dave, Chris, Simon, Beni, and Lubomir. The meeting was in B101 due to the N* workshop.
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Participants: Eugene, Bill, Dave, Chris, Simon, Beni, Caleb Massey (summer student) and Lubomir.
  
 
== Production ==
 
== Production ==
  
- Dave: the set-up for gluing the rigid-flex assemblies is ready; today we will start gluing the assemblies on the first two production cathodes. The set-up was tested today with one flex glued then removed and then glued again. Two other cathode planes were glued, one of them tensioned and the frame glued on it.  
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- Dave: HVAC didn't work starting Tuesday evening  (likely), and today Ron Bartek replaced a fuse in line with the transformer that failed before, but was replaced with a more powerful one. So, the same problem again; people from the clean room company will be there next week. Wednesday and Thursday morning the humidity was 50-60% and all the gluing was postponed.
  
- On one end window the epoxy didn't cure, but a sample from the same epoxy (and the left part in the cup) did cure. We suspect the surface was contaminated. Eugene: it's possible the epoxy was not mixed good enough. Also the surface on the end window is the only surface on the g10 frames that is not machined, and it is very smooth. On the second end window done in the same way the epoxy cured better. Most likely it was a contamination problem: we cleaned better the second end window. For the future production we will sand the surface of the frame.
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- Cathodes: two ready, except gluing the daughter cards to the frame, that will be done today. Third one is ready for gluing the rigid-flexes. The fourth has been tensioned and the frame glued. Fifth cathode foil is ready, as well. End window: Anatoly is finishing the first one.  
  
- Two wires were broken on the first production frame while removing it from the strong-back. Bill will make a tool that separates the frame from the strong-back. The encoder on the motion stage doesn't work and most likely it is the bulb on the encoder head to be blamed. It is an old model, so if we need an encoder we have the replace the whole device. For the first production wire frame we didn't use the encoder; the stepper motor resolution was good enough. The pin rail is now at Vision Machine for fixing and hopefully will be back later today. After that we can fix the two wires. Then we will start stringing the second wire frame which is ready.
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- Wire frames: the two wires of the first wire frame were fixed. We will keep it on the table to study the sensor problem: today we had problems not only with the field wires, but also with the sense wires. Dave will coordinate with Ron Bartek how to turn off the AC units to study the vibration effects. Caleb will work on this problem. Eugene pointed out that before trying to mitigate the vibrations we have to make sure that they are the origin of the sensor problem.
  
 
== Engineering ==
 
== Engineering ==
  
- The vibrations at Blue Crab were investigated on Saturday by Kirk Davis. He used an accelerometer connected with an analyzer and measured the vibration frequencies at different places (see the above link). On the sensor (also table, strong-back) he observed the same frequency (~39Hz) as on the AC unit and on the supporting beam, also on the walls but not on the floor. So, most likely the source is the AC coupled to the stringing table acoustically. Bill suggested putting plastic plates on the ceiling and improving the supporting beam. Eugene insisted that first we have to check if this is the reason for the problem with the wire sensing (10-20% of the field wires are not seen by the laser) and then to try to reduce the vibrations.
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- Report from Olga (linked above) shows some contaminated spots on the filed wires. For the first report she did before, she cleaned the field wire samples ultrasonically and maybe that's why she didn't see the contamination before. It's not critical for the field wires to have some contaminated spots, also we may have to clean them with the ultrasonic cleaner before stringing. This is another possible explanation for the field wire sensing.
 
- Report from Olga (linked above) shows some contaminated spots on the filed wires. For the first report she did before, she cleaned the field wire samples ultrasonically and maybe that's why she didn't see the contamination before. It's not critical for the field wires to have some contaminated spots, also we may have to clean them with the ultrasonic cleaner before stringing. This is another possible explanation for the field wire sensing.
  

Revision as of 15:43, 26 May 2011

May 26, 2011 FDC meeting

Agenda

  1. Production (Dave)
    • HVAC status
    • Cathodes
    • Wire planes
    • Other
  2. Engineering (Bill)
    • Pin rail modification: CMM measurements
    • Rigid-flex gluing
    • Other: encoder, parts/tools for chamber assembly
  3. Electronics (Fernando, Chris)
    • Update
    • Package grounding scheme
  4. Chamber testing (Beni)
  5. Other