Alpha-decay half-life of Hafnium isotopes reinvestigated by a semi-empirical approach

- New estimates of partial α-decay half-life, T_1/2, for ^{156-162,174,176}Hf isotopes by a semi-empirical, one-parameter model are given. The used model is based on the quantum mechanical tunneling mechanism through a potential barrier, where the Coulomb, centrifugal and overlapping components to the barrier have been considered within the spherical nucleus approximation. This approach enables to reproduce, within a factor 2, the measured T_1/2 of ground-state to ground-state (gs-gs) α-transitions for the artificially produced ^156-162Hf isotopes. Half-life predictions for α-transitions from the ground-state of ^159,161Hf isotopes to the first gamma-excited level of ^155,157Yb isotopes are reported for the first time. The model also provides T_1/2-values of (2.43±0.28)×10¹⁶ a and (1.47±0.19)×10²⁰ a for the naturally occurring ¹⁷⁴Hf and ¹⁷⁶Hf isotopes, respectively, in quite good agreement with a number of estimates by other authors. In addition, the present methodology indicates that ^174,176Hf isotopes exhibit α-transition to the first gamma-excited level of their daughter Ytterbium isotopes which half-lives are found (0.9±0.1)×10¹⁸ a and (0.72±0.08)×10²² a, respectively, with a chance of being measured by improved α-detection and α-spectrometry methods available nowadays.