Investigation of radioactive decay modes of oganesson isotopes

We calculate the [Formula: see text]-decay and spontaneous fission half-lives of the artificially synthesized superheavy isotopes of oganesson (Og, Z = 118), which is recognized as the last element of the periodic table, in order to determine the decay modes of Og isotopes. For the [Formula: see text]-decay calculations, the Coulomb and Proximity Potential Model (CPPM) is employed together with the Universal Decay Law (UDL). In addition, the modified form of the UDL proposed by Soylu and Qi, which includes angular momentum and isospin effects and is referred to here as the new-UDL [25], is also used. Royer’s empirical formulas are also applied for comparison. For spontaneous fission, the semi-empirical formula proposed by Xu is modified by introducing an additional term that accounts for shell effects, leading to an improvement in the root mean square (rms) deviation of the model. The spontaneous fission half-lives are calculated using several different formulas, including the shell-effect-dependent formula (KPS) developed by Santhosh, Xu’s semi-empirical formula, Soylu’s formula [69], and the newly proposed Xu-shell formula that incorporates the shell-effect term. By comparing the results obtained from the new-UDL and the spontaneous fission formulas, the dominant decay modes of oganesson isotopes are determined, following the procedure used in [81]. The predicted decay modes are also compared with those reported in the literature, revealing some differences among the models. Furthermore, detailed decay-chain calculations are performed for the isotopes [Formula: see text]Og, [Formula: see text]Og, and [Formula: see text]Og, as previously considered in [78]. The results show that certain decay modes may vary depending on the theoretical model used. The findings of this study may provide useful guidance for future theoretical investigations and experimental studies on oganesson isotopes.