Cosmic-ray background flux model based on a Gamma-Ray Large Area Space Telescope balloon flight engineering model

Cosmic-ray background fluxes were modeled on the basis of existing measurements and theories and are presented here. The model, originally developed for the Gamma-Ray Large Area Space Telescope (GLAST) balloon experiment, covers the entire solid angle (4pi sr), the sensitive energy range of the instrument (similar to10 MeV to 100 GeV), and the abundant components (proton, alpha particle, e(-), e(+), mu(-), mu(+), and gamma ray). It is expressed in analytic functions in which modulations due to solar activity and the Earth's geomagnetism are parameterized. Although the model is intended to be used primarily for the GLAST balloon experiment, model functions in low Earth orbit are also presented and can be used for other high-energy astrophysical missions. The model has been validated via comparison with the data of the GLAST balloon experiment.