Pion Production in Nucleon-Nucleon Collisions

Measurements of the pp → ppπ⁰ reaction at 310, 320, 340, 360, 400 and 425 MeV, and quasi-free pn → ppπ^- production in pd collisions at 320 MeV have been carried out at the PROMICE/WASA facility at CELSIUS. The pp → ppπ⁰ differential cross sections have been parametrised and used to deduce the poorly known σ₀₁ total cross section through the relation: σ₀₁ = 2σ(pn → ppπ^-) - σ(pp → ppπ⁰). Preliminary results show the σ₀₁ and σ₁₁ to be of comparable size for centre-of-mass energies between 8 and 40 MeV.