Interactions of the Heavy Nuclei of the Cosmic Radiation

Fragmentation probabilities have been obtained for the interactions of heavy nuclei with target nuclei of photographic emulsion and a light element absorber (gelatin and cellulose acetate). The predictions of a simple geometrical model for the fragmentation probabilities in light elements derived from those observed in emulsion are in agreement with experimental observations. Measurements of the interaction mean free paths of heavy nuclei at different latitudes indicate that the interaction cross section is energy insensitive and is smaller than geometric. Curves are presented showing the ratio of the secondary light element (Li, Be, B) flux relative to the medium element ($6<~Z<~10$) flux as a function of atmospheric depth.