Evidence for toroidal nuclei

Recent heavy ion experiments have shown a multifragment breakup mode where most of the mass of the total system is divided among three to five fragments of roughly equal mass. The most striking feature of the mode is its large cross section, up to 22% of the total reaction cross section. The lightest member of the reacting pair ranged from Al to Kr. The beam energies ranged from 11 to 44 MeV/u. The available data can be explained as the breakup of nuclei with a toroidal shape. The model suggests that toroidal nuclei will be formed in any nuclear reaction if the reactants are heavy enough and the bombarding energy is the right range. (orig.)