Bombardment of Nitrogen and Oxygen with Protons

Abstract

A REACTION of considerable interest in connexion with Bethe's theory of energy production in the stars¹ is that involving the capture of protons by the isotope of nitrogen ¹⁴N. ¹⁴N + ¹H → ¹⁵O + hv, . . . (1) since this process is one of those involved in his cyclical scheme of nuclear processes. The occurrence of this process was detected by measuring the radioactivity produced in targets of sodium nitride (found to be one of the few compounds of nitrogen that is stable under bombardment). The period of the radioactivity was two minutes, in agreement with the known value² for ¹⁵O, and the excitation function for the reaction is as shown in Curve A in the accompanying graph. Some slight evidence of resonance features is present, but the low yield of the active product prevented very accurate measurement. The yield was found to be 1·5 × 10^-11 positrons per proton of energy 0·96 × 10⁶ ev.