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FDC Weekly Meeting

Date: December 10, 2009

Participants: Daniel, Mark I., Brian, Fernando, Tim, Chuck, Bill, Casey, Simon, Eugene, Beni, Roger

Next Meeting: December 17, 2009 @ 1:30 a.m.

General Construction Updates

 - The two-layer version of the full-scale prototype was reconfigured after
   the gas sealing and spacer modifications. Great new, no leaks were
   detected after careful leak checks of the entire system were performed.
 - Signals from the second wire layer were checked and were fully consistent
   in all respects with those measured for the first layer last week.
 - The third wire layer was prepared for lamination to the second cathode
   sandwich and the lamination was completed. Casey completed additional
   sealing about the O.D. of the different layers of this lay-up.
 - Casey is in the process of preparing the third and final spacer ring using
   the pin-striping tape and the soft o-ring material. This will be ready
   first thing tomorrow.
 - The HV pigtails for the third wire layer will be soldered onto the board
   tomorrow morning in preparation for adding the third layer to the stack.
 - A short developed in layer 1 on the HVTB bus #4 between the field HV
   bus near the join between the two HVTBs and the sense wire it passed
   under. This had been fine yesterday morning during "final" HV check outs.
   Remember this had been covered with epoxy potting. Somehow a hard path
   was made through the epoxy from the -HV bus to the sense wire shorting
   out the supply (at 2 MOhm). We took the stack apart and alleviated the
   problem by removing the epoxy and removing the sense wire over the
   HV bus and repotting. The first two layers of the stack were then
 - We will be ready to complete the full-stack assembly tomorrow before
   lunch time and then spend the afternoon leak checking. If all goes 
   well, we will let gas flow over the weekend, and do final HV check out
   on Monday. We plan to move the full-scale prototype into the cosmic ray
   test facility as soon as we can (i.e. Monday or Tuesday).
 - The W&M folks sent back pictures and details from a first look at a
   sample of our CDC/FDC sense wire order. The wire looked good with a
   smooth surface and a uniform gold coating. There was some surface
   contamination on one of the samples (lines in C, O, and Na). This was
   after cleaning in an ultrasonic bath for 30 minutes. However, everything
   else looked good with no obvious ovality of the sample. The W&M group
   has our full set of samples from the 4 sense spools and 4 field spools.
   DSC will give them the go-ahead to proceed. Interested folks can take
   a peek at the sample photographs.
 - Bill will follow up on getting us access to an oxygen sensor to check
   the oxygen levels in our chamber outflow.
 - The preliminary FDC stack assembly document draft is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. The document will 
   continue to be fleshed out during the assembly procedure for the 
   full-scale prototype. We will have to add steps in our construction plans 
   for leak checking.

Wire Frame Update

 - 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. DSC, Bill, and Keith
   will work to have a meeting next week.
 - 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.
 - We need to prepare a document for the electrical QA of the preamp
   connectors on the wire boards.
 - DSC, Bill, and Fernando will plan a meeting to go over the circuit
   board design work with Kim. We would like to have this first meeting
   scheduled for next week.
 - Kim is following up with the contacts regarding large-area PCBs. Kim
   did not make a contribution to this week's meeting. DSC will follow-up
   with her. There are a host of worries about the time line depending on
   how long it takes to quality the board material and the vendor if we
   go down this road. Stay tuned.

Cathode Update

 - The current draft of the cathode construction document is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
 - We need to prepare a document for QA/stuffing/cleaning for the cathode 
   boards and a similar document for the cathode daughter boards and ground 
 - The order for the cathode material was scheduled to arrive on Dec. 26.
   Roger asked that it be held for delivery until the first week of January
   when shipping and receiving is open for business. Tim suggested that 
   before we store away the board material, that we do an inspection and
   quick QA check to be sure that there are no obvious problems before we
   store the material away.

Leak Issues

 - Bill provided the specifications of his proposed design changes to
   improve the leak-tightness of the FDC system to Simon. Simon will prepare
   a new geometry file version for study of the new material impacts. It
   is not yet clear who will do this study. The last time this study was
   done was for the FDC review and systems review back in Aug. 2008, and this
   study was performed by IU. Beni will contact the IU folks to find what
   needs to be done and if they can complete the studies of photon 
 - We had a bit of a heated (but good) discussion about the time line 
   and work associated with validating the proposed changes. Tim believed
   that our current design, while we have gotten to a leak-free point in the
   current prototype with lots of work, will be a major labor sink for
   construction and may not work long term. DSC was worried about delays to
   our current time line and wanted to be sure that whatever we ultimately
   decide on for the FDC frames, we make versions for inclusion/test in the
   full-scale FDC prototype. 
    * For the wire frame, the place is to include a thin solid G10 annulus
      in the middle of frame to replace a portion of the Rohacell. This
      annulus would go beneath the holes and the o-ring points. Overall
      thickness would be guaranteed with a fly cut just as we do now with
      the Rohacell/G10 laminate that is glued to the circuit boards. Bill
      will prepare a design drawing for the shop to get the pieces or
      pieces made and we can make up a frame using the solder sample boards.
    * For the cathode frames, a similar plan is in place to put a thin G10
      annulus beneath the position where the o-ring sits at the location of
      the through holes. Bill will preapre a design drawing for the shop to
      get the piece or pieces made and we can use some of our mechanical
      cathode prototypes for construction.
    * We dicussed a bit whether these new annular inserts should be made
      from G10, but we didn't make a decision. We will most likely proceed
      with G10 pieces for our tests. 
    * These studies have no impact on moving forward with the final circuit 
      board design and procurement. Neither should they impact our moving
      forward with the final design of the cathode boards and their ultimate

Preamplifier Boards

 - An order for more ASIC chips is expected very shortly. Fernando expects
   that we will have ~40 boards ready by the end of November.

Cosmic Ray Test Stand

 - Several meetings ago we focussed on the wiggles seen in the reconstructed 
   wire position from the cathodes (see log entry 419) in the
   FDC logbook. We believe that the periodicity seen is due to the algorithm
   Beni is using to determine the U and V centroids. Beni get back to this
   soon. Stay tuned.
 - We expect to install the full-scale FDC prototype into the test stand in
   the early part of next week to begin hooking it up and connecting it to
   the readout.

IUCF Phase 3 Meeting

 - At the end of the FDC meeting, we had a phone conference with the folks at
   IUCF. That facility is going through a bit of a management/administrative
   shakeup. They plan on honoring work agreements that are already in place
   or are in place by the end of this year. As we will not have anything
   formal in place for Phase 3, our status is a bit uncertain. The IUCF folks
   asked us to prepare a "letter of intent" as to the work and the time line
   to make things a bit more formal.
 - We discussed the timeline for the start of Phase 3. We would like to see
   work begin formally on production winding on Oct. 1, 2010 (the start of
   the Phase 3 contract). They saw no problem with this.
 - We discussed that we will need some time during the summer to upgrade and
   test the wire winding system based on lessons learned during Phase 2. They
   agreed with this.
 - We also touched on the manpower issues. Keith will retire in Feb. 2010, but
   is committed to the Phase 3 project through its completion. Alan Eads'
   availability is not fully certain, but we would definitely expect that
   the one skilled/experienced technician is put on this project. We also
   discussed a temporary Hall D person assigned to the project stationed at
   IUCF for the duration. More to come.

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.