Near-threshold production of $\omega$-mesons in the $pn\rightarrow d\omega$ reaction

Abstract.The first measurement of the $pn\rightarrow d\omega$ total cross-section has been achieved at mean excess energies $Q\approx 28$ and 57 MeV by using a deuterium cluster-jet target. The momentum of the fast deuteron was measured in the ANKE spectrometer at COSY-Jülich and that of the slow “spectator” proton $(p_{\rm {sp}})$ from the $pd\rightarrow p_{\rm {sp}}d\omega$ reaction in a silicon telescope placed close to the target. The cross-sections lie above those measured for $pp\rightarrow pp\omega$ but seem to be below theoretical predictions.