By using a pair of large Nal spectrometers in a coincidence configuration we have observed the charge exchange of stopped π⁻ in deuterium π⁻ + d → 2n + π°. We have measured the branching ratio of this reaction [equation omitted] and find R = (1.45 ± 0.19) x 10⁻⁴. This measurement is the first observation of pion charge exchange at rest in deuterium and represents an increase in sensitivity of a factor of 40 over previous measurements. The measured value of R agrees well with the recent theoretical result of Beder(1.39 x 10⁻⁴ ≤ R ≤ 1.59 x 10⁻⁴). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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