Energy distribution of the primary cosmic radiation

Abstract

The primary cosmic-ray energy spectrum usually assumed, N(E) = kE-n, where n has been assigned various values ranging from 2.5 to 2.9, by different writers obviously cannot hold for small values of the particle energy, E. To assume a cutoff of the primary radiation at an assigned value of, say, 3 or 4 Bev is also unsatisfactory, since a latitude effect at 30,000 ft,(1) as well as at balloon altitudes,(2,3) has been measured down to energies for protons to at least 1 Bev. It therefore appears (at least at the time these experiments were performed) that no definite cutoff occurs, although the energy brought in by these low energy particles must be relatively small.