Inelastic proton scattering fromBa138andSm144at 30 MeV

Differential cross sections for elastic and inelastic scattering of 30-MeV protons by ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ba}$ and ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$ have been measured with a total energy resolution for the inelastic peaks of 7-10 keV, full width at half maximum. This permitted the observation of 20 excited states in ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ba}$ and 18 excited states in ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$ below $E_x=3.4\mathrm{}$ MeV, and the determination of excitation energies accurate to 2 keV or less for these states. Based on characteristic shapes derived from angular distributions to states of known $J^{\pi }$, spin-parity assignments were made for the majority of the observed states. Collective-model distorted-wave Born-approximation calculations for the observed transitions were compared to the data, and deformation parameters extracted for all states to which $J^{\pi }$ could be assigned. The energy-level structures of these nuclei, obtained by combining the present results with information in the literature, are compared to the predictions of structure calculations based on the assumption of a closed $N=82\mathrm{}$, $Z=50\mathrm{}$ core.