Neutrond52nConfigurations in Zr Isotopes

Energy levels of neutron $2{d_{\frac{5}{2}}}^n$ configurations are analyzed by shell model methods. Good agreement is obtained between experimental and calculated energies. The position of the $\frac{3}{2^{+}}$ level in ${\mathrm{Zr}}^{93}$ is predicted on the basis of this analysis. The energies of these configurations to which a $2p_{\frac{1}{2}}$ is added (in Y isotopes) are also considered by using a closed formula for the energies of $j^n{j}^{\prime }$ configurations, with $j^{\prime }=\frac{1}{2}$, derived in the Appendix.