The Absorption and Reduction in Velocity of β-rays on their passage through matter

Abstract

The early experiments of Lenard(1), Leithauser(2), and Becker(3) on cathode rays led to the exponential law of absorption; those of Rutherford(4), Schmidt(5) and Hahn and Meitner(6) on β-rays indicated that the rays from some radioactive bodies were absorbed exponentially and that those from others were not. It was considered by Hahn and Meitner that the exponential law of absorption was an indication of the homogeneity of the rays. It was found also that the exponential law was not disturbed by the thickness of radiating material and this led to the conclusion that the rays are not appreciably reduced in velocity on their passage through matter. The theories of McClelland(7) and Schmidt(8) attributed the absorption to the stoppage of particles in mid-career.