High spin single particle states inEr152,153

A spectroscopic investigation of yrast and near-yrast states in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Er}$ and ${}_{}{}^{153}{}_{}{}^{}\mathrm{Er}$ is presented. We report measurements of prompt and delayed excitation functions, $\gamma -\gamma$ coincidences, isomeric lifetimes, and $\gamma$-ray angular distribution, obtained chiefly from the reactions ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},xn){}_{}{}^{152,153}{}_{}{}^{}\mathrm{Er}$ using carbon beams of laboratory energy 65-95 MeV. The levels observed extend to a spin of $J\ge \frac{43}{2}$ and include two long-lived isomers in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Er}$. The nuclear structure is discussed in terms of the shell model and compared with the systematic behavior of levels in $N=84\mathrm{}$ and $N=85\mathrm{}$ isotones.