Total Cross Section of Hydrogen for 143- to 205-Mev Positive Pions

Abstract

Using counter techniques, a higher-precision determination of the pi / sup +/ + p total cross section in the neighborhood of the T = J = 3/2 resonance was made. The energy width, statistical errors, and absolute errors were considerably reduced in an extension of our previously reported work. The eight total cross sections which were determined in the pion kinetic-energy range of 143 to 205 Mev are compared to other earlier work and their theoretical interpretation is discussed. (auth) In order to obtain a production spectrum of mesons in the center-of-mass system, three high-energy nuclear collisions were selected which satisfy very stringent criteria for nucleon-nucleon collisions and for which the momenta of all charged particles could be measured in the laboratory system. The results show that more than one-half of the mesons have energies less than 1 Bev in the center-of-mass system. Only a few particles emitted under very small angles in the forward and backward direction have higher energies, extending up to 10 Bev. The low-energy end of the spectrum is compared with results obtained in experiments with the Berkeley Bevatron. (auth)