Difference between revisions of "Minutes-8-25-2011"

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- Bill wrote the procedure for the package assembly (linked), so far for two cells, and will continue working on it. Three types of cooling brackets will be attached to the pre-amps and that's why he suggested marking the corresponding daughter cards with different colors.
  
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- Bill showed pictures (linked above) of the deadened area of one of the samples made by the W&M microscope. The surfaces, including the transition areas, look well polished and free of any sharp edges. The thicknesses along the wire and also for the different wires are very similar of about 66-68 microns, except at the very end of the deadened area where it is ~57 microns. Bill will look also at the last wire sample.  
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- Bill showed pictures (linked) made by Olga from the sample done after the last wire deadening. In the transition region the axes of the thin and thick part of the wire do not coincide which is strange, but other than that the diameters and the surface smoothness are OK.
  
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- Do we need to cut the gusset ring? As estimated by Eugene in case of magnet trip without the cut we may have up to ~7mV e.m.f. That means in the ring (~10^-3 Ohms) we will have 7A current and the power will by ~50 mWatt. Nobody from the participants of the meeting was aware of any problem this power can cause. At the same time cutting the rings introduces some issues: flatness problems, dust from the fiber glass/carbon.
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- Gusset ring cut: Eugene explained that the main problem with the high currents (estimated as 7A in case of magnet quenching) on the gusset rings is the force that can reach several pounds directed mostly radially, but especially for the last package may have also z-component. Even if these forces are not so big it is worth cutting the rings because: the quench could be faster (it could damage the magnet as well but we can save the FDC at least); also these forces may change the positioning of the FDC which will require new calibrations.  
  
 
== Electronics ==
 
== Electronics ==
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- Chris (not at the meeting) is testing the daughter boards and out ~200 he found only several problems mostly on the connectors, that were easily fixed.  
 
- Chris (not at the meeting) is testing the daughter boards and out ~200 he found only several problems mostly on the connectors, that were easily fixed.  

Revision as of 16:22, 25 August 2011

August 25, 2011 FDC meeting

Agenda

  1. Production Construction Tracking (Dave)
  2. Engineering (Bill)
  3. Electronics update (Chris)
  4. Chamber testing at EEL126 (cell#2) (Beni)
    • Results with new gas mixture: [6]
  5. Other: how to assemble a package

Minutes

Participants: Eugene, Bill, Dave, Beni, Chris, Simon, and Lubomir.

Production

- Dave: yesterday finished with stringing and taping wire frame #6, today did the position measurements and by the end of the day the wires will be glued. The cutter is now again operational and the techs will continue with cutting the foils for the cathode set #7; working also on the flaps for the cathode type 2 from set #6.

- HV cap problem (see pictures linked above). Everybody was surprised by the size and the abundance of the solder balls: 1-2mm (compared to the gap of 4.5mm between the pads) under more than 50% of the caps. Based on this observation, a decision was made on Monday to re-solder all the capacitors on the newly built wire planes. The above statistics applies for the two wire frames that were re-soldered by Anatoly so far. The leakage current after re-soldering went down to several nA for the whole frame. Not all the boards are like these: when we started testing the capacitors a month ago, Anatoly re-soldered the capacitors on another board, but we didn't see such solder balls there. After some discussions we agreed that it is worth informing the company. Chris will take care of the communications with them. Eugene: probably it's not worth pursuing this problem legally, but suggested to consult with the procurement.

Engineering

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