Study of theN14(p, γ)O15Reaction

Abstract

The reaction ${\mathrm{N}}^{14}(p, \gamma ){\mathrm{O}}^{15}$ has been studied using an anticoincidence-shielded scintillation spectrometer. Excitation functions were measured for proton energies of 0.85-1.96 MeV. Resonances were found at bombarding energies of 1.061±0.002, 1.55, 1.739±0.002, and 1800±0.004 MeV, corresponding to the well-known excited states of ${\mathrm{O}}^{15}$ at 8.283±0.003, 8.75, 8.915±0.003, and 8.972±0.005 MeV. Gamma-ray spectra show that the 8.28-MeV level decays to the ground state (54%), the 5.24-MeV level (43%), and the 6.18-MeV level (2%). In addition, coincidence spectra revealed a 1% branch through the 6.86-MeV level, which level decays to the 5.24-MeV level. No evidence was found for decay of the 8.28-MeV level to a previously reported level at 7.17 MeV. The 8.75-MeV level decays $\frac{2}{3}$ by way of the 5.19-MeV level and $\frac{1}{3}$ by way of the 6.18-MeV level. The 8.915-MeV level decays to the ground state (21%), the 5.19-MeV level (23%), the 6.18-MeV level (30%), and the 6.86-MeV level (26%). The 8.97-MeV level decays 93% to the ground state and 6% to the 5.19-MeV state. Based upon measured transition strengths and the angular distribution of the ground-state gamma rays, the spin of the 8.915-MeV level is established as $\frac{3}{2}$; the 8.972-MeV level is ${\frac{3}{2}}^{-}$ or ${\mathrm{½}}^{-}$ and the 6.86-MeV level has a spin of either $\frac{5}{2}$ or $\frac{3}{2}$. Off-resonance spectra for $E_p$ near 1.2 MeV indicate direct capture into the 6.79-MeV level, the ground state, and also the 7.55-MeV level. The excitation function of radiation to ground from the bound states of ${\mathrm{O}}^{15}$ indicate that the broad level of ${\mathrm{O}}^{15}$ at 9.53 MeV decays almost entirely directly to the ground state or to the ground state and to unbound levels.