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FDC Weekly Meeting

Date: December 17, 2009

Participants: Daniel, Simon, Mark S., Brian, Roger, Casey, Bill, Fernando, Beni, Eugene, Glenn, Chuck

Next Meeting: January 7, 2010

General Construction Updates

 - We do not plan on flowing gas to the full-scale prototype during the
   holiday shutdown. DSC will plan to start flow on Jan. 2, 2010 in
   preparation for work on Jan. 4, 2010.
 - We put the full-scale prototype together with all layers last Friday and
   were able to establish gas flow at 200 cm**3/min. Leak checking revealed 
   gas leaks at several locations on each of the different layers. We let
   gas flow over the weekend and brought layer 3 to voltage. Its currents
   were consistent with typical numbers seen on the first two layers at
   nominal voltage (2100 V, -500 V) in the 40/60 Ar/CO2 gas. We also checked 
   the anode and cathode signals from the third layer (using just the anode 
   preamplifier board). The signals and noise levels looked similar to what 
   we saw on the first two layers (see FDC logbook entry 422).
 - As the HV pigtails had not been secured on the third layer, the stack
   was disassembled to complete this work and to work on the leaks. As of
   now, the stack is back together and gas flow is now being established to 
   the level of about 150 to 200 cm**3/min. This is most likely as good as we 
   can do with the current (flawed) sealing design. For now, each individual 
   layer is connected to its own output bubbler to be sure all layers are
 - Mark has followed up on getting us access to an oxygen sensor to check
   the oxygen levels in our chamber outflow. George Jacobs in Hall B has
   been our contact. Stay tuned for details as they become available.
 - We will try to install the full-scale prototype in the cosmic ray test
   stand tomorrow if all goes according to schedule.
 - We did some height measurements around two of the wire frames (P3 and P4)
   and their cathode sandwich backings. Frame P4 was subjected to significant
   sealing forces before we set the more reasonable low torque settings.
   Frame P3 was only subject to low torque in stack assembly. Measurements
   at the through-hole locations (whole numbers) and in between points have
   been plotted. There is no obvious evidence for crushing here, although we 
   probably cannot take these measurement data too far.
 - We will need to make a few more sets of HV cables to go between the
   on-chamber HV connections and the SHV cables. We will look to see what
   parts and pieces we have on-hand.
 - The preliminary FDC stack assembly document draft is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.

Frame Redesign Studies

 - Bill has completed basic detailing of the proposed wire frame and cathode 
   frame design changes and has given the information to Simon. Simon has 
   nearly completed work on a new geometry file for the Monte Carlo. Beni will
   contact the folks at IU to have them study the impact of this geometry on 
   photon conversions similar to what they did for the chamber review last 
 - Bill is working on assembly drawings of the G10 annuli for the wire frames
   and cathode frames and is working on getting them to the machine shop. We
   plan to modify the 5th wire frame using the solder sample boards with the
   new design. For the cathodes, Bill would like to put together a cathode
   sandwich with dummy cathodes. The design drawings should be ready to
   submit to the JLab Machine Shop before the break. Stay tuned for details.

Wire Frame Update

 - The wire frame construction document is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
 - 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.
 - Kim is following up with the contacts regarding large-area PCBs. She
   has placed calls, but has not heard back from the board supplier or the
   board house. Kim will follow up with these companies to let them know
   of our urgency in pursuing this option. 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 
   boards. Casey has a draft of a document that Mark S. began preparing. He
   will take this over and complete the document.
 - 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.

Cosmic Ray Test Stand

 - Beni gave a brief overview of the FDC test plan. There was some low level 
   discussion, but it seems that folks are in agreement with the work plans. 
   The full test plan is located on the GlueX portal as (GlueX-doc-1306).
 - A while 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.

Other Meetings

 - On Monday, DSC met with Olga to review the results from the sense wire
   sample measurements and to give feedback for completing the sample tests.
   The work to complete the sample studies should be getting underway 
   shortly. It is not clear when this work will be completed given other work
   on the SEM machine. Results will be posted as they are available.
 - On Tuesday, a group of us had a teleconference with IUCF to begin a
   series of meetings on Phase 3 wire winding preparation work. The minutes
   from the meeting, including work responsibilities and action items is
   posted on the FDC web site at: Phase 3 Preparation Work
 - On Wednesday, a group of us met with Kim to go over the design work for
   the wire frame circuit boards. The present list of work is located on
   the FDC web site at: Frame Modification Work.
 - Tomorrow there will be a meeting to review design discussions on 
   modifications to the rigid-flex board design and connectivity.

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.