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FDC Weekly Meeting

Date: February 25, 2010

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

Next Meeting: March 4, 2010

Construction Space

 - Glenn asked us to prepare a couple of room layouts for EEL 126. The
   first was for the additional 10-ft of space and the second for the
   space up to the wall. Lubomir made the figures and we reviewed them
   and the time lines. We will request that the additional 10-ft of space 
   should be ours within 1 to 2 weeks and the rest by the first part of
   May. Lubomir has prepared a floor plan layout that we will send to 
   Glenn shortly. We also need to start investigation of getting sufficient
   clean room space and to be able to make working conditions within that
   space appropriate (note the 85 to 90 deg temps in our current clean

General Construction Updates

 - The two-layer prototype continues under source tests in the cosmic ray
   test facility. We plan to open up the detector for work on and inspection
   of the HV busses by March 15 to give DSC time to work on the detector 
   and also to diagnose the problem before circuit board procurement.
 - Casey and Mark have finished sealing the 24 through-holes in our third 
   prototype layer with epoxy. For the bench test, we will place the wire
   frame on top of a spacer ring and the big plastic sheet (a sealing
   surface) and fill with the nominal gas pressure. We will then sniff for
   leaks around the upper cathode. This should happen next week. We will
   then make a plan for the next step.
 - We want to try putting the oxygen sensor in our system and measure the
   oxygen contamination on our input and output lines. Due to the worries
   about high input impedance of this device, we have some additional
   checking to do. We expect to attempt this work next week.
 - 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   document in the coming weeks to update out-of-date or old procedures.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 two laminates for the cathode boards (G10 skin + new inner G10 core)
   came back after fly-cutting in the machine shop. We have two dummy cathodes
   mounted to tensioning frames. The first cathode was tensioned to roughly
   600 N/m and allowed to sit overnight. It will be glued to its frame today.
   We will tension the second cathode tomorrow and glue it to its frame on
   Monday. We will then prepare the ground plane and complete the sandwich
   lamination by the end of next week.
 - Bill has put together a few slides showing the frame design changes.
 - The redesigned frame piece for the wire board is expected back from
   the shop within a couple of weeks.

Wire Frame Update

 - The wire frame construction document is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
 - Kim expects to be done with her work on the PCB redesign by tomorrow
   and will prepare the files for distribution to the FDC group early next
   week. We will also send the drawings to IUCF for Keith Solberg to check
   out. We want to start the procurement process for the circuit boards by 
   the end of March. Hopefully none of the current/HV problems with the
   full-scale prototype are due to remaining design problems with the
   circuit boards.

Cathode Update

 - The current draft of the cathode construction document is located at:
   /u/group/halld/Engineering/PRELIMINARY DOCUMENTS.
 - DSC and Fernando have inspected the cathode samples and have signed off
   on them.
 - The next rigid-flex design meeting will take place shortly.
 - We would like to push to get the cathode board procurement done by the
   end of March.
 - 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).
 - To connect the full-scale prototype to the readout electronics, Fernando
   is designing 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 will be ready shortly.
 - The signal cables for the full-scale prototype are being made up by
   Fernando's group and will be ready shortly.
 - The two-layer prototype has been under tests for several weeks. Beni has 
   been measuring plateau curves and studying drift time spectra. His most
   recent studies are in the FDC Log Book. He has been comparing the chamber 
   response to two different gas mixtures, 40/60 Ar/CO2 and 60/40 Ar/CO2.
 - The delivery of the remainder of the preamp cards for the full-scale
   prototype will be in mid-March or so according to Fernando.
 - Fernando will pursue purchasing enough cathode ground boards for all
   six cathode planes for the full-scale prototype.
 - 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.

Construction Updates

 - No new updates on the wire inspection this week.
 - DSC has contacted Keith Solberg at IUCF regarding the status of the
   review of the Phase 3 budget for the wire winding. Keith indicated that
   this work is in progress and should be done shortly.
 - 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.
 - Bill continues working on a brief write-up of the summer IUCF work. When
   it is completed, we will circulate it for discussion with Tim and others.
   It will then be sent on to IUCF for budget estimates.
 - Lubomir presented some preliminary results of the study of secondary
   hits in the FDC as a function of wire length and position relative to
   the frame. More to come next time.

Mechanical Prototype

 - DSC prepared a brief write-up regarding the FDC full-scale mechanical
   prototype. It was circulated around to a small group of folks. We will
   do a bit of work to beef this up and then post it for group comment.

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.