Coulomb excitation of Yb nuclei

Abstract

Multiple Coulomb excitation measurements have been performed with $^{16}\mathrm{O}$ projectiles on $^{168,170,172,174,176}\mathrm{Yb}$, Measured $\ensuremath{\gamma}$-ray yields were compared to the Winther-deBoer calculations in order to extract $B(E2)$ and $B(E3)$ values to vibrational and rotational states. The ${2}^{+}$ member of the $\ensuremath{\gamma}$-vibrational band was observed in all the nuclei, the ${4}^{+}$ member in three cases, and excited ${0}^{+}$ states in $^{168,170,172,174}\mathrm{Yb}$. The $B(E2;{0}^{+\ensuremath{'}}\ensuremath{\rightarrow}{2}^{+})$ values from ${0}^{+}$ states at 1228 keV in $^{170}\mathrm{Yb}$ and 1154 keV in $^{168}\mathrm{Yb}$ are in excess of one single-particle unit, the first such cases observed in Yb nuclei. $B(E3)$ values to octupole states were deduced for $^{172,174}\mathrm{Yb}$. Members of the ground state rotational band up to $I=8$ were excited in each nucleus. The measured yield of the ${8}^{+}$ state relative to that of the ${6}^{+}$ level is compared to calculations and discussed for the five nuclei studied.NUCLEAR REACTIONS $^{168,170,172,174,176}\mathrm{Yb}$($^{16}\mathrm{O}$, $^{16}\mathrm{O}^{\ensuremath{'}}\ensuremath{\gamma}$), $E=58\ensuremath{-}62$ MeV; measured $\ensuremath{\sigma}(E)$, ${I}_{\ensuremath{\gamma}}$. $^{168,170,172,174,176}\mathrm{Yb}$ deduced levels, $J$, $\ensuremath{\pi}$, $B(E2)$, $B(E3)$. Enriched targets; Ge(Li) detector.