The Interaction and Production of Cosmic-Ray Protons in Carbon

Protons in the cosmic radiation at sea level were observed under varying thicknesses of carbon absorber. In the energy range 150 to 570 Mev an interaction mean free path for protons was estimated from the ratio of those emerging from the absorber to those incident upon the absorber and is greater than 140 g/${\mathrm{cm}}^2$ in carbon. The spectrum of protons produced in the carbon by neutral cosmic radiation permits the inference of the flux of neutrons in the cosmic radiation, with the result that neutrons with momenta greater than 550 Mev/c are 6 percent as abundant as all ionizing cosmic radiation at sea level.