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FDC Weekly Meeting

Date: June 5, 2008

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

Next Meeting: June 12, 2008 @ 1:30 p.m.

Cathode Planning

 - Roger has distributed board files to Chuck and Bill to look over
   the gas hole placement.  He will also distribute board files to
   Fernando to look over the circuit layout.  At the same time, Roger
   is preparing a draft of the PR and is working on finalizing the
   fabrication notes.  He will circulate a copy of these notes this
   week for review.
 - DSC spoke with Elke about the total cathode board costs.  The quote
   is expected in the next few working days from Allflex.  We have
   about $20k in the budget and we will decide what we can purchase
   when we have the quote in our hands.
 - Additional solder tests of the rigid-flex assembly to the cathode board 
   mock up will proceed after Roger gets the hot air pencil from Fernando.
   This work will wait until the cathode board PR is completed.
 - 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.  Chuck is responsible for looking into
   this and letting us know.
 - Bill arranged to have the cathode transportation box sent directly
   to Allflex.
 - Brian will modify his Lucite box design for storage of the completed
   cathode planes.  The cathode planes can stack upon one another
   (unlike the strung wire frames).  He will make some minor modifications
   to the existing box drawings and prepare the PR.

Full-Scale Prototype

 - Greg Arnold's group is nearly done with the soldering of the HV
   capacitors to the STBs and HVTBs.  Two completed sets of boards
   have already been delivered to Simon.  Kim has asked Greg's group
   to complete 5 complete board sets (including putting resistors on
   at least one more set).  This will enable us to prepare up to
   five wire frames for winding for the Phase 2 phase.
 - The order for the 5 ft x 5 ft granite table got held up to a snafu
   on shipping costs.  The table will take 4 to 6 weeks to arrive once
   the paperwork is finalized.
 - Brian and Kim are making progress on finalizing the drawing for
   the aluminum tooling plate for the cathode frame and anode frame
   construction.  This should be done very shortly and turned over
   to Casey in the machine shop.  Once he gets this he will modify
   the existing tooling plate and make a second plate.
 - Brian has moved a storage cabinet into the clean tent in the EEL 
   clean room.  He will also shortly move in a work table.  Dennis
   Skopik has been asking when we plan to start to do work in there.
   As Brian will be gone for most of the remainder of the month, it
   appears that work will not take place in the tent for some time.
 - Brian and Bill will work to update our wire frame construction sequence
   document.  Brian will provide a first draft to Bill who will work to
   polish it up.  We would like to provide this to Casey so his group
   (and of course ours) can full understand the procedures.  This work has
   not yet gotten underway.

Cathode Prototyping

 - Brian has attached a ground plane to the back of our tensioned
   cathode plane.  This work was done to develop a way to ground both
   sides of the ground plane.  The technique employed is to use a
   piece of copper tape and stick it into a pocket machined into the
   edge of the G10 skin.  Silver epoxy is used to make a conducting
   connection to the top side of the ground plane.  The external
   ground connection can then be made to that portion of the copper
   that sticks out.  After a bit of discussion, we are worried that
   the copper tabs will be too fragile and will eventually tear off.
   DSC suggested to use a piece of flex board (copper coated Kapton).
   The Kapton will be much less susceptible to tearing.  We will work
   to develop this method.  This method can also be used to make
   additional ground connections to the cathode boards.
 - One thing that Brian noted was that the ground plane that is
   attached is actually a second attempt.  The epoxy did not cure
   on their first attempt.  What is a concern is that the epoxy in
   the sample cup did harden completely, but the thin film under the
   ground plane did not cure.  Brian believes that this was due to
   unusually cold temperature in the machine shop.  The curing time
   of the epoxy is temperature dependent.  This is something that we
   will monitor carefully.  The cooler the temperature, the longer the
   epoxy curing time.
 - We will try to develop a cathode tension measuring system using our 
   laser measurement head.  The procedure will be to direct a puff of 
   air at the center of the cathode and measure the amplitude fluctuation 
   vs. time through the laser measurement system.  Fitting this amplitude  
   distribution will give us (hopefully) the fundamental frequency that 
   we should be able to convert into the membrane tension.  

Test Frame Wire Winding

 - After the regular FDC meeting, we had a teleconference with the
   folks at IUCF on the phase 1 wire winding.  While much progress
   has been made, the facility is still not yet able to meet our
   wire position and tension specifications.  We decided to pursue
   extending the phase 1 contract to allow for up to two additional
   planes to be wound.  Brian and Simon will gather the two additional
   wire planes that we have made for shipment to IUCF.  The bottom
   line is that we will put off discussion of phase 2 with IUCF for
   the time being.  The plan is for IUCF to provide a rough cost
   estimate for the extension work before we move on this end.  We
   will plan to have a meeting with the IUCF management during the
   middle of next week.
 - 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.
 - Note that Brian completed inspection of the wire frame that he
   transported from IUCF to here.  The final report is that there were
   no broken wires.  Good news.

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.

Cathode Flatness Measurements

 - Denny is continuing to study the flatness of our prototype cathodes.
   Presently he is moving the system to EEL 126 to get it ready for
   our summer student Micah to take it over and complete the existing
   measurements and to upgrade the system to automate the 2D scans.
   Friday June 6 is Denny's last day with us and DSC will meet with
   him to go over where we are.

Cooling System Tests

 - Denny reassembled the preamplifier cooling system in F117 and set
   the flow and temperature.  Fernando is getting ready to perform the
   cooling system measurements.  Bill has ordered a flow control
   valve that will arrive shortly and be installed in the system.

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 when we get a chance.

STB/HVTB Discussion

 - 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.

Small-Scale Prototype

 - Work continues on characterizing the preamp daughter boards to
   specify the ASIC dynamic range for both the FDC cathodes and
   wires.  Simon is extracting from the data the amplitude distributions.
   He is making progress in acquiring spectra where noise-related
   events are not included (so that we do not bias our results).  Once
   he has acquired the spectra for minimum ionizing particles, we need
   to convert this into the numbers required for the more heavily
   ionizing particles of interest.
 - Simon, Fernando, and DSC will prepare a write-up of the analysis
   results and assumptions that went into specifying the dynamic range
   numbers for the anodes and cathodes.
 - Brian performed an optical scan of the edges of the 2 micron Cu
   cathode boards in the small-scale prototype (actually he scanned one
   of our spare planes).  He used a x50 microscope for this.  He found
   that the edges were pristine with no evidence of any wavy-ness.  This
   rules this source out as a potential explanation for the wavy
   wire position reconstructions with the current prototype.  This leaves
   possibilities of gain miscalibrations (Simon will take more data in
   the near future).  Another possible source that was discussed in the
   meeting was a surface wave in the cathode.  Brian indicated that these
   cathodes were not a tensioned as previous versions.  We will perform
   a visual inspection when we have time.


 - 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.