Scattering of 217-Mev Positive Pions on Hydrogen

The total and differential cross section for the scattering of 217-Mev positive pions on hydrogen has been measured in nuclear emulsions. The total cross section, excepting Coulomb scattering, was found to be (151.0±{}18.2) mb. The angular distribution in the center of mass was fitted by ${d{σ}}{d{Ω}}=(5.22±{}1.42)+(7.53±{}2.57)cos{χ}+(20.36±{}4.61){cos}²{χ}$ mb/steradian, assuming $S$ and $P$ waves only. A phase shift analysis was carried out using the method of maximum likelihood. The phase-shift solution in agreement with the requirements of causality and corresponding to the preferred solution of de Hoffman et al. was α₃=-22.5^∘±5.8^∘, α₃₃=114.0^∘±7.4^∘, and α₃₁=-11.6^∘±9.7^∘. The angular distribution showed strong forward scattering and a perference for positive Coulomb interference, in agreement with the hypothesis of a resonance in the state with angular momentum 3/2 and isotopic spin 3/2.