Spontaneous fission of the end product in α-decay chain of recoiled superheavy nucleus: A theoretical study

The temperature-dependent preformed cluster model [PCM[Formula: see text]] is employed to extend our recent work [Niyti, G. Sawhney, M. K. Sharma and R. K. Gupta, Phys. Rev. C 91 (2015) 054606] on [Formula: see text]-decay chains of various isotopes of [Formula: see text]–118 superheavy nuclei (SHN), to spontaneous fissioning nuclei [Formula: see text]Lr, [Formula: see text]Rf, [Formula: see text]Db, [Formula: see text]Rg, and [Formula: see text]Cn occurring as end products of these [Formula: see text]-decay chains. The behavior of fragment mass distribution and competitive emergence of the dominant decay mode, i.e., the [Formula: see text]-emission versus spontaneous fission (SF), are studied for identifying the most probable heavy fission fragments, along with the estimation of SF half-life times T[Formula: see text] and total kinetic energy (TKE) of the above noted isotopes of [Formula: see text]–112 nuclei decaying via the SF process. The mass distributions of chosen nuclei are clearly symmetric, independent of mass and temperature. The most preferred decay fragment is found to lie in the neighborhood of doubly magic shell closures of [Formula: see text] and [Formula: see text], with largest preformation factor [Formula: see text]. In addition, a comparative study of the “hot compact” and “cold elongated” configurations of [Formula: see text]-deformed and [Formula: see text]-oriented nuclei indicates significantly different behaviors of the two mass fragmentation yields, favoring “hot compact” configuration.

The restoration of Wigner’s SU(4)-symmetry in the superheavy nucleus and its correlation with the problem “island of stability”, or does the “island of stability” exist?

This paper reviews the history and stages of experimental verification of the hypothesis of Wigner’s spin–isospin SU(4)-symmetry restoration in the field of heavy atomic nuclei and its implications on hypothesis of the “island of stability”. Energies of [Formula: see text]-decay of a number of [Formula: see text]-chains of new superheavy nuclei were calculated based on Wigner’s mass formula without contribution of spin–orbit interaction that correspond to the restoration of Wigner’s spin–isospin symmetry. Calculated energies of the [Formula: see text]-decay fit the experimental data better than other theoretical approaches. It is concluded that there is a need to continue theoretical research of the “island of stability” taking into account mechanisms of restoration of Wigner’s spin–isospin SU(4)-symmetry.