Compound-Nucleus Decay via the Emission of Heavy Nuclei

The typical compound-nucleus decay populates two very distinct mass regions. Evaporation produces nuclei with mgsses of four or less, while fission produces nuclei close to one-half the mass of the compound nucleus. The mass regions populated are so different that the two decay processes have been generally considered to be also quite different, as indicated even by their names. Such a dichotomy is stressed in the formalisms commonly used to calculate the decay widths. Light-particle evaporation is treated by applying the principle of detailed balance to connect the compound nucleus with the residue nucleus plus evaporated particle at infinite separation, whereas the transition-state formalism' applied to the saddle point is used for fission decay.