FPS Meeting Minutes;  December 11, 1998 (4 pm - 6 pm)
at BNL Physics Bldg, Orange Room

In attendance: J. Kotcher, S. Desai (*), A. Patwa (**), M. Zdrazil, Z.
Wang, A. Talalaevskii, M. Liu

(*) = principle scribe, (**) = co-scribe
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Agenda: Construction Plans and Status (J. Kotcher)
        LED calibration system (A. Talalaevskii et al.)
        FPS Connector Status, cover (A. Patwa)
        FPS Test Station at BNL (M. Liu)

1. Module Construction (J. Kotcher)

 o We have the 1st modules back from the water jet cutter.  They exhibit
    uniformity of cut.  Some modifiaction of their jig may be neccessary.
    A visit to the Water-Jet company located in Albany, NY by members of
    the group: A. Gordeev, M. Liu and J. Kotcher proved to be very useful 
    in preventing confusion and at the same time, providing efficient/
    reliable modules for the FPS detector.  Many pictures of progress on
    this can be viewed on the web: http://fps.phy.bnl.gov --> progress for 
    Dec. 9, 1998.  

 o The possibility has been discussed of plugging the scintallor before
    heating it.  This has the adavantage of making it possible to do more
    of the construction work at Stony Brook.  However, questions remain as
    to how the glue will react when heated -- i.e. avoid channeling into 
    the scintillating hole needed for embedding WLS fibers.

2. Calibration System (A. Talalaevskii) 

 o We have settled on the Hohlraum (cylindrical two LED hallow-cavity) as
   the method to use for the FPS LED calibration system.

 o Work still needs to be done in understanding how the cabling
   (electrical -- ribbon cable) to the LED's will be mounted to the  
   detector.  There are issues of strain relief that must be understood
   before we can finalize this.

 o Two LED's are present in each Hohlraum.  Preliminary tests indicate
    that the two provide very different (factor of 4+) levels of
    illumination to the fibers.  The reason for this is as yet
    unclear.  More testing and confirmation may be needed to understand
    whether this effect is real.

 o Variation due to fiber position is slightly more then 10%, and should
    be easy to reduce and is expected not to exceed ~20% order.

Connectors Status and Protective Covers (A. Patwa)

 o We had 1000 good connectors as of Dec 3.  By now we should have the
    full order of 1500 (Dec. 9-10);  The UIC group which includes M. Chung
    have provided a tremendous effort in making this converge to a 
    successful result.

 o Thirteen of the 1000 connectors have been tested for quality control.

 o For the diffuse LED's the average transmission efficiency is 90.1%.
    The range of efficiencies is 89-93%.  Peak to peak variation ranges
    from 6.5 to 10.5% per connector.  

    For point LED's, these numbers are better by roughly 4% in light
    yield (i.e. N=13 measurements provide 96.5% Avg. Transmission) and 
    p2p should decrease by 3-5% per connector.  The measured numbers are
    within specs, and for many, perhaps better.

 o A protective cover has been designed to protect the connectors during
   construction, installation, etc.  The cover will be made via a thermal-
   machine available at lab 8 at Fermilab.  Approximately, 2000 covers
   will be ordered and consist of a rectangular, white polystyrene cavity.

 o The total cost for the connectors (including Hex Screws, alignment
    pins, and covers) is slightly more then $5k.  We have $5K alloted
    for this (from WBS Connector Hardware/Supplies).

 o The first connectors for the VLPC's have been tested.  The 
   have 128 (=8x16 array) channels. The diameter of the fiber hole in the
   connector is 965 micron for FPS 835 micron clear fibers. 
   The peak to peak variation is 4% for 965 micron fibers and slightly
   increases to 9% for our FPS clear fibers.  The Quality Control on these
   connectors look very efficient.

Test Station (M. Liu)

 o Ming has used the test station to check mapping on the prototype
    module.  A three-dimensional plot of ADC pulse count, Channel No. and
    ADC position will provide an indication of swapped channels/fibers
    all measured via a programmable motion control system consisting of
    our (collimated) blue LED.  Things are going well on this front.

The meeting adjourned at 6 PM with a following FPS meeting to be held at
the D0 Upgrade Meeting week (Dec.17/18) at Fermilab.