6. Geant4 Comparison

Geant4

Geant4 is a widely popular open-source toolkit for particle physics. Unlike nrCascadeSim, Geant4 is a large toolkit with a broad range of applications and less focus on any one particular application.

Comparison

Note: You can find the full code for this comparison in: example-usecase/Z_G4Comparison.ipynb.

Most notably, Geant4 seems to be much more likely to generate single-step events, in which all of the energy from the event is deposited at once, than nrCascadeSim. Under-generation of events with multiple energy deposits is problematic for modeling detectors with non-linear yield models - that is, for modeling detectors where the energy read out is not a linear function fo the energy deposited, making it necessary to take the yielded energy from each individual deposit separately. Where nrCascadeSim generated single-step events under 10% of the time for silicon, germanium, neon, and argon, Geant4 generated single-step events over 90% of the time for these elements.

Below are plots comparing the output of nrCascadeSim to the output of Geant4. Each plot has data generated by both programs for a single element. The energies plotted are the total energy deposits for a single event - if an event had multiple steps, then the energies for each step were summed before adding them to the plot. The histograms are weighted to show the portion of events falling in each energy bin.

https://raw.githubusercontent.com/villano-lab/nrCascadeSim/master/example-usecase/plots/Silicon_comparison.png https://raw.githubusercontent.com/villano-lab/nrCascadeSim/master/example-usecase/plots/Germanium_comparison.png https://raw.githubusercontent.com/villano-lab/nrCascadeSim/master/example-usecase/plots/Neon_comparison.png https://raw.githubusercontent.com/villano-lab/nrCascadeSim/master/example-usecase/plots/Argon_comparison.png