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January 27, 2011 FDC meeting


  1. Production (David)
    • Blue Crab status
    • FDC QA docs QA doc
  2. Electronics (Fernando, Chris, Roger)
    • Rigid-flex assemblies
    • Foil production status
    • Other
  3. Engineering (Bill, David)
    • Wire stringing
    • Other
  4. Full-scale prototype studies
  5. Other


Participants: Bill, Dave, Chris, Simon, Beni, Fernando, Glenn, Roger, Eugene, and Lubomir


- Dave showed recent pictures from the clean room that can be found on the M-drive: M:\facilities\Projects\Projects_100K+\Hall D FDC - Blue Crab Road Warehouse\Clean room\Construction\Photos\Construction. We will start moving in on Monday.

- Dave prepared an initial version of the FDC QA plan linked above. Pansophy data base will be used for the travelers: https://pansophy.jlab.org/pansophy/help.cfm.


- Fernando: the first article cables were fixed and will be sent back to us.

- Rigid-flex: once more we discussed the thickness of the rigid board (18.5 mil). Bill suggested reducing this thickness, but only if it's easy and can be done in time, otherwise it is acceptable and we are not going to reject the first article. Roger will communicate with the vendor. The parts needed to test the 3M conductive tape for soldering to the cathodes have not come yet. In any case we will continue with the mass production of the rigid-flexes with bare gold contacts that later can be tinned during the stuffing.

- Roger: still waiting for the written response from Allflex to our report about the first article cathode foils.


- Bill is working on some additional parts for the stringing system. The techs have been working with it last couple of weeks exercising different techniques. We discussed again the main issue so far, the flatness of the wire frame. Bill suggested using clamps that will be inserted between the G10 frame and the Rochacell ring. Fernando suggested a possible way to push the wire frame down from a supporting frame on the top. The way it works now is by taping the wires down to the board close to the soldering pads. This was proven to work: increase of the wire position deviations from ~10 microns to ~15 microns (sigma). Taping of all the wires is almost done and soon we will continue with gluing and soldering the wires.

- The testing of the "cheap" conductive epoxy was not very successful so far, it has high resistivity. Eugene: it might be better instead of spending time on improving the gluing technology, to use the "expensive" epoxy. Bill: the expensive epoxy has high viscosity and increases the thickness of the connections.

Full-scale prototype tests

- Lubomir showed a new plot (page 550) demonstrating how the ratio top/bottom strip signals changes over the plane of the top chamber. One possible explanation is deformation of the cathode/ground planes due to pressure difference in the different volumes. We discussed if it will be an advantage to have the volumes of all the chambers in a package connected together, i.e. to have holes in the ground planes that are now separating the chamber volumes. Now we are testing the bottom chamber.


NO MEETING next week due to the collaboration meeting (Feb 2-3) Beni, Lubomir and Simon will have talks on the collaboration meeting.