Polarization measurements in the pp → pnπ+ and pp → ppπ0 reactions at 517 and 580 MeV

The transverse polarization of the outgoing proton in the pp → pnπ+ and pp → ppπ) reactions was investigated for the first time. The measurements were performed at SIN (now PSI) at 517 and 580 MeV on the pM1 polarized proton beam line with an average beam polarization higher than 82%, using a liquid hydrogen target. A carbon polarimeter spin‐analyzed the scattered proton, 3 MWPC’s tracked the recoil charged particle and a 3.84 m2 neutron detector identified the neutral particle and measured TOF’s.The kinematics of each event was determined by a least square fit method. On and off‐line cuts reduced the total background of this preliminary analysis to less than 2% for pp → pnπ+ and less than 12% for pp → ppπ0.A new set of kinematical variables is proposed that allows a reduction of phase space dimensions without loss of information. Comparison with available theoretical predictions is made.