Neutron physics in the early 1930s

Abstract

Dawning neutron physics was more complex than one might expect. The chance that the neutron comprised a proton and an electron was diffusely taken into account after the discovery of the neutron. Moreover, uncertainties persisted about the composition of beryllium radiation until it was realized that the latter comprised both neutrons and gamma-rays. The interaction of neutrons with matter and nuclei was soon investigated. Both a spatial symmetry, a symmetry of charge, and a symmetry in the nuclear reactions soon emerged. The relation of negative beta-decay to the neutron abundance in nuclei was moreover reviewed. Positive beta-radioactivity induced by alpha-particles was eventually announced, having been foreseen some weeks before. Accelerated deutons and protons shortly afterwards revealed to be efficient in inducing radioactivity. The physics institute in Rome got ready to start research on neutrons, but apparently it only planned to go through alpha-induced radioactivity, at first. If so, it is then plausible that some new results achieved by foreign laboratories eventually bent Fermi to neutrons. Fermi's discovery of neutron-induced radioactivity is reviewed with regard to investigations then current, once more showing simplicity as a distinctive trait of Fermi's way of doing physics.