Deexcitation gamma rays following the photodisintegration of 17O.

Abstract

Bremsstrahlung-weighted integrated cross sections for photoproton and photoneutron emission from $^{17}\mathrm{O}$ to excited residual states in $^{16}\mathrm{N}$ and $^{16}\mathrm{O}$ have been measured by detecting the deexcitation \ensuremath{\gamma} rays emitted from these states in the residual nuclei. The results are compared with the previously reported $^{17}(\ensuremath{\gamma}$,p) and $^{17}(\ensuremath{\gamma}$,n) cross sections. About 90% of photoproton emission from $^{17}\mathrm{O}$ populates the ground-state ${(2}^{\mathrm{\ensuremath{-}}}$) and the 0.298-MeV ${(3}^{\mathrm{\ensuremath{-}}}$) level in $^{16}\mathrm{N}$. It is concluded that this is the result of a single-particle excitation and emission process. The remaining photoproton emission, leading to the 0.120-MeV ${(0}^{\mathrm{\ensuremath{-}}}$) and 0.397-MeV ${(1}^{\mathrm{\ensuremath{-}}}$) levels, occurs during the preequilibrium stage or from the compound nucleus. The results further indicate that these decay fractions are approximately independent of excitation energy in $^{17}\mathrm{O}$. For the $^{17}(\ensuremath{\gamma}$,n${)}^{16}$O reaction, the results show that emission to bound states in $^{16}\mathrm{O}$ is predominantly to the $^{16}\mathrm{O}$ ground state ${(0}^{+}$), with 4% of the decay from the $^{17}\mathrm{O}$ giant dipole resonance going to the 6.13-MeV ${(3}^{\mathrm{\ensuremath{-}}}$) excited state; population of other bound states is not observed.