ABSTRACT
The photographic effect of a pencil of α rays was examined in a magnetic field by the photographic method, using Schumann plates. In a high vacuum, in addition to the main deflected band due to doubly-charged α particles, there appeared a 'midway' band which suffered only half the deflexion of the main band. The conclusion of Henderson by the scintillation method where the energy of the particles can be estimated by the brightness of the scintillations and their number determined by direct counting. The determination of the magnetic spectrum of the doubly-charged α particles gave a method of fixing the lowest velocity of the α particle for which a scintillation could be detected. Therefore, the experiments on the α particle have thus been made at much higher velocities than for hydrogen atoms, and the highest velocity examined by Ruchardt is only one-half of the lowest velocity of the αparticle.
