GlueX TOF Meeting, May 9, 2018

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GlueX Time-of-Flight Meeting
Wednesday, May 9, 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 April 11 meeting
  3. Calibration Status
  4. Amplified Base Prototype (Beni)
  5. NIM Paper (Paul)
  6. 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 .



  • 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 April 11 meeting

We went over the minutes from the April 11.

  • The TOF threshold scan has not been fully analyzed yet.
  • Beni reminded us that in addition to the change in ADC threshold, we changed the NSA read-out parameter from 25 to 15. This occurred a bit after the threshold change. He thinks we may want to move to NSA = 10 in the future.
  • With these changes (threshold and NSA) the monitoring plots show significant improvement in efficiency (based on charge track projections). The efficiency curves as a function of distance of radius are wider and flatter than they used to be.
  • Beni also mentioned that if he can get all of the software ready, he may make a presentation on comparing TOF efficiency between data and Monte Carlo at the upcoming Analysis Workfest.

Calibration Status

Beni gave the report.

  • A significant portion of the first half of the run has been calibrated.
  • The first run after the read-out parameter changes is missing from the set of calibrated runs.
  • Calibration of the second half is waiting on production of the input ROOT files.
  • Calibrations should appears soon after appearance of the ROOT files. The process has been automated and does not take long to run.
  • New constants have not been added to the database.

Amplified Base Prototype

Beni gave the report.

  • Beni has not been able to get decent calibration results from the amplified base channel. The problem is not known at present.
  • Mark speculated that these difficulties may have something to do with the large baseline shift in this channel, and software that does not accommodate this shift.

Re-configuring the TOF

Beni has been reviewing the concept for a TOF upgrade, in particular a new counter arrangement near the beamline, that Paul Eugenio presented at the collaboration meeting in October 2017. The design has a larger beam hole than the current TOF.

Beni thinks that if we go to the new configuration, we can go to high rates without having to resort to the amplified bases. The counters that would have been overwhelmed at high rate would simply no longer be there.

He outlined some issues assuming we go this way:

  • A decision has to be made soon to allow time for procurement and construction in advance of installation during the Summer, 2019.
  • New paddles would have to be constructed. Some are of dimensions we have not made before.
  • Light guides would have to be redesigned for the half-width paddles. The current design will not accommodate more that two such counters in a row and we will have fourteen consecutive half-width'ers in the new design.
  • More electronic read-out and HV channels will have to be procured.
  • The software geometry will have to be changed. Also both reconstruction and simulation software will have to be modified (unless the software engineering for the TOF portions are already of professional-grade quality).