Measurement of differential cross sections for radiative pion-proton capture in the second resonance region

Abstract

Differential cross-section measurements for π −p → γn, consisting of three angular distributions at 618, 676 and 718 MeV/ c, and the energy dependence at θ γ = 90° for seven incident pion momenta between 502 and 888 MeV/ c, are presented. Our data qualitatively support recent multipole analyses. Agreement with the Scheffler et al. results for the inverse reaction, γn → π −p, using a ( π −-recoil p) coincidence technique is good excluding a large violation of time reversal invariance. The agreement with γn → π −p data obtained using the R( π −/ π +) ratio technique or a deuterium bubble chamber is only qualitative.