Angular distribution of the ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$(e,${\mathrm{p}}_0$) reaction has been measured in the giant resonance energy region at 12 laboratory angles ranging from 30° to 140°. The obtained differential cross sections have been decomposed into E1 and E2 components using a resonance model. The E1 and E2 components of the ${}_{}{}^{89}{}_{}{}^{}(\gamma$,${\mathrm{p}}_0$) cross section were estimated to exhaust 2.9% and 1.7% of the E1 and E2 sums, respectively. The derived excitation functions for E1 and E2 are well explained by a direct-semidirect model. The result confirms the isovector giant quadrupole excitation in ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$.

• Received 13 July 1987

DOI:https://doi.org/10.1103/PhysRevC.36.1792