Studies on Muon Veto in the JUNO Liquid Scintillator Neutrino Detector

Abstract

The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid scintillator detector currently under construction near Kaiping, China. It is located 650 m underground with a baseline of 53 km to two nuclear power plants. The reactor neutrinos are measured via inverse beta decay in order to determine the neutrino mass hierarchy. Muons that cross the detector create a correlated background for this measurement. A set of sub-detectors and sophisticated reconstruction algorithms are presented to achieve an efficient veto of cosmogenic backgrounds while keeping a high exposure. On a sample of through-going muons with the expected mean energy of 215 GeV a spatial bias of less than 10 cm and an angular bias better than 0.5 ° can be reached. There is only 1% additional loss in exposure compared to a perfect tracking.