Charge Exchange of Stoppedπ−in Deuterium: Experiment and Theory

Abstract

The branching ratio for the reaction ${\pi }^{-}d\to {\pi }^0\mathrm{nn}$ has been measured for the first time by stopping the ${\pi }^{-}$ in a liquid-deuterium target and detecting the two decay $\gamma \text{'}\mathrm{s}$ in two large NaI detectors. A branching ratio $(\mathrm{B}.\mathrm{R}.\mathrm{})=\frac{\omega ({\pi }^{-}d\to {\pi }^{0}nn)}{\omega ({\pi }^{-}d\to \mathrm{all})}$ of (1.45 ± 0.19) × ${10}^{-4\mathrm{}}$ has been measured; the predicted B.R. lies in the range 1.39 × ${10}^{-4\mathrm{}}$ to 1.59 × ${10}^{-4\mathrm{}}$.