On the absorption and reflection of homogeneous β -Particles

Abstract

Introduction .—Three years ago it was shown by the author that homogeneous β -particles are not absorbed by matter according to an exponential law, but according to a law in which the rate of absorption increases with the thickness of matter traversed. The experiments were repeated by Crowther, who used more homogeneous rays, and found a still greater deviation from the exponential law. Now the absorption coefficient of β -particles increases with decreasing velocities of the rays, which suggests that there is a diminution in the velocity of the β -particles as they penetrate matter. Experiments proving this point were made by the author and Crowther, and later by v. Bayer, Hahn, and Miss Meitner.