NEW ESTIMATION OF THE SPECTRAL INDEX OF HIGH-ENERGY COSMIC RAYS AS DETERMINED BY THE COMPTON-GETTING ANISOTROPY

摘要

The amplitude of the Compton-Getting (CG) anisotropy contains the power-law index of the cosmic-ray energy spectrum. Based on this relation and using the Tibet air shower array data, we measure the cosmic-ray spectral index to be -3.03 ±0.55_(stat) ±< 0.62_(syst), between 6 and 40 TeV, consistent with - 2.7 from direct energy spectrum measurements. Potentially, this CG anisotropy analysis can be utilized to confirm the astrophysical origin of the "knee" against models for nonstandard hadronic interactions in the atmosphere.