Measurement of cosmic-ray muons and muon-induced neutrons in the Aberdeen Tunnel Underground Laboratory

We have measured the muon flux and production rate of muon-induced neutrons at a depth of 611 m water equivalent. Our apparatus comprises three layers of crossed plastic scintillator hodoscopes for tracking the incident cosmic-ray muons and 760 L of a gadolinium-doped liquid scintillator for producing and detecting neutrons. The vertical muon intensity was measured to be I_μ=(5.7 ±0.6 )×10^-6 cm^-2 s^-1 sr^-1 . The yield of muon-induced neutrons in the liquid scintillator was determined to be Y_n=(1.19 ±0.08 (stat)±0.21 (syst))×10^-4 neutrons /(μ .g .cm^-2 ) . A fit to the recently measured neutron yields at different depths gave a mean muon energy dependence of ⟨E^{_μ⟩ 0.76 ±0.03} for liquid-scintillator targets.