Microscopic description of cluster radioactivity in actinide nuclei

Abstract

Cluster radioactivity is the emission of a fragment heavier than an α particle and lighter than mass 50. The range of clusters observed in experiments goes from 14 C to 32 Si while the heavy mass residue is always a nucleus in the neighborhood of the doubly-magic 208 Pb nucleus. Cluster radioactivity is described in this paper as very asymmetric nuclear fission. A new fission valley leading to a decay with large fragment mass asymmetry matching the cluster radioactivity products is found. The mass octupole moment is found to be more convenient than the standard quadrupole moment as the parameter driving the system to fission. The mean-field Hartree-Fock-Bogoliubov theory with the phenomenological Gogny interaction has been used to compute the cluster emission properties of a wide range of even-even actinide nuclei from 222 Ra to 242 Cm, where emission of the clusters has been experimentally observed. Computed half-lives for cluster emission are compared with experimental results. The noticeable agreement obtained between the predicted properties of cluster emission (namely, cluster masses and emission half-lives) and the measured data confirms the validity of the proposed methodology in the analysis of the phenomenon of cluster radioactivity. A continuous fission path through the scission point has been described using the neck parameter constraint.

Fission fragment mass yield deduced from density distribution in the pre-scission configuration

“…The previous investigations performed with this model proven, that it describes with reasonable accuracy the experimental data of the most relevant properties of unstable nuclei for different decay modes, such as spontaneous fission [17,18,19,20] and exotic process of cluster radioactivity [22]. Also the asymmetric fission of 180 Hg isotope was successfully explained within microscopic approach [23].…”

“…Intermediate configurations of the scission region are hard to obtain in the self-consistent procedure as they require multiple constraints, including e.g. neck parameter [22,23].…”

Fission dynamics of Cf252

“…Details of the calculation can be found in Refs. [24][25][26]. The mass parameters are computed within the adiabatic timedependent Hartree-Fock (ATDHF) formalism [27,28].…”

Deformation properties with a finite-range simple effective interaction

“…5 where the HFB energy supplemented by the rotational correction, is plotted as a function of the quadrupole moment for the two sets of EOSs of SEI considered in this paper, as well as for the Gogny D1S force. The Gogny D1S results are used here as a benchmark, given the fact that the force was adjusted to fission barrier heights, and has been successfully tested with very different kinds of fission-see Ref [55] as an example. By looking at the PES in Fig.…”