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FDC Weekly Meeting

Date: September 17, 2009

Participants: Daniel, Bill, Stephen, Mark I., Simon, Fernando, Beni, Eugene, Brian, Roger, Glenn

Next Meeting: September 24, 2009 @ 1:30 p.m.

Manpower Update

 - Manpower will be thinning out soon. Stephen Burnett is going back to
   Hall B at the end of this week. His support is very much appreciated.
   Brian Kross will be off the project for the month of October. We will
   have to rally available manpower to finish stack construction. Stay

General Construction Updates

 - The assembly jig for detector stack construction has been put together 
   and a frame was dry fitted onto the pins. The frame did not go onto the
   pins until they were reamed out, but the fit was still a bit tight. We
   will investigate going to fewer pins or even taking a few mils off the 
   pins if necessary. It was decided that we would wait until stack assembly 
   before making the final decision. Bill does not believe there are any
   issues here.
 - Bill has been working on the FDC stack assembly document. He has made
   a draft availale at: /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
   Folks should look it over and provide feedback. The document will be
   fleshed out during the assembly procedure for the full-scale prototype.
 - Brian will check into whether we can get a sample size order of indium
   (lower temperature) solder paste for the rigid-flex assemblies. If we
   cannot, we will proceed with using convention tungsten solder.
 - Fernando should be able to provide us with our complement of ASIC filled
   preamp boards for the full-scale prototype by the middle of October.

Wire Frame Update I

 - Wire frame P1 status:
    * Nominal test configuration: connect all grounds together and apply
      1 kV to the bus under investigation.
    * P1 is the best frame with the worst bus (a sense bus) drawing below
      200 nA of current. The other 11 busses are well below 50 nA. 
    * We have inspected the surface of P1 on the top of the HVTB and STB 
      and on the back side of the STB to look for evidence of solder flux 
      or other problems. The board looked very clean under the microscope. 
    * The leakage is between sense and ground and the problem has been 
      localized to the STB. Disconnecting the ground on the STB causes the
      current to drop by a factor of 3 to 4.
    * After letting the frame sit in the dry room for several days, the 
      current on the problematic bus dropped to below 50 nA. The other
      busses were below 20 nA. So, humidity is an issue or at least is
      making the problem worse.
    * We coated the blocking capacitors on the STB with Humaseal and took
      P1 out of the dry tent. The current were back to their original values.
      Applying hot air on the HVTB did not change the currents. Applying
      hot air to the STB side caused the currents to creep up by 20 to 30%
      after 1 minute. When the hot air was removed, the currents came back
 - Wire frame P3 status:
   * P3 has the worse current draw problems, with several sense busses
     about 1 microA in the nominal room environment (~45% humidity). After
     several days in the dry tent, all currents were below 50 to 60 nA.
   * The components on P3 were fully sealed with Humaseal (HVTB filters and
     STB blocking capacitors) when the frame was dry. Upon bringing the
     frame back into the room and letting it sit overnight, all currents
     had returned to their original values. 
   * The two highest current draw busses were allowed to sit at voltage
     and quickly came down from levels about 1 microA to several hundred
     nA and then leveled off.  
   * The leakage was always from sense to ground. All field bus currents
     were fine. The leakage issue was always on the STB side. When
     disconnecting the STB ground, the currents dropped by a factor of
     3 to 4. On reconnecting the ground we would trip the supply off
     regardless of the trip scale and there was a spark in one instance.
     Something is charging up.
 - Wire frame P4 status:
   * P4 has current draw problems similar to P3, maybe a slight bit better.
     We only have current draw information at normal room humidity and we
     have let the board sit in the dry tent for a while. We will inspect
     the board and make current measurements this week.
 - Our next test is to make the active area gas tight and leave the rim of
   the frame in air and study the current draws again.

Wire Frame Update II

 - Rich's work from this summer on the wire frames has been prepared as
   a GlueX document (#1327) entitled "Procedures for Inspecting and 
   Troubleshooting of the Wire Frames for the Full-Scale FDC Prototype".
 - In the full-scale prototype, there was a design problem with the circuit
   boards so the wire frames will be laminated to their neighboring cathode
   planes to give a gas seal. We will move forward with this work as we
   certify each wire frame as ready.
 - We need to have a dedicated meeting to design what the schedule for
   work on the Phase 3 wire winding will be. The highest priority for
   work scheduling will be doing work on upgrades of the wire winding
   facility. This includes a better strongback design, the design and
   construction of precision combs, modification to the wire winding
   table, and a list of other items with the system. Stay tuned, more
   to come.
 - The wire frame construction document is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. We will include
   the information on the wire electroplating process shortly.
 - The parts of the jig to use for the wire electroplating operation
   are in our hands. They will be assembled as we find time.
 - Brian received the SEM scans for our wire from the W&M folks. He will
   generate a final QA report with photos and test results for all wires
   when he gets a chance.

Cathode Update

 - Progress updates:
     * The mechanical work on all cathodes is complete. The last thing
       to do is to connect the grounds on the individual panels on each
     * Stephen has been working on the rigid-flex assembly QA checkout.
       There appear to be problems with connectivity on about 20 boards.
     * Mark S. has been working with Roger, Fernando, and Bill to finalize
       the rigid-flex assembly soldering procedure. This is converging but
       we still have a few more tests to complete before considering solder
       work on the "real" cathodes.
 - The current draft of the cathode construction document is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
 - Roger is pressing the Japanese company that has agreed to provide our
   board material. They have agreed to manufacture the material but are
   being non-committal on when it can be ready. Procurement is involved in
   trying to get this order completed.
 - 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.

Cooling System Tests

 - Fernando is in the process of writing up the results from his cooling 
   system studies.  Stay tuned for the GlueX note. He indicated that he
   is back to work on this document and it should be done shortly.

Cosmic Ray Test Stand

 - Beni is continuing work to setup the cosmic ray telescope and test
   system in EEL 126. He is making progress on reducing the noise and is
   working to reproduce the data from the small-scale prototype that Simon
   had last year. The latest plots are in the FDC electronic logbook at:
 - We still have some mysterious behavior with the small-scale prototype
   response with wiggles in the X vs. Y distributions that need to be
   understood. Beni has reproduced this problem qualitatively and we
   discussed some possible causes, but more work needs to be done. Beni has
   yet to complete a pulser calibration run.
 - Beni has started a bench test plan for the full-scale prototype and
   is presently working on it after incorporating feedback. The current
   information is contained on the FDC wiki page under the heading 
   "FDC test cosmic ray test stand".
 - The parts for the support/rotation of the full-scale prototype in the 
   cosmic ray stand will be assembled as we have time.

Work List

 - The FDC short-term work list has been posted on the FDC web site.  
   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.