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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,_March_26,_2019#Minutes">here</a>
and below.</p>
<p> -- Mark</p>
<p>_____________________________________</p>
<p> </p>
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<h1 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">Minutes, HDGeant4 Meeting, March 26, 2019</span></h1>
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lang="en">
<p>Present: </p>
<ul>
<li> <b> JLab: </b> Alex Austregesilo, Thomas Britton,
Sean Dobbs, Mark Ito (chair),Richard Jones, Simon
Taylor</li>
</ul>
<p>There is a <a rel="nofollow" class="external text"
href="https://bluejeans.com/s/96_2v"
moz-do-not-send="true">recording of this meeting</a>
on the BlueJeans site. Use your JLab credentials to
access it. </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_12,_2019#Minutes"
title="HDGeant4 Meeting, March 12, 2019"
moz-do-not-send="true">the minutes</a> without
significant comment. </p>
<h3><span class="mw-headline"
id="Do-over_on_comparison_studies">Do-over on
comparison studies</span></h3>
<p>Simon has run some single-particle gun simulations for
both HDG3 and HDG4 on the OSG. He has not had a chance
to look at them in detail yet. His initial impression is
that differences are seen in calorimetry. </p>
<h3><span class="mw-headline"
id="Further_comparative_studies_of_calorimeter_response">Further
comparative studies of calorimeter response</span></h3>
<p>Richard showed <a rel="nofollow" class="external text"
href="https://docs.google.com/presentation/d/1IDw4LD2GhBpzam9E1V8LRBcb49Kb1V3GMTWR2Inw2V8/edit?usp=sharing"
moz-do-not-send="true">some slides</a> describing
extensions of his work on low-level comparisons of HDG3
and HDG4 for calorimetry. </p>
<ul>
<li> He looked at the residual non-linearity, albeit up
to 8 GeV, for reconstructed shower energy in the FCAL.
Agreement between HDG3 and HDG4 is very good now, at
all energies.</li>
<li> He has examined cluster time, relative to "RF".
Both HDG3 and 4 show the same linear systematic
dependence in relative time as a function of energy.</li>
<li> For BCAL energy response, he showed the same
residual non-linearity study as shown earlier for the
FCAL. Here the qualitative agreement is good, with
perhaps an 8 MeV upward shift of HDG4 relative to
HDG3. The effect of energy leakage out the back of
BCAL dominates the changes in the trends as polar
angle moves from far forward to 90 degrees.</li>
<li> For BCAL timing, he noted a difference in the
algorithm used to get cluster timing between HDG3 and
HDG4
<ul>
<li> HDG3 uses energy-weighted average shower times</li>
<li> HDG4 uses the earliest hit per sector for times</li>
</ul>
</li>
<li> We noted that mcsmear smears the BCAL timing by 55
ps, not a lot. Richard sees this in his study.</li>
<li> The difference in the BCAL algorithms does not make
much apparent difference. He suggests we use energy
weighted for both to be consistent.</li>
<li> Richard is planning to deprecate the bcalSiPMUpHit
and bcalSiPMDownHit elements in HDDM in favor of a
single bcalTruthCell element that can serve
information from both upsteam and downstream ends of
the BCAL,</li>
<li> There is still an issue that Alex sees with the ρ's
albeit with charged tracks and not electromagnetic
showers. Hopefully Simon's single-track studies will
address it.</li>
</ul>
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