Minutes 2-28-2008

FDC Weekly Meeting

Date: Feb. 28, 2008

Participants: Daniel, Mark, Simon, Chuck, Roger, Fernando, Bill

Next Meeting: March 6, 2008 @ 1:30 p.m.

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Test Frame and Prototype Wire Winding

 - Nothing new to report on the status of the contract for the Phase-1
   prototype winding.  An inquiry has been sent to IUCF to find out where
   they are (as the ball is in their court).

Full-Scale Prototype

 - Procurement is underway for materials and boards for the prototype.
   So far the order for the preamplifier daughter board card connectors
   has gone out, the Rohacell foam, and the circuit board components
   (resistors and capacitors).  The PR for the wire frame circuit boards
   is awaiting Elke's signature before being sent to procurement.  
   Hopefully this will happen very early next week when Elke returns from
   her travels.  The cost for these boards was a factor of two higher
   than we expected (based on earlier version of the quotes that we
   received).
 - Brian reported that the company that was our Rohacell supply source will
   no be handling distribution as Rohacell is setting up their own direct
   distribution.  No word on how long a delay we can expect.  However, the
   old supplier will send us part of our full order and the rest will have
   to come from Rohacell when they are up and running.
 - We still need to start procurement on the G10 skins, a second
   construction station, the cathode boards, and the cathode daughter
   boards.  The G10 skins should have a PR put together soon.  The
   cathode flex boards and cathode daughter boards will be ready for
   procurement within two weeks if all goes according to plan.
 - We need a separate meeting to discuss cathode tolerances and construction
   issues with Roger and Brian.

Composite Cathode Updates

 - No further progress has been made on completing the composite cathode
   sandwich.  Brian will get back to this when he has time.
 - Brian still has to prepare a gas inlet and outlet tube and perform
   a trial insertion to finalize this design.
 - We need to finalize our plans for vibration calculations and
   measurements.  Chuck will check with his sources to find out if
   there is an expert on-site who can compute the natural frequency
   of our cathodes using finite-element models.  We also need to devise
   a measurement to make this determination with one of our prototype
   cathodes.

Grounding Issues

 - We believe that we have completed the majority of the design to
   distribute ground to our chambers.  The ground connections for the
   wire frame will include a "faston" spade connector soldered to
   a clear region on the circuit boards.  This same type of connector
   will be included to attach ground to the ground plane, although
   details need to be finalized and a prototype needs to be made.
 - To attach ground to the cathode boards, the best solution is to
   include a 10th daughter board card whose sole purpose is to 
   attach ground to the flex board ground pours.  All circuit boards
   will be connected electrically using a thin layer of conducting
   epoxy at the butt joints.  The 10th daughter board will have a
   ground connection on the back of the G10 skin from a faston connector.
   A rigid flex board will feed through a cut-out in the G10 skin and
   be soldered to the ground pour.  Note that the ground pour on the
   cathodes will not be continuous around the ring to eliminate eddy
   currents in case of a magnet quench.  Note that Chuck needs to provide
   information on where this 10th card can go.
 - For the FDC TDR, Fernando will provide a brief writeup on the
   overall FDC grounding scheme.
 - Fernando has asked for a sample of our ground plane material (about
   1 square meter) for resistivity checks.  Simon will follow up on
   this.

Gas Volume Definition

 - Bill has completed his para-solid model of the FDC.  He will meet
   with Dave Meekins on Friday to begin the flow calculations.  The
   main question that we need to address is what holes to include in
   the cathode board.  One hole is, of course, the beam hole, but we
   also need to consider adding holes in the space between the last
   strip and the G10 skin.  This question should be finalized before
   we order the cathode boards.

Cathode Board Discussion

 - Both Roger and Fernando have been pursuing leads on obtaining
   cathode flex boards with less than 2 microns of copper.  Roger
   contacted CP films, and they cannot go thinner.  Another possible
   contact is Sumitomo in Japan.  They claim on their web site that
   they can sputter copper down to 1 micron.  Roger will follow up
   on this lead.  Fernando has been in contact with 3M in Germany.
   They claim that they can vacuum deposit gold on Kapton down to
   0.2 microns.  He has had very little luck finding anyone knowledgeable
   in the company on this front.  Perhaps Elke can help by talking
   directly with the engineers in their native tongue??  Fernando will
   follow up on this lead.
 - Roger will follow up with Brian on the idea of including the
   through-holes on the flex boards prior to delivery.  Would he
   prefer they be made with an exacto knife later on in the process.
   Tolerances are very tight on the cathode boards due to the placement
   of the cathode daughter boards.
 - Roger needs to prepare a write-up for the QA tests on the cathode
   boards to be done at the board house.  This should be circulated
   for discussion.  He also needs to prepare documentation on the
   QA/stuffing/cleaning details for the cathodes and cathode daughter
   boards.
 - Roger is finishing up on the cathode boards to include the new
   ground connection scheme.  He will then finish up the cathode
   daughter board layout.  He expects that these boards will be ready
   to order in about 2 weeks (maybe less).

