Abstract
The fission barriers of heavy and superheavy nuclei are investigated within the liquid-drop model. Using a simple shape parameterisation the authors specifically study the proximity interaction effects on compact and creviced fission shapes. Double-humped barriers are predicted, as have been found experimentally. In contrast to other theoretical studies, the outer peak in an elongated system is found to be due not only to shell effects but also to the cancellation of the repulsive Coulomb force by the attractive nuclear proximity force, after the rupture of the neck between the two nascent fragments. Consequently, for the heavier systems where Coulomb repulsion is dominant, the second maximum in the fission barrier disappears quickly. Reasonable agreement with experimental data is found for actinide nuclei. Extending the formalism to superheavy nuclei, no double-humped barriers are found and the existence probability of such nuclei is reduced compared with other theoretical studies.