π−−pInteractions in the 1.0-Bev Region

Abstract

We have examined 450 ${\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{-}p$ collisions of energy about 1 Bev. About one-third of these have been found in emulsion and the the rest in the Brookhaven hydrogen diffusion chamber. About one-half of the total cross section at this energy comes from elastic processes. The differential elastic cross section is characterized by a sharp peak in the forward direction and considerable bump in the backward hemisphere. We believe we have demonstrated that a considerable portion of the elastic cross section is produced by refraction rather than diffraction. The target radius of the nucleon at this energy seems to be \ensuremath{\ge}1.1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}13}$ cm which is essentially the same result that has been found at 1.4-1.5 Bev. The inelastic processes seem to exhibit somewhat different features at this energy from those at 1.5 Bev. The angular distributions of all products are almost isotropic. The nucleons seem to slightly prefer the backward hemisphere but not to nearly the same degree as found at 1.5 Bev. The ${\ensuremath{\pi}}^{\ensuremath{-}}$ seem to lose most of their energy in the inelastic processes and this too is somewhat different from the 1.5-Bev results. The momentum change spectrum for the nucleons is nearly the same at 1.0 and 1.5 Bev.These results are discussed in terms of the Dyson-Takeda model which introduces a pion-pion interaction. We also discuss possible isobar formation.