I’m trying the recreate the detector response function for Co-60 using NaI based scintillators. I was able to do so pretty successfully when the detector and scintillator were separate entities. I am now trying to assign my detector NaI as its material and removing the separate scintillator, because I think the result should be the same. However, I am receiving some strange energy peaks in the response function.
Geant4 Version: 11.2.1
Operating System: Ubuntu 24.04
Compiler/Version: g++ 13.2.0
CMake Version: 3.30.0-rc1
GitHub repo: GitHub - PranjaySaini/ImageReconstruction-WIP-
This is what I’m getting:
This is what it used to look like before:
The general shape looks correct for the first plot, just the magnitude is too large. Did you change how you tally energy deposition, or your physics list? I took a look at your stepping action and one issue that could be occurring is that you are counting the energy deposition of all particles, in this case that would be the primary gammas and the secondary electrons so you would expect your tally to be larger than the energy of the primaries.
Hi @PranjaySaini
thank you for the detailed explanation and the source code. I think you have defined optical properties of the scintillator, so when Geant4 deposits energy it will also produce some optical photons.
I noticed that you are scoring energy of all particles, could it be that because Geant4 optical physics do not conserve energy you are scoring twice the same thing? Usually a filter to score only optical photons is used (either a SD filter, or hardcoded as in here) , but after a quick look I was not able to find it.
Best,
Alvaro
