FDC Weekly Meeting
Date: September 12, 2007
Participants: Daniel, Simon, Chuck, Tim, Kim, Roger, Fernando
Next Meeting: September 19, 2007
Composite Wire Frame
- The machine shop has finished drilling the through-holes and o-ring groove in our two composite frames. Brian filled the o-ring groove with epoxy and the machine shop then completed the machining of the o-rings. With the first frame, Brian poured in the epoxy (low viscosity variety) with a squeeze bottle. He noticed that the epoxy flowed under the g10 skin by several inches all around the groove. On the second frame, he sealed the face of the Rohacell and then filled the groove and did not notice any epoxy flow under the g10 skin. - Brian will start next week to do the load test on the wire frame that has our nominal dimensions to study the deflections and to look for failures. - DSC will take some pictures of the frame for the upcoming DOE FDC report.
- No work done yet. Brian will get to this soon.
- Kim has nearly finalized the layout of the dummy STB, HVTB, and side boards for the FNAL wire winding that is slated to begin next month. She circulated drawings of all the boards before today's meeting and got feedback and implemented the suggestions. In our design all neighboring boards will overlap each other to give us improved strength in the design. The overlap region is basically a half-lap design of width about 5 mm. - We discussed the tolerances required and the fabrication notes and came to conclusion on all of this. - Kim will circulate final drawings tomorrow and after we all sign off on them, she will prepare the drawings for the board house.
Magnetic Field Tests
- All network and DAQ problems seem now to be solved. DSC and Simon have finalized the trigger timing and Simon has taken a few runs to make sure that we are seeing sensible data from the MWDCs and the chambers. This work is still in progress. Once this is finalized, then Simon will calibrate the gains of the cathode readout. The plan is to take a long B=0 run over the weekend. The coincidence event rate is about 0.1 Hz (which is similar to the rate that Simon had in the Test Lab).
- 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 has done some work to study the cathode design including a hole in the middle of the board. His layout now includes an 8 cm diameter hole. In this design, only about 12 or 13 of the strips are affected by the hole. However in order to ensure that our readout remains quantized in units of 24 channels, we have decided to split 6 strips on either side of the hole. This gives us a total of 9 connectors on each cathode plane. The splitting of a few extra full length strips will help with the rate problems on these strips that led to higher occupancies than desired. - This new design will ensure that our two cathode designs (6 cm diameter hole and 8 cm diameter hole) will not impact the number of readout channels on the different cathodes.
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.
- DSC has begun work on the DOE FDC report. The text is essentially finished and the document is missing some photographs and Monte Carlo plots. Folks will be contacted if needed to provide help. - DSC has been in contact with David Lawrence and he is working to provide the necessary Monte Carlo figures. The report is due to Elke at the end of next week.
- 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.