Enhancement of α-particle formation near ¹⁰⁰Sn

The superfluid tunneling model is applied to the calculation of ground-state–to–ground-state α decay in the even-even neutron-deficient Te-Ba nuclei. We show that there is a larger α-particle formation probability in nuclei of this region above ¹⁰⁰Sn when compared to analogous nuclei above ²⁰⁸Pb. This is consistent with the expected systematic variation of the pair gap Δ as a function of mass number. The recent experimental data on the α decay of the N = Z nuclei ¹⁰⁴Te and ¹⁰⁸Xe are shown to leave open the possibility of enhanced α-particle formation involving nucleon correlations beyond the standard treatment of like-nucleon pairing, which is the mechanism suggested as underlying “superallowed” α decay.