Internal Pairs Followingπ−Capture in Hydrogen

Internal electron pairs from the two reactions (1) ${\pi }^{-}+p\to n+{\pi }^0\to n+\gamma +e^{+}+e^{-}$ and (2) ${\pi }^{-}+p\to n+e^{+}+e^{-}$ have been studied in a hydrogen bubble chamber. 2184 cases were seen. A geometrical cutoff selected 1523 of these as suitable for momentum measurement. By an analysis of the momentum spectrum, the Panofsky ratio was measured to be 1.51±0.10. The total intensity, momentum partition within the pairs, and distribution in virtual photon mass are in essential agreement with the theoretical predictions of Kroll and Wada as recently extended by Joseph.