Cosmogenic Neutron Production at Daya Bay

Abstract

Spallation neutron from cosmic-ray muon is an important background for underground experiments, such as neutrino oscillation study, dark matter search, and neutrinoless double beta decay search. The neutron yield measurement results at Daya Bay were $Y_n=(10.26\pm0.86)\times10^{-5}$, $(10.22\pm0.87)\times10^{-5}$, and $(17.03\pm1.22)\times10^{-5}\mu^{-1}{g}^{-1}{cm}^2$ at depths of 250, 265, and 860 meters-water-equivalent of the three experimental halls, respectively. The yield results were compared with other experiments as well as the simulated yield in FLUKA and GEANT4. A power law coefficient of $0.77\pm0.03$ was obtained by fitting the dependence of the neutron yield on muon energy。