On the Relevance of EAS Muons Study

Atmospheric muons are studied many years since their discovery. Due to short lifetime muons are absent in primary cosmic rays being a part of EAS (Extensive Air Showers). They are as a rule recorded by special muon detectors of the EAS arrays. In addition, people used muon magnetic spectrometers, muon hodoscopes and muon pair-meters to measure muon fluxes and their energy. In spite of long history of atmospheric muon study, there remain some problems. Last year we proposed to use existing WCDA (Water Cherenkov Detector Array being a part of LHAASO) as a pair-meter to measure near-horizontal atmospheric muon energy spectrum. As shown, the pair-meter method proposed many years ago is the best way to solve the above problem. We show that WCDA without any reconstruction can serve as a huge area pair-meter to study near-horizontal atmospheric muons with energy beyond $${\sim}$$ 10 TeV.