The half-lives of ${}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$ and ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ have been measured by multiscaling $\beta$ rays detected in a plastic scintillator. ${}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$ was formed in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^3{}_{}{}^{}\mathrm{He}, n){}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$ reaction at $E_{{}_{}{}^3{}_{}{}^{}\mathrm{He}}=5.7\mathrm{}$ MeV using a ${\mathrm{Ta}}_2$ ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}_5^{}{}_{}{}^{}$ target depleted in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$. ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ was produced in the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(d, p){}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ reaction with 2.0-MeV deuterons on a Ba${\mathrm{F}}_2$ target. Half-life values of 1.669±0.004 sec for ${}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$ and 10.996±0.020 sec for ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ were obtained. Using the present and other recent results the $A=18\mathrm{}$ $\beta$ decay mirror asymmetry is found to be -0.86±0.80%.

RADIOACTIVITY ${}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$: measured $T_{\frac{1}{2}}$; deduced $\beta$ decay mirror asymmetry.

• Received 9 July 1975

DOI:https://doi.org/10.1103/PhysRevC.12.1690