Forward-angle cross sections for pion-nucleon charge exchange between 100 and 150 MeV/c

Abstract

The differential cross sections for the πN charge-exchange reaction, ${\pi }^{\mathrm{-}}$p→${\pi }^0$n, have been measured in an angular range corresponding to 0.99≥cos${\mathrm{theta}}_{\mathrm{c}.\mathrm{m}.\mathrm{}\ge 0.90}$ at 100.6, 106.7, 113.4, 125.2, 130.9, 136.4, and 147.1 MeV/c. A striking feature of the charge-exchange reaction at forward angles is the presence of a deep minimum near 120 MeV/c, caused by interference between s- and p-wave scattering. The parameters of this minimum, of interest both intrinsically and for applications to π-nucleus single- and double-charge-exchange reactions, are well determined by the measurements. Our data are compared with the results of existing partial-wave analyses, and the data are discussed in terms of the isospin-odd, s-wave scattering length, $a_1$-$a_3$.