From GlueXWiki
Jump to: navigation, search

FDC Weekly Meeting

Date: April 10, 2008

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

Next Meeting: April 17, 2008 @ 1:30 p.m.

Cathode Planning

 - Fernando provided some contact information for several companies
   (Microconnex, Multek, Minco) over the weekend.  Roger has 
   initiated contact with representatives for each of these companies.
   It looks like Microconnex cannot handle boards anywhere near our
   size.  Multek is a sister company of Sheldahl and they are interested
   in our project.  They are looking to see what they have in stock and
   look more into their capabilities.  They will contact Roger again shortly.
   Minco has not yet been contacted.  In making these contacts, Roger was
   turned onto a company called Allflex that could possibly do our etching.
   They told him to contact Nippon Steel Chemical Co about providing the
   material.  Roger has made contact with Nippon and is waiting to hear
   back from their sales representative.
 - Jim has heard from from his contacts at HERMES regarding polyimide
   film.  They do not know of any companies that can provide the
   1-mil Kapton with 25 micron copper.  They did provide some follow
   up questions for us to answer.
 - Gerard has raised some points regarding material specification
   for the cathodes and that we need to put together a specification
   document.  His concern was the minimum isolation resistance between
   adjacent strips at a specific test voltage.  We will work to
   prepare a specification document based on input from the board house
   on their "standard" electrical checks.  We will be sure that our
   required specifications are built into the contract.
 - One possibility that has come up is to move to a cathode with 5 micron
   of Copper if we can eliminate the 2-mm thick backing.  This represents
   only a very modest increase in materials.  It may be our only option
   ultimately.  However, we shall see.
 - Fernando will do some calculations for the strip-to-strip capacitance
   to study signal propagation and noise.  This work will begin after the
   systems review on May 7.  In the mean time, Fernando will be given some
   cathode samples from the small-scale prototype.  He will measure the
   strip-to-strip capacitance and scale the numbers up for the full-scale
   boards.  Brian will provide the samples for Fernando.
 - Roger's test fixture for solder studies with the rigid-flex assemblies
   has arrived.  This will be passed off to Greg Arnold's group to complete.

Full-Scale Prototype

 - The G10 order should have arrived and Brian will find out.  Brian has 
   all of the parts and pieces to begin construction of the full-scale 
   prototype wire frames.  DSC will work with Brian to prepare a construction 
   time line for the wire frames so that they are ready to go to IUCF
   for the Phase 2 shortly after the completion of the Phase 1 winding.
 - The HV capacitors are expected to arrive by the end of May.  These
   are the only components that have not yet been delivered.
 - The order for the cathode rigid flex assemblies (cathode daughter boards
   and cathode ground boards) has arrived.
 - No progress has occurred on modifying the aluminum construction jig
   as Brian has not yet gotten to this.  Hopefully we can converge
   on completing this work before Brian goes to IUCF. 
 - Clean room occupancy: Jack Segal is aware that we will need the space
   shortly.  If possible, we would like to move all prototype detector
   construction into the clean tent.  Only the mechanical prototypes should
   be done in the shop.
 - Second construction station: Brian will soon get to this PR.
 - Greg Arnold has asked us to provide information on what work we
   will need his group to perform and what the timelines are.  Kim
   has provided information for the wire planes.  Roger needs to
   provide information for the cathode planes and cathode daughter
   boards ASAP.
 - The rails and bearings could have been delivered.  Bill will check into
   this.  The folks at FSU will manufacture the attachment pieces once Bill
   provides drawings.  This will happen after the review.
 - Fernando reported that the tool to attach the connectors to the SpectraStrip
   cable has finally arrived.  No more c-clamps and prayers.

