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<p>Folks,</p>
<p>Please find the minutes <a moz-do-not-send="true" href="https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_October_18,_2021#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, October 18, 2021, </span><span class="mw-headline" id="Minutes">Minutes</span></h2>
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<p>Present: Alex Austregesilo, Sean Dobbs, Mark Ito
(chair), Igal Jaegle, Richard Jones, Simon Taylor, Beni
Zihlmann
</p>
<p>There is a <a rel="nofollow" class="external text" href="https://bluejeans.com/s/rTLefPvkJ8H/">recording
of this meeting</a> on the BlueJeans site. Log into
the <a rel="nofollow" class="external text" href="https://jlab.bluejeans.com">BlueJeans site</a>
first to gain access (use your JLab credentials).
</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 the <a href="https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_October_4,_2021#Minutes" title="HDGeant4 Meeting, October 4, 2021">minutes from
October 4th</a>. The issue we discussed, <a rel="nofollow" class="external text" href="https://github.com/JeffersonLab/HDGeant4/issues/198">hdgeant4
with updated support packages crashes, Issue #198</a>.
Has since been solved. It had to do with two fixes for
different issues related using Qt in visualization.
Those fixes were in conflict on nodes that had both Qt4
and Qt5 installed.
</p>
<h3><span class="mw-headline" id="Issues_on_GitHub">Issues
on GitHub</span></h3>
<p>We went over the <a rel="nofollow" class="external
text" href="https://github.com/JeffersonLab/HDGeant4/issues">HDGeant4
issues on GitHub</a>.
</p>
<h3><span class="mw-headline" id="Data.2FMC_discrepancy_in_FCal_Matching_around_Beam_Hole_.23196">Data/MC
discrepancy in FCal Matching around Beam Hole #196</span></h3>
<ul>
<li> Alex posted <a rel="nofollow" class="external
text" href="https://github.com/JeffersonLab/HDGeant4/issues/196">this
issue</a> last month.</li>
<li> Sean mentioned that we have seen effects like this
for a long time. He has some time to look at it now.
He is going to start investigating whether there may
be accidental contributions in real data that are not
included by mixing in random triggers in simulated
events.</li>
<li> Igal reminded us that the geometry has shifted.
That could be part of the problem.</li>
<li> Alex has looked at Bethe-Heitler events from Andrew
Schick. With those, he sees high track matching
efficiency near the beam hole. This may be due to
background events in the sample.</li>
<li> Matt Shepherd and Rebecca Barsotti also had some
suspicions about how we model the background when
comparing photon reconstruction efficiency in the FCAL
between data and simulation.</li>
</ul>
<h3><span class="mw-headline" id="Source_of_Random_Trigger_Files">Source of Random
Trigger Files</span></h3>
<p>Richard wondered whether he needs to continue to serve
out random trigger files over XROOTD from UConn. The are
consuming a lot of space. We will ask Thomas Britton
about whether JLab can serve as the sole source of these
files now.
</p>
<h3><span class="mw-headline" id="Package_Independence">Package
Independence</span></h3>
<p>Mark described work he is doing to build hdgeant4 and
halld_sim independently from halld_recon by extracting
the pieces of halld_recon that generate the
dependencies. So far he has a system that builds against
Richard's stand-alone HDDM (removing
src/programs/Utilities/hddm from halld_recon) and an
interface library (replacing src/libraries/HDDM from
halld_recon) called libhddm at present. To create a
stand-alone interface library, he has to take a
significant number of header files, formerly in the
detector reconstruction library directories, and ship
them over the new libhddm. This is so that halld_sim et
al. can access HDDM-formatted data without having to
depend on halld_recon to provide that functionality.
HDDM is not the only piece responsible for the
dependence of halld_sim on halld_recon; this is only the
first step.
</p>
<p>There was a lot of discussion about this plan. One of
the main concerns was that the header files needed to
read HDDM data, e.g., TOF data, would be separated from
the TOF reconstruction library. Mark argued that that is
the price one must pay for package independence. There
will be more discussion at the next software meeting.
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