[Halld-offline] possible explanation for spurious BCAL hits in sim

[Richard Jones]

Hello Paul and all,

It has been reported and discussed during offline meetings that there are
significant numbers of hits in the BCAL coming late in time. I just
observed a puzzling behavior that might be related. I was working on the
rates normalization factor for the commissioning beamline geometry for
Sean, and I noticed that all events have a gazillion hits in the BCAL, even
in the case where the beam photon was stopped in the primary collimator.
This got my attention, so I looked further into it, and found that these
are noise hits being added in mcsmear. There were no bcal hits in the
hdgeant output, but they are added by mcsmear. I see approximately 120
noise hits in the BCAL per event, and each one has of order 10-20 MeV
amplitude. I don't know what the time window is on the clustering
algorithm, but I can easily see how these would occasionally lead to
~100MeV clusters.

Might this be the cause of the mystery delayed hits?

-Richard Jones
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