α-decay properties of neutron-deficient polonium and radon nuclei

Chemically purified and mass-separated Rn isotopes are used to deduce the α branching ratios of the Po daughter nuclei. The obtained values are systematically lower than the previously known values. Combined with more accurate measurements of the half-lives of the neutron-deficient Po isotopes, a precise set of partial α-decay half-lives is obtained. The α-decay energies of some Po and Rn isotopes have also been remeasured. The α branching ratios of the Rn nuclei can be deduced from the α intensity of the At daughter nuclei, provided their branching is known. This makes it possible to present in a coherent way the partial α-decay half-lives and the α-reduced widths of a long chain of Po and Rn isotopes and to compare them with theory. Evidence is emerging that, for the very neutron-deficient Po isotopes, mixing of intruder configurations into the ground state is slowing down the α decay.