Measurement of Muon-induced Neutron Production at China Jinping Underground Laboratory

Abstract

Solar-, geo-, and supernova neutrino experiments are subject to muon-induced radioactive background. China Jinping Underground Laboratory (CJPL), with its unique advantage of 2400 m rock coverage and distance from nuclear power plants, is ideal for MeV-scale neutrino experiments. Using a 1-ton prototype detector of the Jinping Neutrino Experiment (JNE), we detected 343 high-energy cosmic-ray muons and (6.24±3.66) muon-induced neutrons from an 820.28-day dataset at the first phase of CJPL (CJPL-I). Based on the muon induced neutrons, we measured the corresponding neutron yield in liquid scintillator to be (3.13±1.84stat. ±0.70syst.)×10 −4 µ −1 g −1 cm 2 at an average muon energy of 340 GeV. This study provides the first measurement for this kind of neutron background at CJPL. A global fit including this measurement shows a power-law coefficient of (0.75±0.02) for the dependence of the neutron yield at liquid scintillator on muon energy.

Structural design of the acrylic vessel for the Jinping Neutrino Experiment

“…The CJPL has emerged as the deepest underground laboratory in the world and has a vertical rock cover of roughly 2400 m (figure 1). Several relevant studies [17][18][19] have been conducted to ensure that the environmental background fulfills the needs of the Jinping solar neutrino experiment.…”