GlueX Start Counter Meeting, June 28, 2018

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GlueX Start Counter Meeting
Thursday, June 28, 2018
10:00 am EDT
CEBAF Center, Room L207
BlueJeans: 556 286 544


  1. Announcements
  2. Review minutes from the meeting on June 14
  3. Calibration and Efficiency
  4. Time-dependent geometry adjustments
  5. NIM/TDR
  6. Action Item Review




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 .



  • FIU: Werner Boeglin, Mahmoud Kamel
  • FSU: Sean Dobbs
  • JLab: Mark Ito (chair), Simon Taylor, Beni Zihlmann

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

Review minutes from the meeting on June 14

Review of the minutes was done without significant comment.

Propagation Time Corrections

Mahmoud described a new method for obtaining the light propagation time corrections. This approach fits one-dimensional histograms of walk-corrected times where each histogram comes from a bin in z (actually, length along the counter). z-position is determined by charged particles.

For all of the details, please see Mahmoud's slides.

This method seems much more robust than the previously tried fits to a two-dimensional histogram. The details of the function used to smooth the bin-to-bin fluctuations in the correction is still being developed.

There was some discussion of whether the hits in the forward-most bin, where the exact geometry of the counters is uncertain, should ever be used in reconstruction. We did not come to a conclusion about this.

World Cup Re-Cap

Switzerland is through to the knock-out round. Egypt did not make it. The US is absent from this year's tournament on account of a heart-breaking loss to Trinidad & Tobago.

Time-dependent geometry adjustments

Sean reported that work will resume after the reconstruction launch lock-down is past.

NIM Paper

Werner reported that Eric Pooser has been busy with software presentations lately and that work will resume soon.