The mean lives of the 6.91- and 7.12-Mev excited states of ${\mathrm{O}}^{16}$ have been measured through a nuclear resonance scattering experiment. The ${\mathrm{F}}^{19}(p, \alpha ){\mathrm{O}}^{16*}$ reaction was used as the source of Doppler-broadened gamma radiation. The relative intensities of the 6.91- and 7.12-Mev gamma-ray lines in this source were determined by observations of the associated alpha particles. From the magnitude of the resonance fluorescence effect and the angular distribution, mean lives of (1.2±0.3)×${10}^{-14\mathrm{}}$ second for the 6.91-Mev level and (1.0±0.3)×${10}^{-14\mathrm{}}$ second for the 7.12-Mev level were calculated.

• Received 24 July 1957

DOI:https://doi.org/10.1103/PhysRev.108.982