FDC Weekly Meeting
Date: September 19, 2007
Participants: Daniel, Simon, Brian, Chuck, Tim, Kim, Fernando
Next Meeting: September 26, 2007
Composite Wire Frame
- Brian has ordered everything that he needs to complete the load test. He will employ a 50-lb scale (max rating) for the load measurement. Note that the nominal wire load is 35 lb. A 1/16-in wire will be strung across the center of the frame. - We discussed the procedure for the measurements including the plan to measure both the in-plane and out-of-plane warping. Brian indicated that the out-of-plane warping measurement is the most important here. After the discussion, we had finalized the measurement plan. - Tim will be present for the tests to help Brian and to ensure that the tests are not biased in any way that will affect our conclusions.
- No work done yet. Brian will get to this soon. - We discussed a plan to butt the neighboring cathode pieces up against each other and to seal the joint with kapton tape. This would eliminate the overlap that was used in the last prototype.
- Kim has gotten a quote from San Francisco circuits for the full set of dummy boards. Another quote from Sierra will come in tomorrow and we will make our decision. Kim will complete the P.R. this week. We can also save some money if we will accept a longer delay before delivery (10 days vs. 5 days will save ~15%). - Note: After the meeting, Kim received the quote from Sierra and their quote was a factor of 2 higher than San Francisco circuits. Kim was in favor of S.F. circuits anyway, so we have an easy decision here. - As soon as the dummy boards are out the door, Kim will begin work in earnest on the STB/HVTB design. She has already gotten started. She estimates that she will have something to show us in about two weeks.
Magnetic Field Tests
- Good progress in the past week. We ended up changing the gas in the MWDC chambers from 40-60 Ar/CO2 to 90/10 Ar/CO2 to enable the time to distance calibration to be easier. We energized the magnet today and looked at the day, and all looks good. As soon as the MWDC gas comes to equilibrium (tomorrow), we will start production running.
- Brian has not gotten to the mounting of the +/-75 deg cathode boards. He has everything he needs to do this work, but has not had time. He will get to this soon.
Cathode Rough Out
- Roger is on vacation this week. However, last week a question on the cathode strip pitch arose and we will meet to get this figured out upon Roger's return. Roger had indicated the cathode pitch was 6 mm with a 1 mm gap between strips. Chuck believes that the cathodes in Roger's design were laid out to the outer edge of the cathode frame instead of the inner edge. It seems we should have cathodes with a pitch of 5 mm with a gap of 1 mm.
Cathode Board Readout
- After Roger completes the cathode design including the hole, he will work to complete a design for the cathode readout. The plans are to include a cut out in the cathode support frame through which a flex cable will be fed that connects to the daughter board connector. After we have a design, he will work to make a prototype to test and optimize the design. - In our current FDC design, we have a space of 1 cm between neighboring cathodes in order to have room for the daughter board connectors. DSC wants to eliminate this space and have the neighboring cathode frames in direct contact. With the old design, we had to add an extra spacer ring between the cathodes to give us o-ring compression. We discussed a plan for the design that would mount the daughter board connector on the back side of the 1/32-in thick G10 skin. If we need these frames to be thicker to accommodate the connectors, we can simply use a thicker piece of Rohacell.
- This has been circulated to the FDC group for comments and feedback. The current version is posted on the GlueX portal as GlueX-doc-861.
- FNAL provided their official budget estimate for the FDC wire winding. We were in for a shock as the overhead rate charged was 55% compared to the 15% they told us it would be earlier this year. Elke has been given the news and we will deal with this upon her return. - It may be that one of us will have to go up to FNAL to act as a technician during winding to reduce the associated costs.
- The transition boards that will go between the daughter boards and the small-scale prototype arrived this week. Fernando will stuff them and test them over the next week. - At our next FDC meeting, Fernando will bring some show and tell for the daughter boards, transition boards, and ASICs.
- The order for the readout cable for the cathodes and wires that was placed about a month ago has still not come in. After the meeting Fernando sent email saying that the cable will be shipped this week, however, the connectors will be delayed for some time.
- The FDC short-term work list has been posted on the FDC web site (see http://www.jlab.org/Hall-D/detector/fdc/). This is continually being updated and DSC welcomes any feedback or comments from the group.
Minutes prepared by Daniel. Send any comments or corrections along.