Expectation on probing the origin of the cosmic ray knee with the LHAASO experiment

Abstract

The cosmic-ray (CR) knee and the compositions contain abundant information for probing the CR's origin, acceleration and propagation mechanisms, as well as the frontier of the fundamental physics. Realizing that major proposals toward the knee's shape can be divided into two categories: the rigidity-dependent (also Z-dependent) knee and the mass-dependent (also A-dependent) knee, where the former one relates to the acceleration or the propagation mechanisms and the other one is often associated with the new physics; it is essential to precisely measure the individual compositions. Benefiting from the high altitude and hybrid detection methods, the LHAASO experiment has the ability to determine the individual component and brings us an opportunity in discriminating these two models. We test this expected ability of LHAASO from 100 TeV to 10 PeV with 3-year observation. As a result, these models can be discriminated when the knee is dominated by the CR component equal or heavier than the helium under LHAASO's first operation mode. In this paper, the hypothesis test method is utilized to evaluate the ability of the LHAASO experiment to discriminate different knee models. It is manifested viable with enough observing duration.