Measurement of low-energy elasticπ±pdifferential cross sections

Abstract

We have measured differential cross sections for both ${\pi }^{+}p$ and ${\pi }^{-}p$ elastic scattering at incident-pion kinetic energies of 30, 50, 70, and 90 MeV in the center-of-mass angular range between 50° and 150°. The experiment detected pions scattered from a liquid-hydrogen target with multiwire proportional chambers and scintillation-counter range telescopes. The relative accuracy of each angular distribution is better than 5%, while the absolute cross sections have uncertainties of 4% to 25%. Our results for the absolute cross section for ${\pi }^{+}p$ scattering at 30 and 90 MeV are inconsistent with previous measurements. Our ${\pi }^{-}p$ measurements comprise the first extensive set of precision differential cross sections below 90 MeV.