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January 6, 2011 FDC meeting

Tentative Agenda

  1. Production (David)
  2. Electronics (Fernando, Chris, Roger)
    • PCB inspection
    • Rigid-flex inspection
    • Cathode foil production
    • Foil inspection report
    • Other
  3. Engineering (Bill, David, Lubomir)
  4. Full-scale prototype (Lubomir)
  5. Other


Participants: Bill, Fernando, Mike, Dave, Mark, Chris, Roger, and Lubomir. Mike is our new technician.


- Dave: the clean room will be ready on Jan. 18, but then Jlab will do the wiring (power and internet) inside, which will bring us to the end of January. Right now Dominion Power is working on the power. In the mean time we will get a temporary staging area.

- ETC change request: the package full tests are scheduled to start at the beginning of 2012, but will not have enough electronics for one package until Nov. 2012. At the other hand, the installation is supposed to start at the beginning of 2013. Lubomir will discuss this with Tim.


- Chris: almost all the PCBs were tested channel by channel and all they are holding 2500V. They were cleaned very well. Fernando: the only operation that is needed is to fill the vias that were not sealed, with humiseal or epoxy. The only concern in doing this (Bill) is the thickness of the humiseal that is need; we need to make sure it doesn't interfere with the wires during stringing.

- The first 25 rigid-flex boards have arrived. Fernando and Chris found them acceptable from electrical point of view. Bill will check mechanically how do they fit on the cathodes.

- Roger showed us pictures from the foil production at the Allflex facility. Bill had suggestions how to improve different procedures.

- We discussed the foil inspection report, linked above. Generally, the first article foils are acceptable but we have several remarks and requirements. Bill will work on the document and we will send it to Allflex a.s.a.p.

- Fernando: first article signal cables are arriving (40 in total) and Chris is going to check them channel by channel.


- Wire stringing: the micrometers have to be installed and we will be ready to start exercising. This is our first priority right now and we will start stringing on Monday. We need help with the software to control the movement system. Tomorrow a Parker representative will come to help us. Dave: if needed we may consider hiring him to write the software.

- The tension on all the wires of a full-scale prototype wire frame (P2) were measured using our new procedure. These tensions were measured also at IUCF few years ago. The results are summarized at page 548 of the FDC logbook: apart from a ~5% systematic deviation, our result reproduces very well the IUCF measurements wire by wire. It means: 1)that our procedure is reliable, and 2) that the chamber tension didn't deteriorate during these years. The systematic deviation can be explained by the additional pins used now to stretch the wire frame on the strongback, or by some differences in the measurement procedures. Lubomir suggested to add adjustemnt of the magnet horizontal position, to make the wire oscillating strictly vertically. The main problem of the procedure is making contact with the wire pads. This can be improved on the HV side (Fernando) by using the HV pads and shorten the 1M resistors. On the readout side there were different ideas: clamping directly the wires (Bill) or even using the wires as they are with the weights and lifting one wire at a time with a hook to make contact (Lubomir).

Full-scale prototype tests

- Lubomir: in general using methane reduces significantly the after pulses. Bill: if we want to use methane it has to be discussed first with the safety people, so that we can have a plan for the gas system well in advance.