The nuclear interactions of cosmic rays

This report deals with the types of nuclear interaction, the properties of nuclear-interacting particles, and the correlation of nuclear events in the atmosphere and in condensed matter. The empirical data for evaporation stars are collected and it is shown that the statistical theory of the nucleus can account for much of the data. The methods of investigating meson showers are outlined and the principal results given. Recent work on the new heavy unstable particles is included in this section. An account is then given of the nuclear interaction of non-nucleonic particles, i.e. electrons, photons, μ-mesons and π-mesons. In the next section experiments which give information about the interactions of nucleons in the atmosphere and in condensed matter are discussed. The meaning of interaction mean free path and attenuation length is brought out. Finally, the nucleonic components in the atmosphere and their correlation are discussed in detail. It is shown that the formation of stars of various types in the atmosphere, and the equilibrium of the various components in the lower reaches of the atmosphere, can be understood on the picture of nucleon cascades which start at the top of the atmosphere and end with the formation of slow neutrons and protons. The report concludes with a discussion of some of the main problems to be solved in this field of research.