[Halld-pid] Minutes, GlueX TOF Meeting, Fri. Feb. 18 '11

[Mark M. Ito]

Find the minutes at 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_TOF_Meeting%2C_February_18%2C_2011#Minutes 
and as text below.

   ==

GlueX TOF Meeting, February 18, 2011

Minutes

    Present:
      * FSU: Paul Eugenio
      * JLab: Mark Ito (chair), Yi Qiang, Elton Smith, Sascha Somov, Simon
        Taylor, Tim Whitlatch, Beni Zihlmann


Minutes from the last meeting

    We reviewed the [29]minutes from the meeting on January 21.

    The Hamamatsu PMT arrived at JLab from FSU. Beni has been looking at it
    and has reported his findings in a [30]series of email messages to the
    PID list. He concludes that the tube performs as advertised and its
    contribution to timing resolution is small compared to other factors,
    as well as compared to our spec for the TOF.

Report from trip to the University of South Carolina

    Paul and Sasha Ostrovidov travelled to Columbia to visit Ralf Gothe and
    discuss his work on the forward time-of-flight for CLAS12. Some notes
    on their trip:
      * Goals
           + compare and contrast design choices between USC and FSU
           + identify factors limiting factors in resolution in the FSU
             set-up
           + look at contradictory experiences with ESR wrapping at the two
             institutions
      * Ralf reviewed his construction and QA procedures with Paul and
        Sasha
      * time-walk corrections
           + Sasha trying to fit all parameters at once
           + USC using an iterative approach, not letting all parameters
             float
           + without time walk corrections, USC resolution a factor of two
             worse
           + Elton: 1/sqrt(p.h.) may not be the right functional dependence
      * TDC's
           + resolution from electronics at FSU gives get something like
             the 55 ps value of the least significant bit
           + Ralf gets the same thing (lsb value) except in his case it is
             25 ps from his CAEN device
           + Why not go to CAEN TDC?
                o Paul will get from a loaner from Mark Kibilko
                o readout protocol should be OK for GlueX pipelined DAQ
      * PMT choices
           + USC using 8-stage, not the 10-stage, Hamamatsu PMT
           + 10-stage tube perhaps not available when they made the
             decision
      * ESR
           + improved light collection: results from FSU
           + SC had poorer performance with ESR
           + material USC was ESR: looks like white Tedlar, not specular
           + Ralf had some mylar that he could not use for his counters,
             gave it to Paul
      * Tour of USC lab
           + saw alignment devices
           + saw glueing tools, jigs
      * Contract
           + Paul got a copy of the assembly and testing document from Ralf
             that was part of USC's 12-GeV contract with JLab.


Geometry

    Elton reminded us of the issue of the geometry of the TOF counters that
    has been discussed previously. Some notes from the discussion:
      * making the counters wider may lose light
      * mounting PMT directly on the scintillator like USC is doing is
        attractive
      * Paul has not finalized a proposal yet
      * need to talk about it at the next meeting
      * outside diameter with mu-metal 6 cm
      * USC using 6 cm x 6 cm counters
      * current GlueX design with steel tube more than adequate for
        magnetic shielding


Schedule

    Tim walked us through the [34]schedule in the current project plan.
    Again some notes:
      * PMT's are the kind of thing JLab would buy, scintillator as well
      * other items would likely be bought by FSU
      * contract has to be awarded before PO goes out, say 7 months from
        now

    The overall message is that decision making on the TOF will have start
    now to make this schedule.

Other items

      * Tim will test the mu-metal shield that came on the Hamamatsu tube
        that Beni has been looking at.
      * Elton reminded us that rates for inner-most paddles near the beam
        hole are problematic. We need to decide how to address that.

Retrieved from
    
"http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_TOF_Meeting%2C_February_18%2C_2011"

References

   29. 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_TOF_Meeting%2C_January_21%2C_2011#Minutes
   30. 
https://mailman.jlab.org/pipermail/halld-pid/2011-February/thread.html
   34. 
http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=1705