Excitation functions and mass asymmetric fission barriers for compound nuclei 70,76Se

Excitation functions were measured for complex fragments with atomic number Z=5-20 emitted from the compound nuclei 70,76Se produced in the reactions 58,64Ni+12C. Mass asymmetric fission barriers were extracted by fitting the excitation functions with a transition state formalism. The extracted barriers were compared with those calculated from macroscopic nuclear models. The measured barriers for symmetric fission seem to support the hypothesis of a shape-dependent congruence energy, which doubles for fission of strongly indented saddle-point shapes. All of the measured excitation functions can be scaled onto a single straight line according to the transition state prediction