Neutron production by cosmic-ray muons at shallow depth - art. no. 092005

The yield of neutrons produced by cosmic ray muons at a shallow depth of 32 meters of water equivalent has been measured. The Pale Verde neutrino dete ctor, containing 11.3 tons of Gd loaded liquid scintillator and 3.5 tons of acrylic, served as a target. The rate of one and two neutron captures was determined. Modeling the neutron capture efficiency allowed us to deduce th e total yield of neutrons, Y-tot = (3.60+/-0.09+/-0.31) x 10(-5) neutrons p er muon and g/cm(2). This yield is consistent with previous measurements at similar depths.