Test Frame Wire Winding

 - Work at IUCF continues.  The wire winding machine, tension measurement
   system, and wire position measurement system are all operational.
   IUCF is testing the wire position measurement system with an existing
   wire plan to finalize the measurement procedure and the parameters
   for the equipment.  They are presently working on the construction
   of a support frame for the wire winding and the measurements.  It
   looks like they will be ready for Brian to arrive on April 21.  They
   hope to have the two planes wound by April 25.  Note that IUCF has
   received the wire frames and strongback that we shipped out there.
 - 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

 - Brian and Denny prepared another cathode plane, but there was a
   problem with the epoxy sample used and it did not harden.  The 
   cathode planes were therefore peeled off the frame.  Brian and
   Denny will start again.
 - Brian is working to set up the laser measurement system from
   Acquity Laser that we received so that we can do some measurements
   of our cathode planes in a vertical position.  We are concerned
   that the plane is too "floppy" and has too much gravitational sag
   (the old beer gut problem).  The measurement should quantify this
 - Brian will also work to make a "tensioned" cathode plane without
   the Rohacell backing.  How much can we tension the planes without
   distorting the electrodes (or only distorting them within allowed
   tolerances)?  Is the Rohacell (only 2-mm thick) actually worsening
   the problem?  Of course, if we can successfully design a cathode 
   plane without the Rohacell backing, the issue of sealing the Rohacell 
   becomes moot.

Grounding Issues

 - Fernando will supply an overall grounding specification document 
   very soon.  He is working on it.

Gas Volume Definition

 - Dave Meekins has finally managed to get a model of the gas volume
   that his program can handle.  This version is only twice the size
   of the nominal design.  In this model, there is only the central
   beam hole in the cathode and the gas inlet is at the bottom of the
   space between the ground plane and the cathode plane.  The gas
   outlet is at the top of the space between the neighboring cathode
   and ground plane.  The results employed a 40/60 Ar/CO2 mixture.
 - We have received results with 3 volume exchanges per day and with
   12 volume exchanges per day.  A first glance at the results shows
   the at low flow rates, the gas is quite non-uniform and is quite
   unsatisfactory in terms of ensuring a uniform gas distribution in
   our drift space.  The severity of the problem is reduced significantly
   at the higher flow rate, but is still not satisfactory.  
 - What we need is for the calculation to tell us what a reasonable
   design should be for distributing gas in our chambers.
 - We need to work to come up with a design that allows the gas inlet
   and outlet on the spacer frame.  This will allow for a single design
   for all layers.  It may also be that we will need multiple gas inlets.
   Bill believes that this design can work with our current cathode
   design if we can allow for cathode through-holes at the top and bottom
   of the cathodes.  The only space available is in the G10 frames, this
   needs to be looked into so that we can converge on a design.

STB/HVTB Discussion

 - Kim has worked with Greg Arnold to update Fernando's original
   cleaning and soldering specification document for the wire frame
   PCBs.  Fernando has review it and posted it on the GlueX portal
   as GlueX-doc-1016.

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

Small-Scale Prototype

 - Simon has managed to restore his DAQ system after he got the new
   (used) computer.  He has started a new run with the 40/60 gas
   mixture with the Hall B SIP preamplifiers and the charge integrating
   ADCs.  This configuration will be studied before moving back to
   the ASICs.

ASIC Studies

 - Fernando has prepared a document listing the studies necessary to
   complete with the ASICs for both the FDC and CDC.  The goal is
   to complete this list of measurements in about one month.  The
   main questions to be addressed are the dynamic ranges for the
   FDC anodes and cathodes.  This information needs to be provided to
   Mitch Newcomer so that he can update the ASIC design for the
   June submission deadline.
 - The initial studies with the small-scale prototype will be carried
   out with the SIPs and charge-integrating ADCs to determine the
   dynamic range for required for both the anodes and cathodes.  More
   details will be included in future minutes as we make progress with
   the measurements.


 - The combined CDC/FDC meetings will be on Monday afternoons at
   1:30 p.m..  A schedule for the rooms has been sent around.  We
   will hold our first meeting on April 14.  An agenda will be
   prepared and circulated.
 - DSC has provided an updated system budget to Elke.  The big
   changes to the CD-2 baseline budget were the doubling of costs
   associated with the wire frame circuit boards and the addition
   of Roger's cathode daughter boards (which were not included at
   all in the original budget).  These cost increases were balanced
   by a significant reduction in the signal cables costs.  The overall
   budget was essentially unchanged compared to the 2007 version.


 - 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.