We report the first confirmation of the predicted inversion between the $\pi 2p_{3/2}$ and $\pi 1f_{5/2}$ nuclear states in the $\nu g_{9/2}$ midshell. This was achieved at the ISOLDE facility, by using a combination of in-source laser spectroscopy and collinear laser spectroscopy on the ground states of ${}^{71,73,75}\mathrm{Cu}$, which measured the nuclear spin and magnetic moments. The obtained values are $\mu ({}^{71}\mathrm{Cu})=+2.2747(8){\mu }_N$, $\mu ({}^{73}\mathrm{Cu})=+1.7426(8){\mu }_N$, and $\mu ({}^{75}\mathrm{Cu})=+1.0062(13){\mu }_N$ corresponding to spins $I=3/2$ for ${}^{71,73}\mathrm{Cu}$ and $I=5/2$ for ${}^{75}\mathrm{Cu}$. The results are in fair agreement with large-scale shell-model calculations.

• Received 31 July 2009

DOI:https://doi.org/10.1103/PhysRevLett.103.142501