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FDC Weekly Meeting

Date: February 11, 2010

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

Next Meeting: February 18, 2010

General Construction Updates

 - The two-layer prototype continues under source tests in the cosmic ray
   test facility. When we want to open this up to investigate the several 
   HV bus problems and to consider adding the third layer remains to be
   determined. Stay tuned.
 - We are proceeding slowly with the repairs of the third prototype layer
   (cathode sandwich with laminated wire plane). Casey and Mark are working 
   on sealing the 24 through-holes with epoxy. They are still trying to 
   optimize the procedures and have filled about half of the holes so far. 
   We then will have to decide how to test this layer for the leak that we 
   believe remains in the ground plane (and try to understand how the leak 
   appeared in the first place).
 - The oxygen sensor does not appear to be functional after several quick
   checks. Brian will take care of sending it out for repair and calibration.
 - The preliminary FDC stack assembly document draft is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. We will review this
   document in the coming weeks to update out-of-date or old procedures.

Frame Modification Studies

 - The inner frame pieces for the wire frame and cathode frames were
   delivered by the JLab machine shop. They were not particularly well
   made, but we were able to make some changes and got them to fit. They 
   have been glued up into annuli and had their seams filled with epoxy 
   and sanded down. They are ready to go.
 - One dummy cathode board made from three pieces of Kapton has been laid
   out and attached to the tension transfer frame. We are out of material
   for further dummy cathodes. More material has been ordered and will
   arrive next week to prepare a second dummy cathode.
 - G10 skins for the cathode frame are back from the shop and we are
   ready to laminate the frame filler pieces to the G10 skins and to
   add the Rohacell core. These two pieces (one for each cathode of the
   cathode sandwich) will then be sent on to the JLab machine shop to be
   fly cut to the final thickness. The frames will then be ready to attach
   the dummy cathodes. Then they will be laminated together to form the
   cathode sandwich.
 - Bill has had a G10 skin prepared for the wire frame. It is back from
   the shop. However, he also has the shop making a G10 piece that basically
   combines the G10 skin + filler pieces in one. This should be back from
   the shop in about a week and is will be laminated to the solder sample
   boards. This design looks like it will become our nominal design choice
   based on its design and its preliminary pricing information.
 - Bill has put together a few slides showing the frame design changes.

Wire Frame Update

 - The wire frame construction document is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
 - Casey has worked on a QA document for the preamp card connector checkout
   and will post it shortly.
 - Kim is still working with a board house (Trilabs) to get us meaningful
   quotes for single piece circuit boards (either one single annulus or one
   HTVB and one STB per frame).
 - We met with Kim to review her work on final redesign of the wire frame
   PCBs. She has made good progress on making the required design changes
   to one STB and one HVTB. She is nearly ready to move to the second STB
   and HVTB.
 - Kim provided drawings regarding the geometry of the glue strip area
   and the solder pads, as well as a layout of the proposed wire layout
   fiducials. DSC passed these on to Keith Solberg at IUCF for comment.

Cathode Update

 - The current draft of the cathode construction document is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
 - Casey is preparing a document for QA/stuffing/cleaning for the cathode 
   boards and a similar document for the cathode daughter boards and ground 
   boards. He will circulate it shortly.
 - In order to officially accept the cathode board material, we have asked
   for the company to provide a sample piece for us to test. The sample has
   arrived at JLab and we will measure the surface resistivity before signing
   off on the material.
 - 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.

Prototype Testing

 - 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. You can look in 
   Beni's directory for more recent test results.
 - Beni has been having trouble with current draw at HV that seems to be
   appearing after the bus seems to have behaved for a little while. Beni
   will look into reverse biasing the chamber for some additional cleaning.
   We may try to fill the chamber with nitrogen and try to separate problems
   with the wires from problems with the boards.
 - Beni will be including the cathode preamp card and hooking it up to
   ADC readout shortly.
 - Fernando will pursue purchasing enough cathode ground boards for all
   six cathode planes for the full-scale prototype.

Construction Updates

 - Two wire spool samples have been studied and reports have been provided.
   The reports have been posted at: S3 Samples and S4 Samples. Comments 
   are welcome.
 - Keith Solberg at IUCF is reviewing the preliminary Phase 3 FDC budget and
   expects to have us an update in about a week. He will also provide a
   budget estimate for the summer wire winding facility work. DSC and Bill
   are working on planning for the summer work. Once we have a Phase 3 budget
   that is reasonable, we will move forward with developing a formal statement
   of work for Phase 3. We expect significant progress on this front by the
   end of this month.
 - It is time for the next Phase 3 preparation meeting with Keith Solberg,
   Bill, and DSC. DSC will work to schedule this only after we have 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.
 - We talked a little bit on the gas handling system for the Hall D chambers.
   It is not fully clear exactly what we want to build, but we agreed to have
   a few offline discussions to try to come to some level of convergence. Beni
   will give an update at the next Tracking Meeting to get Curtis' input.

Mechanical Prototype

 - DSC will prepare a brief write-up with input from Bill on what we plan to
   use the mechanical prototype. This will give us some idea of how important
   this prototype is, when we want to put design effort into it, and the 
   level of complexity of this system. Stay tuned.

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.