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FDC Weekly Meeting

Date: August 14, 2008

Participants: Daniel, Simon, Brian, Tim, Fernando, Bill, Micah, Herun, Mark, Jim, Beni

Next Meeting: August 28, 2008 @ 1:30 p.m.


 - It has been announced officially that a new technician is joining
   the Hall D group.  Mark Stevens, who had been in Hall A, will be
   starting with us on Monday.  He will be assigned to work mainly on
   the FDC prototype design and testing.

Readiness Review

 - The planning for the readiness review is underway.  The idea (tentatively)
   is to schedule the review for next Thursday (Aug. 21) afternoon.  If
   folks feel that they cannot be ready on this time scale, we will work
   to push it back an additional week.  
 - The main topics for discussion and their presenters are:
   - Wire frame design : Bill (assisted by Brian)
   - Cathode R&D planning: DSC (assisted by Chuck)
   - Cathode frame design: Brian (assisted by Bill and Eugene)
   - Assembly construction: Tim (assisted by Bill and Brian)
 - The review will be informal in the sense that it will be just
   internal JLab/Hall D folks participating.  However, the talks
   should be powerpoint or pdf presentations.  Be sure that all
   required test results, calculations, models, drawings, figures,
   and photographs are included in your presentations or brought to
   the session.
 - A more complete listing of the subtopics for presentation are
   given in a planning document.  Please talk to DSC if you
   have any questions.  This review represents our highest short term 
   priority and folks should ask others for assistance as needed to cover 
   all of the defined talking points.  
 - More details will be sent around soon, but nominally we will replace
   the FDC meeting with the readiness review except that we will go
   longer into the afternoon.  I would hope that each of the 4 major
   topics listed above can be scheduled to be for about an hour.
 - DSC will be talking to folks next week as well to see how they are
   coming along.

Cathode Planning

 - The cathode boards should be shipped to JLab today.  We expect that
   they will arrive at JLab before next week is over.  Shipping and 
   Receiving has gotten instructions not to open the transportation box.  
   This will be done in the clean room.  The cathodes will not be removed 
   from the box until we have our own handling instructions in place.  All 
   relevant folks will be on hand for this event.
 - In preparation for opening the cathode box, the clean tent will be
   made clean and all supplies needed to carry out the QA plan devised
   by Fernando (GlueX-doc-1082) will be gathered together. 
 - The shipping box will be modified after its arrival to include gas
   fittings so that we can flow nitrogen through the environment.  The
   addition of the gas fittings must be carefully planned out to ensure
   that no damage is done to the cathodes and no dust gets into the
   transport/storage box. 
 - Bill spent some time during the past week laying out some preliminary
   drawings for a system to cut the edges of the cathodes.  We went over
   his plans and the planned cutting procedures.  One area of focus is
   that we want to be able to sight the cutting head along the edge of the
   cathode strip to allow for precision alignment.  Bill is nearly ready
   to prepare the PR for this system.  We will be able to test it on
   existing pieces of the dummy cathode boards to finalize how well this
   system works and to devise the edge cutting procedures.
   any progress this past week on designing the system for the cutting of
   the cathode edges.  He will return to this work when he has time.
 - Roger plans on preparing an order for the new cathode rigid flex
   assemblies with the copper fingers (cathode boards and cathode ground
   boards).  This procurement will be completed by the end of August after
   Roger completes some additional design work.  We will need a minimum of 
   60 rigid flex assemblies (not the 54 reported in last week's minutes)
   for the full-scale prototype.  We will get a quote for these as part of 
   the ordering process, but we are looking at a charge of roughly $5k 
   (including board stuffing) for this order.
 - We did not have time in this meeting to talk about cutting holes in
   the cathodes (gas holes and central beam hole).  This is an important
   issue that we will have to seriously consider.  The worry is about
   losing tension in the cathodes if the holes (especially the big
   central hole) is cut after the cathode is tensioned.  This work is
   an important part of our upcoming R&D planning for the cathodes.

