The electron scattering cross sections from the enriched ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ (96.5%) and ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$ (99.2%) isotopes have been measured between 5 and 33 MeV excitation energies for incident energies in the range of between 150 and 215 MeV and scattering angles of 30°, 35°, and 40°. The giant resonances at $E_x=14.8\mathrm{} \left(78\mathrm{}{A}^{-\frac{1}{3}}\right), 11.6 \left(61\mathrm{}{A}^{-\frac{1}{3}}\right), 15.5 \left(82\mathrm{}{A}^{-\frac{1}{3}}\right), \mathrm{and} 24 \left(129\mathrm{}{A}^{-\frac{1}{3}}\right)$ MeV for ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ were classified according to their momentum transfer dependence. The $K$ splittings of the giant $E1\mathrm{}(T=1\mathrm{})\mathrm{}$ and $E2\mathrm{}(T=0,1\mathrm{})\mathrm{}$ resonances for deformed ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$ were observed in agreement with a vibrating potential model. The splittings between the $K=0^{+} \mathrm{and} 2^{+}$ components for the isoscalar and isovector quadrupole resonances are ∼2 MeV and ∼5 MeV, respectively. The fitted parameters classified as the giant monopole resonance are the same for spherical ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ and for deformed ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$. The difference between the isoscalar giant resonance parameters for resonance energies and width found from hadron scattering and those for electron scattering is discussed for the rare-earth region.

NUCLEAR REACTIONS ${}_{}{}^{148,152}{}_{}{}^{}\mathrm{Sm}$($e$,$e^{\prime }$), enriched targets, $E_0=150\mathrm{} \mathrm{to} 215$ MeV, $\theta =30\mathrm{}°, 35°, 40°$, $q=0.38-0.64\mathrm{}$ ${\mathrm{fm}}^{-1\mathrm{}}$. Measured $\frac{d^2\sigma }{d\Omega d{E}_x}$ up to 33 MeV in excitation energy; deduced multipolarity, excitation energy, width, sum rule exhaustion of giant resonances.

• Received 30 November 1981

DOI:https://doi.org/10.1103/PhysRevC.25.2255