[Halld-offline] HDGeant4 Meeting Minutes, May 5, 2020

[Mark Ito]

Folks,

Please find the minutes from last week's HDGeant4 Meeting here 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_May_5,_2020#Minutes> 
and below.

   -- Mark


    HDGeant4 Meeting, May 5, 2020, Minutes

Present: Sean Dobbs, Mark Ito (chair), Igal Jaegle, Naomi Jarvis, 
Richard Jones, Justin Stevens, Simon Taylor, Nilanga Wickramaarachchi, 
Beni Zihlmann

There is a recording of this meeting <https://bluejeans.com/s/uyFb9/> on 
the BlueJeans site. Use your JLab credentials to get access.


      Review of minutes from the last Meeting

We went over the minutes from April 21 
<https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_April_21,_2020#Minutes>. 
On the subject of upgrading our version of Geant4 and the possible need 
for an upgraded GCC, Richard mentioned that he is using the Developer 
Toolset from Software Collections 
<https://www.softwarecollections.org/en/> to get GCC versions beyond 
that native to his CentOS7 distribution.


      Issues on GitHub


        BCAL structure in E/p distributions for kaons

We went over Issue #149 
<https://github.com/JeffersonLab/HDGeant4/issues/149> again. There has 
been a lot of work and discussion on this issue since the last meeting. 
See the issue on GitHub for all of the details.

The big take-away is that the CUTS card in the hdgeant/hdgeant4 
control.in files was causing unphysical behavior for hdgeant4. The 
problem was that particles that went below energy thresholds specified 
in that card disappeared and were not allowed to interact or decay. 
Their rest energy was therefore not accounted for. There is a history 
associated with how this came to be (basically a communication failure), 
but bottom line is that this card was not intended for use in production 
runs of HDGeant4. For hdgeant (GEANT 3) its affect is more benign, but 
even there its use is not required and not recommended. Unfortunately, 
it has been included in the MCwrapper template from the beginning of 
that system so nearly all of our hdgeant4-generated Monte Carlo has had 
this pathology.

Many of our studies need to be repeated with the CUTS card properly 
excluded.

Richard also requested that going forward Geant3 simulations be run with 
both HADR=1 and HADR=4 settings. For him this has been useful in that 
there can be differences in some of the quantities we have been studying 
due to differences in the hadronic interaction model used. Using both 
setting allows one to judge the rough size of what those differences 
might be.

This issue will be discussed at the Collaboration Meeting next week in 
the Tuesday afternoon session.


        K particle gun request to resolve G3/G4 difference near p 0.5
        GeV/c and theta 120 degrees

We went over Issue #137 
<https://github.com/JeffersonLab/HDGeant4/issues/137>. Activity on this 
issue picked up last week after the root cause of Issue #149 was 
discovered. Again, see the issue on GitHub for all of the details.

Unfortunately, the root cause here was not obvious. Richard pointed out 
that if one expands the phase space simulated beyond the narrow region 
populated by the reaction of interest, there are clear features in the 
$theta;-momentum plane that could lead to the features that first 
prompted submission of the issue. Work continues with Richard and 
Nilanga leading the charge.

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  * This page was last modified on 12 May 2020, at 19:55.

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