The Velocity Spectrum ofα-Particles

Abstract

A 60° magnetic $\alpha$-particle spectrograph has been constructed and used on a number of natural $\alpha$-particle emitters, with photographic plates to detect the particles. The energy of the main group of protoactinium $\alpha$-particles was found to be 5.053±0.007 Mev. With the thinnest sources of Po, ThC, and ThC' $\alpha$-particles, as many as 10 percent of the particles were found to have energies 5 percent or more below the energy of the maximum of any one group.