Minutes 1-31-07

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FDC Weekly Meeting

Date: January 31, 2007

Participants: Daniel, Tim, Roger, Fernando, Kim, Simon, Brian, Elke, Chuck, Gerard, Joe

Next Meeting: Wednesday, February 7, 2007 @ 1:30 p.m.

Cathode Mechanical Mockups

 - A second cathode frame has been made up and Brian will attach this
   to the first on Monday of next week to complete our first mechanical
   cathode sandwich mock-up.
 - The full-scale tensioning system was used to stretch a 6.3 micron
   sheet of aluminized mylar on one of our g10 frames.  The process
   went quite smoothly as long as the mylar sheet had no defects in
   it.  Any defect in the material would cause a rupture in the sheet
   as it was being tensioned.
 - The aluminized mylar had 250-300 angstroms of aluminum on each side.
   If this is acceptable for a ground plane, we will use this material
   for final cathode construction.
 - A meeting with the JLab survey group is schedule for Thursday at
   10:00 a.m. to talk about measuring the flatness of the cathodes
   in preparation for the upcoming chamber review.
 - Brian received a call from the company manufacturing our dummy
   cathode boards (those with the copper strips).  They should arrive
   within two weeks.
 - We will make our second cathode sandwich using these boards.  Brian
   is concerned that the copper will have some impact on the procedures
   developed for the naked kapton sheets.
 - Gerard suggested that we measure the capacitance of the strips on
   these boards.


 - Daniel has prepared a list of design rules of thumb for Kim and
   Roger to provide general guidelines for the design of the HVTBs
   and STBs.
 - The list has been passed on to Fernando and Gerard for comments
   before we pass this on to Kim and Roger.
 - Once they receive this list they will get back to work on the
   layout of the STB.
 - Gerard pointed out an oversight on the HVTB design that DSC passed
   around.  He will fix this and re-post the document to the GlueX
   portal and give copies to Roger and Kim.

FNAL Visit

 - DSC reviewed some lessons learned from the FNAL visit made last
   Thursday (DSC, Simon, Brian, Tim went).  He will prepare a write-up
   for the collaboration.
 - We discussed some of these at the meeting.  This includes solder
   pad size, modifications to the STB, sighting marks, solder pad
   length, ground plane layout, etc.

Chamber Design

 - Tim pointed out an issue with the layer design that looks like it
   leads to different half gaps on either side of the wire plane.  We
   need to see a complete mechanical drawing to make more sense of
 - DSC stated that the half-gap can be no larger than 6 mm.  The 6 mm
   half-gap is actually defined by the height of the daughter board
   connector (believe it or not).  Gerard suggested that we contact
   the connector manufacturer and see if the connector can be machined
   thinner.  Perhaps we could ultimately get back to the 5 mm half-gap.

Thermal Simulations

 - Fernando provided a write-up to the collaboration regarding his work
   on the thermal simulations.  He has asked us all to read this and
   provide feedback.
 - Gerard stated that basing the thermal cooling system on an assumed
   40 mW/channel power dissipation of the ASICS could be a worry.  Given
   that we may still be several revisions away, the power dissipation
   could go up.
 - Fernando stated that the current cooling system design is marginal
   even for the 40 mW/channel number.
 - We discussed the idea of liquid cooling again, and we may have no
   choice but to move in this direction.  Tim, Elke, and others cited
   that this is a standard design and we should not be too worried by

Cable Issues

 - Joe provided an update on his work to layout the cables, initially
   around the FDC itself, and also on routing the cables to the
 - Joe now has the spec. sheet for the 50-conductor cables that we
   are considering (I assume this is the halogen-free version).  He
   will provide budget numbers in the next few days.  They will cost
   more than the simple shielding cables currently in the FDC budget
 - Joe and/or Tim will produce an engineering drawing shortly to make
   it clear how tight we are on space outside the FDC.
 - Elke made it clear that the cables will have to evenly surround
   the FDC system to provide a uniform thickness in all directions so
   as not to bias the physics.


 - Gerard has been working with Simon all week on implementing the
   shaper board into the FDC test set up.  Based on the initial
   studies, Gerard has prepared a second board with improve performance
   from the standpoint of gain, rise time, and tail cancellation.
 - Simon is working to provide resolution numbers for the new

Monte Carlo Meeting

 - DSC and Simon will meet with David Lawrence tomorrow to discuss
   work on the GEANT Monte Carlo, especially with regard to preparations
   for the upcoming tracking system review (March 6,7,8).

Minutes prepared by Daniel. Send any comments or corrections along.