Structure of the 11/2− isomeric state in La133

Abstract

We report measurement of the $g$-factor for the ${11/2}^{\ensuremath{-}}$ isomeric state at 535 keV in $^{133}\mathrm{La}$, employing the time differential perturbed angular distribution technique (TDPAD). This isomer was populated in the reaction $^{126}\mathrm{Te}(^{11}\mathrm{B}$, $4n)^{133}\mathrm{La}$ at beam energy of 52 MeV. From the observed nuclear spin precession, analysed through combined, magnetic dipole and electric quadrupole hyperfine interactions, we obtain the $g$ factor for the $11/{2}^{\ensuremath{-}}$ state as $g=1.16\ifmmode\pm\else\textpm\fi{}0.07$. In addition, this analysis provides the spectroscopic quadrupole moment $|Q|=1.71\ifmmode\pm\else\textpm\fi{}0.34\phantom{\rule{3.33333pt}{0ex}}b$, yielding the deformation parameter $\ensuremath{\beta}=0.28\ifmmode\pm\else\textpm\fi{}0.10$. Further, we have performed theoretical calculations using the large-scale shell model and the Monte Carlo shell model. The results successfully describe the low-lying levels and the band structures of $^{133}\mathrm{La}$, and the calculated $g$ factor compares well with the values obtained from our experiment. The dominant configuration of $11/{2}^{\ensuremath{-}}$ isomeric state in $^{133}\mathrm{La}$ is inferred to be $\ensuremath{\pi}({h}_{11/2})\ensuremath{\bigotimes}^{132}\mathrm{Ba}({0}^{+})$.