Low-energy β-delayed fission of 194,196At and 200,202Fr was studied in detail at the mass separator ISOLDE at
CERN. The fission-fragment mass distributions of daughter nuclei 194,196Po and 202Rn indicate a triple-humped
structure, marking the transition between asymmetric fission of 178,180Hg and symmetric fission in the light Ra-Rn
nuclei. Comparison with the macroscopic-microscopic finite-range liquid-drop model and the self-consistent
approach employing the Gogny D1S energy density functional yields discrepancies. This demonstrates once
more the need for dynamical fission calculations, because for both models the potential-energy surfaces lack
pronounced structures, in contrast to those for the actinide region.status: publishe