The a Particles from Radio-Active Substances

Abstract

THE experiments of Rutherford and Hahn have shown that the ratio e/m has the same value, 5 × 10³, for rays, no matter from what source the rays are derived. They are, however, taken alone, incapable of deciding whether the particles are hydrogen molecules carrying the usual ionic charge, or helium atoms with twice that charge. In a recent paper in Roy. Soc. Proc., Prof. Townsend has shown that the positive ion produced by Röntgen rays has twice the ionic charge at the moment of formation. If his further experiments prove this true generally, then the question whether the a rays are hydrogen or helium must be definitely decided in favour of the latter, and the association of this gas with radio-active substances is accounted for.