GlueX TOF Meeting, February 13, 2019

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GlueX Time-of-Flight Meeting
Wednesday, February 13, 2019
10:00 am EST
JLab: CEBAF Center, Room F226
BlueJeans Meeting number is 350 531 998


  1. Announcements
  2. Review of minutes from the January 30 meeting
  3. Lucite Shield Geometry (Ashley)
  4. Upgrade Plan
  5. NIM Paper (Paul)
  6. Action Item Recap


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2019 on the JLab CUE. This directory is accessible from the web at .



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

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

Announcement: Machine Learning and the TOF

Thomas told us that ML-based online monitoring needs experts to label histograms. He has conscripted Beni to do so for the Time-of-Flight. The automatic system is trained on PNG files from the online monitoring program. It is doing well on the FCAL occupancy plots, with a false positive rate of less than 2%. Colin Gleason did the training for the FCAL in 20 to 30 minutes.

Review of minutes from the January 30 meeting

We went over the minutes from last time.

  • Mark reported that Tim Whitlatch is going to get a designer (probably Stephanie Worthington) going on Paul's upgrade ideas sometime in the next few weeks.
  • On Monday, Mark and Ashley made a tagged release of HDDS with (a) the Lucite shielding, (b) no DIRC, and (c) overlaps resolved. They leveraged Richard Jones additions and corrections to Ashley's initial draft of the shielding. The release was produced by using version 3.13 as a base and importing HDDS XML files from the CCDB for run 41000, i. e., a pre-DIRC run.

Lucite Shield Geometry

Ashley ran us through slides from Richard that detailed his validation of the shield geometry. He identified and performed three classes of verification (slide 4):

  1. alignment verification (look at pictures)
  2. geometry verification (checks proper embedding, overlaps)
  3. functional verification (run HDGeant4 and analyze hits)

Please see his slides for the details and the plots.

Added in press: Ashley reported some clarifications she obtained from Richard.

  1. There is a swap in plot positions between the low energy photon simulation. and the coherent bremsstrahlung beam simulation. The former shows the situation with shielding on the left and without shielding on the left. The latter is the reverse.
  2. For both simulations the two geometry arrangements were (1) with shield, without DIRC and (2) without shield, with DIRC.