Energy spectrum of cosmic ray primaries at super high energies estimated from the recent balloon-borne calorimeter measurements

Abstract

The energy spectrum of primary cosmic ray particles has been estimated from the analysis of the chemical composition data of high energy cosmic rays, data obtained by the Japanese American cooperative emulsion experiments for proton and helium intensities and the Goddard Space Flight Centre measurements for cosmic ray nuclei. The results indicate no drastic change in abundance ratios at high energies. The elemental fluxes have been calculated by assuming that the primary cosmic ray nuclei break up into their constituent nucleons near the top of the atmosphere. The calculated total primary spectrum in the range 2–300 TeV follows the form N(E) dE = 2.24 × 104 E−2.7 dE where E is the energy expressed in GeV/nucleon and N(E) is the intensity expressed in (m2∙s∙sr∙GeV/nucleon) −1.Using this primary spectrum as the source of nucleons near the top of the atmosphere, the sea level proton and neutron spectra have been estimated by using the Feynman scaling hypothesis and the conventional nucleon-atmospheric diffusion equation. The derived spectra are in accord with the measured proton and neutron spectra of Brooke and Wolfendale, Ashton and Coates, and Ashton et al.