Cathode R&D

 - DSC is working with Chuck to put the cathode R&D work into an
   official project schedule.  We have a preliminary time line laid out
   and are now working on finalizing the required ordering of the tasks
   and the manpower assignments.  This work is required so that we
   respect the FTE assignments of various folks to the project and that
   there are nominally 8 hours in a work day.  We will work to post this
   schedule very soon so that we can use it as our official project guide
   and tracker.  We will work to incorporate contributions from the
   new technician as well.  DSC is having trouble with the scheduling
   software and/or input file provided by Chuck.  Additional work will
   have to wait for Chuck to get back from vacation.
 - Cathode flatness measuring system:
     * We are waiting for the parts n' pieces to arrive.  We have about
       1 week until they show up (roughly).
     * The system will employ an old granite table that is now in the
       Physics Storage Building and is ready to be moved to EEL 126.
       This table (4 ft (w) x 6 ft (h) x 1 ft (d)) will be used to support 
       and to define the flatness of the cathode support ring. Bill will 
       ensure that all relevant safety issues are dealt with in the design.
     * Bill is planning on overseeing the assembly of the system once 
       everything shows up.
     * Bill has a number of smaller parts for the project that have been
       submitted to the FSU machine shop.  These parts should be ready
       before the end of August.
     * Micah reported on work that he has been doing to generate contour
       plots of the surface flatness from the 2D data.  He will send around
       samples shortly.
     * We will have to work out a time-sharing plan for the laser measurement
       head for the flatness measurements and the tension measurements.
 - Eugene is working to define the allowable surface flatness variations
   for the cathodes.  What can we tolerate and still deliver a system that
   an meet the resolution requirements for the cathodes and the wire plane?        
   Eugene should provide some answers by the end of August.
 - Brian and Bill should begin to layout a detailed outline for the cathode
   construction steps and circulate for feedback.

Cable Procurements

 - Fernando and Kim will work to put together the PR for the manufacture
   of the LV cables needed for the small-scale prototype and the connectors
   for the signal cables. We have the signal cable material and the
   tool for crimping on the connectors.  The plan is to have the LV
   cables made by an outside company and to make the signal cables

Machine Shop Work

 - The modification to our aluminum assembly jig is complete and it is
   now sitting in EEL 126.  The new aluminum assembly jig is also
   complete and is now in the EEL clean room.  The machine shop is
   finishing making up the dowel pins that screw into the jig plate.
   Brian has test fitted the STBs and HVTBs onto the jig plates and
   has reported that everything fits properly and the clearances are
   adequate for all components.
 - Bill has prepared all of the necessary material to submit the
   modifications of one of our prototype wire frames to the shop for
   a new load test.  No further wire frame machine shop work will be
   submitted until the new round of load tests has been completed.

Wire Frame Construction

 - The frame that was used for our wire tension load test (which is 
   discussed in the FDC TDR) has been under the full nominal
   wire load for about a year now.  This frame will be modified to
   include the pockets for the rigid flex assembly and the bolt holes.  It
   will be machined to the nominal I.D. and O.D. of our wire frames.
   The foam core and the G10 skin will be removed to an I.D. of 1032 mm
   to account for the problem with the HV decoupling capacitor placement
   (discussed in last week's minutes).  The plan is to redo our loading
   tests and measure the in-plane and out-of-plane distortions of the
   wire frame up to a load of roughly 50 lbs (the full wire load is about
   35 lbs).  We still have some details to work out on the test plan
   specifics, and this will happen before the tests and after we think a bit
   more about the modified frames.  If Tim has time, he will work through
   some FEA calculations.
 - The pockets that we were originally planning to include in the back
   of the G10 skin of the wire frames have disappeared in favor of much
   more straightforward milling machine cuts.  This will become our
   nominal design if there are no problems with the new load tests.
 - The nominal wire frame construction plan devised by Brian will be
   our starting point for construction.  Folks should look this plan over 
   in some detail and we will step through it before the start of 
   construction to make sure that no steps are left out.
 - We are presently planning on borrowing an A-frame for EEL 126 for the
   wire frame construction (that Tim arranged).  However it was reported
   that there may be some usable A-frames in long term storage (Blue Crab)
   that could be ours.  This would eliminate having to share an A-frame
   with another group (which would be a pain for us and could impact our
   construction schedule for the full-scale prototype).
 - Simon and Herun are working to complete the HV checkout of the STBs.
   Some details are included in the FDC logbook entry #377.
   They have tested 4 sets of boards and have 1 more to go.  Only 2 suspect
   capacitors have been found that need to be replaced.
 - The HVTBs will be tested next.  At present some of the filter capacitors
   that have been soldered on will not be possible to leave on due to
   the fact that they will get in the way for wire winding.  Fernando
   will work to get them removed.  Once these few capacitors are removed,
   these boards will be Ohm'd out (to check the HVTB resistors).
 - The PCBs for the FDC will need to be handled by all folks involved with
   more care.  Many of the boards have sustained damage to the fragile
   lap ends.  The damage is not severe enough to cause any construction
   worries, but handling procedures do need to be established and followed.
 - Brian is working to put together an order for another spool of sense
   wire and another spool of field wire.  DSC will finalize the wire
   specification document.  It would be nice to use this with the
   vendors now and get the kinks worked out so that the specifications for 
   the final detector wire order can be worked out.

