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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,_February_12,_2019#Minutes">here</a>
and below.</p>
<p> -- Mark</p>
<p>________________________</p>
<p>
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<h1 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">HDGeant4 Meeting Minutes, February 12, 2019</span></h1>
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<p>Present:
</p>
<ul>
<li> <b> CMU: </b> Naomi Jarvis</li>
<li> <b> JLab: </b> Thomas Britton, Mark Ito (chair),
Simon Taylor, Beni Zihlmann</li>
<li> <b> UConn: </b> Richard Jones</li>
</ul>
<p>Today's meeting did not follow the published agenda.
</p>
<p>Mark has tagged a <b>version of HDDS that uses the
pre-DIRC geometry</b> found in the CCDB. Recall that
this version has overlaps removed and includes the
Lucite shield in front of the TOF. The new tag is 3.14.
Mark will prepare a version set using it for general
use.
</p>
<p>Thomas has looked at the plots of the recent <b>HDG3
vs 4 comparison simulation and does not see any
concerning differences.</b> These were done with most
physics processes turned off (no multiple scattering,
etc.). He will re-run with all physics processes turned
on as a further check. Naomi reported that she had seen
HDG4 executing many times more slowly that HDG3 several
months ago. Thomas will look at the execution times when
he does the running.
</p>
<p>Peter Pauli has done a <b>detailed high-level
comparison of results from HDG3 and HDG4.</b> He has
been on owl shift and could not be at the meeting to
present his results. He did send his slides to Mark.
Find them <a rel="nofollow" class="external text"
href="http://nuclear.gla.ac.uk/~pauli/pres.pdf">here</a>.
We will hear from him at a future meeting.
</p>
<p>We discussed the nature of the advice Thomas should
give at his talk at the Collaboration Meeting vis-a-vis
readiness of HDG4 for prime time. We agreed that <b>we
can recommend use of HDG4 going forward now;</b> no
known problems exist. In particular, tuning of the
smearing should now be done against HDG4 so that that
effort will transmit to future efforts. Richard made the
point that we are now in a situation where, if HDG3 and
HDG4 give different results, it may not be the case that
HDG3 is "right" and HDG4 is "wrong." For example, there
are processes in Geant4 that are better modeled than
they were in GEANT.
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