摘要
The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment.One of the main goals is to determine the neutrino mass ordering by precisely measuring the energy spectrum of reactor antineutrinos.For the detection of reactor antineutrinos,cosmogenic backgrounds,such as^(9)Li/^(8)He and fast neutrons induced by cosmic muons,should be rejected carefully by applying muon veto cuts,which require good muon track reconstruction.With a 20-kton liquid scintillator detector,the simulation shows the proportion of muon bundles(muon multiplicity≥2)to be approximately 8%in JUNO,whereas its reconstruction has been rarely discussed in previous experiments.This study proposes an efficient algorithm for muon track reconstruction based on the charge response of a photomultiplier tube array.This is the first reconstruction of muon bundles in a large-volume liquid scintillator detector.In addition,the algorithm shows good performance and potential for reconstruction for both a single muon and double muons(muon multiplicity=2).The spatial resolution of a single-muon reconstruction was20 cm,and the angular resolution was 0.5°.For doublemuon reconstruction,the spatial and angular resolutions could be 30 cm and 1.0°,respectively.Moreover,this paper also discusses muon classification and the veto strategy.
基金
supported by the National Natural Science Foundation of China(Nos.12005044 and 11975258)
the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDA10011200 and XDA10010900)。
