Using the gamma-gamma coincidence method and an electronic time-to-amplitude converter, the lifetimes of the first excited states in the mirror pair ${\mathrm{O}}^{17}$(0.87 Mev) and ${\mathrm{F}}^{17}$(0.50 Mev) have been measured. The reactions initiating the gamma cascades were ${\mathrm{O}}^{16}(d, p){\mathrm{O}}^{17*}$ and direct proton capture in ${\mathrm{O}}^{16}$. The time resolution of the coincidence circuit was good enough to allow the lifetime measurements to be made by direct observation of ${\mathrm{O}}^{17*}$ is (2.55±0.13)×${10}^{-10\mathrm{}}$ sec; the measured mean life of ${\mathrm{F}}^{17*}$ is (4.45±0.22)×${10}^{-10\mathrm{}}$ sec. Both of these results are in reasonable agreement with earlier, less accurate values.

• Received 20 May 1960

DOI:https://doi.org/10.1103/PhysRev.120.162