Cosmic-ray muon flux at Canfranc Underground Laboratory

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 a flux-defining area of 1 m2 and covers all azimuth angles, and zenith angles up to 80∘ . The measured integrated muon flux is (5.26±0.21)×10−3 m−2s−1 in the Hall A of the LAB2400 and (4.29±0.17)×10−3 m−2s−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.