Geant4 Version: 11.4.0
Operating System: Ubuntu 24.04.4 LTS
Compiler/Version: gcc 14.3.0
CMake Version: 3.28.3
Dear experts,
I am comparing 500 keV electron elastic backscattering from an ultrathin tungsten foil between FLUKA and Geant4.
In FLUKA I use PRECISIO and force electron/positron Coulomb single scattering with:
MULSOPT 0.0 0.0 0.0 1.0 1.0 1001.0 GLOBEMF
In Geant4 11.4 I use G4EmStandardPhysicsSS.
I extracted the primary-electron cross section integrated over θ>90 using 0.5, 1, and 2 nm tungsten foils and the results (based on 1e8 primaries) are thickness-independent:
Thickness Geant4 [cm2/atom] FLUKA [cm2/atom] G4/FLUKA
0.5 nm 8.04e-22 5.92e-22 1.36 ± 0.13
1.0 nm 8.45e-22 6.37e-22 1.33 ± 0.09
2.0 nm 8.49e-22 6.24e-22 1.36 ± 0.06
The difference appears largest in the 90–110° angular range and becomes smaller at larger backward angles as can be observed below:
I am trying to understand the origin of this discrepancy between FLUKA and Geant4. Could you please help me determine which differences in the electron elastic-scattering models or transport settings might explain it?
Thanks,
Lovepreet