Origin of Cosmic Rays

Abstract

ALTHOUGH cosmic rays have been known for more than forty years, their origin has not been satisfactorily elucidated. At present, it is believed that primary cosmic rays comprise nuclei of heavy elements ≈1 per cent apart from protons and α-particles. The presence of cosmically rare elements, for example, lithium, beryllium and boron in cosmic rays is of considerable importance for any theory of their origin. The other characteristic of cosmic rays is the energy spectrum which is of the form: where I is the intensity of a given kind of particles and E is the total energy of a proton or nucleon. Here γ varies between 1.9 and 3.0, depending on the energy range. Their energy lies between 5 × 10⁸ and 10¹⁸ eV. They also show in general the isotropy. The small anisotropy is, however, generated by the local sources and the local magnetic fields.