Minutes 5-23-2007

FDC Weekly Meeting

Date: May 23, 2007

Participants: Daniel, Simon, Brian, Kim, Roger, Chuck, Fernando

Next Meeting: Wednesday, May 30, 2007 @ 1:30 p.m.

---

New Prototype Cathodes

 - CCT continues to work with Sheldahl on the issues with making our
   cathode boards.  We clearly do not have the full story, but here is
   what seems to be the case.  CCT has made several sets of cathode
   boards for our small-scale prototype.  Now they cannot make boards
   without shorts between the strips.  They claim (even though they are
   using the same material as they used for our previous planes) that
   there is a problem with the material.  There are also rumors that due
   to safety issues, they are not using the chemicals for the etching.
   This is most likely the case.  They claim that the current cathode
   material has a chrome flashing.  They believe that if Sheldahl replaces
   this with a nichrome flashing, their process will work.  CCT stated
   emphatically that they will give us a final answer by June 4.
 - Brian has contacted an EE who used to be with F. Sauli's group about
   providing European contacts.
 - Roger has also found an alternative manufacturer and he will forward
   this information on to Brian.
 - There is still hope that we can find a materials manufacturer who
   can supply the material to make a single piece cathode board.

Circuit Boards

 - No progress on the HVTB and STB development this week as Kim was busy
   on other projects.
 - Fernando reported that the existence of magic circuit boards made
   from HVPF may be a myth.
 - We discussed how to make the connections from the cathode boards to
   the back side of the cathode frames.  The present idea is to include
   a cut-out and feed a flex cable through the cut out to the back side
   connector.  We want to prototype this.  Roger will look into purchasing
   some parts and pieces that Brian can use to play some games.

FDC CD-2 Document

 - DSC and Simon had a phone conference with Richard Jones regarding
   the different options that we want simulated for the FDC active
   area.  We provided a written document to Richard (see the Hall D
   FDC wiki).  He will get to work on preparing the geometry files
   and pass them on to David Lawrence and Matt Shephard.  Hopefully
   he can complete his work within a week.

Magnetic Field Tests

 - Simon has contacted Bogdan W. from Hall A.  He has two small Si
   counters that he can lend us.  We shall continue to look for other
   alternatives.  DSC contacted Alex after the meeting regarding IUCF 
   contacts.

Cathode Frames

 - We discussed the issue of carbon fiber support rings in the magnetic
   field and magnet quench issues again.  It is clear that we need some
   outside information.
 - Brian will contact Paul Brindza on this topic when he gets back from
   his trip to Russia.
 - We also began to discuss alternative materials that are non-conducting,
   for example Kevlar that could replace the carbon fiber, or even
   e-glass.

Cathode Backing

 - Now that Brian is back from his lengthy hiatus, we began discussing
   cathode backing options that replace the 5-mm of low density Rohacell
   with something even lighter.  Brian will begin to think about.  One
   idea that came up was a foam composite, with a thin layer of low
   density Rohacell to define the surface flatness (say 1 mm) and a
   4-mm backing of ultra-low density foam (large air pockets).  More
   to come on what we can do.  Once Brian has a few ideas, we can go
   about computing the thicknesses and compare to the 5-mm Rohacell
   option.

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.