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FDC Weekly Meeting

Date: February 4, 2010

Participants: Daniel, Simon, Beni, Eugene, Lubomir, Mark S., Bill, Kim, Roger, Glenn, Brian

Next Meeting: February 11, 2010

Work Coordinator

 - The interview for the FDC Work Coordinator candidate took place
   yesterday. Eugene stated that he is looking to have the position filled
   by April 1.

General Construction Updates

 - The two-layer prototype continues under source tests in the cosmic ray
   test facility. Two of the busses on one layer that were initially fine
   are now drawing a huge persistent current. We will investigate this at a 
   later point when the chamber is opened up again. It is possible that
   at some of the higher voltages being used for the HV scans have exposed
   thin places in our Humaseal potting. More to come on this.
 - We are proceeding slowly with on repairs of the third prototype layer.
   Our first step is to reseal all of the through-holes. DSC suspects that
   this was a self-inflicted wound when we pressurized the cathode layer in
   search of the leak in the ground plane. The repair has involved removing
   the Rohacell about the through holes in the different layers and filling
   with epoxy. Casey and Mark have epoxied three of the holes, but are still
   fine tuning their technique before proceeding. As we have not decided
   when we will add this back into the prototype, we will continue to work
   slowly and carefully on the third layer. More to come, stay tuned.
 - All of the current testing of the prototype has been in the vertical
   position. We still have to add the stiffening pieces to the gusset arcs 
   to help reduce the flexing of the structure when it is rotated into a 
   horizontal position for cosmic ray studies. 
 - As we could not find a system to measure the oxygen contamination in our
   chamber gas, Brian has contacted Illinois Instruments (the company that
   made the system we have). They recommended that we test it with nitrogen.
   If it registers ~10 ppm of oxygen, it is still in calibration. If it is
   out of calibration, they suspect that it could be easily recalibrated for
 - The preliminary FDC stack assembly document draft is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. We will review this
   document after tests get underway on the full-scale prototype to update
   out-of-date or old procedures.

Frame Redesign Studies

 - Mihajlo Kornicer has completed his studies of photon reconstruction
   efficiency comparing the nominal FDC design to that including Bill's
   frame support pieces. (See Frame Modification Study) Bill's design 
   includes an annulus of 19 mm width of G10. This is most certainly a 
   worst case design. Bill expects to be able to at least reduce the wire 
   frame insert thickness to about 10 mm with a scalloping-type design. 
   Eugene has O.K.'ed the thickening design and we are moving ahead with 
   the mechanical prototypes to finalize the design.
 - The inner frame pieces for the wire frame and cathode frames were
   delivered by the JLab machine shop, but had some minor problems. They
   were returned to the shop and are now back in our hands.
 - We are preparing a modified wire frame using the solder sample PCBs. We
   have removed the G10/Rohacell laminate from the PCB annulus, removed the
   STB capacitors and preamp card connectors, and filled in the seams between 
   the PCBs with epoxy. The board is read for the next step, which is to
   prepare the G10 ring/foam laminate with the new support pieces and then 
   laminate this to the PCB annulus. Note that this PCB will be used for wire 
   winding tests later this summer.
 - We are also working to prepare a cathode sandwich with the new frame
   support pieces. So far, a dummy cathode panel has been taped together and
   we are starting to prepare the transfer ring so that we can tension the
   cathode panel. 
 - Bill has put together a few slides showing the proposed frame design changes 
   for folks to ponder.

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.
 - We have not gotten a pricing update on the single piece circuit boards,
   but what we have gotten for preliminary numbers are off-the-charts high.
   Kim will look into pricing for a four piece design (i.e. going to a
   single HVTB and a single STB per wire frame.
 - Kim gave a run down of the work she has completed on the PCB redesign.
   So far she has focussed work on a single STB and a single HTVB. After
   her design work is approved, she will work on the second STB and second
   HVTB. Kim has so far updated the silkscreen labels of all wires, increased
   the bolt hole sizes, redefined the ground pours around the through holes,
   Changed the HV grouping from 3 to 2, removed the inner ground vias on the
   STB, moved the STB capacitor positions, and removed traces under the 
 - DSC will try to schedule the next PCB design meeting for the first part
   of next week.

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.
 - Roger will ask the distributor that has our cathode board material to
   test a sample to measure conductivity (Cu thickness). If this is O.K.,
   we will officially accept the full order. It will then be sent to Allflex
   for storage until our order is ready.
 - The next rigid-flex design meeting will take place later this month.
 - We would like to push to get the cathode board procurement done on the
   time scale of this March. Stay tuned.
 - David Lawrence is working to give us input on the hole size in the
   cathode center. Stay tuned.

Cosmic Ray Test Stand

 - The current version of the full-scale prototype test plan is on the
   GlueX portal as (GlueX-doc-1304).
 - 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. Stay tuned.
 - To connect the full-scale prototype to the readout electronics, Fernando
   will design a simple translator board that allows connection from the
   24-channel preamp connector to the 16-channel connectors on the ADCs and
   TDCs. These boards should be ready in the next few weeks.
 - The signal cables for the full-scale prototype are being made up by
   Fernando's group and should be ready shortly.
 - The two-layer prototype has been under tests for several weeks. Beni has 
   been measuring plateau curves and studying efficiencies. Some 
   results were presented by Simon in his FDC Status talk from
   last week's GlueX Collaboration meeting. You can also look in Beni's
   directory for more recent test results.
 - Beni will be including the cathode preamp card and hooking it up to
   ADC readout shortly.

Construction Updates

 - The wire sample checks are in progress with the W&M folks. Have not 
   gotten a recent progress update, but they are expected to be done with
   their work soon.
 - DSC had a teleconference with the IUCF management regarding the Phase 3
   wire winding contract and the plans for work at IUCF this summer to
   update the wire winding facility. Matt Shepherd has also been in contact
   with IUCF on all things GlueX. The IUCF folks have encouraged us to
   start on the required Statement of Work paperwork. Keith Solberg is
   presently reviewing the budget and manpower requirements for Phase 3
   that he prepared as a Phase 2 deliverable. DSC has been providing updates
   to IUCF on the FDC requirements and time lines. Stay tuned for further
 - It is time for the next Phase 3 preparation meeting with Keith Solberg,
   Bill, and DSC. DSC will work to schedule this, but it probably does not
   make too much sense to detail things without having at least a preliminary
   Phase 3 budget in our hands. See the work plan at: 
   Phase 3 Preparation Work
 - Master list on wire and cathode frame redesign work is located at:
   Frame Modification Work.

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.