The fission process

As a fissioning nucleus passes from its ground state to the scission point - the point where it breaks into two fragments - the sequence of shapes it follows depends principally on the potential energy surface of the deformed nucleus. The main features of the potential energy surface are now well established. In the review the theoretical techniques used to predict the potential energy are described and the predictions are tested against theory. Other properties of nuclei on the path to scission are also discussed: the structure of individual low-lying states, level densities at high excitation, and the magnitude of inertial parameters may all be important in determining the nature of the fission process. Finally, the current state of knowledge about specifically dynamical effects in fission is summarized. (author)