Minutes 12-6-2006

FDC Weekly Meeting

Date: December 6, 2006

Participants: Daniel, Brian, Simon, Tim, Chuck, Roger, Fernando, Stan

Next Meeting: Wednesday, December 13, 2006 @ 1:30 p.m.

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Mechanical Drawings

   We began by reviewing the latest mechanical drawings of the FDC
   produced by Tim and Chuck.  We currently have the following:
   - 5.5 mm wire spacing
   - 6 daughter boards (16 channels each) on the wire planes
   - 8 daughter boards (24 channels each) on the cathode planes
   - Tim and Chuck are still optimizing the anode and cathode 
     layouts; they will work with groupings of 8 channels
   - The cathode pitch may be adjusted slightly from 5 mm to get strip
     numbers to match up with preamp channels.
   - 3 STBs have 24, 48, 24 wires, respectively.
   - DSC has produced a document on the FDC circuit board layout for
     the wire plane - request feedback on the layout and component
     choices.

   Tim and Chuck need to interact with Roger and Kim soon to make
   progress on the board layout for the wire plane.  We need to know
   how much space is needed for the traces and components, as well as
   the daughter boards.

Preamplifier Cooling

   Fernando discussed his ideas for cooling the preamps.  He proposes
   a connection to a ground plane on the back side of the ASIC.  This
   plane then leads to a connector on the edge of the daughter board.
   Tim then suggested that with a small copper wire (~2mm in size), we
   could connect to the rods going through the chamber stack to get the
   heat out.  We could use a flow of dry air in the FDC ``cocoon" to
   cool.  Using dry air could also help with humidity control.  We should
   strive to avoid having to use water or other liquid coolants.
     - Both Fernando and Tim will continue to think about this.  However
       it now looks like we can keep the daughter board design relatively
       simple with respect to cooling, which should keep costs down.

Temperature Monitoring

   Stan suggested that we include a thermistor on each daughter board.
   This should be added to the budget estimate.  

Cathode Board Drawings

   Roger and Kim provided design drawings for the dummy cathodes and
   the on-chamber electronics for the wire planes.  We need to come up
   with labels for the title blocks.  Roger and Kim will use the JLab
   naming convention for all FDC-related drawings.

Daughter Boards

   Fernando will work with us to select an appropriate connector for the
   daughter boards.  Roger needs this soon.  In looking quickly through
   a catalog, we did find connectors with the required 5 mm profile.

   Fernando argued that the daughter boards should have the ASICs spread
   out horizontally instead of vertically on both the cathodes and
   anodes to make the board design easier.  Tim and Chuck will modify
   the mechanical drawings to handle this.

Cathode Flatness

   Brian and Simon have talked to the JLab survey group (contact Chris
   Curtis) about the cathode flatness measurements.  They may be able to
   modify an existing system they have to perform a non-contact measurement
   with the required tolerance.  They are looking into this and will get
   back to us.  The survey group could also measure the wire separations
   using optical techniques (slow and tedious) if we needed this.

Wire Winding

   Brian has been in contact with Karen Kephart about the stringing of
   the FDC wire planes.  We would like FNAL to perform the stringing,
   the deadening of the central 7 cm hole, the wire tension measurements,
   and the wire spacing measurements as part of this task.  We need an
   estimate for the budget.
   - We further discussed when the boards would be stuffed.  It would
     be best for us if the boards could be stuffed before winding.  Brian
     will talk to Karen about this.  Roger indicated that this would not
     be a problem in the design.
   - Karen has asked us to think about pre-tensioning the boards before
     winding.  We need to think about this.

FDC Spec. Sheet

   We reviewed the spec. sheet that Elton had made for the FDCs. Stan
   will look this over and provide feedback to us (as well as any
   questions that he thinks about after considering what we are doing).

F1 Modifications

   DSC reported that he had talked to Chris Cuevas about modifications
   of the F1 TDCs to include the ability to pulse the ASICs for
   calibration purposes.  This approach is being designed into the
   FADCs.  Chris indicated that this would not be a major deal.

HV Mainframe

    Simon will follow up on the design of the HV system (mainframe,
    modules, channels, etc) and get back to Elton.  This will close
    the loop on this budget item.

Force Calculations

    Fernando stated that we need to perform force calculations for the
    wire planes to converge on tensions and forces on the wire plane
    board.

Cathode Mechanical Mockups

    Cathode mechanical mockups will be constructed in the EEL shop
    area on the flat table.  Brian is presently gathering materials
    and parts for this task.  We will need to keep on top of this
    work so that we can make sure that we can meet our mid-January
    time line for a design decision.

FDC Budget

    We reviewed the FDC budget that is being prepared.  It is due 
    December 19 to Curtis and Elton.  The remaining work areas are:
    - Printed circuit boards (STBs, HVTBs): Fernando
    - Preamp daughter boards: Fernando
    - Ground planes: Brian
    - Mounting system: Tim, Chuck
    - Chamber cooling: Fernando, Tim
    - Chamber stringing: Brian

Site Visit

    We visited Chuck's office after the meeting and he showed us his
    mechanical 3D drawings of the FDCs.  They are progressing nicely.
    We will have much more complete drawings by the time of the FDC
    review in Feb/Mar.  Note that Brian has suggested a modified keep
    out zone for neighboring cathode and anode daughter boards that
    Tim and Chuck will incorporate to be sure that we have no space
    conflicts.

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