The energy spectrum of primary cosmic rays above 10¹²eV

Abstract

Recent direct experimental measurements of the primary proton spectrum have given a power law with differential slope gamma d approximately -2.75 for energy less than about 1012 eV. Extrapolation of this spectrum gives intensities of the order of those derived from extensive air showers in the region of 1018-1019 eV. The data from a variety of experiments which had previously indicated intensities significantly above this spectrum, particularly in the range 1014-1016 eV, are re-examined critically. It is concluded that the intensities are indeed higher and that a single exponent is quite inadequate to describe the spectral range 1010-1020 eV.