  Fission excitation functions of He-3 and He-4 induced compound nuclei are
shown to scale exactly according to the Bohr-Wheeler transition state
prediction once the shell effects are accounted for. The presented method
furthermore allows one to model-independently extract values for the shell
effects which are in good agreement to those obtained from liquid-drop model
calculations. The fact that no deviations from the transition state method have
been observed within the experimentally investigated excitation energy regime
allows one to assign an upper limit for the transient time of 10 zs.
