Minutes-8-20-2009

FDC Weekly Meeting

Date: August 20, 2009

Participants: Daniel, Simon, Beni, Brian, Bill, Mark S.

Next Meeting: August 27, 2009 @ 1:30 p.m.

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General Construction Updates

 - Stephen Burnett from Hall B will be providing technical assistance to
   FDC prototype construction work for the next couple of months. He will
   begin with us for a significant portion of this time starting on Monday.
 - Brian will be off of the FDC project for most of October. This schedule
   should be fine if we can complete detector construction by the end of
   September, which is what we are presently expecting.
 - Mark S. has completed the emergency solenoid work from last week and is
   back to his normal work level for the FDC.
 - The parts for the assembly jig on which the detector stack will be
   constructed will be put together as there is time.
 - Bill has begun work on the FDC stack assembly document. The draft will
   be made available after he completes a bit more work on it.  The document
   will be fleshed out during the assembly process with relevant photographs.
   He expects to have a draft available shortly as he has made significant
   progress on it.
 - The composite frames for the two gas windows have been completed. Sealing
   of the I.D. and O.D. of the frames has been completed, with the sealing
   of the bolt holes remaining. The tensioning of the gas windows and the 
   lamination to the composite rings will begin next week. Due to the stresses
   on the gas window frames (with the tensioned gas window attached), Bill
   wants them attached to their corresponding cathode frames just after
   they are prepared. The plan is that the gas windows will be laminated to
   the end cathode planes.

Wire Frame Update

 - Mark S. will go through Rich's notes to provide information on the
   problematic wire frame HV busses so that we can know where things were during 
   their last tests. What is needed is a list of frame number, bus number, and
   current draw.
 - One of the wire frames has been sitting in the tent for several weeks now
   and still needs to have HV checks completed. No work has been completed on 
   this but it needs to get done as the wire planes are soon to become our 
   construction bottleneck. Brian and Beni will work on this starting on Tuesday
   of next week. Based on the results obtained, we will then make a plan on
   how to proceed to diagnose the high current problems seen on several of the
   HV busses.
 - The last wire plane that needs checking and repairs is P1. This work will
   not happen in the short term as only 3 frames are needed for the
   full-scale prototype and we don't have the manpower to work on this now.
   Three of the frames have been cleaned and had wire repairs done.
 - We were worried about torques applied to the preamp card associated with
   the cooling loops. We will most likely improve the bonding strength to
   the wire frame by adding epoxy around the perimeter. We will investigate
   this when we get a bit further in prototype assembly.
 - 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. Stay tuned, more
   to come.
 - 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.
 - Brian received the SEM scans for our wire from the W&M folks. He will
   generate a final QA report with photos and test results for all wires
   when he gets a chance.

Cathode Update

 - Progress updates:
     * Bill has all safety work in place to remove the epoxy from the
       contaminated cathode. This work will begin shortly. We are presently
       planning to use this cathode in the full-scale prototype.
     * Flatness measurements for the two cathode boards for the second
       cathode sandwich have been completed and are in spec. There does
       seem to be some sort of systematic problem at the 20 micron level
       that always shows up on the left side of the flatness scan. Bill
       will look into this.
     * The first cathode sandwich is done up to the point of attaching
       the rigid-flex assemblies.
     * The two cathodes for the second cathode sandwich will be laminated
       together today. It will then be ready for soldering of the rigid-flex
       assemblies. We have simplified the design for the ground tab
       attachment for the cathode that the ground plane was laminated to.
       This reduced the number of pigtails by six.
 - The end cathodes will need to have their ground planes attached. These
   mylar planes will have holes added to them to keep the differential gas
   pressure at zero. Work will begin on make some test holes before working
   on tensioning the full-scale foils next week.
 - We will be investigating strain relief design for the ground pigtails to
   be sure that they cannot be over stressed and ripped off.
 - Rigid-flex assembly electrical QA status is unknown. Mark S. will check with
   Armen Stepanyan. We expect Fernando to be back to work at JLab next week
   to follow up.
 - Mark S. will begin test soldering of the rigid-flex assemblies to
   test cathode pieces to finalize the soldering procedures. He will work
   under the direction of Roger and Fernando. As this project is another
   bottleneck in the completion of the prototype, we are eager to get started
   to understand the schedule for completing this work.
 - Bill would like some additional design work done on the cathodes to give
   more space between traces and holes. He sketched out his concerns, but we
   will need to have a separate meeting with Roger to find a solution.
 - Bill has been working on the cathode construction document building in
   the pictures that are being taken. The current draft of the document 
   is located at /u/group/halld/Engineering/PRELIMINARY DOCUMENTS. We need
   feedback from folks involved in the process to be sure that all steps
   are included and accurately detailed.
 - We are standing by waiting for information on the PR for the 2-um board
   material. 
 - Roger needs to prepare a document for QA/stuffing/cleaning for the
   cathode boards and a similar document for the cathode daughter
   boards and ground boards.

Cooling System Tests

 - Fernando is in the process of writing up the results from his cooling 
   system studies.  Stay tuned for the GlueX note. He indicated that he
   is back to work on this document and it should be done shortly.

Cosmic Ray Test Stand

 - Beni is continuing work to setup the cosmic ray telescope and test
   system in EEL 126. He is now battling a noise source somewhere broadcasting
   at about 30 kHz. He has also found some isolation transformers to give
   him some clean power sources. It looks like one important source of noise 
   (among several) is the CAEN HV supply that we are using for the hodoscope
   scintillators.
 - Beni has been working to reproduce Simon's picket fence plot for the 
   small-scale prototype and has made some good progress. Presently his is
   chasing down some potential problem with the gas and will work to verify
   the gas mixture.
 - We still have some mysterious behavior with the small-scale prototype
   response with wiggles in the X vs. Y distributions that need to be
   understood. Beni is now trying to reproduce the "picket fence" plots from
   the small-scale prototype to get back to where Simon was last year. He is
   getting close.
 - Beni has started a bench test plan for the full-scale prototype and
   is presently working on it after incorporating feedback. The current
   information is contained on the FDC wiki page under the heading 
   "FDC test cosmic ray test stand".
 - The parts for the support/rotation of the full-scale prototype in the 
   cosmic ray stand will be assembled as we have time.

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.