Measurement of π−p → π0π0n at 6, 8 and 12 GeV/c

All γ's and the neutron from the reaction π − p → π 0 π 0 n are detected. The magnitude of the π 0 π 0 S-wave and the cosine of its phase angle (relative to the known D-wave) are determined. The I = 0 amplitude, S 0 , is near the unitarity limit in the range 600 to 900 MeV and again around 1200 MeV.