Shell effect in the mean square charge radii and magnetic moments of bismuth isotopes near N=126

Isotope shift relative to Bi-209 and hyperfine splitting for Bi-211,Bi-213 have been measured by in-source laser spectroscopy at the 306.77-nm atomic transition. The pronounced shell effect both in radii and magnetic moments in Bi isotopes at N = 126 has been observed. The isotopic trend of magnetic moment for 9/2(-) ground states of even-N Bi isotopes has been qualitatively explained by the change in the first-order core-polarization correction. The possible influence of the octupole degree of freedom on the magnetic moment behavior at N > 126 has been discussed.