Stability of superheavy nuclei against α-decay and spontaneous fission

The stability of superheavy nuclei is mainly determined by the competition between α-decay and spontaneous fission. We investigate the half-lives of both α-decay and spontaneous fission for the heaviest nuclei with proton numbers up to Z=121. The agreement between theoretical half-lives and available experimental data is fairly well for the superheavy nuclei. Enhanced stability against spontaneous fission is found for the Z=119 and Z=120 isotopic chains, which are of current experimental interests. α-Decay is predicted to be the dominating decay mode for the Z=119 and Z=120 isotopes with estimated half-lives ranging from microseconds to milliseconds.