Minutes-4-24-2008

FDC Weekly Meeting

Date: April 24, 2008

Participants: Daniel, Simon, Fernando, Roger, Mark, Kim

Next Meeting: May 1, 2008 @ 1:30 p.m.

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Cathode Planning

 - Roger heard back from the representative at Allflex.  They have
   said that they can have our board material in house from Nippon
   Steel Chemical Co. by the end of May and deliver the boards to
   us within two weeks after this.  Roger will work to complete the
   PR in the next few days.
 - Roger still needs to discuss with Allflex our electrical test/QA
   requirements.  He needs a statement from Fernando.  This will
   be built into the PR.
 - Roger still needs to discuss with Allflex our surface defect
   specifications and needs to prepare details on how the boards
   needs to be handled and prepared for shipping.  He should start
   with the specs for the wire frame circuit boards that Kim used
   and they should be reviewed.  This will be built into the PR.
 - The draft PR with all of the above issues and specifications
   included will be circulated internally for comment and feedback
   before this PR is signed and submitted.
 - No progress has been made during the past week on additional
   solder tests of the rigid-flex assembly to the cathode board
   mock up.  Greg Arnold's group will begin this work after the
   solder pencil that they order arrives.  This should be shortly.
 - Note that due to the height of the solder connection between the 
   cathode board and the rigid flex assembly, we will have to revisit
   the design from the standpoint of adding clearance pockets on the
   surfaces that mate up against this solder region.  This discussion
   will begin when Brian is available.

Full-Scale Prototype

 - Outstanding procurements for the full-scale prototype: 
     * The HV capacitors will be delivered to us in about 1 month.
     * The 2nd construction station PR has not been started.  Brian
       will get to this when he is available.
     * The rails will actually not be delivered until mid-May.
     * The rail attachment assemblies are not ready for FSU to
       work on until Bill has time to complete the relevant drawings.
     * We are still awaiting delivery of the 2-mm Rohacell for
       the cathode backing.
 - We had a meeting with Dennis Skopik on the clean room availability
   for the full-scale prototype construction.  We expect that the
   negotiations are nearly complete and we should expect occupancy
   in the EEL building clean room (in the clean tent) in about 2 or
   3 weeks.  More to come once plans are finalized.
 - Brian talked to Casey in the machine shop about completing the
   modifications on our aluminum tooling plate for the wire frame
   construction.  Casey thought it best to do this until just before
   construction.  DSC has suggested that this work is completed first
   thing after Brian returns from IUCF (April 28-30) so that it is
   ready after Brian gets back to JLab from vacation on May 6.
 - Brian will begin wire frame construction for the full-scale
   prototype in earnest during the week of May 4.  He expects the
   frame construction to take 3 days/plane.

Test Frame Wire Winding

 - A phone conference with IUCF took place just after the meeting.
   Both wire planes are wound.  The tension and wire placement
   measurements have begun.
   * The tension measurement is going very slowly due to the technique
     employed.  Everyone is convinced that the results are reproducible.
     Preliminary analysis shows (for the wires measured) that the 
     tension is stable to +/-10%.  This seems to be reasonably under
     control.  IUCF will complete the tension measurements for portions
     of only 1 of the planes today.
   * There are some issues with the wire placement measurements.  Sizeable
     deviations from the nominal placement position have been seen in
     the measurements.  IUCF claims that several effects may be
     responsible.  One is that the wires were laid on the table with
     specifications but that there could be a problem with the 
     measurements.  We mapped out a strategy to test this theory by
     measuring the same plane in the same position but at different
     positions along the measurement system.  A second theory is that
     the problems occurred due problems getting the wire plane to the
     correct vertical height under the wires before soldering.  The
     third theory is that the wires were not laid down on the table
     accurately due to problems with the spooling system.
     ** IUCF will test the first theory day (about the problems with the
       measurements).  They will wind the third frame that Brian brought
       after modifying the frame support to put the frame at the correct
       height relative to the wires.
     ** The last theory about the problems with laying the wires on
        the table is a bit trickier and we may not be able to solve
        in the short term.
  * Brian will be heading back to JLab tomorrow.  He will bring back
    the wound frame with the low-density Rohacell core.  This will
    enable us to test our proposed transport method.
 - IUCF is having a meeting tomorrow to go over the Phase 1 budget
   situation and how much money they have spent.  The Phase 1 contract
   runs out on May 2.  If they require a no-cost extension, then this
   can be done very easily.  If they are not able to demonstrate that
   they can meet our specs and have run out of money, then we will need
   to discuss this internally.  DSC transmit all of these points clearly
   to IUCF.
 - DSC is working with Steve Christo to prepare a wire specification
   document for the tungsten and CuBe wires leading up to procurement.
   Steve is preparing a document for the Hall B chambers and we will
   most likely adopt this document for Hall D.  DSC reviewed the
   existing Hall B documents to give folks a flavor of how these
   documents have been prepared in the past.  We need to make decisions
   on what is required for the FDCs.

