[Halld-pid] Start Counter Meeting Minutes, August 21, 2014

[Mark M. Ito]

Folks,

Find the minutes below and at

https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_August_21,_2014#Minutes 
.

   -- Mark
__________________________________________________________

GlueX Start Counter Meeting, August 21, 2014
Minutes

    Present:
      * FIU: Anthony Llodra, Eric Pooser
      * JLab: Fernando Barbosa, Mark Ito (chair)

Construction Status

    Eric showed [16]some slides detailing the status of assembly and
    testing. He also wrote a [17]report for yesterday's GlueX meeting since
    he could not attend.

    The slides show measurements of timing resolution for the 30 paddles
    selected for the detector. Average resolution over the entire length is
    360 ps improving to 275 ps in the nose. This is better than the best
    prototypes tested.

    He also showed photographs illustrating the procedure used to shim the
    ends of the scintillators to bring them into alignment with the SiPMs.
    About 30 mils of shimming is needed, and the technique allows variation
    from counter to counter.

    Next week work on the transportation crate will begin.

    Delivery to JLab is planned for September 2. The MPOD will be shipped
    back separately so that it will not crowd the start counter in Eric's
    SUV.

    [Added in press] Mark talked to Tim and Beni and at present the plan is
    to put the start counter in EEL 126 where it can be light-tight'ed and
    tested in the dark box there.

Electronics Status

    We decided to go ahead with the gain adjustment on the ST-2s back to
    their original values, a factor of five less than the previous version.
    We also decided to reduce the gain on the TDC side of the split on ST-3
    by a factor of 2 to avoid saturation on the output of the split.

    Nine of the ten ST-2 boards are at JLab and will be modified there.
    They will stay at JLab and will be installed when the start counter
    arrives.

    The modification on the ST-3 will be made on the spare board and then
    swapped into the enclosure.

    The cables going from the ST-3 to the read-out electronics have not
    been strung yet. Nick Sandoval and Tim Whitlatch have a plan to run
    them downstairs through the same penetration used by FDC/CDC cables.

References

   16. 
https://halldweb1.jlab.org/talks/2014-3Q/Start_Counter_Construction_Update.pdf
   17. 
https://halldweb1.jlab.org/wiki/index.php/Start_Counter_Status,_August_20,_2014

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