Measurement of np-->pp pi - at 443 MeV.

We have measured the relative differential cross section and spin observables for the reaction np\ensuremath{\rightarrow}pp${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ at 443 MeV. Our measurements have been compared with predictions of the model of Kloet and Lomon. Some of the variables show marked disagreement with predictions; for other variables there is surprisingly good agreement.