Estimation of alpha-decay half-lives and fission barriers from the viewpoint of a new mass formula

We estimate the alpha-decay half-lives from Q_α-values with a phenomenological relation. The parameter values of the phenomenological formula are adjusted by using the experimental half-lives and Q-values of the Evaluated Nuclear Structure Data File (ENSDF) for a wide nuclidic region. The half-lives T_α for unknown nuclei are estimated by this phenomenological formula with the use of Q_α-values taken from KUTY mass formula. In addition to the half-lives, we calculate the potential energy surface for spontaneous fission calculated by the same method as used for obtaining the shell energies of KUTY mass formula. In the superheavy region, the fission barrier heights of the nuclei near the nucleus ³⁰⁴122 are about 8 MeV and their widths are fairly wide. Therefore the spontaneous-fission half-lives are expected to be very longer than the alpha-decay half-lives. On the contrary, there are some neutron-deficient nuclei whose spontaneous-fission half-lives are expected to be rather short because their fission barrier heights are small and the widths are narrow. (author)