INTRUDER STATES IN THE LEAD REGION, STUDIED BY ALPHA-DECAY

The alpha decay of nuclei around the Z=82 closed proton shell is a powerful tool for the study of shape coexistence and intruder states in the lead region. Systematic measurements of alpha-decay properties of even-even mercury, lead, polonium and radon nuclei have been performed. From the deduced set of precise alpha-reduced widths in this region, we conclude that, in contrast to what has been suggested from recent alpha-decay rate calculations, alpha-decay rates do contain nuclear structure information. The fine-structure studies of the alpha decay of Rn-202,Po-194,Po-196,Po-198,Pb-188 and Hg-180,Hg-182 reveal feeding to low-lying O+ states in the daughter nuclei, which are proposed to be proton particle-hole pair excitations coexisting with the groundstate configurations. These data support the idea that the alpha-decay rate towards excited states relative to the groundstate, enables us to extract information about the structure of these low-energetic excited configurations.