Induced -Radioactivity by -Particle Bombardment

Abstract

LORD RUTHERFORD'S classical experiments showed that the emission of protons from the nuclei of the light elements, when these were bombarded with -particles, was a fairly general phenomenon. No protons, however, were observed from helium, lithium, beryllium, carbon or oxygen. These results are significant, and suggest that ₂He⁴, ₆C¹² and ₈O¹⁶ are very stable structures, probably consisting of close combinations of -particles. The great stability of these isotopes is confirmed by Aston's work and by their behaviour under bombardment by high-speed ions. But both lithium and beryllium are disruptible by -particles with the emission of neutrons, and while the structure 2 + n for ₄Be⁹ will explain why no protons are emitted from this isotope under -particle bombardment, it is difficult to see why no proton emission has been observed from lithium when bombarded with -particles.