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

Abstract

- New estimates of partial α-decay half-life, T1/2, for 156–162,174,176Hf 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 T1/2 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 T1/2-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.