Narrow Results

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 $\alpha$-decay of a number of $\alpha$-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 $\alpha$-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.

The idea of treating the trinucleon systems as elementary entities in the elementary particle model (EPM) as an Effective Field Theory has been a success in explaining the weak charge-changing processes in nuclei. The EPM results are found to be as good as those obtained from nuclear microscopic models using two-and three-body forces. We extend this concept to investigate the validity of the elemental nature of $A=3$ nuclei through studies of nuclear structure of neutron-rich nuclei. By treating neutron-rich nuclei as primarily made up of tritons as its building blocks, we extract one- and two-triton separation energies of these nuclei. Calculations have been performed here within relativistic mean field (RMF) models with latest interactions. Clear evidence arises of a new shell structure with well-defined predictions of new magic nuclei. These unique predictions have been consolidated by standard one- and two-neutron separation energy calculations. The binding energy per nucleon plots of these nuclei also confirm these predictions. We make unambiguous prediction of six magic nuclei: ${}_8^{24}{\mathrm{\text{O}}}_{16}$, ${}_{20}^{60}{\mathrm{\text{Ca}}}_{40}$, ${}_{35}^{105}{\mathrm{\text{Br}}}_{70}$, ${}_{41}^{123}{\mathrm{\text{Nb}}}_{82}$, ${}_{63}^{189}{\mathrm{\text{Eu}}}_{126}$ and ${}_{92}^{276}{\mathrm{\text{U}}}_{184}$.

In this paper, Isotopic yield and half-lives of cold spontaneous fission for ${}^{279}Ds$ and ${}^{281}Ds$ superheavy isotopes are studied. The interacting potential between fragments includes mean field proximity and Coulomb potentials. Fission $Q$-value, driving potential, $(V(r)-Q)$ and partial penetration probability of each possible individual fragmentation are calculated using $WKB$ approximation. According to the tunneling effect, the most favored pair of fragments is produced for the highest $Q$-value or the lowest driving potential. A few fragmentation with higher $Q$-value are selected for each atomic number Z. It is found that for ${}^{279}Ds$ isotope, the highest relative yield belongs to the ${}^{134}$Te + ${}^{145}$Ce fragmentation while for ${}^{281}Ds$, the combination ${}^{134}$Te + ${}^{137}$Ce has lowest driving potential and highest yield due to presence of fragments with magic or near magic proton and neutron numbers ($Z=50$ and $N=82$). By calculating yield of each fragmentation, its partial fission decay constant and then by summing over all decay constants for possible fragmentation, the fission decay constant for each superheavy isotope is obtained. Furthermore, half-life of each superheavy isotope is also estimated. Finally, the calculated half-lives using this method are compared with the experimental data. Good agreement achieved between our calculated half-lives and the experimental data.