A Model of the Cosmic Ray Induced Atmospheric Neutron Environment

In order to optimise the design of space instruments making use of de-tection materials with low atomic numbers, an understanding of the at-mospheric neutron environment and its dependencies on time and posi-tion is needed. To produce a simple equation based model, Monte Carlo simulations were performed to obtain the atmospheric neutron fluxes pro-duced by charged galactic cosmic ray interactions with the atmosphere. Based on the simulation results the omnidirectional neutron environment was parametrised including dependencies on altitude, magnetic latitude and solar activity. The upward- and downward-moving component of the atmo-spheric neutron flux are considered separately. The energy spectra calcu-lated using these equations were found to be in good agreement with data from a purpose built balloon-borne neutron detector, high altitude aircraft data and previously published simulation based spectra