Limiting angular momentum for statistical model description of fission

Fission fragment cross sections and angular anisotropies have been measured to high accuracy for the ¹⁹F+²⁰⁸Pb reaction, together with evaporation residue cross sections, at bombarding energies from below the fusion barrier to 1.75 times the barrier energy. These data allow reliable calculations of the partial waves contributing to fission. Extensive statistical model calculations of the anisotropies are presented, including the effects of different fission transient delay times. The anisotropies at the highest bombarding energies can only be reproduced assuming that the fission barrier no longer controls the fission process when its height is less than the nuclear temperature.