[Halld-pid] Time-of-Flight Meeting Minutes for May 30 ,2017

[Mark Ito]

Please find the minutes below and on the meeting page 
<https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_May_30,_2017#Minutes>.

_________________________

Agenda

3. Calibration Status

 1. first run calibration done
 2. investigate calibration procedure identify potential improvements (Brad)
    DeltaTVsPaddleNum.png
    <https://halldweb.jlab.org/wiki/index.php/File:DeltaTVsPaddleNum.png>
    Paddle40.png
    <https://halldweb.jlab.org/wiki/index.php/File:Paddle40.png>
    Paddle18.png
    <https://halldweb.jlab.org/wiki/index.php/File:Paddle18.png>
 3. Track position vs tof hit position very linear
    However, left and right side do not necessarily point to zero or
    same value.
    Tof trackpos vs tofpos p8.jpg
    <https://halldweb.jlab.org/wiki/index.php/File:Tof_trackpos_vs_tofpos_p8.jpg>
    Left fit p8.jpg
    <https://halldweb.jlab.org/wiki/index.php/File:Left_fit_p8.jpg>
    Right fit p8.jpg
    <https://halldweb.jlab.org/wiki/index.php/File:Right_fit_p8.jpg>


    Minutes

Present:

  * *FSU*: Sasha Ostrovidov
  * *JLab*: Thomas Britton, Brad Cannon, Mark Ito (chair), Simon Taylor,
    Beni Zihlmann


      Calibration Status

  * Beni reports that the first calibration pass through all runs from
    Spring 17 is done. He got around the previously reported wall-time
    problem by running the analyses of mean time and time difference in
    parallel.
  * Brad is studying some systematics of the current calibration
    procedure. He has looked at the difference between a single-Gaussian
    fit (as is done presently) and and a double-Gaussian fit to the time
    difference histograms. See plots in section 3.2 of the agenda above.
    The difference is only about 30 ps in the case shown, which was
    judged acceptably small.
      o There appear to be shoulders on both sides of the accidental
        peak at Δt=0 in all counters. We discussed their origin, but did
        not come to firm conclusions.
  * Beni has looked at whether there is any systematic position
    dependence in the position measured in the TOF via end-to-end
    timing. He compared the difference in position between charged track
    projection and the TOF-determined position separately for opposite
    sides of the beamline. See plots in section 3.3 of the agenda above.
    He sees good agreement, although there are a few counters which show
    offsets, relative to charged particle projections, of several tens
    of picoseconds (position measured in units of Δt, end-to-end).


      Active Dividers

The test counter is still in the Hall. Nothing new to report on this 
project.

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

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