Pion-Proton Scattering below 150 Mev. I

Positive-pion proton differential cross sections have been measured at 41.5 Mev for six angles. The angles in the center-of-mass system are 53^∘{}, 69.1^∘{}, 100.4^∘{}, 128^∘{}, 141.7^∘{}, and 163.5^∘{} and the corresponding cross sections in mb/sterad in the center-of-mass system are 0.252±{}0.020, 0.354±{}0.025, 0.777±{}0.038, 1.145±{}0.067, 1.495±{}0.084, and 1.750±{}0.110. Negative pion elastic cross sections have been measured for the first five of the above angles and are, respectively, in mb/sterad in the c.m. system: 0.338±{}0.047, 0.281±{}0.038, 0.148±{}0.029, 0.112±{}0.042, and 0.085±{}0.25. Phase-shift analyses of these data and those of other authors lead to the following expressions for the low-energy behavior of the T=3/2 phases: α₃₁N=-(0.0418±0.004)η³, α₃N=-(0.1145±0.0026)η, and $cot{{{α}}₃₃}N={4/3{{η}}³(0.0877±{}0.0014)}{[{{ω}}*(1{-}{{{ω}}*}{2.17})]}$.