Minutes 11-15-2006

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FDC Weekly Meeting

Date: November 15, 2006

Participants: Daniel, Brian, Simon, Chuck, Tim, Roger Flood, Kim Shinault

Next Meeting: Wednesday, November 22, 2006 @ 1:30 p.m.

Project Designers

   Roger Flood and Kim Shinault, designers from the Accelerator Group
   joined our meeting today as they will be working on the wire frame
   circuit boards.  We reviewed the FDC system for them to describe
   its basic purpose and the design constraints.  They will begin
   work to layout the 3 signal boards and 3 HV boards for the wire
   plane.  Brian will be their point of contact.  Tim and Chuck will
   be in communication as well.

Board Design

 - Roger asked about using 4-layer boards (which still can be 1/32 in
   thick) to allow for better ground plane coverage and definition.
 - This was viewed as a good idea.

Frame Hole Patterns

   We discussed reducing the number of through bolts.  The fewer
   the bolts, the easier servicing becomes.  We started out with 48
   and are now down to 24.  There is no practical way to clamp the
   chamber from the outside, and the number of through bolts is
   necessary to compress the o-rings.  So, bolts are located every
   15 deg.

Electronics Cooling

 - We began discussing electronics cooling.  Tim will begin to think
   about this.  We have been told that each preamp channel uses 40 mW.
   The nominal solution is to use water through small copper lines.
 - This cooling line could be integrated into the preamp daughter board.

Daughter Boards

 - We have been told that each daughter board will include 3 ASICS
   (i.e. 24 channels) for the cathode planes.  For the anode readout,
   we must have 2 preamps per daughter board for compatibility with
   the F1 TDC (unless a junction box is constructed).  This still
   works nicely with our number of channels.
 - We need to be in contact with the Alberta group to specify the
   tolerances, thickness, connectors, cooling requirements, pulser
   line, etc.
 - DSC will talk with Elton about this.

Cathode Boards

 - The full-scale flex boards can be made by the company if we can
   find a kapton vendor.  The kapton vendor cannot deliver the size
   kapton we need with 1/7 oz of copper.
 - We decided to split the cathode plane into 3 separate pieces to
   get around this.
   >Tensioning option: Overlap kapton and epoxy -- then tension.
   >Rohacell option: Use butt joint and roll kapton flat.
 - The kapton is currently specified as 50 microns thick.  Can we
   go thinner to reduce the material budget?

Cathode Flatness Measurements

 - ATLAS had an automated system to measure the flatness of their
   cathodes and we would like information on their approach and
 - Simon contacted Paul O'Connor at BNL and he provided some names.
   Simon contacted them and has not yet gotten a reply.
 - Brian will follow up on this using his contacts at BNL.

Component Storage

 - Brian has contact with a plastic manufacturer in Norfolk who he
   will get to make a case for the cathode planes.  Kapton is
   hydroscopic and while the completed planes sit around, we want
   them encased with dry air flowing over them.

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