Minutes 7-25-2007

FDC Weekly Meeting

Date: July 25, 2007

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

Next Meeting: August 8, 2007

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Cathode Update

 - Still no word from Optiprint or Sierra on producing the small-scale
   prototype or large-scale prototype boards.  CCT Marketing is, to
   our understanding, proceeding on the manufacture of the boards for
   the small-scale prototype.  We should expect them shortly.
 - Elke suggested at the morning Hall D meeting that we should pursue
   at least two companies to produce the boards for the small-scale
   prototype in order to compare the quality of the boards.

Prototype Design Planning

 - DSC received a list of design questions from Kim and Chuck regarding
   the large-scale prototype design.  DSC produced a list of answers to
   all questions that was distributed before the meeting.  We discussed
   some of the open questions and areas where the design of the large-scale
   prototype has been changed or reconsidered.  This includes:
   > the copper thickness on the STB and HVTB boards
   > the physical size of the STB and HVTB boards
   > the placement of the capacitors on the underside of the STB boards
   > the placement of the daughter board connectors
   > the distribution of power and ground on the STBs and HVTBs
   > the HV connection scheme for the HVTBs
   > the placement of the components on the STBs and HVTBs
   > clearance issues with the FDC mounting rails
   > the size of the dead zone
   > the number of channels on the daughter boards for the STBs and cathodes
   > the attachment of the ground planes
 - The main issues for the short term are:
   > our plans to use 2 STBs and 2 HVTBs per wire plane.  As Kim is
     committed to other work for the next 3 weeks, Roger will prepare
     and outline for the STBs and HVTBs that can be sent to a board
     manufacturer to check on the size.
   > we decided that we will employ 24-channel readout for the daughter
     boards on the cathode and the anodes.
 - Based on our discussions, DSC will update the list of answers to the
   design questions and redistribute the list for comments. 

Magnetic Field Tests

 - Work continues on the preparation for the upcoming magnetic field test.
   On Monday, eight small area MWDCs arrived from IUCF.  These chambers
   are 1-cm thick and roughly 45 x 25 cm**2.  These chambers consist of
   4 X chambers and 4 Y chambers.
 - Upon arrival, DSC and Simon carefully inspected each chamber. All were
   opened up and cleaned thoroughly.  After connecting the chambers to
   nitrogen, it was discovered that there were a number of small leaks
   in the chambers and these were repaired.  As of today, nitrogen is
   flowing through all chambers.  If we cannot get sufficient through-put
   of gas, we will open up the problematic chambers and inspect and
   regrease the o-rings.  
 - We plan on flowing nitrogen through the chambers to drive out any
   water until they are needed in the Hall.  
 - Other planning work that is ongoing includes:
   > update of the test plan
   > preparation of a list for electronics and cables needs (we do not
     want anything to fall between the cracks)
   > Joe will obtain several isolation transformers for our electronics
     to provide clean power
   > Simon will talk to Doug about the construction of supports and
     tie downs for the detectors inside and outside the magnet
   > Simon will talk to Bill Gunning about modifications to our preamp
     power distribution center for the 2735B cards
   > Gas for the test run has been ordered and is on sight.  A bottle
     of argon and CO2 needs to be moved to Hall B
   > Simon will put some voltage on the chambers (should be able to
     put at least a few hundred volts on the sense busses to look for
     shorts and bussing problems
   > Simon will start work on reconnections of the electronics in
     Hall B
   > Simon will start work on preparing the software and analysis code
     for the test run.  He should have all of the ingredients and
     subroutines already available, but just needs to start putting 
     things together

Simulations

 - We had a meeting on Thursday with Dave and Elke to discuss the Monte 
   Carlo results and planning for the FDCs.  We finalized exactly what
   studies we want to perform and the priorities.  The work that needs
   to be completed includes: 
   > comparison of photon conversion probability in the inactive area 
     (frames + cables) between the latest FDC design to the FDC design 
     presented in the chamber review.  This will require another version
     of the geometry to include the stripped readout cables, the composite
     wire frames and spacers, better modeling of the electronics, and
     a reorganization of the layers in the CDC.
   > rates per strip and wire for the latest FDC review.
   > momentum resolution vs. momentum and angle for the latest FDC
     design.
 - David Lawrence will be spear-heading the work in consultation with
   Richard Jones and the IU folks (Mijailo and Matt).

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/).  This is continually
   being updated and DSC welcomes any feedback or comments from the group.

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