Study of the ReactionsO18(p, n)F18,O18(p, p′γ)O18, andO18(p, α1,2γ)N15fromEp=2500 to 3000keV

The reactions ${\mathrm{O}}^{18}(p, n){\mathrm{F}}^{18}$, ${\mathrm{O}}^{18}(p, p^{\prime }\gamma ){\mathrm{O}}^{18}$, and ${\mathrm{O}}^{18}(p, {\alpha }_{1,2}\gamma ){\mathrm{N}}^{15}$ were investigated in the energy range $E_p=2500\mathrm{} \mathrm{to} 3000$ keV by simultaneous observation of the neutrons, 1.98-MeV $\gamma$ rays, and 5.30-MeV $\gamma$ rays. Angular distributions of the 1.98-MeV $\gamma$ rays were measured at the five prominent inelastic scattering resonances. The threshold for neutron production was found to be 2577±3 keV. The following resonances in the three decay channels were identified: (neutron) 2645, 2696, 2722, 2769, and 2926 keV; (alpha) 2645, 2769, and 2926 keV; and (proton) 2633, 2705, 2732, 2769, and 2926 keV. Spins and parities were assigned to several of these resonances: 2633, ${\frac{5}{2}}^{\mathrm{}(+)\mathrm{}}$; 2645, ($\frac{3}{2}$); 2705, ${\frac{3}{2}}^{\mathrm{}(+)\mathrm{}}$; 2732, ${\frac{5}{2}}^{\mathrm{}(+)\mathrm{}}\left(\frac{7}{2}\right)$; and 2769, ${\frac{5}{2}}^{\mathrm{}(+)\mathrm{}}$. All parity assignments, as well as the spin assignment of the 2645-keV resonance, are based on physical arguments. Comparison of the properties of the elastic scattering resonance at 849 keV and the resonances at 2633 (and 2732) and 2705 keV with those of the known and theoretically predicted states in ${\mathrm{O}}^{19}$ indicates that they are isobaric-spin analog states; however, isobaric-spin impurities are present.