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

TL;DR

This paper introduces a muon tomography experiment using RPC detectors to analyze cosmic-ray composition and search for muon-philic dark matter, achieving precise particle measurements and setting new constraints on dark matter interactions.

Contribution

It presents a novel muon scattering technique with detailed analysis, providing new insights into cosmic-ray composition and dark matter constraints.

Findings

Resolved electron component at ~2% precision.

Recorded 1.18 million cosmic-ray scattering events in 63 days.

Set upper limits on muon-philic dark matter cross-sections at 95% confidence.

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 1.61 $\times$ $10^{-17}$ $\rm{cm}^{2}$ for 1 GeV slow DM, demonstrating sensitivity limit to light muon-coupled slow DM, in scenarios where a strongly interacting dark matter component is captured and thermalized within the Earth, leading to large surface densities.