N D LyN N DuyK Y ChaeVinh N T PhamT V Nhan-Hao2022-11-032022-11-032020https://repository.vlu.edu.vn/handle/123456789/81510.1088/1402-4896/abd49bIn this paper, we estimated half-lives using semi-empirical formulae for isotopes with Z=100−126 in four α-decay chains, which can appear in the syntheses of the 309−312126 nuclei. The spontaneous fission half-lives were calculated using the Anghel, Karpov, and Xu models, whereas theα-decay ones were predicted using the Viola-Seaborg, Royer, Akrawy, Brown, modified formulae of Royer, Ni, and Qian approaches.Wefound that there are large differences among the spontaneous fission half-lives estimated using the Xu model and those calculated using the others, which are up to 50 orders of magnitude. The α-decay half-lives also have large uncertainties due to difference in either methods or uncertainties in nuclear mass and spin-parities. Subsequently, there is an argument in determination of α-emitters, especially for the 312126 isotope. On the other hand, the α-decay half-lives are in the range from a few microseconds (309−312126) to thousands of years (257−260Fm) in the decay chains. It was found that the half-lives are very sensitive to not only the shell closure but also the angular momentum in theα decay. For experiments, with relatively long half-lives (a few milliseconds), the 289−292Lv isotopes can be observed as evidences for syntheses of the unknown super-heavy 309−312126 nuclei. Furthermore, measurements for precise mass, fission barrier, and spin-parity are necessary to improve accuracy of half-life predictions for super-heavy nuclei.en-USsuper-heavy nucleialpha decayspontaneous fissionfission barrierhalf-lifejournal-article