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→pnπ+ reaction have been performed at 400 and 450 MeV incident proton energy. The measurements covering an angular range from 460 to 900 (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→dπ+ 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