Speaker
Description
The seasonal variation of single muons is a well-understood phenomenon, mainly driven by a positive correlation with atmospheric temperature fluctuations. However, the rate of multi-muon events measured by several experiments has revealed an opposite seasonal modulation in multi-muon events, which remains unexplained by any previous studies using CORSIKA simulations. For the first time, we quantitatively describe the phase and amplitudes of the seasonal variation for cosmic multi-muon events detected by the NO$\nu$A Near Detector. We can further explain the amplitude dependence for multi-muon events across various multiplicities. To address this, we use the general-purpose Monte Carlo code FLUKA-CERN 4.4.1, which provides a more realistic description of the detector, atmospheric profiles, and muon propagation underground. Finally, we compare our results with those obtained from the latest CORSIKA version 7.8000, utilizing the most up-to-date high-energy hadronic interaction models Sibyll 2.3e, QGSJETIII-01, and EPOS LHC-R. Our findings provide a fresh perspective on seasonal muon flux modulation and offer key constraints for cosmic-ray interaction models and underground detector studies.
