Mean Life of theπ0Meson

An estimate of the ${\pi }^0$ mean lifetime has been obtained from a sample of 232 $K_{\pi 2}^{}{}_{}{}^{+}(K^{+}\to {\pi }^{+}+{\pi }^0)$ decays at rest. The ${\pi }^0$'s were detected by the Dalitz mode (${\pi }^0\to e^{+}+e^{-}+\gamma$), and the decay distances from the $K^{+}$ ending to the ${\pi }^0$ decay points were measured. These events were found in an area scanning of an emulsion stack of 600-μm Ilford $G5\mathrm{}$ emulsion pellicles exposed to a 400 $\frac{\mathrm{MeV}}{c}$ separated $K^{+}$ beam. The observed mean ${\pi }^0$ lifetime is (1.0±0.5)×${10}^{-16\mathrm{}}$ sec.