gFactor Measurements of High-Spin (Iπ≤10+) Rotational States

The ion implantation perturbed angular correlation (IMPAC) technique was used to measure the precession angles of the $4^{+}$, $6^{+}$, $8^{+}$, and ${10}^{+}$ rotational states of ${}_{}{}^{158,160,162}{}_{}{}^{}\mathrm{Dy}$ nuclei recoil implanted into magnetized Gd ($T=77\mathrm{}$ °K). The $\mathrm{Gd}(\alpha ,2n)\mathrm{Dy}$ reaction ($E_{\alpha }=27\mathrm{}$ MeV) on natural Gd was used to populate the levels studied. By comparing the precession results obtained from the ($\alpha ,2n$) experiments for the $4^{+}$ and $6^{+}$ states to those obtained from Coulomb excitation IMPAC measurements one can conclude the following: (i) $g\left({}_{}{}^{158}{}_{}{}^{}\mathrm{Dy}\right)=0.36\mathrm{}\pm 0.06$ for $I^{\pi }=4^{+},6^{+}, \mathrm{and} 8^{+}$; (ii) no effect due to final feeding times into the g.s. rotational band can be observed; and (iii) the deduced $g$ factors are constant for members of the g.s. bands of ${}_{}{}^{158,160,162}{}_{}{}^{}\mathrm{Dy}$ up to $I^{\pi }\le 8^{+}$ but a possible drop in $g$ for the ${10}^{+}$ states may be indicated by the data. A reduction in the $g$ factors is theoretically expected to accompany the "back bending" in the energy levels which was recently observed for high-spin rotational states in some deformed nuclei.