Fission Energy Surfaces and Ternary Fission

A three-center phenomenological model, able to explain qualitatively the recently obtained experimental results concerning the quasimolecu-lar stage of a light-particle accompanied fission process is presented. It was derived from the liquid drop model under the assumption that the aligned configuration, with the emitted particle between the light and heavy fragment, is reached by increasing continuously the separation distance, while the radii of the heavy fragment and of the light particle are kept constant. In such a way, a new minimum appears in the deformation energy at a separation distance very close to the touching point. This minimum allows the existence of a short-lived quasi-molecular state, decaying into the three final fragments. The influence of the shell effects is discussed. The half-lives of some quasimolecular states which could be formed in the 10Be and 12C accompanied fission of 252Cf are roughly estimated to be of the order of 1 ns and 1 ms, respectively.