Massive Nuclei in the Cosmic Radiation

Abstract

The most energetic nuclei in the contemporary universe are to be found in the Cosmic Radiation. The paper starts with comments about low energy nuclei but goes on to discuss the situation in the ‘knee’ of the cosmic ray spectrum at ∼ 3·10¹⁵ eV. This is followed by an examination of the evidence for ’heavy’ nuclei (probably iron) in the Galactic component, at higher energies, extending to somewhat above 10¹⁸ eV. Finally, the enigmatic extragalactic particles are considered, these particles being presumed to be mainly confined to energies above about 10¹⁹ eV. Arguments advanced by Wibig and Wolfendale [1] which claim evidence for heavy nuclei here, too, will be considered.