A note on the absorption of β-rays

Abstract

It is clear, from the experiments of W. Wilson and others, that one of the main factors in the absorption of β -rays is the loss in velocity of β -rays in passing through matter. It follows from this that β -rays of a definite speed must have what may be called a maximum range, and also that an exponential law of absorption for β -rays can only be approximate. These facts are brought out in the following experiments on the β -rays of radium E. Two preparations of radium (D + E + F) were used, one relatively weak. The weaker preparation was placed 2 cm. below an electroscope 4 cm. cube, and absorbing sheets of paper were placed directly below the electroscope, the mass per unit area of one sheet being 0·00877 grm.