${\mathrm{O}}^{16}(\gamma ,n){\mathrm{O}}^{{15}^{*}}$ and ${\mathrm{O}}^{16}(\gamma ,p){\mathrm{N}}^{{15}^{*}}$ Reactions and the Electromagnetic Decay of ${\mathrm{O}}^{15*}$ and ${\mathrm{N}}^{15}$

$\gamma$ rays resulting from the decay of excited states in ${\mathrm{O}}^{15}$ and ${\mathrm{N}}^{15}$ have been observed when these states were produced from ($\gamma ,n$) and ($\gamma ,\mathrm{p}$) reactions on ${\mathrm{O}}^{16}$. Bremsstrahlung from the Naval Research Laboratory's 60-MeV Electron Linac was used as a source of x rays to produce the photonuclear reactions leading to ${\mathrm{N}}^{15*}$ and ${\mathrm{O}}^{15*}$. The 5-MeV positive-parity quadruplet resulting from the above-described reactions was resolved into its four separate components and the width of each component was observed. Limits on lifetimes for all of the observed transitions were determined from the Doppler broadening of these lines. The ${\frac{5}{2}}^{+}$ states at 5.240 MeV in ${\mathrm{O}}^{15}$ and at 5.270 MeV in ${\mathrm{N}}^{15}$ were observed to have lifetimes considerably greater than ${10}^{-13\mathrm{}}$ sec. All other observed transitions showed lifetimes short compared to ${10}^{-13\mathrm{}}$ sec. It was also observed that the branching ratio of the 9.223-MeV level in ${\mathrm{N}}^{15}$ to the ${\mathrm{½}}^{+}$ state at 5.299 MeV could not be greater than ∼50%.