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Thanks Igal,
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<div>If I understand you correctly, this sample is statistically </div>
<div>insignificant. Your generated samples is worth of a second </div>
<div>compared with the typical run time of hours.</div>
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<div>Just on the example of the empty target run:</div>
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<div>The photon flux equivalent to all empty target runs is </div>
<div>~2.4 x 10^12 (with E_gamma > 8 GeV). For all production runs </div>
<div>it's several times larger.</div>
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<div>The total number of runs in PrimEx is ~420; you processed</div>
<div>10^6 events for each run, i.e., 4.2 x 10^8 events in total (?)</div>
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<div>If you reconstruct 1000 empty-target BG events below 1 degree </div>
<div>(as an example), the average production rate is 1 event per 2.4 x 10^9 photons.
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<div>You need ~5 more samples like this to see at least one bg event </div>
<div>in the empty target run (on average).</div>
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<div>(I guess that your bg is less than 1000 events below one degree).</div>
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<div>The background might also be a combination of the em and hadronic events.</div>
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<div>You need many more samples like this to exclude the em bg (if I understood </div>
<div>you correctly).</div>
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<div>Cheers,</div>
Sasha<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Primexd <primexd-bounces@jlab.org> on behalf of Igal Jaegle <ijaegle@jlab.org><br>
<b>Sent:</b> Monday, March 15, 2021 8:38 AM<br>
<b>To:</b> primexd@jlab.org <primexd@jlab.org><br>
<b>Subject:</b> [Primexd] Beamline background MC simulation & meeting tomorrow</font>
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All,</div>
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The first batch of background produced along the beamline can be found here:</div>
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/cache/halld/gluex_simulations/PRIMEX/primex-beam-line-bkg-batch01-15032021</div>
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In this batch, 1M photons with an energy above 8 GeV and following the DB flux distributions are shot upstream the target for each run with an entry for the flux in the DB. There are no entries below 1 degree for all runs combined (Be, He, empty targets). All
the entries above 1 degree correspond to hadronic processes (following the SAID DB) producing pi0/eta/etaprime. It is not clear if the physics list is adapted for what we want to simulate.
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Also, the meeting will be short as we have an 11 am GlueX Physics Meeting. Note, Sasha and I might be a little bit late as we have a mandatory meeting between 9:30 and 10:30 am.<br>
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tks ig.<br>
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