HDGeant4 Meeting, July 13, 2021

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HDGeant4 Meeting
Tuesday, July 13, 2021
3:00 pm EDT
BlueJeans: 968 592 007


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


Present: Alex Austregesilo, Tegan Beattie, Sean Dobbs, Mark Ito (chair), Igal Jaegle, Richard Jones, Zisis Papandreou, Beni Zihlmann

There is a recording of this meeting on the BlueJeans site. Log into the BlueJeans site first to gain access (use your JLab credentials).


Mark announced that a new version set with Geant4 10.06.p01 is coming soon. It depends on running Developers Toolset 8 on CentOS 7.

Review of minutes from the last meeting

We went over the minutes from the meeting on June 29th. Action Item #1, "Re-do comparisons of overall event reconstruction efficiencies," seemed to us a bit off the critical path. Rather consistency check of cross sections measured in data under various conditions, with efficiency corrections from simulation, seem more important now.

Adding Efficiency as a Function of Drift Distance to the FDC Simulation

Richard outlined his plan for adding information from Lubomir Pentchev's Garfield simulation of the FDC. See his plots starting at 16:40 in the recording. Lubomir sees a fall off in efficiency at long drift distances. This effect is not in the simulation. Richard plans to use the relative drop (and not the absolute level) as a function of drift distance from Lubomir's curves. He notes that if one looks at the current discrepancy in efficiency between data and Monte Carlo, generated by Alex, the curve from Lubomir appears to be a good representation of the extra inefficiency seen in data as a function of drift distance.

Issues on GitHub

We went through the issues on GitHub. For links to the issues themselves see the issues page for HDGeant4.

  • Vertex generation used with BHgen
    • Richard is working on this one. The first step is to translate an atomic form factor from Ilya Larin from FORTRAN to C++.
  • Add incident angle dependence to DIRC mirror reflectivity
    • This is a request for an enhancement[?].
  • unknown particle type 50 being generated through interactions
    • Cerenkov photons in the FCAL is not a bug but a feature. This one should be closed.
  • hits in both CALs from the same track
    • Sean reminded us that this is due to the mathematical track trajectory properly extrapolated to the FCAL after passing through the BCAL. Real particles will not do this. Should be closed.
  • unexpected jumps in MC yield vs photon energy
    • We are waiting on feedback from Hao Li.
  • Incorrect TAGH counter number assignment
    • We went to a lot of effort to fix this one. We marked it as closed.
  • G3/G4 Difference in FDC wire efficiency at the cell boundary
    • Richard went through the solution to this issue in the meeting proper (see above).
  • G4 exceptions for certain run numbers
    • Elton Smith should review this issue and tell us if it is still a problem.
  • Difference in Acceptance between G3 and G4
    • We felt that we have come to the end of this issue as written. There may be on-going related mysteries, but those should be re-stated and entered as new issue. We will ask Colin Gleason if this one can be closed.

Action Items

  1. Think about how to study the Schick-Smith-Dalton effect(s). (all)
  2. Think about a GlueX Doc on simulation. (all)
  3. Think further about how to get to modern versions of external software packages.