Implementation of the EPICS2017 database for photons in Geant4

This paper describes in detail the implementation of Geant4 Livermore electromagnetic physics models based on the EPICS2017 database for the low energy transport of photons. These models describe four photon processes: gamma conversion, Compton scattering, photoelectric effect and Rayleigh scattering. New parameterizations based on EPICS2017 were performed for scattering functions of Compton effect, subshell cross-sections of the photoelectric effect and form factors of Rayleigh scattering, in order to improve the precision of fitted values compared to tabulated values. Comparisons between new and old parameterizations were also carried out to evaluate the precision of the new parameterizations. The models were tested through a comparative study, in which the mass attenuation coefficient was calculated for both total photon interaction and each process using Geant4 simulations based on EPICS2017 and EPDL97 respectively. The results obtained from the simulations were found in good agreement with the XCOM reference data.

Automated summary

This paper describes the detailed implementation of Geant4 Livermore electromagnetic physics models based on the EPICS2017 database for low energy photon transport. Four photon processes, including gamma conversion, Compton scattering, photoelectric effect, and Rayleigh scattering, are described by these models. New parameterizations based on EPICS2017 were performed to improve the precision of fitted values compared to tabulated values for the scattering functions of Compton effect, subshell cross-sections of the photoelectric effect, and form factors of Rayleigh scattering. The precision of the new parameterizations was evaluated by comparing them with the old parameterizations. The models were tested through a comparative study, in which the mass attenuation coefficient was calculated for total photon interaction and each process using Geant4 simulations based on EPICS2017 and EPDL97. The results showed good agreement with the XCOM reference data.