GlueX TOF Meeting, August 1, 2018

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GlueX Time-of-Flight Meeting
Wednesday, August 1, 2018
10:00 am EDT
JLab: CEBAF Center, Room F226
BlueJeans Meeting number is 350 531 998


  1. Announcements
  2. Review of minutes from the July 18 meeting
  3. Calibration Status
  4. Geometry & Alignment (Beni)
  5. Upgrade Plan
  6. NIM Paper (Paul)
  7. Action Item Recap


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2018 on the JLab CUE. This directory is accessible from the web at .



  • FSU: Sasha Ostrovidov
  • JLab: Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting on the BlueJeans site. Use your JLab credentials.

  1. Announcements
  2. Review of minutes from the July 18 meeting

Review of minutes from the July 18 meeting

We reviewed the minutes.

Study of amplified base performance

Beni followed Sasha's suggestion from last time and repeated method 3 using paddle 31 rather than 14. 31 is on the opposite side of the array, farther away from the test PMT. He compiled the results, along with those from paddle 14, in an updated version of hist note. There is a significant reduction in time resolution when using 31 versus 14.

Sasha suggested that some combination of methods 1 and 2 might give more robust results.

The overall conclusion remains the same, that resolution from the amplified base is not as that from a regular base.

Geometry & Alignment

Prompted by Sean's presentation of parametrizations for geometry corrections for the TOF, Beni looked at measuring these corrections using charged particles. For each track he takes the TOF point closest to the projection of the track to the TOF. The projection position is used to update a 2D histogram, with separate histograms for each TOF paddle, as reported by the TOF point. The procedure was done separately for positive and negative tracks. See his plots in the talks directory and his draft note describing the study for details.

Straight lines are fit separately for each half of the paddle (left/right or upper/lower). May paddles give fits inconsistent with one straight line describing both halves. This is especially true for the half-length paddles, as might be expected, but also for the full-length paddles. The simplest geometry-correction scheme may not be adequate.