5−‘‘octupole’’ states inNd146,148andSm148via proton scattering

The cross sections for populating the $2_1^{+}$, $3_1^{\mathrm{-}}$, and $5_1^{\mathrm{-}}$ states of ${}_{}{}^{146,148}{}_{}{}^{}\mathrm{Nd}$ and ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ have been determined by inelastic scattering of 26 MeV protons and analyzed using coupled-channels calculations. In these nuclei, the $5_1^{\mathrm{-}}$ states are usually considered to be ‘‘octupole coupled’’ states arising from the coupling of the $2_1^{+}$ and $3_1^{\mathrm{-}}$ states. It is found that the differential cross sections for excitation of the $5_1^{\mathrm{-}}$ states are somewhat larger than would be expected for octupole coupled structure. This excess strength can be explained in terms of small admixtures of two quasiparticle excitations in the $5_1^{\mathrm{-}}$ states.