Secondary β-rays

Abstract

In various papers published during the last three years I have given an account of work dealing with the emission of secondary β -rays by substances when exposed to the β -rays from radium. The present paper deals with some further points of importance connected with the same subject. It is not necessary to summarise with any detail the results discussed in previous papers, but the following facts may be briefly mentioned. In these papers no steps were taken to separate the effects due to the primary β radium rays from those produced by the γ -rays that accompanied them; it was sufficiently clear from a few preliminary experiments that the secondary effects due to the γ -rays were very small compared with those produced by the β -rays. As this point has been referred to by other workers when discussing the results, and as much as 20 per cent, of the total secondary taken as possibly consisting of secondary γ -rays or secondary β -rays due to the γ -rays, I have made some further experiments on the subject.