# Cosmic-ray muon flux at Canfranc Underground Laboratory

## TL;DR

This study measures the residual flux and angular distribution of high-energy cosmic muons in two underground locations at the Canfranc Laboratory, providing detailed flux values and directional information relevant for underground physics experiments.

## Contribution

It introduces a dedicated Muon Monitor with high angular coverage and provides new measurements of muon flux and angular distribution at Canfranc Underground Laboratory.

## Key findings

- Measured muon flux in two underground locations: 5.26e-3 and 4.29e-3 m$^{-2}$s$^{-1}$.
- Angular distribution aligns with known mountain profiles and rock density.
- Clear flux maximum observed from the Rioseta valley direction.

## Abstract

Residual flux and angular distribution of high-energy cosmic muons have been measured in two underground locations at the Canfranc Underground Laboratory (LSC) using a dedicated Muon Monitor. The instrument consists of three layers of fast scintillation detector modules operating as 352 independent pixels. The monitor has flux-defining area of 1 m${}^{2}$, covers all azimuth angles, and zenith angles up to $80^\circ$. The measured integrated muon flux is $(5.26 \pm 0.21) \times 10^{-3}$ m${}^{-2}$s${}^{-1}$ in the Hall A of the LAB2400 and $(4.29 \pm 0.17) \times 10^{-3}$ m${}^{-2}$s${}^{-1}$ in LAB2500. The angular dependence is consistent with the known profile and rock density of the surrounding mountains. In particular, there is a clear maximum in the flux coming from the direction of the Rioseta valley.