GlueX TOF Meeting, April 11, 2018

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GlueX Time-of-Flight Meeting
Wednesday, April 11, 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 March 28 meeting
  3. Calibration Status
  4. Amplified Base Prototype (Beni)
  5. TOF threshold scan The Runs
  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: Thomas Britton, Mark Ito (chair), Simon Taylor, Beni Zihlmann

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

Review of minutes from the March 28 meeting

We went over the minutes.

Sasha reported that he will finish the database of the tested PMTs soon.

Calibration Status

Beni is starting to turn back to calibrations. Some runs done, but nothing new has been added to the database.

Going to an ADC read-out threshold of 160 has improved the efficiency, but not as much as he had hoped, although the efficiency for the half-width paddles has improved dramatically. Resolution may have suffered, but he has a suspicion that the increased width he sees in the global time distribution may be due to mis-calibration of individual channels.

Amplified Base Prototype

Since changing the ADC threshold, analysis shows improvements for the prototype base channel. Individual PMT widths look better (after walk correction). There is a puzzle in that the comparison of mean-time distributions between the test paddle and a nearby part-of-the-regular-TOF paddle has the regular better paddle with better resolution.

TOF threshold scan

Beni called our attention to the log entry where he recorded the run numbers used the ADC-threshold/NSA scan done a couple of weeks ago. The thresholds were set at 150, 160, 170, and 180 ADC counts (160 is the new normal) and NSA was set, for each threshold, at 10 and 15. the data have yet to be analyzed.

Beni noted that 160 is still below the discriminator threshold applied on the TDC side. If a pulse height of 168 or lower is seen in the ADC, the corresponding TDC is generally absent.

Action Item Recap

  1. Finish the PMT testing database. (Sasha)
  2. Finish calibration of the post-threshold-change data. (Beni)
  3. Analyze the ADC-threshold/NSA scan data.