[Halld-pid] Minutes, GlueX Start Counter Meeting, March 22, 2012

[Mark M. Ito]

Folks,

Find the minutes below and at 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_March_22,_2012#Minutes

   -- Mark
   _____

GlueX Start Counter Meeting, March 22, 2012

Minutes

    Present:
      * FIU: Werner Boeglin, Puneet Khetarpal, Eric Pooser
      * JLab: Fernando Barbosa, Chuck Hutton, Mark Ito (chair), Beni
        Zihlmann

Prototype Report

    We are still waiting for a prototype counter from McNeal.

Readout Design

    Since the last meeting, we had a meeting with Fernando to answer some
    basic mechanical questions. At that meeting we decided on a
    segmentation of 10, to aid alignment and to simplify fabrication of the
    circuit board. Since then Chuck has done some work on the design and we
    reviewed [? his slides] showing the latest version. He showed a new
    scheme for attaching the start counter to the target vacuum chamber and
    a circuit board concept showing the location of the individual SiPM SMD
    components.

Cooling

    We had a short discussion on cooling. Fernando reported that in the
    case of the BCAL readout it was recently discovered that non-uniformity
    in the contact pressure between the cooling elements and the SiPM
    arrays was causing temperature variation channel-to-channel with
    attendant gain variation. For the start counter we plan to cool with
    air flow so the details of maintaining a stable temperature are
    different. Fernando suggested that we could use some sort of
    heat-sink/heat-spreader/radiator to make sure there are no hot spots
    among the read-out elements.

Discussion of Design

      * Chuck asked Fernando for some details on the non-SiPM side of the
        boards, e. g. a rough profile of components, connectors, cabling,
        etc.
      * Werner suggested an alternate scheme for mounting where the entire
        start counter array, including electronics, is assembled on a
        separate rigid mounting collar independent of the target. The
        current design has the counters mounted on the vacuum chamber first
        and then the SiPM's aligned and fastened to the vacuum chamber as
        well. In the alternate scheme there would be simple way to bolt the
        mounting collar rigidly to the vacuum chamber. It would have the
        advantage of providing a simple way to detach the start counter
        from the target when/if that is required. The scheme would require
        modification of the current design of the vacuum chamber, but it
        was thought that this could be accommodated.
      * We realized that now we are at the stage where the many details of
        the mechanical design that need to be worked out, especially
        related to supporting and light-tighting the scintillators and SiPM
        read-out. We will try to arrange a meeting with Youri Sharabian to
        review how some of these issues were solved for the Hall B start
        counter.

New Action Items

     1. Get some details of circuit board design to Chuck. -> Fernando
     2. Arrange a meeting with Youri to discuss design details. -> Mark

    Retrieved from
    
"https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_March_22,_2012"


-- 
Mark M. Ito
Jefferson Lab (www.jlab.org)
(757)269-5295