On the theory of emission of alpha particles as related to the structure of the nucleus

Abstract

The internal problem of the formation of the alpha particles emitted in alpha disintegration is considered. In this respect the mean free path of alpha particles in nuclear matter is important. A comparison is made with the optical model treatment of alpha particle scattering; the significance of the alpha particle potential well parameters is discussed. A short mean free path for the alpha particles in nuclear matter suggests that the alpha particle formation can be characterized approximately by a boundary condition on the nuclear surface, which further determines the alpha particle propagation in the external region. An approximate wave function representing a nucleus with shell structure emitting an alpha particle is proposed and provides an expression for this boundary condition. Such an expression can be used for the calculation of absolute as well as relative transition probabilities in alpha decay. The value for the radius of the alpha particle potential well, which is obtained in this way from the alpha decay probability is in good agreement with the radius of the potential well determined from alpha particle scattering. A summary is given of the experimental information which would be useful for a further test of the picture of alpha particle formation.