Investigation of States in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ via Neutron-Polarization Measurements in the ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(\alpha ,n) {}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ Reaction

Neutron-polarization angular distributions have been measured at six $\alpha$-particle energies between 3.36 and 4.80 MeV for the ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}(\alpha ,n_0){}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ reaction in order to investigate the level structure of ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ between 8.7 and 10.2 MeV. These measurements have been analyzed together with the previous cross-section data of Walton, Clement, and Boreli and Kerr, Morris, and Risser using an $S$-matrix search code to yield a number of $J^{\pi }$ assignments to ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ levels in this energy interval. Although most assignments agreed with previous results, the assignment for the 9.95-MeV state must be changed to ${\frac{5}{2}}^{+}$. The existence of broad states near 8.7 and 9.6 MeV have been confirmed and assigned $J^{\pi }$ values of ${\mathrm{½}}^{-}$ and ${\frac{3}{2}}^{-}$, respectively.