Chinese Physics C ( IF 3.6 ) Pub Date : 2021-01-29 , DOI: 10.1088/1674-1137/abccae Zi-yi Guo 1, 2 , Lars Bathe-Peters 1, 3 , Shao-min Chen 1, 2, 4 , Mourad Chouaki 1, 5 , Wei Dou 1, 2 , Lei Guo 1, 2 , Ghulam Hussain 1, 2 , Jin-jing Li 1, 2 , Qian Liu 6 , Guang Luo 7 , Wen-tai Luo 6 , Ming Qi 8 , Wen-hui Shao 1, 2 , Jian Tang 7 , Lin-yan Wan 1, 2 , Zhe Wang 1, 2, 4 , Ben-da Xu 1, 2, 4 , Tong Xu 1, 2 , Wei-ran Xu 1, 2 , Yu-zi Yang 1, 2 , Minfang Yeh 9 , Lin Zhao 1, 2
China Jinping Underground Laboratory (CJPL) is ideal for studying solar, geo-, and supernova neutrinos. A precise measurement of the cosmic-ray background is essential in proceeding with R&D research for these MeV-scale neutrino experiments. Using a 1-ton prototype detector for the Jinping Neutrino Experiment (JNE), we detected 264 high-energy muon events from a 645.2-day dataset from the first phase of CJPL (CJPL-I), reconstructed their directions, and measured the cosmic-ray muon flux to be cm s . The observed angular distributions indicate the leakage of cosmic-ray muon background and agree with simulation data accounting for Jinping mountain's terrain. A survey of muon fluxes at different laboratory locations, considering both those situated under mountains and those down mine shafts, indicates that the flux at the former is generally a factor of larger than at the latter, with the same vertical overburden. This study provides a convenient back-of-the-envelope estimation for the muon flux of an underground experiment.