Nucleus-nucleus collisions produced in nuclear emulsions by heavy cosmic ray primaries have been analysed. The kinetic energy of the incident nuclei are larger than 100 MeV/nucleon. The angular and energy distributions of protons with energies <10 MeV and alpha-particles with energies <200 MeV have been studied. Low energy protons and alpha-particles are emitted isotropically in a system moving with a mean velocity component in the forward direction of 0.02 c. It is found that there is an excess of low energy protons which cannot be explained without using extremely low values of the Coulomb barrier. It is also found that evaporation theory cannot account for all the alpha-particles. In high energy nucleus-nucleus interactions alpha-particles are produced partly by emission from disintegrating fragments and partly by a knock-on process in which quasi-elastic collisions between nucleons and alpha-clusters take place. This last statement is supported by the fact that alpha-particles are emitted with high momentum components in the forward as well as in the transverse direction.

vestigation show that also nucleus-nucleus interactions in the hundreds of MeV regions can be looked upon as a superposition approximation. In that paper we have also shown that heliumInteractions between nuclei at 100-500 MeVlnucleon. R. Resman and I. Otterlund (