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FDC Weekly Meeting

Date: May 1, 2008

Participants: Daniel, Simon, Fernando, Roger, Kim, Bill

Next Meeting: May 15, 2008 @ 1:30 p.m.

Cathode Planning

 - Roger is working to complete the cathode board PR in the next
   several days.  The goal is to have this on Elke's desk before
   the start of next week's systems review (which starts on
 - Roger has prepared a draft of some language for the PR that
   includes material handling language, electrical testing requirements
   (prepared by Fernando), and information on packing and shipping.
   On the shipping front, we were not sure if it was best to ship
   the cathodes flat or to have them rolled on a cylinder.  Roger
   will talk to the Allflex company's sales representative for
 - As we are still not fully sure of the performance of the 2 micron
   Cu boards, we are still considering 5 micron Cu boards as an
   option (if we can make the boards without the 2-mm Rohacell backing,
   then the thickness is about the same).  We thought that our best
   course would be to order boards with both 2 micron and 5 micron
   Cu.  DSC talked to Elke about this, and she thinks this is a 
   sensible approach.  She wanted to better understand the costs.
   Roger is talking to the Allflex folks about prices and we will
   know more early next week.
 - No progress has been made during the past week on additional
   solder tests of the rigid-flex assembly to the cathode board
   mock up.  Greg Arnold's group will begin this work after the
   solder pencil that they order arrives.  This should be shortly.
 - Note that due to the height of the solder connection between the 
   cathode board and the rigid flex assembly, we will have to revisit
   the design from the standpoint of adding clearance pockets on the
   surfaces that mate up against this solder region.  This discussion
   will begin when Brian is available.

Full-Scale Prototype

 - Outstanding procurements for the full-scale prototype: 
     * The HV capacitors will be delivered to us in about 1 month.
     * The 2nd construction station PR has not been started.  Brian
       will get to this when he is available.
     * The rails will actually not be delivered until mid-May.
     * The rail attachment assemblies are not ready for FSU to
       work on until Bill has time to complete the relevant drawings.
     * We are still awaiting delivery of the 2-mm Rohacell for
       the cathode backing.
 - DSC talked to Jack Segal during the week about our occupancy date
   for the EEL clean room tent.  If all goes according to plan (and
   negotiations are still ongoing), we will be able to take over the
   tent in about 2 weeks.
 - Simon talked to Casey in the JLab machine shop about the modifications
   of the aluminum tooling plate used for the wire frame construction.
   Before he begins, he will need Brian to provide a detailed drawing.
   This still needs to be done.  DSC will get Brian on this when he gets
   back to town.
 - Brian will begin wire frame construction for the full-scale
   prototype in earnest during the week of May 4.  He expects the
   frame construction to take 3 days/plane.  We will most likely
   prepare 4 wire planes for the prototype.
 - The keys to CC F117 are alledgedly available for folks to pick up.
   However, they are locked in the Forestry Building and we need to
   find someone who can let us in.  More to come.

Test Frame Wire Winding

 - The Phase 1 wire winding contract ended officially on Friday
   May 2.  DSC has received a preliminary report on the status of
   the work, and this report will be improved by IUCF and updated
   over the next week.  Basically they gave us what they had to
   fulfill the contract requirements, but it is not complete.
 - IUCF ended up winding 3 planes.  Brian brought back two of them
   with him to study the transport scheme (looks like no wires broke
   on the 12 hour ride from Bloomington to NN).  There were some
   problems that were found during the winding process:
   * The technique used to support the wire frames under the wires
     was non-ideal and this cause significant problems with the
     final wire placement on the boards.  This problem was diagnosed
     after winding the first two wire planes.  A modified procedure
     was used on the third plane with improved results.
   * The placement on of the field wires on the winding table, done
     after the sense wires were wound, had a minor problem.  The
     technician did not account for the differences in wire size.
     Thus the wire spacing had an offset (too big on one side of the
     sense wire, too small on the other).  This is not a real problem,
     and will be accounted for in future winding.
   * The wire placement distribution shows a fairly sizeable number
     of wires outside the +/-50 micron spec.  The fraction of these
     outliers is about 10%.  This is more than an order of magnitude
     too large.  The folks at IUCF are investigating this, but believe
     that it may be caused by worn equipment on their wire spooling
     and winding equipment.
   * There was suspicion that the wire measurements had a correlation
     of where on the measuring machine the wire frame was placed.  Data
     were taken to quantify this problem, but DSC has not gotten the
     analysis as of yet.
   * The wire tension measuring system was painfully slow, and so full
     tensions measurements on all wires were not completed.  Kim provided
     the IUCF folks with the wire lengths, and they have taken hopefully
     sufficient tension measurement data to give us a feeling of what
     tolerance they can provide.  We had requested +/-5%, but it may
     be that +/-10% is what their system can provide.  We will know more
   * DSC will go over the Phase 1 data and meet with Elke to plan on
     when and if Phase 2 will take place.  We need to be sure that
     IUCF can meet our specifications, both in terms of the detector
     requirements and the budget.
   * Finally, much thanks to Brian who spent a long week at IUCF
     representing our group.
 - DSC is working with Steve Christo to prepare a wire specification
   document for the tungsten and CuBe wires leading up to procurement.
   Steve is preparing a document for the Hall B chambers and we will
   most likely adopt this document for Hall D.  DSC reviewed the
   existing Hall B documents to give folks a flavor of how these
   documents have been prepared in the past.  We need to make decisions
   on what is required for the FDCs.

