Modeling the ionizing radiation environment in Earth's atmosphere
Abstract
The constant bombardment of the Earth by cosmic radiation leads to an atmospheric radiation environment comprised of many species of energetic secondary particle. Aside from carrying out full Monte Carlo simulations from scratch, no software models currently exist for use to investigate the nature and composition of the ionizing radiation environment, e.g., secondary neutron, electron, positron, and heavy charged particle spectra, as functions of altitude, geomagnetic latitude, time, etc. The FAA has developed a publicly available program, CARI-7, for use in estimating biologically relevant quantities, such as ambient dose equivalent and effective dose, during air travel. CARI-7 is based on extensive simulations of cosmic ray air showers in the atmosphere using the MCNPX radiation transport code, and the MCNPX output files contain secondary particle spectral data. The focus of this research was the development of the Atmospheric Ionizing Radiation Environment Code (AIREC) that uses data from these MCNPX simulations to generate a detailed picture of the structure of the radiation environment in the atmosphere. AIREC takes as inputs global coordinates, a date of interest, and a particle of interest, and returns the corresponding flux energy spectrum. This provides a tool for calculating energy spectra for secondary particles of interest that would be impractical or impossible to measure experimentally. Outputs from AIREC were used as source particles in further MCNP simulations to model radiation detector response to atmospheric radiation.
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- OSU Dissertations [11222]