Scattering of 10-30 Mev Negative Pions by Hydrogen

Fifty-seven π^--p scattering events in the energy range 10-30 Mev have been observed in a hydrogen bubble chamber. The S-wave scattering length 1/3η^-1(2α₁+α₃)=0.077±0.011 is found to give the best fit to the data assuming α₁₃=α₃₁=α₁₁=0, α₃₃=0.235η³. This result is combined with the results of other low-energy scattering experiments to give estimates of α₁ and α₃.