[Halld-offline] HDGeant4 Meeting Minutes, January 14, 2020

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_January_14,_2020#Minutes> 
and below.

   -- Mark


    HDGeant4 Meeting, January 14, 2020, Minutes

Present:

  * *CMU: * Naomi Jarvis
  * *FSU: * Sean Dobbs
  * *JLab: * Alex Austregesilo, Colin Gleason, Mark Ito (chair), Igal
    Jaegle, Keigo Mizutani, Simon Taylor, Jon Zarling, Beni Zihlmann
  * *ODU: * Nilanga Wickramaarachchi
  * *UConn: * Richard Jones

There is a recording of this meeting <https://bluejeans.com/s/Q@6MF/> on 
the BlueJeans site. Use your JLab credentials to get access.


      Review of Minutes from the December 17 Meeting

We went over the minutes 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_December_17,_2019#Minutes> 
without significant comment.


      Issues on GitHub

We went over two of the issues 
<https://github.com/JeffersonLab/HDGeant4/issues>.


        Calorimeter timing mismatch between g3 and g4

This is Issue #93 <https://github.com/JeffersonLab/HDGeant4/issues/93>

Since the last meeting Alex has found much better agreement on ρ 
efficiency between G3 and G4 when the timing agreement requirement 
between charged track times, measured in the outer detectors, agrees 
with the RF time to within ±5 ns. The standard cut is ±1 ns. See the 
plots below.

<https://halldweb.jlab.org/wiki/index.php/File:Efficiency_rho_standard.png>
with ±1 ns timing cut
<https://halldweb.jlab.org/wiki/index.php/File:Efficiency_rho.png>
with ±5 ns timing cut

We focused on timing in the BCAL shown below.

<https://halldweb.jlab.org/wiki/index.php/File:Bcal_timing_aa.png>
BCAL timing for charged particles in ρ events after ±1 ns cut.

The high side tail of the G3 distribution is cut off by the timing cut 
(there is a resolution effect in the cut), consistent with different 
efficiency for different timing cuts.

Justin pointed out that the picture is a bit different for Colin's 
analysis as presented in Issue #111 
<https://github.com/JeffersonLab/HDGeant4/issues/111> for π^+ s from the 
reaction γp→π^- ηΔ^++ , Δ^++ →π^+ p. Here G3 seems to agree with data 
better. See below:

<https://halldweb.jlab.org/wiki/index.php/File:Bcal_timing_colin.png>
BCAL timing for π^+ from Colin.

Alex and Colin agreed to study this effect with a single particle gun 
simulation over appropriate angles and momenta.


        BCAL Reconstructed Energy skewed in runs less than 40000

This is Issue #138 <https://github.com/JeffersonLab/HDGeant4/issues/138>.

Jon has done a photon gun study where he compares (a) G3 and G4 for a 
run before 40,000 and (b) simulations for different run numbers using G4 
for both. For both scenarios he sees significant differences.

For the different run number scenario, Jon mentioned calibrations as a 
possible cause and Sean also suggested a detailed comparison of the 
constants involved. Sean pointed out the BCAL saturation tables may not 
be doing the same thing for all run numbers. He also pointed out that 
the BCAL is the only system that produces digi hits which means a lot 
more has to go into mcsmear since all effects for which corrections are 
applied to real data need to be incorporated into the smearing as well 
and constants supplied to take them out in reconstruction.

The difference between G3 and G4 for the same run number is puzzling. 
Jon will try to repeat that comparison for a high run number.

Jon has looked at pull distributions for photons in several reactions 
and sees pretty good agreement between data and G4 bggen. We did not 
have time to go through his slides 
<https://halldweb.jlab.org/wiki/images/b/b9/QuickPeekPhotonPulls.pdf>, 
but hopefully will next time.

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  * This page was last modified on 16 January 2020, at 15:11.

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