Minutes 2-21-2007

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FDC Weekly Meeting

Date: February 21, 2007

Participants: Daniel, Tim, Fernando, Simon, Brian, Chuck, Roger, John Schaapman, Lars Holm

Next Meeting: Monday, March 5, 2007 @ 11:00 a.m.

Design Issues

 - We discussed the possible repositioning of the daughter board
   connectors for the cathode in the middle of the cathode sandwich.
 - Fernando stated that for the 50-pin connectors, we must use
   surface-mount components as this is all that is available.
 - He has found a connector that is only 4-mm thick.  This is good
 - Tim had prepared as design sketch (via "foot-CAD") that was used
   as the basis for our discussions.
 - The best solution seems to be to use a double-sided cathode board
   with a via that takes the signals to the back side of the board
   where the connector can be soldered into place.
 - The tricky part is that we will have to cut flaps into the
   cathode board and route this flap through a cut-out on the G10
   frame.  The flap would be threaded though the cut-out and glued
   to the back side of the G10 frame.  Once glued down, the connector
   could be soldered on.
 - Note that the cathode board material comes from the manufacturer
   with copper on both sides, so the material is not an issue.  However
   the cost will increase due to the fact that we are constructing now
   a two-sided board with via.  Brian will look into the cost increases.
 - As this approach would involve cutting the cathode boards with
   scissors (sounds crude, we know), we can lay out copper on board
   sides of the board to define the region to cut.  This will also
   act to prevent the board from ripping once the cut is made.

Ground Plane Thickness

 - Gerard Visser did some thinking on the ground plane issue based
   on the sample that Brian had provided him.  Gerard states that
   Fernando will have some simulations to run, but basically it
   looks like this material will do an adequate job and is O.K. to

Cathode Mechanical Mockups

 - Brian has left the cathode sandwich with the JLab Survey folks as
   they had some additional things that they wanted to work on
   regarding the flatness measurement.  Brian assured us that the
   sandwich is safe where it is located.
 - Brian will start on preparing a stretched cathode tomorrow.  The
   construction should be done and measured by next week.  After the
   plane is constructed, Brian will measure the distortions of the
   cathode boards by locating some marks that he will put on the
   kapton before stretching.  This will be done via a simple optical
 - Brian has been told by the folks manufacturing our dummy copper
   strip circuit boards that they will get the material by Mar. 5
   and we should have the boards in our hands about a week later.
   Brian ordered 20 sets of boards (each set has 3 pieces and makes
   up one cathode plane).  We spec'ed flatness of the kapton for
   the order.

Circuit Board Material

 - We discussed the HVPF board idea again (as a review). Fernando
   will discuss this with Chris Cuevas at some point and will look
   into getting us a quote on boards made with this material.

Drift Chamber Review

 - The FDC TDR (Technical Design Document) has been posted on the
   GlueX portal and has gone out to the reviewers for the upcoming
   Drift Chamber review on Mar. 6-8.
 - All talks have been posted, but they are still being worked on.
   You can look at the GlueX portal for the latest versions.
 - We discussed what show and tell we want for the review.  We
   agreed on the cathode sandwich, the FDC prototype (in a protective
   box so folks can't touch), and DSC added the cathode planes for
   the prototype.

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