Giant resonance spectra have been measured for ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, and ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}$, using inelastic scattering of 152-MeV alpha particles. In addition to some low-lying states, the spectra were analyzed to yield separate peaks for the giant quadrupole resonance and giant monopole resonance, except in ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}$, where no evidence was found for a giant monopole resonance. The results for the monopole resonance when compared to distorted-wave Born-approximation calculations show that ∼100% (±20%) of the $T=0\mathrm{}$, $L=0\mathrm{}$ energy weighted sum rule is depleted for nuclei with $A>\mathrm{}90\mathrm{}$. For ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ only 40% of the monopole sum rule is found. The excitation energy of the giant monopole resonance follows the systematic trend $\sim 80A^{-\frac{1}{3}}$ MeV. The data are also compared with folding model calculations using Tassie transition densities and an effective interaction derived from elastic data. Good agreement was obtained for low-lying quadrupole and octopole excitations, but this model yields considerably too little cross section for the monopole resonance. This probably indicates a deficiency in the Tassie model breathing mode transition density.

NUCLEAR REACTIONS ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}(\alpha , {\alpha }^{\prime })$, $E_{\alpha }=152\mathrm{}$ MeV, $E_{\chi }=0-40\mathrm{}$ MeV; measured $\sigma (E_{\chi }, \theta )$; discuss giant resonances, folding model calculations, deduced $L$, ${\beta }_L$.

• Received 12 May 1980

DOI:https://doi.org/10.1103/PhysRevC.22.1832