Oblate Deformation of High-Spin Levels in Gd Isotopes

Abstract

Oblate shapes of four high-spin isomers in Gd isotopes (${10}^{+}$ in $^{144}\mathrm{Gd}$, ${\frac{13}{2}}^{+}$, ${\frac{27}{2}}^{\ensuremath{-}}$, and ${\frac{49}{2}}^{+}$ in $^{147}\mathrm{Gd}$) were established in measurements of the signs of the respective quadrupole moments. A combined tilted-multifoil and time-differential perturbed-angular-distribution technique was employed. The present results are direct evidence for the presumed oblate nature of high-spin states in the $A\ensuremath{\approx}150$ region.