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<p>Colleagues,</p>
<p>Please find the minutes <a moz-do-not-send="true"
href="https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_April_21,_2020#Minutes">here</a>
and below.</p>
<p> -- Mark</p>
<p>
</p>
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<h2 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">HDGeant4 Meeting, April 21, 2020, </span><span
class="mw-headline" id="Minutes">Minutes</span></h2>
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lang="en">
<p>Present: Mark Dalton, Sean Dobbs, Mark Ito (chair),
Igal Jaegle, Naomi Jarvis, Richard Jones, Simon Taylor
</p>
<p>There is a <a rel="nofollow" class="external text"
href="https://bluejeans.com/s/kCBOV/">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,_March_24,_2020#Minutes"
title="HDGeant4 Meeting, March 24, 2020">the minutes
from March 24</a> without comment.
</p>
<h3><span class="mw-headline"
id="BCAL_structure_in_E.2Fp_distributions_for_kaons">BCAL
structure in E/p distributions for kaons</span></h3>
<p>We went over <a rel="nofollow" class="external text"
href="https://github.com/JeffersonLab/HDGeant4/issues/149">Issue
#149</a>, recently submitted by Peter Pauli. He sees
sharp features in the distribution of E/p in the BCAL
for K<sup>−</sup>s in hdgeant4 and not in data. They are
present both in the simulation of his reaction and in
the single particle gun. The discussion went on for
quite a while as we worked our way through the plots and
comments in the issue. Please see the recording and the
postings in the issue for all the details. In summary:
</p>
<ol>
<li> We thought one way to untangle the various features
that Peter has pointed out might be by turning on and
off (a) decays and (b) hadronic interactions. Note
that at Beni's suggestion, Peter has already looked at
decays.</li>
<li> Richard is suspicious that there might be a problem
in the treatment of kaons stopping in the BCAL. If
energy released by capture of stopped kaons is not
accounted for in the Monte Carlo, then that could
explain the difference Peter observes between MC and
data. Richard thought that before Peter spends time on
item(1), he (Richard) should take a look at this.</li>
</ol>
<h3><span class="mw-headline" id="Reports_from_UConn">Reports
from UConn</span></h3>
<ul>
<li> Richard has some students working on MC. They have
discovered some issues, including seg faults, that
they have reported to Richard. At this point they have
not been submitted as GitHub issues.</li>
<li> Richard raised the issue of upgrading our version
of Geant4.
<ul>
<li> We are at 10.02.p02, released June 29, 2016.
The latest release is 10.06.p01, released February
14, 2020. That is a big gap.</li>
<li> About half of the custom fixes from Richard
that we needed for 10.02.p02 are incorporated in
10.06.p01. He has produced the correspondingly
reduced set of custom fixes need for this latest
release, as well as fixes need for other releases
since 10.02.p02.</li>
<li> Going to 10.02.p02 requires GCC 5.x. We are
using 4.8.5 on RHEL7 and CentOS7. Past experience
tells us that this is no small deal.</li>
<li> There is a start-up delay with G4 10.02.p02
that was not present in 10.02.p02 due to
"voxelation". There is an option to skip this
step, at a possible cost in execution speed.</li>
</ul>
</li>
<li> When working remotely, there is a package called <a
rel="nofollow" class="external text"
href="https://www.virtualgl.org/">VirtualGL</a> that
will allow graphics commands to be executed on the
local graphics card. This speeds things up
considerably.</li>
</ul>
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