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 $$1~\hbox {m}^{2}$$ 1m2 and covers all azimuth angles, and zenith angles up to $$80^{\circ }$$ 80∘ . The measured integrated muon flux is $$(5.26 \pm 0.21) \times 10^{-3}~\hbox {m}^{-2}\hbox {s}^{-1}$$ (5.26±0.21)×10-3m-2s-1 in the Hall A of the LAB2400 and $$(4.29 \,\pm \, 0.17) \times 10^{-3}~\hbox {m}^{-2}\hbox {s}^{-1}$$ (4.29±0.17)×10-3m-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.