STB/HVTB Issues

 - Kim needs to prepare a document of instructions for the wire board
   stuffing.
 - Kim needs to prepare a document for QA procedures for the wire
   boards upon delivery.
 - No update on the modifications to the aluminum construction jig
   for wire frame and cathode frame assembly.  This needs to be
   done soon.
 - A group of us met with Greg Arnold over in accelerator about the
   work to stuff our prototype circuit boards.  We provided detailed
   descriptions of the system and the work to be done.  Greg gave
   us a tour of their facilities.  We were all impressed with their
   infrastructure and it seems clear that they can handle the stuffing
   of our boards following industry standard procedures.  One issue
   that will need to be addressed soon is the post-winding stuffing
   that needs to be done.  Does this work have to be done in a 
   clean-room environment?  How will the final board cleaning stages
   be handled with the wires in place? 

Cooling System Update

 - Denny is working to set up our cooling system test.  Bill has
   provided him with some of the materials and instructions.  We need
   to follow up with Denny to find out if he has everything necessary
   to proceed.  The consensus was that once the composite prototype
   is completed, setting up for the cooling test should be a higher
   priority.
 - Part of the cooling tests will include studies of air-cooling for
   the CDC. Fernando will contact Curtis to bring him up to speed on
   the proposed test plan and to get his direct input.
 - Note that Fernando has the thermistors and readout for these studies.
   We need to include the thermistors on the preamp daughter card
   voltage regulator, the copper bracket on the card, the mating
   bracket to the cooling line, and possibly the cooling line itself
   so that we can map out a complete temperature profile and gradient.
   These measurements will allow us to finalize the system design.

Dry Air Flow

 - Part of the nominal environment control plan for the FDC is a 
   dry air flow system.  Chuck will begin thinking about this and
   provide a block diagram for the system.  It could be that we can
   tap into the air cooling system for the CDC and provide some
   ducts that feed into the solenoid.  The gas flow should be low
   to avoid introducing and pressure waves

Small-Scale Prototype

 - Brian has mounted the first 75 deg cathode (no connector yet).  The
   second one will follow shortly.  As soon as they are ready, Simon
   will move to immediately install them into the small-scale prototype
   and test them out.  Remember, these are the first cathodes that we
   have with 2-micron copper traces (all others are 5 microns).  Simon
   should prepare a test plan and circulate (especially seeking feedback
   from Fernando and Gerard on steps needed to bless these boards).  Keep
   in mind that we are still actively looking to go down to 1 micron
   (or thinner) copper if we can get away with it!

Cathode Flatness Measurements

 - Bill has been continuing to track down leads.  He talked to the
   folks at Brown and Sharpe about a non-contact measurement system
   for their coordinate measurement machine (like the one in the JLab
   machine shop).  They turned him on to an outfit in Charlotte that
   has a system presently capable of performing these measurements.
   Bill will get a price quote and see when we could bring a cathode
   down to them for measurement.  Bill will also continue to follow
   up on putting together a measurement system here at JLab.

Meeting on LV/HV System Design

  - We are progressing on the design for the chamber LV and HV systems.
    Fernando is updating his system design documents and will circulate
    them when they are ready.

FDC Insertion Planning

 - A meeting on FDC (and other system) cabling is being scheduled
   (tentatively next Wed. at 1:00 p.m.).  We need to converge on
   FDC insertion plans, cable layouts, and cable routing.  There are
   a number of important issues that need to be addressed, such as
   the ability to pull the FDC out the downstream end of the solenoid,
   the coupling of the FDC to the CDC, and the cabling system and
   support that runs from the FDC out the upstream end of the magnet.

FDC Mini-Review

 - An official version of the close-out report is not yet available.
   It will be circulated once it is finalized.

Gas System Design

 - Brian (or someone like him) will need to advance the design of the
   chamber gas handling system beyond the preliminary system design
   that he prepared quite some time ago.

Upcoming Reviews

  - The combined tracking/PID review for Hall D is scheduled to take
    place on March 27 and 28.  At this point, we are converging on
    a charge and the list of speakers.  We have to prepare talks and
    backup materials for the FDC, CDC, and charged particle PID systems.
    The details will be worked out over the next week or so and
    preparations will continue from now until the review.
  - In preparation for the meeting, we will need an updated set of
    design drawings for the FDC web site.  New drawings from the
    mechanical model will need to be provided that reflect the current
    design.
  - DSC will circulate the modified FDC TDR and solicit new/updated
    system drawings to replace outdated ones that he has.

Drawings

 - DSC has collected all of the available FDC subsystem design drawings
   and placed them on the FDC website.  The URL is:
   http://www.jlab.org/Hall-D/detector/fdc/drawings.html.  Folks should
   go through the drawings and let DSC know what drawings and/or categories
   are missing for a complete design set.
 - Also folks should send DSC the latest design drawings where there
   have been changes to keep this web site up-to-date through the
   review season.

Meeting with ERNI Representative

 - After the FDC meeting a number of us met with Susan Price, a
   sales rep for ERNI.  They will be able to make our signal cables
   to our specifications, including handling of the 3M connectors,
   and shielding modifications.  She will prepare a price quote for
   us.
 - We also discussed details of the mini-bridge connectors for power
   and the daughter board connectors.  She will investigate the issues
   with long lead times and get back with us.

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.