Evolution of the cosmic ray anisotropy above 1014 eV
Abstract
The amplitude and phase of the cosmic ray anisotropy are well established experimentally between 1011 eV and 1014 eV. The study of their evolution into the energy region 1014-1016 eV can provide a significant tool for the understanding of the steepening ("knee") of the primary spectrum. In this letter we extend the EAS-TOP measurement performed at E0 around 1014 eV, to higher energies by using the full data set (8 years of data taking). Results derived at about 1014 and 4x1014 eV are compared and discussed. Hints of increasing amplitude and change of phase above 1014 eV are reported. The significance of the observation for the understanding of cosmic ray propagation is discussed.
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