Zero neutron emission in spontaneous fission of²⁵²Cf: a form of cluster radioactivity

Abstract

By using the triple gamma coincidence technique with 20 Ge detectors at the Holifield Laboratory in the spontaneous fission of 252Cf, neutronless fragmentations, like 104Mo-148Ba, 106Mo-146Ba, 108Mo-144Ba and 104Zr-148Ce, are experimentally observed directly for the first time. When zero neutron emission spontaneous fission occurs, essentially all the available energy goes into the total kinetic energy of the fragments (cold fission). This process is seen theoretically to be an extension of cluster radioactivity, which involves the emission of one light fragment like 14C, 20O, (24)Ne or 28Mg to nearly equal fragments. In the neutronless spontaneous fission reported here, double fine structures (i.e. decays to the excited states of both fragments) are observed experimentally in contrast to fine structure in only the heavy partner populated by the light partner in earlier cluster radioactivity work. Neutronless spontaneous fission is discussed in the framework of cluster radioactivity.