Rate of emission of α-particles from uranium and its products

Abstract

The object of this investigation was to find directly how many α -particles are emitted per second per gramme of uranium in equilibrium with all its products. The number can be calculated from the rate of emission of the particles from radium, determined by Rutherford, but no direct experiment has previously been performed with uranium as it occurs in Nature. To estimate the number of α -particles emitted, their well-known property of producing scintillations when they strike a zinc sulphide screen (each α -particle producing one scintillation) was employed. The scintillations were observed through a microscope provided with a special objective.