HDGeant4 Meeting, January 26, 2021

From GlueXWiki
Revision as of 15:45, 9 February 2021 by Zisis (Talk | contribs) (G3/G4 comparison: FDC Wire Efficiency)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

HDGeant4 Meeting
Tuesday, January 26, 2021
3:00 pm EST
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, Dmitry Romanov, Simon Taylor, Nilanga Wickramaarachchi, Jon Zarling, Beni Zihlmann

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


Mark announced a brand new version set, 4.35.0.

Review of minutes from the last meeting

We went over the minutes from December 15.

  • Mark reported that he can no longer reproduce the "make clean" error. Richard reported that there is no explicit "clean" target in the HDGeant4 makefile. Instead it depends on the default target.
  • Mark built the no-heavy-light (NHL) branch of HDGeant4 at JLab.

G4 Standard/No Heavy Light comparison

Tegan showed a plot of proton BCAL timing from HDGeant4 comparing the NHL branch with a standard build. The reaction simulated was γp→ηp. Very little difference is seen.

  • Richard suggested checking that the deposited energy is different between the two versions, as a cross-check that the right branch is being tested.
  • Sean mentioned that Colin was looking at pions and that momentum dependence may be important.
  • Zisis asked for suggestions for studies for Tegan to do in pursuing Issue #179. Richard suggested looking along the track and study how energy is deposited along the path. Sean endorsed this approach, especially for secondaries, as a function of particle type.
  • Sean noted that his PDF linked to the issue shows the timing tail.
  • Sean also noted that Hao Li has a large sample of protons in his studies and a comparison of that sample with Monte Carlo might shed some light on the issue.

No TAGH Hits in Simulation

Drew Smith reported a lack of tagger hodoscope hits in the sampling region in HDGeant4. Richard explained that this is due to a bug where the scheme for converting tagger counter ID to photon energy is inconsistent with the way the tagger energy scale is reported from the CCDB. Drew and Igal will submit an issue and Richard will come up with a fix.

G3/G4 comparison: FDC Wire Efficiency

Alex has noticed a difference in FDC wire efficiency when calculated with GEANT 3 vs. Geant4. He analyzed his ρ photoproduction sample. We mainly discussed the drop of efficiency at large drift distance seen in GEANT 3, but not in Geant4. Although one expects such a drop due distortions of the field lines near the edges of the cell, those effects are in neither version of the simulation. Alex will submit a GitHub issue on this.

Problems at Low-t in genBH Generator

Richard announced a GitHub issue-to-appear soon on the kinematic distributions from the genBH generator.

Mark mentioned that he has started to look at building Diracxx as part of our standard software stack. genBH requires this package.