[Halld-offline] HDGeant4 Meeting Minutes, February 9, 2021

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_February_9,_2021#Minutes> 
and below.

   -- Mark

    _______________________________________


    HDGeant4 Meeting, February 9, 2021, Minutes

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

There is a recording of this meeting 
<https://bluejeans.com/s/eCLxtFpOkd5/> on the BlueJeans site. Log into 
the BlueJeans site first to gain access (use your JLab credentials).


      Announcements

The Collaboration Meeting Agenda has been announced and there are no 
slots for HDGeant4-related topics scheduled. If folks have ideas for 
topics that should be presented to the Collaboration, please contact Mark.


      Review of minutes from the last meeting

We went over the minutes from January 26 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_January_26,_2021#Minutes> 
without significant comment.


      G3/G4 Comparison

Tegan presented simulation results on BCAL response separately for 
charged pions 
<https://halldweb.jlab.org/DocDB/0048/004878/001/FEB05_PiPlusComparison.pdf> 
and protons 
<https://halldweb.jlab.org/DocDB/0048/004878/001/FEB05_ProtonComparison.pdf>. 
For each particle type he compared responses with

 1. Standard HDGeant4
 2. The bcal_nolight_heavy_rtj branch of HDGeant4 (NHL)
 3. hdgeant (GEANT3) with HADR1
 4. hdgeant (GEANT3) with HADR4

 From the discussion:

  * Particles were generated between 10 and 40 degrees in polar angle an
    with momenta from 400 MeV to 2.0 GeV.
  * The frequency of secondary electrons shows a difference of almost a
    factor of two between the two HDGeant4 simulations with NHL higher
    than the standard. We did not come up with a good explanation for this.
  * Sean remarked on the long late timing tail for secondary
    electrons[?] in HADR1.
  * Beni suggested making a 2D histogram of the number of hits in a
    cluster vs. "BCAL Shower Time - Truth Shower Time". He was
    suspicious that the tail may be coming from single- or few-counter
    clusters.
  * Richard wondered how energy thresholds are treated in the detector
    "smearing."
  * Sean suggested looking at individual hit times vs. the true shower
    time. This distribution might tell us something.
  * For protons there appears to be a difference in the number of
    produced neutrons with HADR4 compared to the same population when
    plotted as a function of time. Many of the former and very few of
    the latter.
  * Sean and Richard advocated starting to do comparisons with data.
    Richard thought that using exclusive ρ events might give a
    relatively uniform and plentiful sample of protons hitting the BCAL.
    Sean suggested that Alex pass such a sample on the Tegan for study.


      Other Issues on GitHub

We went through the list <https://github.com/JeffersonLab/HDGeant4/issues>.

  * Incorrect TAGH counter number assignment
    <https://github.com/JeffersonLab/HDGeant4/issues/182>. Richard will
    have a look.
  * G3/G4 Difference in FDC wire efficiency at the cell boundary
    <https://github.com/JeffersonLab/HDGeant4/issues/181> Richard will
    study this one as well. He cautioned us that the FDC geometry is not
    super easy to navigate.
  * inconsistent results generated by genBH
    <https://github.com/JeffersonLab/HDGeant4/issues/180>. Richard was
    not able to reproduce the anomalies reported.
  * G4 exceptions for certain run numbers
    <https://github.com/JeffersonLab/HDGeant4/issues/167>. We need to
    follow up with Elton to see if this is still an issue.


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