[Halld-offline] HDGeant4 Meeting Minutes, February 26, 2019

Mark Ito marki at jlab.org
Wed Feb 27 11:59:19 EST 2019


Please find the minutes here 
and below.

   -- Mark


    Minutes, HDGeant4 Meeting, February 26, 2019


  * *CMU: * Naomi Jarvis
  * *JLab: * Alex Austregesilo, Thomas Britton, Sean Dobbs, Stuart
    Fegan, Mark Ito (chair), Dmitry Romanov, Simon Taylor, Beni Zihlmann
  * *UConn: * Richard Jones
  * *W&M: * Justin Stevens

There is a recording of the meeting on the BlueJeans site 
<https://bluejeans.com/s/fai_B/>. Use your JLab credentials to access it.

      Review of minutes from the last HDGeant4

We went over the minutes of the February 12 meeting 
Mark reported that there is still no version set using the HDDS 3.14, 
the release with pre-DIRC geometry baked in.

      Do-over on comparison studies

Simon is working on a set of studies using the particle gun, with all 
the physics of particle interaction with matter turned on. He will 
report on it at a future meeting.

      Peter's comparative study of HDG3 vs. HDG4

Thomas led us through Peter Pauli's slides 
<https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=3932> on 
a comparative study of pKK in both Monte Carlo and data. Several slides 
showed comparisons of histograms from four points of view:

 1. as generated
 2. as reconstructed after simulation with hdgeant
 3. as reconstructed after simulation with hdgeant4
 4. real data

In many cases the hdgeant4 results looks a lot more like data. Note that 
it is unlikely that the generated distributions are the same as occur in 
the real world (as Matt pointed out at the collaboration meeting), but 
often the better agreement of data with hdgeant4 is due to a lack of 
sharp features seen in the hdgeant simulation and not in any of the 
other distributions. Also the fits to SDME's look a lot better when 
using hdgeant4 than with use of hdgeant. Peter concluded that he needs 
to use hdgeant4 for his work.

      G3/G4 Comparison for ρ(770) cross section

Alex showed his recent comparative analysis of the low-energy ρ data.

First he showed a plot comparing acceptance as a function of energy 
<https://halldweb.jlab.org/wiki/images/2/2b/G3_G4_comparison_1M.pdf>. He 
gets differences between G3 and G4 at lower beam photon energy in 
constrast to results from Peter and Simon.

He then showed highlights from comparisons of monitoring histograms 
<https://halldweb.jlab.org/talks/2019/Independent_rho_G3_G4.pdf>, with 
the results of G3 and G4 overlayed on a single histogram. He used a 
macro from Sean to do this. There are 1,277 such plots in total. Here 
are the items he bookmarked:

  * FDC Cathode (32, 54)
  * StartCounter (290, 412++)
  * BCal (77, 252, 316)
  * FCal (287, 373)
  * Protons (526++, 976)
  * Pions (1028++)
  * Beam Photons (639)
  * Vertex time (113), Track timing (872++)

There was some question about whether the HDG3 results used the pre-DIRC 
geometry. Alex and Thomas will check on this a re-run the simulation if 
necessary. Two features stood out:

 1. The start counter is missing its complement of recoil protons at 60
    degrees in polar angle. Alex will submit an issue; Richard will
 2. The effect of the trigger for low-energy beam photons, seen in HDG3
    is absent in HDG4. This could be due to differences in the way
    charged hadrons are treated in the FCAL. Differences in FCAL energy
    are seen in the relevant plots which go in the right direction (more
    energy for HDG4). More investigation is needed.

      Written Report

Mark proposed an outline for a written report 
from this committee describing the work we have done and recording our 
recommendations. There were no strenuous objections to going in the 
direction indicated.

      Issues on GitHub

We looked at Issue #89: Hit Energy Agreement 
<https://github.com/JeffersonLab/HDGeant4/issues/89>, submitted earlier 
in the day by Rebecca Barsotti. Richard summarized his explanation of 
why differences in shower energy are not surprising when comparing HDG3 
and HDG4.

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  * This page was last modified on 27 February 2019, at 11:51.

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