Abstract
The paper studies \(1^{+}\) excitations in the \({}^{16}\) O nucleus within the shell model. There are at least three \(1^{+}\) excitations in the ( \(p\) , \(\gamma\) ), ( \(e\) , \(e^{\prime}\) ), and ( \(p\) , \(p^{\prime}\) ) reactions at energies of 16.22, 17.14, and 18.79 MeV. To produce such excitations, the valence space of the shell model should minimally contain at least the \(0p_{1/2}\) and \(0d_{5/2}\) subshells. The shell model was calculated for this and various other extended valence spaces. Various interaction Hamiltonians were also used. Excitations in nuclei are characterized by spin and current transition densities, which are different for different excited levels. Inelastic electron scattering excites both, but inelastic zero-angle proton scattering excites mainly the spin degrees of freedom. By comparing these two types of level excitation, one can determine the role of the spin and current degrees of freedom in each excitation. Unfortunately, the accuracy of this method is not very high. In this paper, we study the effect of the excitation type (spin or orbital) on the polarization characteristics of inelastically scattered protons, namely, on the spin-flip probability \(S_{NN}\) . The calculated angular dependence of the spin-flip probability on the excitation type is investigated, and its strong dependence on the excitation nature is demonstrated.
