Abstract
The interactions of 20 to 300 Mev mesons on free protons and on emulsion nuclei have been studied and their decays analyzed. The -meson mean lifetime is found to be (1.38±0.24)× sec. Examples of the decay modes , , , , and are identified. The branching ratios are found to be in agreement with those for mesons. The () elastic scattering cross section is found to be 35±16 mb and the () cross section 27±13 mb in the energy region of 150 to 300 Mev. The mean free path for -meson captures and inelastic scatters on emulsion nuclei, except hydrogen, can be represented by , where is the laboratory -meson kinetic energy, for -meson energies from 20 to 300 Mev. This increase in the mean free path with -meson energy is explained in terms of the decreasing nucleon cross section. The fraction of the interactions of mesons on nuclei which are inelastic scatters increases from 2% at low -meson energies to about 15% at 150 Mev. This increase in inelastic scattering with energy is additional evidence that the nucleus is becoming partially transparent to mesons at about 150 Mev. Data are presented for the fraction of events with observed mesons, hyperons, and meson- hyperon pairs. The data are discussed in terms of the model which was previously presented to explain meson captures at rest on nucleons bound in nuclei.
- Received 20 October 1959
DOI:https://doi.org/10.1103/PhysRev.118.564
©1960 American Physical Society