The Validity of Using Only Primary Protons in Van Allen Belt and Solar-Flare Proton Shielding Studies

The validity of the approximations of neglecting proton attenuation due to nuclear collisions and all reaction products from nuclear collisions in space vehicle shielding studies is tested. Comparisons of absorbed-dose and dose-equivalent results obtained with the production and transport of nuclear-reaction products included with similar results obtained using the approximations are presented. The use of the approximations is found to lead to an overestimation ( a factor of two) of the absorbed dose and dose equivalent for a wide range of incident Van Allen belt and solar-flare proton spectra and for a variety of shield thicknesses and shield materials.