Investigation of Excitation Energy Dependence of Fission Modes in Actinides through Transfer-Induced Fission

Nuclear fission outcomes are strongly driven by different shell-stabilized fission modes. The resulting fission fragment properties sensitively depend on the excitation energy and the fissioning nuclide. To directly observe how they depend on the excitation energy of the fissioning nucleus, (d,p) transfer-induced fission of 233Th has been measured at the Australian National University. The excitation-energy dependence of the reconstructed fragment mass distributions reveals a systematic evolution of the fission modes, with distinct thresholds for the onset of asymmetric and symmetric fission, and for the emergence of multi-chance fission.