Systematics of alpha decay hindrance factors in doubly-even nuclei

The alpha Hindrance Factors (HFs) which is the ratio of experimentally observed partial half-life to the calculated partial half-life is an important parameter which quantifies the overlap of nuclear wave functions of the initial state of parent and final state of daughter nuclei. In this study, we calculates HFs of 182 even-even alpha emitters using ALPHAD program based on Preston's equations and presents the HFs systematics of 1-, 3-, 2+, 4+ and 6+ states with neutron number. In Figure 1, we present the variation of HFs of 1- and 3- states observed in ^218-226Ra isotopes with neutron number. From this figure it is clear that, the HFs of both 1-and 3-states decrease with reduction in neutron number. This decrease of HFs is attributed to onset of intrinsic reflection asymmetry, but there is a trend reversal at N=132 (²¹⁸Ra), which might be a possible indication of departure from static octupole deformation. Similar HFs systematics is studied in Rn, Th, U and Pu isotopes. (author)