ABSTRACT

The Earth is steadily bombarded by high-energy electrons, photons (γ-rays,) protons and nuclei. For energies above a few GeV, these particles originate from outside the solar system; they are `COSMIC RAYS'. (The energy unit used here is the ELECTRON VOLT (eV), or the giga electron volt (GeV): 1 eV=1.60×10−19 J