Alpha decay half-life of bismuth isotopes

The observed alpha decay half-life values of favoured alpha transitions of l = 5 in bismuth isotopes have been analysed in the framework of a model based on quantum mechanical tunnelling through a potential barrier where the centrifugal and overlapping effects are taken into account. In particular, the very recently measured alpha decay half-life value of (1.9 +/- 0.2) x 10(19) y for the unique naturally occurring Bi-209 isotope has been reproduced by the present approach as (1.0 +/- 0.3) x 10(19) y. Also, the partial alpha decay half-lives for a number of unmeasured alpha transitions of l = 5 in bismuth isotopes are predicted by the model, thus making it possible to demonstrate the influence of the 126 neutron shell closure on the alpha decay half-life. The present approach is shown to be successfully applicable to other isotopic sequences of alpha-emitter nuclides.