HDGeant4 Meeting, December 17, 2019

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HDGeant4 Meeting
Tuesday, December 17, 2019
2:00 pm EST
JLab: CEBAF Center, A110
BlueJeans: 968 592 007


  1. Review of minutes from the last Meeting (all)
  2. Issues on GitHub
  3. Pull Requests on GitHub
  4. Action Item Review



  • CMU: Naomi Jarvis
  • JLab: Alex Austregesilo, Mark Dalton, Colin Gleason, Mark Ito (chair), Keigo Mizutani, Simon Taylor
  • UConn: Richard Jones

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

Review of Minutes from the December 3 Meeting

We went over the minutes. Alex will close the issue on neutron generation.

genBH Output Format

At the last software meeting Mark D. reported problems reading the output from the genBH generator. The code is in the HDGeant4 repository. Richard was able to reproduce the problem and submitted a pull request that fixes the problem.

Issues on GitHub

We went over the issues. Most of the time was spent discussing Issue #111, "Difference in Acceptance between G3 and G4". Colin led the discussion.

  • Colin went back and revisited his study from last May with recent versions of software.
  • When looking at the comparison of efficiency as a function of eta-pi mass, the agreement is between G3 and G4 is reasonable, but when viewed as a function of cosθGJ there is a noticeable difference between the forward and backward directions (at 7:17 in the recording). This is similar to the results of the original study and the initial cause of concern. Colin noted that the data is more similar to the G3 efficiency as opposed to that for G4.
  • Mark Dalton pointed out that in this and other efficiency studies, the overall event acceptance is less that that one would expect from single particle studies.
  • After sorting through some some confusion, we concluded that the single particle yield comparisons that were shown are actually after the events are accepted by the analysis library. This means that they reflect not only the efficiency of the particle shown, but the overall event efficiency. In particular differences in the efficiencies for one type of particle will effect the apparent comparative yield of other particle types.
  • Alex suggested that the problematic effect might also the the effect of timing cuts placed on charged particles in the calorimeters, a problem he illustrated in his post to Issue #93. Colin will pursue this possibility, in particular repeating the analysis with looser timing cuts on matching between charged tracks and calorimeter clusters.
  • Eugene Chudakov made a suggestion to Colin: do the G3 vs. G4 comparison with the same input events and see where the differences occur on an event-by-event basis. Perhaps a pattern will emerge.