Minutes 8-8-2007

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FDC Weekly Meeting

Date: August 8, 2007

Participants: Daniel, Simon, Brian, Tim, Chuck, Fernando

Next Meeting: August 15, 2007

Cathode Update

 - The +/-15 degrees cathodes for the small-scale prototype have arrived 
   from CCT Marketing.  The order consists of 6x2 boards total.  These 
   boards have 2 um of copper on a 1 mil Kapton backing.
 - Simon checked the boards out after the meeting with an Ohm meter
   and found no short problems!  
 - Brian will mount two of the boards to our remaining G10 frames.
 - Brian has still not heard from Sierra if they can make the boards for
   our large-scale prototype.

Prototype Design Planning

 - No discussion on the STBs and HVTBs as Kim and Roger were absent
 - We need to get the outline of the two-piece STBs and HVTBs completed
   and sent out so that we are certain that boards of this size will
   not be a problem to manufacture.
 - We all agreed that the list of design questions have been suitably
   answered for now.  The remaining issue is the size of the deadened
   beam area on the wire planes and whether we need to split the cathodes
   in the middle.  David Lawrence is looking into this presently and
   work continues.
 - Fernando has completed the layout and design of the daughter boards.
   He will send the final specs to Chuck and to Kim.  He will send these
   boards out for manufacture.  He presently has 10 ASICs in his possession
   and the daughter boards will be stuffed and tested when the board
   are done.  Fernando will begin work on the interface board between
   the small-scale prototype and the daughter board shortly.  We would
   like this to be ready for October so that we can thoroughly check
   out the performance of the ASICs.  Fernando will contact Mitch and
   Gerard to find out what we should plan on measuring and quantifying.
 - Fernando sent the LV connector information to Joe who will order
   the ERNI connectors.  The good news is that these connectors are
   rated for currents up to 3.7 A/pin.
 - Fernando and Joe have also had recent discussions on the layout of
   the LV system.
 - The sample readout cable order is out and the shipment is expected
   to arrive in about 6 weeks.

TDC Design

 - We had a meeting earlier this week on the TDC design.  There it was
   decided to have a single TDC design for both the BCAL and the FDCs.
   The differences between the modules will be in the front-panel
   connections and the number of chips installed.  The readout will
   have two 50-pin connections on the front for the FDC version.
 - We also discussed the issues with the pulser calibration circuitry
   for the FDC anodes.  The purpose of this system is to provide for
   a fixed time delay measurement and life check of the electronics
   and cabling.  DSC was concerned about the possibility of cross talk
   on the daughter board circuitry, although Fernando stated that this
   was expected to be negligible.  The pulser system would be nice to
   have integrated into the TDC design (which Fernando believes amounts
   to a minimum of manpower effort), but it is not viewed as critical
   for the chamber calibration.

Wire Frame Studies

 - Brian will be constructing a second composite wire frame with the
   final dimensions needed for the large-scale prototype.  He will then
   do a stress test of this design to compare to the calculations 
   provided by Tim.  This frame will have all of the through-holes
   drilled into it as well as the o-ring groove.  The design is made
   up from a 3.8-mm thick inner layer of high density Rohacell foam
   and two 0.6-mm thick G10 skins.
 - The Rohacell has just arrived and Brian has the G10 skins.  He will
   be work this week to make up the composite frame.  The frame will
   then go to the JLab Machine Shop and it will be completed at the
   end of this month.
 - Brian has an epoxy in mind for sealing the o-ring groove, and this
   will be an important part of the test as the groove goes all the
   way through the G10 and into the Rohacell.

Magnetic Field Tests

 - Work continues apace for the upcoming magnetic field test of the
   small-scale prototype chamber in Hall B.  Simon is working on
   reconnecting the electronics and stringing the signal, HV, LV,
   and gas lines.  The 8 IUCF MWDC chambers that will define our
   cosmic ray outside of the magnet are now in the Hall and the gas
   system will be completed by tomorrow.  The chambers will then be
   conditioned and run up to full operating voltage (cathodes and
   field wires at ground, sense wires at ~3 kV).
 - The magnet will be energized later this week and the field mapping
   will begin.  We would like a reasonable size grid in the magnet
   plane to be completed so that we know the strength of the field
   and its uniformity.  We also need to measure the field above and
   below the magnet to ensure that the PMTs will not be affected nor
   the operation/calibration of the MWDCs.  Simon will talk to Paul
   Brindza about TOSCA calculations for this magnet.
 - We should be able to install our detectors in and around the magnet
   starting early next week.  Our goal is to start cosmic ray runs
   at zero field by the end of next week.


 - David Lawrence is completed an updated geometry document that includes
   the latest FDC geometry and materials (including electronics, cables,
   support structures, cooling system, rails + supports, and composite
   frames).  This document also details the changes to the CDC design.
   This document will then be circulated for review and then sent to
   Richard Jones to implement the changes.

Cooling System

 - We had a short discussion of the plans for the cooling system for the
   on-chamber electronics.  We still have a way to go to flesh out the
   design, but we all felt that all issues were solvable.

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.