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<p>Please find the minutes <a moz-do-not-send="true"
<p> -- Mark</p>
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<h2 id="firstHeading" class="firstHeading" lang="en"><span
dir="auto">HDGeant4 Meeting, January 29, 2019, </span><span
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<li> <b> JLab: </b> Alex Austregesilo, Thomas Britton,
Sean Dobbs, Mark Ito (chair), Simon Taylor, Beni
<li> <b> UConn: </b> Richard Jones</li>
<p>There is a <a rel="nofollow" class="external text"
this meeting</a> on the BlueJeans site. Use your JLab
minutes from last time</span></h3>
<p>We went over <a
title="HDGeant4 Meeting, January 15, 2019">the minutes
from January 15</a> with no new issues raised.
id="How_to_run_hdgeant_without_the_DIRC">How to run
hdgeant without the DIRC</span></h3>
<p>Richard led us through <a rel="nofollow"
email</a>, sent earlier today, which addressed two
<li> How to run pre-DIRC geometry, when the DIRC is
present in the master branch of hdds
<li> Richard has embellished David Lawrence's
mechanism whereby hdgeant can generate its HDDS
FORTRAN code and corresponding libraries on the
fly. The details are in <a
title="HOWTO run hdgeant simulations using ccdb
geometry">his new HOWTO</a>.</li>
<li> We discussed the utility of having HDDS XML
files in the source code repository at all.
Richard stated that he finds the version stored
there useful for development.</li>
<li> We also discussed the need to built legacy
(pre-DIRC) versions of HDDS on disk for general
use. We thought that that might be more trouble
than they are worth. [Added in press: second
thoughts on this have been had by the secretary.]</li>
<li> How to run with the DIRC present, but not suffer
the overhead of following CKOV photons
<li> CKOV turns of Cerenkov photons for all
detectors, i. e., globally. Its historical default
is CKOV=1 or on. We did not pay the computational
price since no detector in the default geometry
had an index of refraction defined, a necessary
condition for optical photon tracking.</li>
<li> Turning off optical photon tracking in the DIRC
should speed things up by a factor of several.</li>
<p>Thomas presented the first plots from his effort at
repeated the studies we did when we first starting
having HDGeant4 meetings. Find the plots <a
class="internal" title="Pim 1 70.pdf">here</a>. They
are all for 1 GeV/c π<sup>−</sup>'s at 70 degrees in θ
and 0 degrees in φ, and they all show the results from
HDG3 and HDG4 side-by-side (or top-and-bottom, as the
case may be). The plots and accompanying discussion
appear starting at 23:00 in the recording.
<p>A more careful look needs to be taken. More particle
settings are to come. [Added in press: some ROOT files
have been posted by Thomas:
<p>File names have the form G[version
number]_[particle]_[p GeV]_[theta deg].root]
id="Note_on_Upstream_Bug_Fixes">Note on Upstream Bug
<p>Richard reported that he has passed the information on
bugs he has found in Geant4 up to the Geant4 team. He
hopes to eventually be able to operate without the
"G4fixes" part of the HDGeant4 distribution.
Pull Requests on GitHub</span></h3>
<p>There weren't any to review.
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<li id="lastmod"> This page was last modified on 30 January
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