Minutes 7-18-2007

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FDC Weekly Meeting

Date: July 18, 2007

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

Next Meeting: July 25, 2007

Cathode Updates

 - There was a bit of a misunderstanding on the reasons why Sierra,
   Optiprint, and others were turning down our request for manufacture
   of the cathode boards.  This had to do with the physical size of
   the boards needed for the full-scale chamber, and not with the
   requirements of the boards themselves.  Elke thought it best if
   we gave the other companies the opportunity to make the boards
   for the small-scale prototype and to not pay the $14k setup charge
   to CCT.  This may save us some money down the road if we do not
   end up using the cathode readout for the FDCs.  
 - Brian sent around the Gerber files for the small-scale chamber to
   get quotes.
 - CCT called Brian and changed their attitude quickly regarding the
   setup charges once he told them about getting quotes from the other
   companies.  They will let him know about the quote for the small
   cathodes in the next few days.  They are confident that they can
   make them. 

Prototype Design Planning

 - DSC talked with Elke regarding how much design work we should pursue
   as we wait for answers regarding the performance of the cathode design
   in a magnetic field.  She fully supported us pushing ahead on the
   design of the full-scale prototype.
 - Kim and Chuck provided lists of questions that they need to get
   answered before they can continue on the design.  DSC will work offline
   to get these questions answered and communicate the work to the folks
   doing the designs.
 - DSC stated that our goal is to complete the design of the full-scale
   prototype chamber by September.
 - Fernando discussed his idea to use the same preamp daughter boards
   on the cathodes and the wire planes.  Thus now all daughter boards will
   be 24-channels.  This will require a special version of the F1 TDC,
   but Fernando believes that this would have to happen anyway.  The
   current F1 TDCs are 64 channel, but they are extremely dense and there
   is no space on the boards for the required calibration circuitry needed
   for the FDC.  The new F1 TDC is envisioned to be reduced to 48 channels,
   which will leave sufficient space for the calibration circuitry.
   Fernando indicated that he most likely would be the person to do the
   design work.


 - The parts and pieces for the second wire composite wire frame should
   be arriving next week.  Brian will put this together and then tension
   it.  He will compare the deflections to the numbers computed by Tim.
 - This new frame will have the final 5-mm thickness required for this 
   frame (as opposed to the first composite frame that was cobbled out
   of existing pieces and was 6-mm thick).  Brian will use high-density
   Rohacell in the inside.
 - This second composite wire frame will also be used for long term
   stability testing of the design.

Prototype Cathodes

 - Brian has ordered some 2-mm thick Rohacell that should be arriving
   next week.  This material will be used to make a new dummy cathode
   with this Rohacell as backing.  We will then perform flatness measurements
   on the cathode.  As these measurements have to be done with the
   plane laying horizontally, we will outfit the backing layer with a 
   dummy layer 3-mm thick to eliminate the gravitational sag.

Magnetic Field Tests

 - Much planning for this test is in progress.
   > DSC has arranged for some wire chambers to be borrowed from IUCF
     to serve as our cosmic ray telescope and they should arrive first
     thing next week.
   > DSC and Simon readied the electronics, cables, and gas racks in
     the test lab for movement to Hall B.  Last Friday they were 
     transported to the Hall and craned into the downstream alcove.
   > The dipole magnet that will be used for these tests will be
     reconnected and tested next week.  Field maps will then be performed
     and we should have access to the space in about about two weeks.
   > Simon has prepared a TSOP for the test period and turned the paperwork
     in for review and signature.
   > DSC will work with the Hall B folks to prepare the TSOP for the
     magnet operation.
   > DSC has prepared a detailed checklist for work to prepare for the
     test run.
   > Simon and DSC are finalizing the test plan.

Daughter Board/ASICs

 - It seems that folks are very keen on getting feedback on the ASIC
   performance on a real detector in the short term.  This will be
   necessary to provide feedback to the chip manufacturer and to Mitch
   Newcomer about the performance and the next round of modifications.
 - Fernando and Gerard had an exchange via email regarding what needs to
   be done to enable compatibility of the daughter board with the ASICS
   with the small-scale prototype chamber and the readout.  We will have
   to construct a go-between board to mate the daughter board to the
   small-scale prototype.  We may also need to construct a patch panel
   on the read-out side.  The main issue is the input and output
   connectors on the daughter board and compatibility with Gerard's
   shaper/amplifier board.
 - Fernando has been charged to get this worked out, to design the
   go-between board, and to interact with Gerard so that we will have
   the boards and connectors needed for these tests by September.


 - We have scheduled a meeting to discuss the Monte Carlo results for
   the FDC tomorrow morning.  There we will finalize 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.
   > rates per strip and wire for the latest FDC review.
   > momentum resolution vs. momentum and angle for the latest FDC
 - 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.