Cold-fission modes in [sup 252]Cf

Abstract

The binary and ternary cold fragmentations of heavy nuclei are studied in the framework of a deformation-dependent cluster model in which the final fragments are produced in their respective ground states and interact via a double-folded potential with M3Y forces. The deformation effects are taken into account up to multipolarity λ=4. It is shown that two regions of cold fragmentation arise. The first one has large quadrupole and even hexadecapole deformations and mass number of the heavy fragment ranging between 138 and 158. In the second region, the Q-value principle dictates the occurrence of a few spherical nuclei around the doubly magic nucleus 132 Sn , which is similar to the case of heavy-cluster radioactivity, where the daughter nuclei are around 208 Pb . This structure is similar for binary and ternary cold fission. The cold-fission yields are computed for the binary fragmentation and for the alpha-accompanied fission of 252 Cf . For the ternary cold-fission mode we derive the most likely geometrical and dynamical characteristics of the fragments at the moment of release of the light particle and perform classical trajectory calculations, in order to compute the final kinetic energy of the alpha particle. The recent observation of 10 Be in cold ternary fission is discussed in connection with the concept of a giant nuclear molecule.