Test Frame Wire Winding

 - IUCF has completed the wire winding of an additional frame and
   has completed the wire position and tension measurements.  For the
   wire position measurements, things look much better than the last 
   attempt. However, there is an offset in the positioning of the field 
   wires on the frame relative to the sense wires of about 40 microns.  
   Keith is now reviewing the procedures used and we will work to rectify    
   this problem.  The wire tensions show a systematic drop from the
   frame edge to the middle.  This may be due to the fact that the frame
   is now loaded and is warped.  Tim will provide an estimate for the
   length decrease due to the load to check whether this is consistent
   with the IUCF measurements. 
 - As the time to complete Phase 1 and Phase 2 winding before the end
   of the fiscal year will be super tight, DSC will work with Elke to
   complete as much of the required Phase 2 paperwork as we can in the
   next few weeks so that we can move quickly to getting Phase 2 in
   place before time runs out.

Spacer Design

 - It is looking like a CH2 spacer is becoming our nominal design
   choice instead of a composite design.  During the past week, the
   machine shop cut a straight o-ring groove into a sample piece of
   G10.  The edge was crisp and well defined.  Machining does not seem
   to be an issue whatsoever.
 - Bill raised a concern about the different differential expansion of
   CH2 relative to G10.  Bill stated that for an unconstrained CH2
   spacer, a 40 deg change in temperature would result in a 3 mm size
   change across a diameter.  Some calculations will be done and Bill
   would like to have a full-size CH2 spacer made for testing.

Stack Assembly Procedures

 - DSC, Brian, Tim, and Bill will work to finalize the stack assembly
   construction document that has been prepared.  This document should
   be in place before we get too far in the construction process.
 - Bill has found some plastic threaded rods that could be use to 
   compress the stack.  We will be receiving some samples shortly and
   will carry out some loading tests.

Cooling System Tests

 - Bill and Fernando completed the planned cooling system measurements
   for the daughter boards.  Fernando is working to put together a
   document of the test results.  He indicated that no further cooling
   system tests are planned until we have more cards and can test a
   bigger portion of the system.  So far, things are working according
   to expectations.

Gas System Design

 - Slava is working on a preliminary layout of the gas handling system 
   for the CDC and FDC.  He provided two options for the FDC system design 
   that were essentially a basic version and a fancier version.  Slava's 
   design work was based on the original concept that Brian came up with 
   long ago.  Slava provided some drawings that DSC will review.  We will 
   then continue the design work as we have time.


 - 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.
 - Kim needs to provide an instructional writeup for the Phase 1 and
   Phase 2 wire frame PCB component attachment.  This is on her to-do
   list, and DSC will talk to her about getting this writeup done.

Small-Scale Prototype

 - Simon and Fernando are in the home stretch on completing the specification
   of the cathode and anode ASIC dynamic range.  All required measurements
   have been completed and work is ongoing to finalize the test results in 
   the document.  What we have so far is posted as GlueX-doc-1070.
 - We still have the lingering issue of the problematic x-y plots from the
   2-micron Cu cathodes.  Simon will revisit this problem by taking some
   new pulser calibration data to see if this makes the apparent problem
   go away.

CAD Model

 - We discussed a bit about making sure all relevant design features
   of the FDC are in the full CAD model.  Tim will have Slava work to
   put in the capacitors and resistors on the wire frame PCBs into the 

Work List

 - The FDC short-term work list has been posted on the FDC web site
   (see http://www.jlab.org/Hall-D/detector/fdc/).  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.