Measurements of cross sections and analyzing powers for the inclusive pp→pnπ+reaction at 400 and 450 MeV

Single arm spectrometer measurements of the differential cross sections and analyzing powers of the pp→pn${\pi }^{+}$ reaction have been performed at 400 and 450 MeV incident proton energy. The measurements covering an angular range from 46° to 90° (lab) spanned pion energies corresponding to production of the np system with relative energies between 0 and 30 MeV, a region where the influence of the np final state interaction is particularly important. The trend of the measured analyzing power is very similar to that of the pp→d${\pi }^{+}$ reaction, and is well explained by calculations that use this latter data as input. Dominance of the triplet pn final state is implied by these results.