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

Abstract - New estimates of partial α-decay half-life, T 1 / 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 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 ) × 10 16 a and ( 1.47 ± 0.19 ) × 10 20 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 ) × 10 18 a and ( 0.72 ± 0.08 ) × 10 22 a, respectively, with a chance of being measured by improved α-detection and α-spectrometry methods available nowadays.