The relative abundances of the heavy nuclei in the primary cosmic radiation

In an attempt to resolve the present controversy about the relative abundances of the heavy, Z≤6, nuclei in the primary cosmic radiation, the magnitude of the corrections introduced by the overlying atmosphere has been redetermined. For this reason it has been necessary to use nuclear emulsions to determine the fragmentation parameters of nuclei having 20≤Z≤28. The results of this work show that the relative abundances calculated previously by considering the diffusion of nuclei through the atmosphere were not seriously in error, and that outside the atmosphere the ratio of H, Z≤10, to M, 6≤Z≤ 9, nuclei is 0.38 ± 0.04. The significance of this result is considered briefly.