The nature of the ϒ-rays excited by β-rays

Abstract

In a previous paper, it was shown that the β -rays of radium E excited ϒ-rays in different materials, the amount increasing with the atomic weight of the substance used. It was found that the ϒ -radiation was largely increased when the β -rays fell on a lead screen suitably placed, and as the active material, radium (D + E + F), was mixed with lead sulphate confined in a small space, it was obvious that some, if not all, of the ϒ -radiation issuing from the mixture was due to ϒ -rays excited by β -rays in the lead impurity. It thus seemed possible that no primary ϒ -rays were emitted by radium E. By using a more suitable source, in which the active material was spread in a thin layer over biter paper, it has been found that a primary ϒ -radiation is emitted from the active matter. This radiation, however, is much sorter than that excited by the β -rays in lead. more detailed account of these primary rays will be given later.