[Halld-offline] HDGeant4 Meeting Minutes, January 26, 2021

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_January_26,_2021#Minutes> 
and below.

   -- Mark

    ____________________________________________


    HDGeant4 Meeting, January 26, 2021, Minutes

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 
<https://bluejeans.com/s/0dT7O1tS3dq/> on the BlueJeans site. Use your 
JLab credentials to get access.


      Announcements

Mark announced a brand new version set, 4.35.0 
<https://mailman.jlab.org/pipermail/halld-offline/2021-January/008443.html>. 



      Review of minutes from the last meeting

We went over the minutes from December 15 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_December_15,_2020#Minutes>. 


  * 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 
<https://halldweb.jlab.org/DocDB/0048/004878/001/c1.pdf> 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 <https://github.com/JeffersonLab/HDGeant4/issues/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
    <https://github.com/JeffersonLab/HDGeant4/files/5639678/Nov20_g3_vs_g4_dtlog.pdf>
    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 
<https://halldweb.jlab.org/talks/2021/FDC_Efficiency/g3_g4_comparison.pdf> 
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 
expect 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.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/halld-offline/attachments/20210126/848c4bdc/attachment.html>