A new semi-empirical formula for calculations of α decay halflives is presented. It was derived from Royer relationship by introducing new parameters which are fixed by fit to a set of experimental data. We are using three sets: set A with 130 e-e (even-even), 119 e-o (even-odd), 109o-e, and 96 o-o, set B with 188 e-e, 147 e-o, 131 o-e, and 114 o-o, and set C with 136 e-e, 84 e-o, 76 o-e, and 48 o-o alpha emitters. A comparison of results obtained with the new formula and the following well known relationships: semFIS (semiempirical based on fission theory); ASAF (analytical superAsymmetric fission) model, and UNIV (universal formula) is made in terms of rms standard deviation. We also introduced a weighted mean value of this quantity, allowing to compare the global properties of a given model. For the set B the order of the four models is the following: semFIS; UNIV; newF, and ASAF. Nevertheless for even-even alpha emitters UNIV gives the 2nd best result after semFIS, and for odd-even parents the 2nd is newF. Despite its simplicity in comparison with semFIS the new formula, presented in this article, behaves quite well, competing with the others well known relationships

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We have performed a systematic calculation on the alpha decay half-lives of heavy mass nuclei with 106 [Formula: see text] 118, within the universal decay law (UDL) and modified universal decay law (MUDL). The calculated half-life values are found to be in agreement with the experimental data. The standard deviations of the logarithm of half-lives are found to be the least for MUDL in all cases of even–even, even–odd, odd–even and odd–odd, so the MUDL formula is better than UDL formula for alpha decay studies. We have predicted half-lives of some superheavy nuclei (SHN) in the region [Formula: see text]–118 that are not yet experimentally detected. The decay energies are computed using three different mass models. We hope this study will help future measurements on alpha decay half-lives of SHN.

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A set of empirical formulae have been proposed to calculate the [Formula: see text]-decay half-lives from ground state to ground state transitions of 356 nuclei classified to different set of e–e, e–o, o–e and o–o isotopes. Within these formulae, modification of the previous set of Royer expressions were done by introducing three different physical terms, including the orbital angular momentum and isobaric asymmetry factors. The predicted [Formula: see text]-decay half-lives compared with those adopted by former proposed models for the depended experimental data, and significant improvements were noticed for all the studied sets of isotopes.