Examination of α-decay half-lives of undetected transfermium isotopes

This study reports the alpha-decay half-lives of 39 transfermium isotopes with Z = 105 - 113, most of which have not been observed. The half-lives were calculated using micro-macroscopic approaches and semi-empirical formulae, applying current alpha-decay Q-values from the latest mass database, AME2016. These results were compared to predicted values in previous works to evaluate the efficiency of and difference between various calculation methods. We found that the alpha-resonance approach used in a previous study is not appropriate to predict though most other approaches are mutually consistent. An uncertainty of 70% was observed in the present theoretical calculations, similar to that observed in measurements. A Q-value uncertainty of 10% can lead to a large variation of 3 orders of magnitude in predicted alpha-decay half-life. We also found that the dominance of either alpha decay or spontaneous fission is unclear for the isotopes with Z = 105-108, whereas most of the nuclei of Z = 109-113 can be clearly identified as alpha emitters. Finally, we provide the updated alpha-decay half-lives for the isotopes of interest, including their uncertainties and corresponding decay modes.