# Large Fluctuations for Scintillation Photons

Hi again,

I have a geometry with rock and scintillator. I am simulating some particles through them and reaching the scintillator bar. Usually at lower amounts of events the Scintillation Photons agree with Energy deposition however at 10,000 events, there is a significant discrepancy. I have couple of events that produce a significant amount of Scintillation Photons (see image below).

Zoomed in for 1 event

Now comparing to Energy deposition histogram I have:

If I remove the high Scintillation photon event then the Scintillation photon produced roughly matches energy deposition as I have RESOLUTIONSCALE =1.

The question is will there be such large fluctuations or perphas a gamma event from rock is entering the Scintillator ?

Ah it seems the Edep calculation doesnâ€™t take account of secondaries, so that may explain some secondaries depositing energy while it doest show up in Edep ?

Iâ€™m not sure what the question is exactly. Are you wondering why there is 1 event with many times more scintillation photons? I donâ€™t know what the energy deposition part of your question is about.

1. yes, the energy given to secondaries is not part of energy depositionâ€“makes sense, as that energy isnâ€™t deposited.
2. Scintillation photons are generated without regard to energy conservation. In this case the energy deposit could be double counted (if you score energy deposit of optical photons).

Hi dsawey, yes I was wondering why there is 1 event with many times more. Your point two seems interest to be regarding Scintillation photons are generated without regard to energy conservation.

The energy deposition histogram is energy deposited on Scintillator bar (via Sensitive detector method). I was trying to compare energy deposited in Scintillator bar to Number of Photons produced.

In theory could one deposit a certain energy and Scintillation photons produced more that the yield ? i.e if deposit energy is 0.01 MeV and Scintillation yield is 10000 photons per MeV. Could in theory produce more photons than one would normally expect?

I donâ€™t think I am double counting energy deposit.

Hello,

in a typical simulation case the of all energies of optical photons is much less than actual energy deposition of a particle inside scintillator. 10000 optical photon energy is very small.

VI

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