ALPHA-DECAY PROPERTIES OF NEUTRON-DEFICIENT POLONIUM AND RADON NUCLEI

Chemically purified and mass-separated Rn isotopes are used to deduce the a 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 alpha-decay half-lives is obtained. The alpha-decay energies of some Po and Rn isotopes have also been remeasured. The alpha branching ratios of the Rn nuclei can be deduced from the alpha intensity of the At daughter nuclei, provided their branching is known. This makes it possible to present in a coherent way the partial alpha-decay half-lives and the alpha-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 alpha decay.