Minutes 8-15-2007
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FDC Weekly Meeting
Date: August 15, 2007
Participants: Daniel, Simon, Brian, Chuck, Kim, Roger
Next Meeting: August 22, 2007
Contents
Cathode Update
- Brian will mount the +/-15 deg cathodes on the G10 frames in the next two weeks. Bill Gunning will do the component soldering. We need to contact to him to get on his schedule. If possible, we would like these frames available for installation into the small-scale prototype before the end of the upcoming magnetic field tests.
Prototype Design Planning
- Roger will layout out an outline of the STBs and HVTBs and contact a circuit board manufacturer (or two) to see if they will fit into their tanks. We would much prefer a two-piece design compared to a three piece design. - Kim will get back to work on the STB and HVTB layout next week. We are hoping to have the circuit boards in our hands for installation on the wire frames that we send to FNAL in October. If they are not ready, we will have to prepare dummy STBs and HVTBs that include the solder pads and the sighting fiducials. - No decision has yet been made on the size of the deadened region of the FDC. David Lawrence is presently working on the simulations. We expect that the deadened region will be 3 to 4 cm in radius and probably get bigger with increasing z. While we can easily accommodate a z-dependent deadened region, we would like to have a single cathode design. Roger will rough out a cathode with a hole where we have strips about the hole readout above and below. As we are quantized in units of 24 channels, we need to see if this will work.
Wire Frame Studies
- Brian and Simon have completed a prototype of the composite wire frame using two 1/32-in G10 skins and a 3.4-mm thick piece of high density Rohacell. The prototype took about 2 hours to construct and represents the nominal design thickness for the FDC. - The JLab machine shop will take care of machining the o-ring groove and the bolt holes. The o-ring groove will be filled with epoxy and then machined out to form a seal. They did a test of machining epoxy with very encouraging results. This machining will be completed before the end of this month. - Once the frame is completed, Brian will do a stress test of the frame using the nominal wire load information to look for failure and deflections of the frame. These quantitative results will be compared to the calculations provided by Tim. We will leave the frame under tension to study long term stability and look for any evidence of creep effects. - Brian has stated that the assembly procedure is essentially finalized.
Cathode Frames
- After the composite wire frame is completed, Brian will make a full scale version of our composite cathode frame with the dummy cathodes to study the procedure. This work will be started very soon and all parts are in hand.
Magnetic Field Tests
- Good progress has been achieved in preparing for the upcoming magnetic field tests with the small-scale prototype. The MWDC stack is now in Hall B sitting at nominal HV with the 40-60 Ar-CO2 mixture and is awaiting installation above and below the magnet. The electronics and cabling is coming along. We have a new computer (as the old one died) that Simon is getting ready for the start of acquisition tests. - The folks mapping the pair spectrometer magnet are nearly done, and we should be able to start installing the MWDCs and small-scale prototype before the week is out. By next Wednesday, we would like to be reading out the chambers.
Daughter Boards
- Fernando reported at this morning's Hall D meeting that the FDC preamp daughter boards have gone out for manufacture. He has ordered 10 boards. They should be in our hands in 1 to 2 weeks. Upon arrival they will be stuffed and tested. - Fernando is starting to lay out the transition board that will go between the daughter board and the small-scale prototype for testing of the ASIC preamplifiers and daughter boards.
Procurement
- Elke has reviewed our R&D fund request for this fiscal year and given approval to place the necessary orders. This includes the shop charges for the wire frame, dummy circuit boards for the wire frames, a spool each of field and sense wire, additional G10 skins, and shipping funds to send a sample of the readout cable to Gerard.
Work List
- 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.