Atmospheric ionization induced by precipitating electrons: Comparison of   CRAC:EPII model with parametrization model
  A new model CRAC:EPII (Cosmic Ray Atmospheric Cascade: Electron Precipitation Induced Ionization) is presented. The CRAC:EPII is based on Monte Carlo simulation of precipitating electrons propagation and interaction with matter in the Earth atmosphere. It explicitly considers energy deposit: ionization, pair production, Compton scattering, generation of Bremsstrahlung high energy photons, photo-ionization and annihilation of positrons, multiple scattering as physical processes accordingly. The propagation of precipitating electrons and their interactions with atmospheric molecules is carried out with the GEANT4 simulation tool PLANETOCOSMICS code using NRLMSISE 00 atmospheric model. The ionization yields is compared with an analytical parametrization for various energies of incident precipitating electron, using a flux of mono-energetic particles. A good agreement between the two models is achieved. Subsequently, on the basis of balloon-born measured spectra of precipitating electrons at 30.10.2002 and 07.01.2004, the ion production rate in the middle and upper atmosphere is estimated using the CRAC:EPII model 
A.A. Artamonov and A.L. Mishev and I.G. Usoskin
astro-ph.EP physics.space-ph