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<div class="">Hi Richard,</div>
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<div class="">My understand is that you have reproduced the effect that I originally documented: the energy response of the FCAL in the MC somehow changed and is now not correctly calibrated. This is the original observation that motivated the issue. From
what I can tell, you seem to have verified that there is a problem. </div>
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<div class="">This problem was first documented in this log entry:</div>
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<div class=""><a href="https://logbooks.jlab.org/entry/3621347" class="">https://logbooks.jlab.org/entry/3621347</a></div>
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<div class="">What I really wanted to know is: why did the response of the FCAL in the MC change? For this, we have seem to have no answer.</div>
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<div class="">So, we can retune the MC calibration of FCAL and mark the issue as "resolved." But without understanding the reason the issue emerged, then it may sneak up again.</div>
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<div class="">Matt</div>
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<div class="">On Mar 23, 2019, at 4:39 PM, Richard Jones <<a href="mailto:richard.t.jones@uconn.edu" class="">richard.t.jones@uconn.edu</a>> wrote:</div>
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<div dir="ltr" class="">Hello Matt and all,
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<div class="">I have updated my FCAL mc response study to single-photon events (0-8 GeV) in the forward direction. This shows the final adjustment in the energy scaling factors in hdgeant and hdgeant4. Unless I hear something to the contrary, I consider the
energy scale issue reported on github Jeffersonlab/hdgeant4 to be resolved, if someone could agree and make it as resolved.</div>
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<div class="">Also shown in the updated report is a new timing comparison study, where I used the position recorded for the fcal shower together with the mc generated vertex information to produce a time-of-flight corrected shower time, which should be zero
if the reconstruction and simulation are consistent. Notice that there is still a residual time-walk that we might want to understand and correct.</div>
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<div class=""><a href="https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=3852" class="">https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=3852</a><br class="">
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<div class="">-Richard Jones</div>
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