The lifetime of the 1.04 MeV ($J^{\pi }=0^{+}$, $T=1\mathrm{}$) state in ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ has been measured to be ${2.7}_{-0.4\mathrm{}}^{+0.6\mathrm{}}$ fs using the Doppler shift attenuation method through the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}(p, n){}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ reaction. An ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ target implanted into Ta was used in the measurement. Experimental correction factors for the nuclear and electronic stopping powers were used in the deduction of the lifetime. Based on the revised lifetime, the predicted circular polarization $P_{\gamma }\left(1.08\mathrm{} \mathrm{MeV}\right)$ of the transition 1.08 MeV ($0^{-}$,0) → 0 MeV ($1^{+}$,0) is related to the parity nonconserving matrix element $〈1.04(0^{+}, 1)\left|V^{\mathrm{PNC}}\right|1.08(0^{-}, 0)〉$ by $P_{\gamma }\left(1.08\mathrm{} \mathrm{MeV}\right)=\pm \left({5.8}_{-0.7\mathrm{}}^{+0.5\mathrm{}}\right)\times {10}^{13} \mathrm{Me}{\mathrm{V}}^{-1\mathrm{}}〈1.04(0^{+}, 1)\left|V^{\mathrm{PNC}}\right|1.08(0^{-}, 0)〉$.

NUCLEAR REACTIONS ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}(p, n){}_{}{}^{18}{}_{}{}^{}\mathrm{F}$, $E=3.75\mathrm{}$ MeV; measured Doppler-shift attenuation, ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ 1042-keV level; deduced ${\tau }_m$. Implanted target.

• Received 17 March 1980

DOI:https://doi.org/10.1103/PhysRevC.22.351