Study of the reactions π+p→π+pπ0π0 and π+p→π+pπ0π0π0 at 3.5 GeV

The reactions π+p→π+pnπ0(n=2,3) are studied at 3.5 GeV/c, with 940 and 143 events, respectively. Complete final states are recorded and measured in a heavy liquid bubble chamber. The cross sections: sigma(π+p→π+p2π0)=1300+-210μb, sigma(π+p→π+p3π0)=320+-70μb, are found, below the values predicted by statistical models from charged pion data. The mass spectra are given and channel suparations are performed using Van Hove variables. The results are in agreement with charged pion experiments. A description of the 3π0 system, with 61 events is presented. Under certain hypotheses a spin-parity analysis favours 0- at low mass and 1- at high mass. (Auth.)