Fission modes are not always Gaussian

The traditional interpretation of fission fragment mass and total kinetic energy (TKE) distributions relies heavily on the assumption of Gaussian-shaped modes. However, theoretical models of the underlying fission dynamics support different shapes with a dependence on excitation energy. Accurate identification of the fission yield shape and modes is crucial if measurements are to be used to constrain properties of the nuclear many-body problem. In this talk, I elaborate on the dangers of assuming all modes to be Gaussian, using selected examples. Additionally, I show measured fission fragment mass distributions and assess the efficacy of multi-modal Gaussian fits against non-Gaussian models. Our results support mode identification based on excitation energy dependence rather than isolated measurements. This approach provides a more comprehensive understanding of the pre-scission dynamics and the energy landscape of the fissioning nucleus.