[Halld-target] Minutes, GlueX Target Meeting, Apr. 12, 2011

[Mark M. Ito]

Find the minutes at 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_Target_Meeting%2C_April_12%2C_2011#Minutes 
and below as text.

   ==

GlueX Target Meeting, April 12, 2011
Minutes

    Present: Hovanes Egiyan, Mark Ito, Chris Keith, Rory Miskimen, Tim
    Whitlatch (chair), Elliott Wolin
      * Tim brought along drawings and notes made two years ago, modeled on
        the Hall B cryotarget.
           + We may need to pick Steve Christo's brain, especially about
             lessons learned in Hall B.
           + The Hall B targets are Kapton, with DP190 epoxy joining the
             seams. The scattering chambers are made of Rohacell.
           + We will have to perform pressure tests on the cells. Current
             code may be more stringent than standards at the time the Hall
             B targets were commissioned.
      * The refrigerator will be bought in October or November.
           + The model being considered can liquify hydrogen starting from
             room temperature, at about a liter per hour, corresponding to
             15 watts at 20 K. Liquid hydrogen volume looks to be of order
             a liter. Helium-4 will take longer to liquify.
           + The requirement that we want to be able to empty/fill the
             target on the time-scale of a few hours (preferably less) was
             restated.
           + The refrigerator have no cold moving parts.
      * We will have to design and build the heat exchanger and heating
        element. The refrigerator will stay on continuously and temperature
        of the hydrogen controlled with a heater in the cold head.
      * The gas panel can probably copied from that used by Q-Weak.
      * Mechanical considerations
           + The target, its plumbing, and the refrigerator (including cold
             head) will all be a "rigid body". Adjustment of the position
             of the target on the beam line will be accomplished by
             positioning the entire structure.


Items for the Next Meeting

      * Chris will create a P&I diagram for the gas/refrigerator system
      * Chris will distribute the manual for the refrigerator so others can
        get started thinking about the relevant controls and monitoring.
      * We will invite Steve to the next meeting.
      * Next meeting in about a month.

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