Spin Flip in the Inelastic Scattering of 19.6-MeV Protons fromFe54andFe56

Abstract

The spin-flip probability in the excitation of the first $2^{+}$ states in ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ has been studied at 19.6 MeV using the ($p, p^{\prime }\gamma$) coincidence technique. Differential cross sections have also been measured at this energy. The spin-flip data for ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ are quite similar, in contrast to asymmetry data from Saclay which show distinct differences between the two nuclei. Collective-model distorted-wave Born-approximation calculations generally underestimate the magnitude of the spin-flip probability at forward angles and predict too little structure. Simple microscopic-model calculations give improved agreement with the spin-flip data only when the terms arising from spin transfer of 1 are significant. These terms had little effect on the predicted cross sections and asymmetries.