F. Guzmán

Alpha decay and nuclear deformation: the case for favoured alpha transitions of even-even emitters ∗

Alpha decay half-life for ground-state to ground-state transitions of 174 even-even alpha emitters has been calculated from a simple, Gamow-like model in which the quadrupole deformation of the product nucleus (assumed to have an ellipsoidal shape) is taken into account. The assumption made is that before tunnelling through a purely Coulomb potential barrier the two-body system oscillates isotropically, thus giving rise to an equivalent, average polar direction θ0 (referred to the symmetry axis of the ellipsoid) for alpha emission. It is shown that the experimental half-life data are much better reproduced by the present description than in the spherical shaped approximation for the daughter nucleus.

Effective liquid drop description for alpha decay of atomic nuclei

Alpha-decay half-lives are presented in the framework of an effective liquid drop model for different combinations of mass transfer descriptions and inertia coefficients. Calculated half-life values for ground-state-ground-state-favoured alpha transitions are compared with available, updated experimental data. Results have shown that the present model is very suitable to treat the alpha-decay process on an equal footing as cluster radioactivity and cold fission processes. Better agreement with the data is found when the subset of even-even alpha emitters is considered in the calculation.

Half-life predictions for decay modes of superheavy nuclei

We applied the effective liquid drop model to predict the alpha-decay, cluster emission and cold fission half-life values of nuclei in the region of superheavy elements (SHE). The present calculations have been made in the region of the ZN plane defined by 155 ≤ N ≤ 220 and 110 ≤ Z ≤ 135. Shell effects are included via the Q-value of the corresponding decay case. We report the results of a systematic calculation of the half-life for the three nuclear decay modes in a region of the ZN plane where superheavy elements are expected to be found. Results have shown that, among the decay modes investigated here, the alpha decay is the dominant one, i.e. the decay mode of smallest half-lives. Half-life predictions for alpha-decay, cluster emission and cold fission for the isotopic family of the most recent SHE detected of Z = 115 and for the isotopic family of the already consolidated SHE of Z = 111 are presented.