Elastic scattering of positive pions onO16at 40.0 and 49.7 MeV

Differential cross sections for elastic scattering of positive pions on ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ at 40.0 and 49.7 MeV were measured at about 10° intervals for laboratory angles from 25° to 160°. Relative uncertainties between angles are 3%, with the overall normalization known to 7% for each angular distribution. The angular distributions are similar in shape, being dominated by a minimum at about 60°. The differential cross sections are presented along with the results of a partial wave analysis which gives good fits at both 40.0 and 49.7 MeV. The data are also fitted by a simple phenomenological first-order Kisslinger nonlocal optical model calculation.