Synthesis of superheavy nuclei in the reactions of \chem{^{244}Pu} and \chem{^{248}Cm} with \chem{^{48}Ca}

This paper presents results of the experiments aimed at producing long-lived superheavy elements located near the spherical-shell closures with $Z \geqslant 114$ and $N \geqslant 172$ in the \chem{^{244}Pu} + \chem{^{48}Ca} and \chem{^{248}Cm} + \chem{^{48}Ca} reactions. The large measured $\alpha$-particle energies of the newly observed nuclei, together with the long decay times and spontaneous fission terminating the chains, offer evidence of the decay of nuclei with high atomic numbers. The decay properties of the synthesized nuclei are consistent with the consecutive $\alpha$-decays originating from the parent nuclides $^{{288}{,}{289}}$114 and $^{292}$116, produced in the $3n$ and $4n$ evaporation channels with cross-sections of about a picobarn. The present observations can be considered as experimental evidence of the existence of the “island of stability” of superheavy elements