For the first time, we obtained the $g$ factor for the ground state of ${}^{23}\mathrm{Al}$ by use of a β-NMR measurement. ${}^{23}\mathrm{Al}$ has a small proton separation energy and is a potential proton-halo candidate. The obtained $g$ factor, $\left|g\right|=1.557\pm 0.088$, clearly shows the spin and parity, $J^{\pi }=5/2^{+}$, for ${}^{23}\mathrm{Al}$, which is the same as that of its mirror partner, ${}^{23}\mathrm{Ne}$. The possible nuclear structure of ${}^{23}\mathrm{Al}$ is also discussed.

• Received 20 December 2005

DOI:https://doi.org/10.1103/PhysRevC.74.021301