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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,_January_14,_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, January 14, 2020, </span><span
class="mw-headline" id="Minutes">Minutes</span></h2>
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<p>Present:
</p>
<ul>
<li> <b> CMU: </b> Naomi Jarvis</li>
<li> <b> FSU: </b> Sean Dobbs</li>
<li> <b> JLab: </b> Alex Austregesilo, Colin Gleason,
Mark Ito (chair), Igal Jaegle, Keigo Mizutani, Simon
Taylor, Jon Zarling, Beni Zihlmann</li>
<li> <b> ODU: </b> Nilanga Wickramaarachchi</li>
<li> <b> UConn: </b> Richard Jones</li>
</ul>
<p>There is a <a rel="nofollow" class="external text"
href="https://bluejeans.com/s/Q@6MF/">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_December_17_Meeting">Review
of Minutes from the December 17 Meeting</span></h3>
<p>We went over <a
href="https://halldweb.jlab.org/wiki/index.php/HDGeant4_Meeting,_December_17,_2019#Minutes"
title="HDGeant4 Meeting, December 17, 2019">the
minutes</a> without significant comment.
</p>
<h3><span class="mw-headline" id="Issues_on_GitHub">Issues
on GitHub</span></h3>
<p>We went over two of <a rel="nofollow" class="external
text"
href="https://github.com/JeffersonLab/HDGeant4/issues">the
issues</a>.
</p>
<h4><span class="mw-headline"
id="Calorimeter_timing_mismatch_between_g3_and_g4">Calorimeter
timing mismatch between g3 and g4</span></h4>
<p>This is <a rel="nofollow" class="external text"
href="https://github.com/JeffersonLab/HDGeant4/issues/93">Issue
#93</a>
</p>
<p>Since the last meeting Alex has found much better
agreement on ρ efficiency between G3 and G4 when the
timing agreement requirement between charged track
times, measured in the outer detectors, agrees with the
RF time to within ±5 ns. The standard cut is ±1 ns. See
the plots below.
</p>
<div class="thumb tright">
<div class="thumbinner" style="width:402px;"><a
href="https://halldweb.jlab.org/wiki/index.php/File:Efficiency_rho_standard.png"
class="image"><img alt=""
src="https://halldweb.jlab.org/wiki/images/thumb/1/11/Efficiency_rho_standard.png/400px-Efficiency_rho_standard.png"
class="thumbimage" width="400" height="272"></a>
<div class="thumbcaption">with ±1 ns timing cut</div>
</div>
</div>
<div class="thumb tright">
<div class="thumbinner" style="width:402px;"><a
href="https://halldweb.jlab.org/wiki/index.php/File:Efficiency_rho.png"
class="image"><img alt=""
src="https://halldweb.jlab.org/wiki/images/thumb/1/12/Efficiency_rho.png/400px-Efficiency_rho.png"
class="thumbimage" width="400" height="272"></a>
<div class="thumbcaption">with ±5 ns timing cut</div>
</div>
</div>
<p>We focused on timing in the BCAL shown below.
</p>
<div class="thumb tright">
<div class="thumbinner" style="width:402px;"><a
href="https://halldweb.jlab.org/wiki/index.php/File:Bcal_timing_aa.png"
class="image"><img alt=""
src="https://halldweb.jlab.org/wiki/images/thumb/5/5f/Bcal_timing_aa.png/400px-Bcal_timing_aa.png"
class="thumbimage" width="400" height="291"></a>
<div class="thumbcaption">BCAL timing for charged
particles in ρ events after ±1 ns cut.</div>
</div>
</div>
<p>The high side tail of the G3 distribution is cut off by
the timing cut (there is a resolution effect in the
cut), consistent with different efficiency for different
timing cuts.
</p>
<p>Justin pointed out that the picture is a bit different
for Colin's analysis as presented in <a rel="nofollow"
class="external text"
href="https://github.com/JeffersonLab/HDGeant4/issues/111">Issue
#111</a> for π<sup>+</sup>s from the reaction γp→π<sup>-</sup>ηΔ<sup>++</sup>,
Δ<sup>++</sup>→π<sup>+</sup>p. Here G3 seems to agree
with data better. See below:
</p>
<div class="thumb tright">
<div class="thumbinner" style="width:402px;"><a
href="https://halldweb.jlab.org/wiki/index.php/File:Bcal_timing_colin.png"
class="image"><img alt=""
src="https://halldweb.jlab.org/wiki/images/thumb/1/14/Bcal_timing_colin.png/400px-Bcal_timing_colin.png"
class="thumbimage" width="400" height="746"></a>
<div class="thumbcaption">BCAL timing for π<sup>+</sup>
from Colin.</div>
</div>
</div>
<p>Alex and Colin agreed to study this effect with a
single particle gun simulation over appropriate angles
and momenta.
</p>
<h4><span class="mw-headline"
id="BCAL_Reconstructed_Energy_skewed_in_runs_less_than_40000">BCAL
Reconstructed Energy skewed in runs less than 40000</span></h4>
<p>This is <a rel="nofollow" class="external text"
href="https://github.com/JeffersonLab/HDGeant4/issues/138">Issue
#138</a>.
</p>
<p>Jon has done a photon gun study where he compares (a)
G3 and G4 for a run before 40,000 and (b) simulations
for different run numbers using G4 for both. For both
scenarios he sees significant differences.
</p>
<p>For the different run number scenario, Jon mentioned
calibrations as a possible cause and Sean also suggested
a detailed comparison of the constants involved. Sean
pointed out the BCAL saturation tables may not be doing
the same thing for all run numbers. He also pointed out
that the BCAL is the only system that produces digi hits
which means a lot more has to go into mcsmear since all
effects for which corrections are applied to real data
need to be incorporated into the smearing as well and
constants supplied to take them out in reconstruction.
</p>
<p>The difference between G3 and G4 for the same run
number is puzzling. Jon will try to repeat that
comparison for a high run number.
</p>
<p>Jon has looked at pull distributions for photons in
several reactions and sees pretty good agreement between
data and G4 bggen. We did not have time to go through <a
href="https://halldweb.jlab.org/wiki/images/b/b9/QuickPeekPhotonPulls.pdf"
class="internal" title="QuickPeekPhotonPulls.pdf">his
slides</a>, but hopefully will next time.
</p>
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