[Halld-pid] Start Counter Meeting Minutes, February 6, 2014

[Mark Ito]

Folks,

Find the minutes below and at

https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_February_6,_2014#Minutes 
.

   -- Mark
______________________________________________________________________________

GlueX Start Counter Meeting, February 6, 2014
Minutes

    Present:
      * FIU: Werner Boeglin, Eric Pooser
      * JLab: Eugene Chudakov, Chuck Hutton, Mark Ito (chair), Tim
        Whitlatch, Beni Zihlmann

Construction News

Problem with Scintillator Manufacturer

    Eric reported news from McNeal that the 50 pieces of scintillator
    received from Eljen were flawed. There are [26]visible bubbles in the
    bend region and the edges are not in a single plane, i. e. there is a
    [27]skew in the nose relative to the barrel. These pieces are clearly
    unacceptable.

    McNeal will send them back to Eljen. Eric contacted Chuck Hurlbut of
    Eljen; they will investigate the cause. Currently the thinking is that
    the bend was overheated (thus the bubbles) and not held in place long
    enough during cooling (thus the skew). They are pressing new
    scintillator already. Eljen will not charge FIU for this batch. Note
    that the previous set of five counters looked very good in all aspects:
    visual appearance, shape, and timing resolution.

    We estimated that this introduces a two-month delay in the schedule.
    June is now the target completion date for construction.

Assembly Jig

    The assembly jig is coming together. FIU will start practicing with the
    five prototype counters so they will be ready when the production
    modules come in.

Support Structure

    The new 3-layer carbon fiber inner sleeve complete. The Rohacell foam
    should be in any day now. Machining and assembly should take four
    weeks.

    Eric has seen a situation where in the test stand, the aluminum support
    contacted some resistors on the SiPM board if the spacing between the
    two is not controlled. Chuck will check on this issue for the full
    detector.

Fast Shutdown

    Mark raised the question that Hovanes has posed to the groups about
    whether there are any special considerations for fast-shutdown systems
    that the controls group needs to know about. There seem not to be any
    equipment safety issues. Temperatures will be monitored via on-board
    thermisters. Those channels have been accounted for in the controls
    design. They can presumably initiate a shutdown of the MPOD, likely in
    the same way it is done for other SiPM-based read-out systems.

Quality Assurance

    In light of the recent troubles with the scintillator, Mark passed on a
    reminder from Bruce Lenzer that we be sure to collect documentation
    from the manufacturer about pieces passing inspection at their
    facilities, at least a certificate of conformance.

TDR

    Eric got an email from Mike Dugger about reviewing the start counter
    section of the current draft of the TDR. It appears to be quite a bit
    out-of-date right now. Eric will do an update and circulate a draft to
    the group.
    Retrieved from
"https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_February_6,_2014"

References

   26. https://halldweb1.jlab.org/talks/2014-1Q/Bubbles.jpg
   27. https://halldweb1.jlab.org/talks/2014-1Q/Skewed.jpg

-- 
Mark M. Ito, Jefferson Lab, marki at jlab.org, (757)269-5295