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FDC Weekly Meeting

Date: August 27, 2009

Participants: Daniel, Simon, Bill, Mark S., Stephen, Mark I., Beni, Eugene, Brian

Next Meeting: September 3, 2009 @ 1:30 p.m.

General Construction Updates

 - Stephen Burnett from Hall B will be providing technical assistance to
   FDC prototype construction work for the next couple of months. He has
   been working with our group during the past week and getting up to speed
   on all things FDC.
 - The assembly jig on which the detector stack will be constructed will 
   start to go together over the next several days and we will do some dry
   fits to be sure there are no problems. We are waiting for some parts to
   be delivered from the shop that are expected tomorrow.
 - Bill has begun work on the FDC stack assembly document. The draft will
   be made available after he completes a bit more work on it.  The document
   will be fleshed out during the assembly process with relevant photographs.
   Stay tuned.
 - Bill figured out that the thin annuli for the gas windows can be 
   laminated to the end cathodes before attaching the mylar windows. This
   will help to reduce stresses on this rings that were worrisome to him. The 
   two gas frames are ready for attachment to the end cathodes.

Wire Frame Update

 - Mark S. has gone through Rich's notes and provided the data that he had
   recorded from the HV tests to give us a baseline to compare to.
 - We did HV tests on frame P1 after it sat in the dry room for nearly 3
   weeks. We measured either 10 or 20 nA/bus for 11 busses and one was at 
   50 nA/bus. As these numbers were so different from Rich's last recorded 
   numbers (we could not find final numbers in Rich's notes after his
   extensive cleaning efforts), we opened the tent up to re-expose the frame 
   to the 60+% humidity of the room. After one day, the bus currents were 20 
   or 30 nA (with the one bus up to 140 nA). After another day, the currents 
   were about the same. We decided that we would study the currents over the
   next several days to see how things evolve. We will probably do some
   additional cleaning and inspection to see if the one high current draw
   bus can be affected by our efforts.
 - In the mean time, Beni looked at the currents on frames P2 and P3 today. 
   These frame also sat in the dry room for ~3 weeks and we opened up to the
   60+% humidity yesterday. Here we were able (more or less) to reproduce 
   the numbers that Rich recorded after cleaning. However, there seemed to be 
   a steady decrease of the currents with time (on the scale of 3 -4 hours). 
   The plan is to do some additional cleaning studies on a few of the high 
   current draw busses during the next several days to see if we have any
 - 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 are hoping that frame P1 will be ready for 
   lamination by the middle of next week if the leakage currents do not rise 
   too high after letting it sit out over the weekend. We will decide how to 
   proceed with planes P2 and P3 next week after more studies are completed. 
   If Fernando is back next week, we will bring him into the discussion and 
 - We were worried about torques applied to the preamp card associated with
   the cooling loops. We will most likely improve the bonding strength to
   the wire frame by adding epoxy around the perimeter. We will investigate
   this when we get a bit further in prototype assembly.
 - 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:
     * Bill has all safety work in place to remove the epoxy from the
       contaminated cathode. He has successfully cleaned the epoxy from
       a full-scale dummy cathode and is planning to work on the real
       cathode on Friday. Once the plane is certified clean, we will scan
       it for flatness and attach the ground plane and gas window.
     * This past week we have finalized the procedures for putting the gas
       holes in the end cathode ground planes. The ground planes were attached
       to the tensioning frames. One ground plane was tensioned, attached to
       its end cathode, and the lamination of the annulus for the gas window
       will be completed this week. The gas window will be attached early
       next week. The second end cathode, ground plane, gas window frame, and
       gas window assembly will be completed next week. 
     * We are now ready to begin soldering the rigid-flex assemblies onto the
       cathodes. Still waiting for them from the electrical QA step.
 - The parts for the QA system for the rigid flex assemblies should all
   be in hand this week and probably assembled tomorrow. Testing and
   certification will take place next week. We will most likely have to
   supply the manpower for these tests.
 - We will be investigating strain relief design for the ground pigtails to
   be sure that they cannot be over stressed and ripped off.
 - In the next few days, Roger and Mark S. will have to get together and
   start soldering rigid-flex assembly boards to test cathode pieces to
   finalize the procedures. We can use the old (flipped) flex assemblies for 
   this test soldering. We are eager to get started on the soldering work so 
   that stack construction for the full-scale prototype can get underway soon.
 - Bill would like some additional design work done on the cathodes to give
   more space between traces and holes. He sketched out his concerns, but we
   will need to have a separate meeting with Roger to find a solution.
 - Bill has been working on the cathode construction document building in
   the pictures that are being taken. The current draft of the document 
   is located at /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. We need
   feedback from folks involved in the process to be sure that all steps
   are included and accurately detailed.
 - We have heard that the Japanese company that made the polyimide with for
   our 2 micron Cu boards has agreed to provide the material for our
   detector. They expect to be able to complete the order by the end of this
   year. DSC will talk to Roger about moving on with the purchase.
 - 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.
 - 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 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.