  The recent discovery of heavy-ion fusion hindrance at far sub-barrier
energies has focused much attention on both experimental and theoretical
studies of this phenomenon. Most of the experimental evidence comes from
medium-heavy systems such as Ni+Ni to Zr+Zr, for which the compound system
decays primarily by charged-particle evaporation. In order to study heavier
systems, it is, however, necessary to measure also the fraction of the decay
that goes into fission fragments. In the present work we have, therefore,
measured the fission cross section of 16O+197Au down to unprecedented far
sub-barrier energies using a large position sensitive PPAC placed at backward
angles. The preliminary cross sections will be discussed and compared to
earlier studies at near-barrier energies. No conclusive evidence for
sub-barrier hindrance was found, probably because the measurements were not
extended to sufficiently low energies.

Nuclear Experiment