The complex EAS hybrid arrays in Tibet

The Tibet hybrid experiment is an extensive air shower experiment that operated at Yangbajing (E90°31', N30°06'; 4300 m above sea level) in Tibet, China, since 1996. This multi-detector system is used to observe air showers of high energy celestial gamma-ray origin and that of nuclear-component origin. Both observations aim to investigate the origin of cosmic rays using different methods. In this paper, based on the energy spectrum of the nuclear component and its chemical composition around the knee, we would like to discuss whether they could be described by the theoretical picture of the diffusive shock acceleration at SNRs. The consistency of the experimental data with rigidity dependent cutoff spectrum of CRs is examined using Tibet data and KASCADE data. It is found that both experimental data cannot be fully interpreted by such a simple approach. The sharp knee observed by Tibet experiment suggests the contribution of nearby source(s).