The Doppler-shift attenuation method was used in conjunction with ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ bombardment of tritium targets to measure the mean lives of five levels in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$, and ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$. The results are [nucleus, $E_x$ (keV), $\tau$ (psec)]: [${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, 3632, 1.45 ± 0.25]; [${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$, 1701, 1.16 ± 0.12]; [${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$, 984, 2.30 ± 0.25]; [${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$, 1309, 1.45 ± 0.25]; and [${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$, 1971, 1.40 ± 0.40].

• Received 23 February 1973

DOI:https://doi.org/10.1103/PhysRevC.8.418