[Halld-offline] HDGeant4 Meeting Minutes, April 9, 2019
marki at jlab.org
Fri Apr 12 12:52:58 EDT 2019
After the meeting, Peter pointed out to me that we need an action plan
to address the discrepancies he sees with the energy response of the
calorimeter for protons and charged kaons and with the drop in
acceptance he sees in tracking when comparing G4 with G3.
On 4/9/19 5:51 PM, Mark Ito wrote:
> Please find the minutes here
> and below.
> -- Mark
> HDGeant4 Meeting Minutes, April 9, 2019
> * *CMU: * Naomi Jarvis
> * *Glasgow: * Peter Pauli
> * *JLab: * Alex Austregesilo, Thomas Britton, Mark Dalton, Stuart
> Fegan, Mark Ito (chair), Simon Taylor, Beni Zihlmann
> There is a recording of this meeting
> on the BlueJeans site
> Use your JLab credentials to access it.
> Review of minutes from the last meeting
> We went over the minutes from the March 26th meeting
> without significant comment.
> Do-over on comparison studies
> Simon is working on analysis of his particle gun simulations.
> Geant3/4 comparisons for the K-, K+ and p particle gun
> Peter led us though the set of summary slides
> from his particle gun studies. He chose protons and charged kaons
> because they are relevant to his analysis. Further he chose kinematic
> regions for each that match his reaction. He created monitoring plots
> for each species and had posted the complete set of plots for each as
> part of his GlueX Note.
> The summary alone runs to 72 slides and we went through them all in
> the course of about an hour. The secretary does not have detailed
> notes on each slide, but will record here some general remarks:
> * Peter told us he chose plots that seemed interesting, either
> because they showed good agreement between GEANT and Geant4 or,
> more likely, because there were puzzling differences.
> * As a general guide, if two plots are shown on the same pad, the
> blue is GEANT and the red is Geant4. If there are two separate
> pads, then the top is GEANT, the bottom is Geant4.
> * He sees a charged particle reconstruction efficiency for Geant4
> that is about 10% lower than that for GEANT. Alex noted that this
> is similar to what he is seeing when he studies ρ^0 events.
> * Peter mentioned that the differences he picked out are mostly of
> two broad classes: (1) energy or (2) timing, in each case as
> measured by the calorimeters.
> * We noted that since the z-position of charged particles is not
> well measured for single particles, some the the timing
> distributions may be hard to understand. Still they should have
> similar features in GEANT vs. Geant4.
> * The versions of the code he used came before Richard's most recent
> pull request
> symmetrizing the treatment of timing between the FCAL and BCAL.
> Some of the differences may have lessened in the new code; this
> should be checked.
> Please consult the recording if interested in a plot-by-plot discussion.
> Issue on GitHub: missing thrown events
> Thomas called our attention to Issue #101 on GitHub
> "Differences between G3 and G4 in eta.pi," submitted by Carlos
> Salgado. Carlos sees a completely different thrown momentum
> distribution for protons when using GEANT vs. Geant4 even though the
> generated events are identical in the two cases. Indeed they come from
> the same HDDM file.
> Retrieved from
> * This page was last modified on 9 April 2019, at 17:48.
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