GlueX Offline Meeting, November 12, 2014

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GlueX Offline Software Meeting
Wednesday, November 12, 2014
1:30 pm EST
JLab: CEBAF Center L207


  1. Announcements
  2. Light Meson Decay in CLAS (Moskov Amaryan)
  3. Review of minutes from October 29 (all)
  4. track, itrack, and the Truth (Richard, Justin)
  5. Commissioning Simulations
  6. Offline Data Monitoring (Paul M.)
  7. Action Item Review

Communication Information

Remote Connection


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2014-4Q on the JLab CUE. This directory is accessible from the web at .



  • CMU: Curtis Meyer
  • FSU: Aristeidis Tsaris
  • IU: Matt Shepherd
  • JLab: Alex Barnes, Mark Ito (chair), David Lawrence, Paul Mattione, Kei Moriya, Eric Pooser, Mike Staib, Simon Taylor
  • NU: Sean Dobbs
  • ODU: Moskov Amaryan

Light Meson Decays in CLAS

Moskov presented a list of topics that could be addressed with GlueX along with an impressive set of plots that show the signals seen in the CLAS detector. See his slides for details. You can also view a video of his talk.

Commissioning Simulations

Sean made several points:

  • Rate estimates were presented at the last calibration meeting.
  • With inconsistent beam it is hard to make comparisons with what we are seeing.
  • Simon will look into moving the start counter around to see if the known tilt is responsible for the up/down asymmetry in rates.
  • We discussed issues around putting in known effects due to non-ideal geometry both in simulation and in reconstruction. There are a lot of issues on how to handle it; different solutions may be appropriate for different types of non-idealism. For the start counter rates you need the geometry changed in HDDS. For small displacements in relative detector positions, it may be enough to put it into the reconstruction and ignore it in Monte Carlo. Matt wondered whether the different pieces of the detector could be assembled with parameters to match the as-built geometry.
  • The code is ready to go, but we will wait a few days before proceeding. The geometry may be changing rapidly over the next few days and we need to let that settle down.
  • Energy threshold is a big driver of simulated rates, but we have incomplete information on what those thresholds are.

Offline Data Monitoring

Paul let the discussion.

  • The online monitoring is not working at the moment, but Kei has been running the online monitoring offline and results are available on the monitoring website.
  • Matt asked about re-running monitoring analysis on old data with improved code as it comes out. We settled on doing a re-run of the entire data set once a week. The amount of data so far is small enough that that is not a problem.
  • Justin asked for feedback on the plots and time-lines available on the site. If there are things missing or requests for new items, please let him know.
  • Kei showed some results of the monitoring histograms he has been producing as well as a few plots on analysis he has done on his own. In particular he showed a nice correlation between start counter times and FCAL times as measured with the FADCs. He sees a time difference distribution with a 2.6 ns sigma. Unfortunately we ran out of time and were not able to look at all of his slides, so those interested should take a look at the link given just above.