Analysis of Some Deuteron-Induced Reactions in Oxygen-18

Abstract

The reactions ${\mathrm{O}}^{18}(d, t){\mathrm{O}}^{17}$, ${\mathrm{O}}^{18}(d, {d}^{\ensuremath{'}}){\mathrm{O}}^{18*}$, and ${\mathrm{O}}^{18}(d, p){\mathrm{O}}^{19}$ are studied using 15-Mev deuterons and magnetic analysis of reaction particles. Absolute cross sections are determined for all reactions studied and the Butler-Born approximation is used to extract reduced widths when possible. Angular distributions of triton groups corresponding to the ground, 0.871-, 3.846-, 4.555-, 5.083-, and 5.378-Mev states of ${\mathrm{O}}^{17}$ are obtained. An estimate of the configuration admixtures in the ${\mathrm{O}}^{18}$ ground state is made from analysis of the reduced widths and indicates the presence of a sizable (about 6%) ${(1{{f}_{\frac{7}{2}}}^{2})}_{0}$ component. The experimentally determined admixtures are compared with several theoretical estimates. All ${\mathrm{O}}^{18}$ levels observed in the inelastic deuteron scattering have been previously reported---the known 5.01-Mev state is not observed. The angular distribution of inelastic deuterons corresponding to the 1.982-Mev state of ${\mathrm{O}}^{18}$ is obtained and comparison of the absolute cross section with theory provides an estimate of the ${\mathrm{O}}^{18}$ deformation. Proton groups from ${\mathrm{O}}^{18}(d, p){\mathrm{O}}^{19}$ reactions are observed corresponding to ${\mathrm{O}}^{19}$ excitations of 0, 1.469, 3.164, 3.948, (4.123), (4.586), (4.706), (5.165), 5.45, 5.707, and 6.279 Mev, where assignment of the levels in parentheses to ${\mathrm{O}}^{19}$ is uncertain. The known 0.096-Mev state is not observed and the proton group corresponding to 5.45-Mev excitation contains contributions from at least two states. Angular distributions leading to the ${\mathrm{O}}^{19}$ ground, 1.469-, 3.164-, 3.948-, 5.707-, and 6.279-Mev states are obtained and reduced widths extracted. The ${l}_{n}$ values for these angular distributions are ambiguous except for the ground-state reaction (${l}_{n}=2$) and the 1.469-Mev state reaction (${l}_{n}=0$). Analysis of the data suggests that ${J}^{\ensuremath{\pi}} (\mathrm{ground}\mathrm{state})={\frac{5}{2}}^{+}$ and ${J}^{\ensuremath{\pi}}(0.096\ensuremath{-}\mathrm{M}\mathrm{e}\mathrm{v}\phantom{\rule{0ex}{0ex}}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{e})={\frac{3}{2}}^{+}$. Using parameter values estimated from the ${\mathrm{O}}^{19}$ energy level spectrum or obtained from neighboring nuclei, a description of this nucleus in terms of the strong-coupling unified model agrees with the data.