Let-Distributions and Radiation Doses Due to Cosmic Rays

A radiation transport calculation of all nuclides in cosmic rays has been carried out for elements H to Ni. (The unattenuated flux at solan min, outside the magnetosphere is 108/cm2 year.) The computer code treats nuclear spallation reactions, ionization losses and geomagnetic effects. LET-distributions and radiation doses due to cosmic rays can be calculated at any point in spacecraft and at various depths in any material. Results of sample calculations, including single event upsets, are presented. Hydrogenous material s are shown to be more effective than aluminum for shielding against the high-LET components that generate soft upsets.