Fine Structure and Spin Excitations in the Giant Resonance Region ofZr90

Cross sections, analyzing powers, and spin-flip probabilities have been measured at small angles in the reaction ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}(p,p^{\prime }){}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}_{}^{*}{}_{}{}^{}$ at 319 MeV. A rich fine structure is observed in the previously proposed $M1\mathrm{}$ giant resonance region; angular distributions of most of these structures are consistent with $M1\mathrm{}$ excitation. The spin-flip measurements reveal a large cross section for spin excitations distributed roughly uniformly over the excitation energy region from about 8 to 25 MeV.