Difference between revisions of "Minutes-10-7-2010"

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== Engineering ==
 
== Engineering ==
  
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- Bill and a person from the machine shop will visit "Vision machining" to set up the wire production.
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- Wire stringing table: The holes in the granite table are ready. Bill glued pins into the holes. David is working on the movement system. Two options: buying a $2k controller that works with new computers/software or using the existing JLab controllers with the existing software. First will try the second option; Beni will help
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with the controller and the documentation.
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- Preparation for wire stringing: the holes in the granite tables are being drilled now and all the initial parts to be attached to the table are ready. David has been working
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on the movement system and the encoder. Two options to connect the stepper motor to a new computer: one  would require a $2K adapter that will work with new
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computers and software, the other is to use existing JLab controller with existing software. We will try first the second option; Beni will help with the controller and
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documentation.
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- Bill made a 3D model of the wire stringing system, linked above,  and explained the procedure. Wire by wire first sense then field wires: stringing, pressing with screws, taping down to the outer side of the board, measuring/adjusting the tension. After stringing all the wires: applying epoxy, measuring/adjusting the position, soldering, and cleaning.
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The improvement proposed by Bill is to tape the individual wires to make sure they touch the board (something we discussed last time).
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- Beni continued testing different gas mixtures (90/10, 85/15 and now 80/20) and showed some plots above. Pictures from the scope show after-pulses that are typical for these gas mixtures with high Ar content at high enough HV. Because of the after-pulses the ADC saturates. Fernando: where's the plateau? The end of the plateau is where the after-pulses start. The beginning has to be find by lower the HV, Beni covered so far ~150V for some of the mixtures. To reduce the after-pulses Beni wants to use the pre-mixed bottle Ar/CH4 95/5% and to mix it with CO2. Methane is flammable above 5% in air. Using methane in the hall has to be discussed, but first Lubomir will simulate it with Garfield
 
- Beni continued testing different gas mixtures (90/10, 85/15 and now 80/20) and showed some plots above. Pictures from the scope show after-pulses that are typical for these gas mixtures with high Ar content at high enough HV. Because of the after-pulses the ADC saturates. Fernando: where's the plateau? The end of the plateau is where the after-pulses start. The beginning has to be find by lower the HV, Beni covered so far ~150V for some of the mixtures. To reduce the after-pulses Beni wants to use the pre-mixed bottle Ar/CH4 95/5% and to mix it with CO2. Methane is flammable above 5% in air. Using methane in the hall has to be discussed, but first Lubomir will simulate it with Garfield
 
to estimate the advantages. It is know that organic molecule cause polymerization on the wires at high rates and gains. The other halls (A and C) have been using ethane
 
to estimate the advantages. It is know that organic molecule cause polymerization on the wires at high rates and gains. The other halls (A and C) have been using ethane
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as quencher (mxied with alcohol to prevent polymerization) for a long time.
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as quencher (mixed with alcohol to prevent polymerization) for a long time.
  
 
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Revision as of 16:45, 7 October 2010

October 7, 2010 FDC meeting

Tentative Agenda

  1. Production
    • Blue Crab status
    • Frame production
  2. Electronics
    • Update on PCBs, fADC125 and other (Fernando, Chris, Gerard)
  3. Engineering
    • Wire stringing: fixtures, movement system (Bill, David)
    • Update on tension measurements (Lubomir)
    • Wire tension requirements (Lubomir)
    • Other: gas system using methane
  4. Full-scale prototype
  5. Other


Minutes

Participants: Eugene, Fernando, Chris, Simon, Beni, Glenn, Gerard (on the phone), and Lubomir. Bill, David, and Casey were busy at 126 laminating the first wire frame.

Production

- There was a meeting between JLab people and AdvanceTEC that will build the clean room. Completion date: January 7th. AdvanceTEC had two concerns: the power coming to building (from Dominion Power) is close to the expected use and has to be checked. The second is related to the quality of the floor, not good enough for 10K clean room. AdvanceTEC will send a quote to re-seal the floor.

- Bill, David and a machinist from our machine shop visited "Vision machining". The frame production has started. About half of the spacer rings are ready. Two of the wire frames are here at JLab, being laminated in the moment with the Rohacell rings in 126. Five Rohacell rings were made by Casey and David. Tomorrow morning David with techs will be at Blue Crab to turn up two granite tables. The idea is to start using them for the lamination because of the limited space in 126.

Electronics

- Gerard will use the pulses generated from Garfield to study the timing of the fADC125 and will try different interpolation algorithms. He's working now on the firmware.

- Chris: all 28x4 boards were shipped to the company for stuffing and will have 2x4 (two of each type) ready within a week.

- Fernando will finalize the rigid-flex design (Roger is busy the next several weeks) and then submit it to the procurement. In a week (Oct. 14) we must here from the procurement about the cathode foils.


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