Nuclear Polarization and Sign of the Quadrupole Moment of theFe54(10+) Isomer

A novel approach to the determination of signs of quadrupole deformations of high-spin isomers is presented. Recoiling ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$(${10}^{+}$) isomers, populated by the reaction ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}({}_{}{}^{12}{}_{}{}^{}\mathrm{C}, p2n)$,, are polarized by passage through an array of tilted carbon foils and stop in a Cd single crystal. The observation of a quadrupole precession serves to measure both the induced nuclear polarization and the sign of the quadrupole moment. A positive sign of $Q\left({}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}\right({10}^{+}\left)\right)$ has been deduced.