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

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.


 - 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.