Minutes 4-18-2007

FDC Weekly Meeting

Date: April 18, 2007

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

Next Meeting: Wednesday, April 25, 2007 @ 1:30 p.m.

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Design Drawings

 - In preparation for CD-2 we need to put together a directory with
   all of our design drawings for the various subsystems.  Kim, Roger,
   Chuck, Tim, and Fernando were asked to send DSC electronic files
   of all representative drawings for the different subsystems and
   components by this Friday.  This set of drawings should reflect the
   level of the FDC design.

Cathode Prototyping

 - The no-Rohacell version of the cathode frame was tensioned during
   the past week.  Brian, Simon, and Tim worked to perform a measurement
   of the force on the cathode surface at its center.  A calibrated
   dial indicator was used.  Tim is still working on calculations to
   finalize the measurement.  His crude calculations indicate that we
   can expect a 0.25 mm deflection at the center (going down to 0 mm
   at the edge of the frame with a parabolic shape).  Simon has
   calculated that the electrostatic force on the cathode at our
   nominal HV/gain setting is about 0.02 Pa.
 - DSC commented that we still need to aggressively pursue the R&D
   on a cathode backing option.  We can use Rohacell thinner than
   5 mm or use a Rohacell composite (thin Rohacell skins sandwiching
   a Nomex honeycomb interior).  Brian will be back next week and
   we will start to focus this discussion.

Circuit Boards

 - Roger has not heard from any of his contacts regarding finding
   a company to produce our cathodes material in a size suitable to
   manufacture a single piece board.  He will stay on top of this.
 - The company that we asked to provide a quote for our small-scale
   prototype boards (+/-75 deg UV) has stated that they will not
   be able to make a two layer board.  Roger will modify the design
   to produce a single-layer board.  We will discuss things with
   Brian up his return.

Wire Frames

 - We discussed again the idea of leaving cut-outs in the G10 wire
   frame behind the capacitors again (now that Fernando is back).  He
   thought the idea was a good one.  

FDC CD-2 Document

 - Elke has asked that we prepare a brief (4-5 page) document for
   the FDC and CDC systems regarding how we have addressed the
   design concerns of the DC review committee.  Simon will produce
   a draft document.
 - Simon will follow up with Richard Jones and David Lawrence regarding
   the Monte Carlo comparing the old FDC design (with G10 cathode frames)
   and the new design (with composite cathode frames).
 - DSC will contact Matt Shepard regarding redoing the cathode and
   anode rate studies with the different options that we are considering
   in the active area.
 - DSC and Simon will contact Curtis to get him involved regarding the
   CDC concerns (i.e. the downstream endplate).

Magnetic Field Tests

 - No news from any of our outside contacts.
 - We have begun to pursue the idea of performing our B-field tests
   in Hall B using the old pair spectrometer magnet.
 - Simon will look into defining the modifications to the small-scale
   prototype to be able to fit it into the 6-in gap.  If we need to
   replace the aluminum end frames, we should get Roger on this soon.
 - Simon and DSC will begin work on a test plan for the study.  This
   is needed so that we can define exactly what we want/need to learn
   and to make a formal request to Volker for the time.  
 - DSC will find out about the space to ensure there is room to place
   our trigger scintillators above and below the magnet.  We also need
   to ensure that the stray fields about the magnet will not affect our
   trigger scintillators.

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/).  DSC is still
   waiting for feedback and comments from the group.

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