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<p>Folks,</p>
<p>Please find the minutes from last week's HDGeant4 Meeting <a
moz-do-not-send="true"
href="https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_May_5,_2020#Minutes">here</a>
and below.</p>
<p> -- Mark</p>
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</p>
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<h2 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">HDGeant4 Meeting, May 5, 2020, </span><span
class="mw-headline" id="Minutes">Minutes</span></h2>
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lang="en">
<p>Present: Sean Dobbs, Mark Ito (chair), Igal Jaegle,
Naomi Jarvis, Richard Jones, Justin Stevens, Simon
Taylor, Nilanga Wickramaarachchi, Beni Zihlmann
</p>
<p>There is a <a rel="nofollow" class="external text"
href="https://bluejeans.com/s/uyFb9/">recording of
this meeting</a> on the BlueJeans site. Use your JLab
credentials to get access.
</p>
<h3><span class="mw-headline"
id="Review_of_minutes_from_the_last_Meeting">Review of
minutes from the last Meeting</span></h3>
<p>We went over <a
href="https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_April_21,_2020#Minutes"
title="HDGeant4 Meeting, April 21, 2020">the minutes
from April 21</a>. 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 <a rel="nofollow" class="external text"
href="https://www.softwarecollections.org/en/">Software
Collections</a> to get GCC versions beyond that native
to his CentOS7 distribution.
</p>
<h3><span class="mw-headline" id="Issues_on_GitHub">Issues
on GitHub</span></h3>
<h4><span class="mw-headline"
id="BCAL_structure_in_E.2Fp_distributions_for_kaons">BCAL
structure in E/p distributions for kaons</span></h4>
<p>We went over <a rel="nofollow" class="external text"
href="https://github.com/JeffersonLab/HDGeant4/issues/149">Issue
#149</a> 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.
</p>
<p>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.
</p>
<p>Many of our studies need to be repeated with the CUTS
card properly excluded.
</p>
<p>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.
</p>
<p>This issue will be discussed at the Collaboration
Meeting next week in the Tuesday afternoon session.
</p>
<h4><span class="mw-headline"
id="K_particle_gun_request_to_resolve_G3.2FG4_difference_near_p_0.5_GeV.2Fc_and_theta_120_degrees">K
particle gun request to resolve G3/G4 difference near
p 0.5 GeV/c and theta 120 degrees</span></h4>
<p>We went over <a rel="nofollow" class="external text"
href="https://github.com/JeffersonLab/HDGeant4/issues/137">Issue
#137</a>. 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.
</p>
<p>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.
</p>
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