Stack Assembly Procedures

 - DSC, Brian, Tim, and Bill will work to finalize the stack assembly
   construction document that has been prepared.  This document should
   be in place before we get too far in the construction process.

Composite Cathode Updates

 - Denny has extracted the tensioning system from mothballs and it is
   now being setup in the shop.  Brian will work to make a tensioned 
   cathode without foam backing on his return.  In tensioning the
   cathode plane he will study how the 3 piece cathode reacts under
   tension.  He will also measure the electrode distortion as the
   tension is increased.  Note that after the meeting, there was some
   confusion on what was happening in the machine shop.  Casey thought
   that he was supposed to do the tensioning exercise.  There were
   clearly no plans in place for doing the measurements of the
   cathodes and Brian did not talk to Denny before he left town.  DSC
   therefore put a hold on this work until Brian gets back.  We do
   not want things done without a clear plan and communication is
 - Denny has the Acquity Laser system from Fernando and has it fully 
   set up trailer 94B.  He has done some test measurements and verified
   that the measurement results agree with crude measurements.  DSC
   told Bill to go ahead and purchase the system from Acquity.  After
   the test measurements, Denny started measurements on the two
   prototype cathode planes.  Measurements will be available early
   next week.

Grounding Issues

 - Fernando completed preparations of an overall Hall D grounding 
   specification document (GlueX-doc-1021).  He incorporated the
   comments that he received from the collaboration and posted a
   new version on the portal.

Cooling System Tests

 - Denny completed the set up of the cooling system.  He then packed
   it up and will move it to F117 after the system review.  Fernando
   will take over the measurements and study the cooling properties
   with a fully loaded preamp daughter board in place.

Gas System Design

 - Vladislav (Slava) Razmyslovich is working on a preliminary layout
   of the gas handling system for the CDC and FDC in preparation for
   the upcoming systems review.  We will sit down with him in a
   specialized meeting to review the design concepts after the review
   is over.

Gas Volume Definition

 - No progress on new calculations during the past week.  We will
   revisit the issue of modeling the gas in the drift cell region
   if the input is in the wire frame or spacer after the systems

STB/HVTB Discussion

 - Kim has updated the wire frame PCBs to widen the STBs and HVTBs by
   3 mm to beef up the overlap region.  We will not work more on these
   boards until after study of the existing boards on the full-scale
   prototype.  We can revisit the design of the overlap region again
   before production submission.
 - Kim needs to provide an instructional writeup for the Phase 1 and
   Phase 2 wire frame PCB component attachment.  This is on her to-do
   list, but is not a high priority for now.

Cathode Board Discussion

 - Roger needs to prepare a document for QA/stuffing/cleaning for the
   cathode boards and a similar document for the cathode daughter
   boards and ground boards.

Small-Scale Prototype

 - Work continues on characterizing the preamp daughter boards to
   specify the ASIC dynamic range for both the FDC cathodes and
   wires.  Simon is extracting from the data the amplitude distributions.
   He should be close to completing this analysis of the data.  He will 
   circulate it for discussion.  He will also circulate plots of the 
   charge collected as a function of the readout time.
 - Simon, Fernando, and DSC will prepare a write-up of the analysis
   results and our analysis of the required dynamic range of the
   anodes and cathodes.  Fernando will be in contact with Mitch
   Newcomer on our progress and plans.  Our goal is to have a first
   draft of a report on this work by the end of next week.  After
   the systems review, we will spend a few days to polish up the
   report and circulate it to a wider group for comments before passing
   the information on to Mitch.

PID/Chamber Review

 - The final report of the committee that reviewed the Hall D PID
   system and chambers was circulated.  The marks for the reviewed
   systems were high.


 - DSC has collected all of the available FDC subsystem design drawings
   and placed them on the FDC website.  The URL is:
   http://www.jlab.org/Hall-D/detector/fdc/drawings.html.  Folks should
   go through the drawings and let DSC know what drawings and/or categories
   are missing for a complete design set.
 - Also folks should send DSC the latest design drawings where there
   have been changes to keep this web site up-to-date through the
   review season.

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.