Evidence from α decay that Z = 82 is not magic for light Pb isotopes

To resolve the reported anomalous behavior of the α-decay rates of /sup 186,188,190,192/Pb we determined more accurate α-decay branches for these isotopes. Our data result in α-decay reduced widths whose dependence on N is similar to that observed for other elements. However, contrary to the expectation of a shell effect at Z = 82, this new information indicates lead nuclei to be less hindered toward α decay than mercury isotopes. It appears that midway between n = 82 and N = 126 the proton number of 82 is not magic