Observation of structure in the annihilation reactions (anti p)n → pions

A measurement of the ratio R=sigma((anti p)n→π-π-π+) / sigma((anti p)n→π-π-π+π0) is presented. It was determined using data from deuterium-filled bubble chambers exposed to low energy anti-proton beams. Strong evidence is presented for the observation of the S-meson in the reaction (anti p)n→3π. A partial wave analysis of this reaction also indicates more tentative evidence for a higher mass state