The cosmic-ray anisotropy and the relative fluxes of heavy nuclei and protons in high-energy cosmic radiation

Abstract

New results on cosmic-ray anisotropies from the Akeno extensive air shower array by Kifune et al. (ibid., vol.12, p.129, 1986) are analysed from the standpoint of the information that can be gained about the relative fluxes of heavy nuclei and all particles above an energy of 1015 eV/nucleus. Heavy nuclei are selected by virtue of their ensuing 'muon-rich' showers and a comparison of the amplitude and phase anisotropy of these showers (more specifically, the data for both first and second harmonics) with the same quantities for the showers in general allows the heavy-nucleus fraction to be determined. The authors find that the fraction varies from approximately 10% at 1015 eV to approximately 3% at 1017 eV. An interesting feature of the analysis is that it demonstrates that the sources of protons and heavy nuclei at energies above 1013 eV/nucleus or so must be radically different. The method described should have even more value when anisotropy results of higher precision are available.