GlueX TOF Meeting, June 3, 2020

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GlueX Time-of-Flight Meeting
Wednesday, June 3, 2020
10:00 am EDT
BlueJeans: 350 531 998


  1. Announcements
  2. Review of minutes from the last meeting
  3. Calibration TOF energy calibration
  4. TOF NIM paper
  5. Action Item Recap


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2020 on the JLab CUE. This directory is accessible from the web at .


Present: Paul Eugenio, Mark Ito (chair), Susan Schadmand, Simon Taylor, Beni Zihlmann

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


The lab has a plan in place for starting to re-open and it has been submitted to DOE. No announcement of a date when things will start happening.

Review of minutes from the last meeting

We went over the minutes from May 6.

  • Beni would like to re-do his position study using the reverse Kalman filter. Simon has given him examples of how to use it.
  • Paul reports that the shop at FSU is back working on fabrication of the six units of PMT-replacement-glue-joint holders. He was wondering if we had candidates for swapping out. He reminded us that we have a cache of new tubes at FSU. Beni has a candidate that shows strange pulse shape and low amplitude. Increasing the HV on this channel did not help much. He is afraid that this may be the PMT that seemed to have a loose mechanical connection to the light guide. Beni would like to take raw mode data during the upcoming run to evaluate other candidates for replacement via their pulse shape characteristics.

TOF energy calibration

Beni led us through his recent work on the energy calibration. He is reviewing the current procedure, both for calibration and the reconstruction algorithm that uses the calibration, and making improvements. Please see his slides for the details.

In summary, he is able to find peak values of the Landau distribution for minimum ionizing particles in bins of position along the counter for each channel. Position is determined by end-to-end timing using the ADCs themselves. He can then extrapolate the pulse area to that which comes from the middle of the counter (or the end of the counter for single-ended counters) and find the conversion constant to energy, where energy is determined from Monte Carlo.

He proposes that the TOF reconstruction should report the energy found in each layer of a TOF point, rather than the average of the two layers in the case of two double-ended counters. It turns out the currently, if the contribution of one of the layers is from a single-ended counter, that layer is ignored in the reported energy.

This is work in progress.

TOF NIM paper

  • Sasha Ostrovidov has recently added to the section on testing.
  • Paul has some changes that he needs to add to Overleaf.
  • Beni would like to review the section he wrote on calibration. He suspects that procedures have improved since the original draft was written.