Empirical formula for β −-decay half-lives of r-process nuclei

Abstract

Experimental data of $\beta^{-}$-decay half-lives of nuclei with atomic number between 20 and 190 are investigated. A systematic formula has been proposed to calculate $\beta^{-}$-decay half-lives of neutron-rich nuclei, with a particular consideration on shell and pair effects, the decay energy $Q$ as well as the nucleon numbers ($Z$, $N$). Although the formula has relatively few parameters, it reproduces the experimental $\beta^{-}$-decay half-lives of neutron-rich nuclei very well. The predicted half-lives for the r-process relevant nuclei obtained with the current formula serve as reliable input in the r-process model calculations.