Probing Cosmic Ray Composition and Muon-philic Dark Matter via Muon Tomography

Abstract: This work presents a novel cosmic-ray scattering experiment employing a Resistive Plate Chambers (RPC) muon tomography system. By introducing the scattering angle between incident and outgoing cosmic-ray tracks as a key observable, this approach enables simultaneous studies of secondary cosmic-ray composition and searching for new physics. During a 63-day campaign, 1.18 million cosmic ray scattering events were recorded and analyzed. By performing combined template fits to the observed angular distribution, particle abundances are measured, for example, resolving the electron component at $\sim 2\%$ precision. Furthermore, constraints are established on elastic muon-dark matter (DM) scattering cross-sections for muon-philic dark matter. At the 95\% confidence level, the limit reaches 1.62 $\times$ $10^{-17}$ $\rm{cm}^{2}$ for 1 GeV slow DM, demonstrating sensitivity limit to light muon-coupled slow DM.