Gamma-Rays of Lithium and Fluorine Under Alpha-Particle Bombardment

The energies of the $\gamma$-rays emitted from lithium and fluorine under bombardment by polonium $\alpha$-particles are determined, and their variation with the energy of the incident particles is studied. In the case of lithium no change in $\gamma$-ray energy is observed as the range of the incident $\alpha$-particles is reduced from 3.9 cm to 2.5 cm. This is taken to support the view that the radiation results from excitation of the lithium nucleus without capture of the $\alpha$-particle. At an incident range of 3.9 cm the $\gamma$-radiation from fluorine is shown to consist of two components. When the incident range is reduced to 3.1 cm the harder component disappears. Possible explanations are discussed, and the existence of a hitherto undetected proton group of low energy is suggested.