Simulation of particle fluxes and cosmogenic nuclide production in the Earth's atmosphere

A purely physical model for the simulation of cosmic ray particle interacti ons with the Earth's atmosphere and subsequent production and transport of secondary particles is presented. Neutron and proton spectra as a function of the coordinate in the atmosphere were calculated using a GEANT / MCNP-ba sed code system. The calculated neutron fluxes are in good agreement with e xperimental data based on neutron monitor measurements. These fluxes, toget her with experimental or evaluated cross sections, were used to calculate t he production rates of H-3, Be-7, Be-10 C-14, and Cl-36. The dependencies o f these production rates on solar activity and geomagnetic field intensity were investigated in detail. The obtained production rates agree well with most published experimental and theoretical values. Possible reasons for so me differences are discussed.