Shell stabilization and the survival of heavy compound nuclei

Knowledge of the influence of nuclear shell structure on the survival probability of heavy compound nuclei against fission is important for a quantitative understanding of the production rates of spherical super-heavy elements (SHE). Fission probabilities of N = 126 isotones beyond astatine can be used as test cases for the production of spherical super-heavy elements, as those isotones possess a strong shell correction energy and are highly fissile. Here, we report on two new experimental approaches which probe the effect of the closed neutron shell at N = 126 on the competition between fission and particle evaporation using projectile fragmentation and electromagnetic-induced fission of radioactive beams. We conclude that these nuclei lose at least a great part of their stability against fission at low excitation energies and angular momenta-mostly due to the influence of collective contributions in the level density. Implications on the production of spherical SHE will be!
discussed.