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.

Composite Cathode Updates

 - Denny has extracted the tensioning system from mothballs and it is
   now setup in the shop.  Brian will work to make a tensioned cathode
   without foam backing on his return from IUCF.  In tensioning the
   cathode plane he will study how the 3 piece cathode reacts under
   tension.  He will also measure the electrode distortion as the
   tension is increased.
 - Denny has the Acquity Laser system from Fernando and has it nearly
   fully set up trailer 94B.  The sensor is attached on a precision
   vertical pole with its position controlled by a stepper motor.  He
   has downloaded all of the GUI software from Acquity and has gotten
   it all working.  He will pick up the two prototype cathodes and
   bring them out to the trailer.  He has designed and constructed
   a support frame for the cathodes and will make final adjustments to
   it once he has the planes.  In short, he is essentially ready to
   begin the flatness/bulge measurements.  Results will be posted
   once they are available.

Grounding Issues

 - Fernando has completed preparations of an overall Hall D grounding 
   specification document (GlueX-doc-1021).  This is needed for pre-brief 
   material for the upcoming Systems Review on May 7.  Please read it
   over and provide feedback to Fernando soon.

Cooling System Tests

 - Denny has nearly completed the set up of the cooling system.  He
   still has to include the thermistors for reading out the coolant
   temperature local to the preamplifier board.  DSC has received
   the attachment brackets from Bill and passed them on to Fernando.
   Fernando will take care of the measurements.  The tests will take
   place in F117.  The cooling system will be moved over there once
   we have gotten the keys to this room (the order has been placed).

Gas System Design

 - Vladislav (Slava) Razmyslovich is working on a preliminary layout
   of the gas handling system for the CDC and FDC in preparation for
   the upcoming systems review.  We will sit down with him in a
   specialized meeting to review the design concepts after the review
   is over.

Gas Volume Definition

 - No progress on new calculations during the past week.  We will
   revisit the issue of modeling the gas in the drift cell region
   if the input is in the wire frame or spacer after the systems
   review.

STB/HVTB Discussion

 - Last week we discussed the overlap design of the neighboring
   wire frame PCBs.  It was agreed that this overlap is a critical
   part of the design and must be kept.
 - We reviewed the weak areas of the boards.  DSC asked Kim to
   modify the ends of the STBs and HVTBS to add 3 mm of 1/32-in
   material to the ends before the overlap region to improve the
   strength.  Kim did not think that this would improve things too
   much, but the corners of these boards have no 1/32-in material
   in contact with the portion removed for the lap joint.  This
   leads to fragility and pealing of the boards.  Kim will make
   the minor modifications to the STBs and HVTBs, as well as the
   corresponding adjustments to the filler boards.  She has already
   checked with the board house on width, and we can add the few
   mm of width without any problems.
 - 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, but is not a high priority for now.

Cathode Board Discussion

 - 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.
 - Roger was planning to do some test soldering for the rigid flex
   cables to a sample cathode board.  No update was given during the
   meeting.

Small-Scale Prototype

 - Simon has gotten the readout of the cathodes working with the
   ASICs/shapers/FADCs.  Some same pulses have been placed in the
   FDC elog.
 - Simon is now extracting from the data the amplitude distributions
   for the anodes and cathodes.  He should be close to completing
   this analysis of the data.  He will circulate it for discussion.
   He will also circulate plots of the charge collected as a function
   of the readout time.
 - Simon, Fernando, and DSC will prepare a write-up of the analysis
   results and our analysis of the required dynamic range of the
   anodes and cathodes.  Fernando will be in contact with Mitch
   Newcomer on our progress and plans.

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.

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.