Transition state rates and mass asymmetric fission barriers of compound nuclei 90,94,98Mo

Abstract Excitation functions were measured for complex fragments with atomic number Z = 5–25 emitted from the compound nuclei 90,94,98 Mo produced in the reactions 78,82,86 Kr + 12 C . Mass-asymmetric fission barriers were extracted by fitting the excitation functions with a transition state formalism. The extracted barriers are several MeV higher on average than the calculations of the Rotating Finite-Range Model and substantially lower than predicted by the Rotating Liquid Drop Model. The symmetric fission barriers measured support the hypothesis of a congruence term that doubles for the fission of strongly indented saddle-point shapes. The excitation functions were analyzed to search for atomic number Z - and energy E -dependent deviations from transition-state-method predictions. All of the measured excitation functions can be scaled onto a single universal straight line according to the transition-state predictions. No Z - and/or E -dependent effects that could be attributed to transient effects are visible.