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<p>Hi Seamus, <br>
</p>
<p>I'll give a brief update at the simulation meeting tomorrow on
some improvements I've made/am making to the "under-the-hood"
machinery of g4sbs: <br>
</p>
<p>1) Option to turn on rejection sampling for the built-in event
generators, which produces events distributed according to the
calculated differential cross section; the code generates a
user-specified number of "pre-events" thrown flat in phase space,
that aren't tracked through the setup, in order to determine the
maximum event weight within the user-defined generation limits.
This process is fast, and leads to reasonably good efficiency for
the rejection sampling, provided the differential cross section
does not vary by too many orders of magnitude within the event
generation limits. Then it uses this maximum event weight for a
rejection sampling to produce events distributed according to the
model cross section. This option is useful in particular for
physics analyses where one wishes to avoid the complications of
estimating statistical uncertainties for weighted Monte Carlo
statistics. This modification is finished, tested, and pushed to
the uconn_dev branch of the github repo. <br>
</p>
<p>2) Modifying the sensitive detector and hit classes to define a
hit time window and energy threshold for "calorimeter" type; i.e.,
showering detectors (or scintillators when we don't want to turn
on the optical photon machinery). This modification improves on
the existing machinery in that the existing machinery only allows
for one "hit" per detector channel per simulated event; i.e., all
energy deposition in a given sensitive volume in a given simulated
event is summed into a single "hit", regardless of the timing of
those energy depositions. The "hit timing" calculated using this
machinery would sometimes be distorted by averaging in low-energy
secondaries that are significantly delayed relative to the primary
particle hits. <br>
</p>
<p>The new machinery allows more than one hit per sensitive detector
channel per simulated event by defining a "hit timing window"
analogous to a gate for charge integration in an ADC and/or a
sampling window for a Flash ADC type digitization. Starting with
the time of the earliest energy deposition in a channel, all
energy depositions arriving within a user-configurable timing
window of the "hit start time" will be accumulated in the first
hit, and any energy depositions occurring later than the hit start
time plus the gate width will start a new hit in the same detector
channel. For now I do not consider pulse shape/pileup, but I
simply assume that the hit timing window will be chosen suitably
wide to encompass >~ 99% of the primary signal. Note that the
simulation only includes the time dependence of the energy
deposition itself, and does not account for the pulse shaping
effects of the PMT multiplication or process and/or
amplification/shaping by front-end electrons. <br>
</p>
<p>This modification gives a more accurate measure of the hit timing
and time resolution, and the energy resolution, for simulated
hits. I also now allow the user to define an energy threshold for
sensitive detector hits on a per-detector basis. Currently, a zero
threshold is used, meaning that any non-zero energy deposition in
a sensitive volume (that is not an optical photon detector)
produces a sensitive detector hit. Allowing the user to define a
threshold allows for a more realistic view of detector background
rates/occupancies/efficiencies (assuming the threshold is defined
in a sensible way) and can in principle reduce the size on disk of
simulation output files. But it could also be somewhat redundant
with the external digitization libraries and give misleading
results if sensible values are not used. <br>
</p>
<p>I have already finished coding and testing this change for
"calorimeter" type detectors that measure energy deposition, but
I'm still working on the appropriate machinery for the other
detectors, including "GEMs" and "ECALs". I have tried to define
sensible default values for each of the detectors in the various
experiments, and will add the relevant UI commands for user
customization. Time permitting (I have to catch a flight at 1 PM
tomorrow), I will show a few slides about my progress on these
developments. <br>
</p>
<p>Best regards,</p>
<p>Andrew<br>
</p>
<br>
<div class="moz-cite-prefix">On 1/30/18 9:56 AM, Seamus Riordan
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:70633275-f8c5-0883-ff77-d28998195d17@jlab.org">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
Hi everyone,
<pre wrap="">We will have our next meeting regarding the SBS simulation and DAQ, Wednesday, at 9AM ET.
You can call in at:
<a href="tel:%2B1-888-240-2560" value="+18882402560" target="_blank" moz-do-not-send="true">+1-888-240-2560</a>
(US and Canada) and see <a href="http://bluejeans.com/numbers" target="_blank" moz-do-not-send="true">international numbers</a>
Access number: 9989030149
<span class="meeting_url" id="meeting_url_text_9989030149"><a class="moz-txt-link-freetext" href="https://bluejeans.com/9989030149" moz-do-not-send="true">https://bluejeans.com/9989030149</a></span>
TED 2561B has been reserved for those attending locally at the lab.
An agenda can be found here:
<a class="moz-txt-link-freetext" href="http://hallaweb.jlab.org/12GeV/SuperBigBite/sbssimwg/20180131/" moz-do-not-send="true">http://hallaweb.jlab.org/12GeV/SuperBigBite/sbssimwg/20180131/</a>
Please add anything you want to share to this week's page from the CUE
/group/halla/www/hallaweb/html/12GeV/SuperBigBite/sbssimwg
or email me slides or plots that you have to show before the meeting!
Best,
Seamus</pre>
<pre class="moz-signature" cols="72">--
Seamus Riordan <a class="moz-txt-link-abbreviated" href="mailto:sriordan@anl.gov" moz-do-not-send="true">sriordan@anl.gov</a>
Argonne National Laboratory Office: (630) 252-4101
Assistant Physicist Fax: (630) 252-3903
Physics Division Building 203 Room C265
Argonne National Laboratory
9700 S. Cass Ave
Argonne, IL 60439
</pre>
<br>
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<br>
<pre wrap="">_______________________________________________
Sbs_software mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Sbs_software@jlab.org">Sbs_software@jlab.org</a>
<a class="moz-txt-link-freetext" href="https://mailman.jlab.org/mailman/listinfo/sbs_software">https://mailman.jlab.org/mailman/listinfo/sbs_software</a>
</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Andrew Puckett
Assistant Professor, Department of Physics, University of Connecticut
2152 Hillside Road, U-3046
Storrs, CT 06269-3046
E-mail: <a class="moz-txt-link-abbreviated" href="mailto:puckett@jlab.org">puckett@jlab.org</a>, <a class="moz-txt-link-abbreviated" href="mailto:puckett@phys.uconn.edu">puckett@phys.uconn.edu</a>
Office phone: 860-486-7137</pre>
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