On the Classical Model of Nuclear Fission

Abstract

The first experiments on neutron bombardment of various elements carried out by Fermi and his collaborators included the study of the group of activities observed in uranium which were at that time ascribed to transuranic elements. The great number of studies following this first work led finally to the results of Hahn and Strassmann which showed clearly that many of the activities ascribed to transuranic elements came, instead, from nuclei of approximately half the mass of uranium. The startling conclusion that these activities must arise from the splitting of the uranium nucleus under neutron bombardment into two fragment nuclei was pointed out by Meitner and Frisch, and was quickly confirmed by subsequent experiments. In the first theoretical discussion of this new type of nuclear reaction, Meitner and Frisch proposed the name fission for the process, and compared it with the splitting that may take place in a liquid drop in oscillation. This model was supported by Bohr who correlated it with other nuclear properties and, at the same time, emphasized how far the phenomenon of nuclear fission may be described classically. A very complete theoretical discussion of both the classical and quantum aspects of fission was given by Bohr and Wheeler, and it is proposed here to describe some of the classical theory of fission developed by these authors.