Ground-state electric quadrupole moment of {sup 31}Al

The ground-state electric quadrupole moment of {sup 31}Al(I{sup {pi}}=5/2{sup +},T{sub 1/2}=644(25) ms) has been measured by means of {beta}-ray-detected nuclear magnetic resonance spectroscopy using a spin-polarized {sup 31}Al beam produced in the projectile fragmentation reaction. The obtained Q moment, |Q{sub exp}({sup 31}Al)|=112(32) e mb, is in agreement with conventional shell model calculations within the sd valence space. Previous results on the magnetic moment also support the validity of the sd model in this isotope, and thus it is concluded that {sup 31}Al is located outside of the island of inversion.