HDGeant4 Meeting, May 5, 2020

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HDGeant4 Meeting
Tuesday, May 5, 2020
3:30 pm EDT
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


Present: Sean Dobbs, Mark Ito (chair), Igal Jaegle, Naomi Jarvis, Richard Jones, Justin Stevens, Simon Taylor, Nilanga Wickramaarachchi, Beni Zihlmann

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

Review of minutes from the last Meeting

We went over the minutes from April 21. On the subject of upgrading our version of Geant4 and the possible need for an upgraded GCC, Richard mentioned that he is using the Developer Toolset from Software Collections to get GCC versions beyond that native to his CentOS7 distribution.

Issues on GitHub

BCAL structure in E/p distributions for kaons

We went over Issue #149 again. There has been a lot of work and discussion on this issue since the last meeting. See the issue on GitHub for all of the details.

The big take-away is that the CUTS card in the hdgeant/hdgeant4 control.in files was causing unphysical behavior for hdgeant4. The problem was that particles that went below energy thresholds specified in that card disappeared and were not allowed to interact or decay. Their rest energy was therefore not accounted for. There is a history associated with how this came to be (basically a communication failure), but bottom line is that this card was not intended for use in production runs of HDGeant4. For hdgeant (GEANT 3) its affect is more benign, but even there its use is not required and not recommended. Unfortunately, it has been included in the MCwrapper template from the beginning of that system so nearly all of our hdgeant4-generated Monte Carlo has had this pathology.

Many of our studies need to be repeated with the CUTS card properly excluded.

Richard also requested that going forward Geant3 simulations be run with both HADR=1 and HADR=4 settings. For him this has been useful in that there can be differences in some of the quantities we have been studying due to differences in the hadronic interaction model used. Using both setting allows one to judge the rough size of what those differences might be.

This issue will be discussed at the Collaboration Meeting next week in the Tuesday afternoon session.

K particle gun request to resolve G3/G4 difference near p 0.5 GeV/c and theta 120 degrees

We went over Issue #137. Activity on this issue picked up last week after the root cause of Issue #149 was discovered. Again, see the issue on GitHub for all of the details.

Unfortunately, the root cause here was not obvious. Richard pointed out that if one expands the phase space simulated beyond the narrow region populated by the reaction of interest, there are clear features in the $theta;-momentum plane that could lead to the features that first prompted submission of the issue. Work continues with Richard and Nilanga leading the charge.