Interpretation of the Fragment Mass Distribution forU235Thermal-Neutron-Induced Fission with Long-Range Alpha Emission

An analysis of the fragment mass distribution for the thermal-neutron-induced ternary fission of ${\mathrm{U}}^{235}$ is given. Quantitative comparison of the mass-distribution data for binary and ternary fission is consistent with the influence of the closed-shell configurations in fission, although it is shown that these mass distributions of themselves are not sufficient to determine unambiguously the origin of the alpha particle. Results of this analysis are discussed in relation to some recently proposed models of ternary fission. It is shown that the results of measurements of the number of neutrons emitted in binary fission, as a function of fragment mass, are consistent with the cluster-model interpretation.