Computation of electron precipitation atmospheric ionization: Updated model CRAC-EPII

Abstract

A new model of the CRAC family, CRAC:EPII (Cosmic Ray Atmospheric Cascade: Electron Precipitation Induced Ionization) is presented. The model allows one to calculate atmospheric ionization induced by precipitating electrons. The model is based on pre-computed with high-precision ionization yield functions, which are obtained using full Monte Carlo simulation of electron propagation and interaction in the Earth's atmosphere, explicitly considering all physical processes involved in ion production. The simulations were performed using GEANT 4 simulation tool PLANETOCOSMICS with NRLMSISE 00 atmospheric model. A quasi-analytical approach, which allows one to compute the ionization yields for events with arbitrary incidence is also presented. It is compared with Monte Carlo simulations and good agreement between Monte Carlo simulations and quasi-analytical approach is achieved.