Minutes 9-19-2007

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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.

Composite Cathode

 - 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.

Small-Scale Prototype

 - 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.

DOE Report

 - 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 Budget

 - 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.

Daughter Boards

 - 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.

Cable Order

 - 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.

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.