Low-energy fission of gold nuclei by protons and α particles

Study of the reactions 197Au(α, f ) and 197Au(p, f ) yielded for the first time direct experimental data on the mass--energy distributions of the fragments from symmetrical fission of rather cold nuclei (198Hg and 201Tl) with saddle-point excitation energy ∼10 MeV. A new property of this fission was established, viz., an anomalously strong ''threshold'' dependence of the variance (width) of the kinetic-energy distribution on the excitation energy for large mass-asymmetric deformations of the fissioning nuclei