gFactor of theJπ=25+2Isomer inTl205and the Anomalous Orbital Magnetism of the Proton

Abstract

The nuclear gyromagnetic ratio of the 3291-keV $J^{\pi }={\frac{25}{2}}^{+}$ ${}_{}{}^{205}{}_{}{}^{}\mathrm{Tl}$ level has been measured with use of $\gamma$-ray perturbed angular distribution techniques with the result $g=0.544\mathrm{}\pm 0.008$. The state was populated with the reaction ${}_{}{}^{204}{}_{}{}^{}\mathrm{Hg}(t, 2n){}_{}{}^{205}{}_{}{}^{}\mathrm{Tl}$. With use of the known quantities $g({}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}{7}^{-}; E_x=2200\mathrm{} \mathrm{keV})$ and $g({}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}{\frac{9}{2}}^{+}; E_x=0\mathrm{} \mathrm{keV})$ the proton orbital magnetic $g$ factor for the $1h$ orbital was deduced to be $g_l=1.115\mathrm{}\pm 0.02$. This result has been corrected for wave-function admixtures and core polarization effects.