A Monte Carlo study to check muon numbers in hadronic interaction models observed by the Tibet hybrid experiment (YAC-II plus Tibet-III plus MD)

The interpretation of the EAS data relies on the employment of hadronic interaction models, which are subject to theoretical and experimental uncertainties that may hamper composition studies of cosmic rays. To check the reliability of such models at the energies relevant for EAS studies, the predictions of the models can be compared with data from air shower observatories. In this regard, the study of the number of muons becomes extremely useful, since they are sensitive to the hadronic interactions that occur in the early phases of the EAS development. In the paper, we propose a Monte Carlo study to test the number of muons in hadronic interaction models by the hybrid experiment (YAC-II + Tibet-III + MD). For an air-shower event, the Tibet air-shower array (Tibet-III) provides the arrival direction and the air-shower size which are interrelated to primary energy, the Yangbajing Air shower Core detector (YAC-II) array measures the high energy electromagnetic particles in the very forward region so as to obtain the characteristic parameters of air-shower cores, at the same time, the underground MDs record the number of high-energy muons above 1 GeV. Since we can select proton events with high accuracy by YAC-II almost independently of the hadronic interaction models, the accompanying number of muons induced by proton events can be fed out. With the unique settle of YAC-II, our results show that the description of muon numbers in different hadronic interaction models can be well systematics-checked to avoid the ambiguity of the primary cosmic-ray mass composition around the knee energy region by the Tibet hybrid experiment (YAC-II + Tibet-III + MD).