Shielding of Manned Space Vehicles Against Galactic Cosmic-Ray Protons and Alpha Particles

Calculated results are presented of the absorbed—dose rates and dose-equivalent rates as a function of depth in tissue when galactic cosmic-ray proton and alpha-particle spectra are isotropically incident on a spherical shell shield with a tissue sphere at its center. Aluminum shield thicknesses of 5 and 20 g cm^-2 are considered. It is found that the dose rates from incident alpha particles are comparable to those from incident protons, and that for both protons and alpha particles there is a very appreciable contribution to the dose rates from nuclear-reaction products.