GlueX TOF Meeting, March 18, 2015

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GlueX Time-of-Flight Meeting
Wednesday, March 18, 2015
8:00 am EDT
JLab: Hall D Counting House


  1. Announcements
  2. Review of minutes from March 10
  3. Calibration Status (Sasha)
  4. TOF Reconstruction Performance (Sean)
  5. Preparations for Spring Run (All)
  6. Meeting participation:
    1. Daily Planning Meeting
    2. Bi-Weekly Calibration Meeting



Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2015 on the JLab CUE. This directory is accessible from the web at .



  • FSU: Paul Eugenio
  • JLab: Mark Ito (chair), Sasha Ostrovidov, Beni Zihlmann
  • NU: Sean Dobbs

Calibration Status

Sasha showed plots illustrating one of the difficulties he is having with the outer counters of the detector. For front-back coincidences, he shows x determined by the known location of the counter in the back plane vs x determined by time difference in the front plane. For module 19 in the front, near the middle of the array, the correlation is clear and time difference easy to calibrate. For module 0 at the edge the statistics are much less and there are a lot more uncorrelated hits.

Sasha is still formulating a plan for calibration of the short paddles. Since they are in the middle of the array, their occupancy is high and calibrating them is important.

TOF Reconstruction Performance

Sean showed some plots showing widely varying charged-track matching efficiency with charged tracks for two nearby runs from the Fall run. Even for the "good" run the match efficiency is not so great. For the "bad" run, there are very few good TOF hits from the hit factory to begin with. Beni thought that this might be due to the entire time frame shifting between runs due to trigger changes. If so it emphasizes the importance of keeping track of trigger changes, especially where the timing is affected.