Studies of muon track reconstruction based on timing and charge in Water Cherenkov Detector

[Background]The reconstruction of cosmic ray tracks is highly important in large neutrino detectors. Precise track reconstruction can effectively eliminate isotopic backgrounds around the tracks without requiring anti-coincidence measures across the entire detector. The muon reconstruction in the water buffer region (interlayer water) of the central detector (CD) has not been studied, which called CWB muon. The CWB muon event number is about 20% of the muons those through the CD. [Purpose] This study aims to measure the mass ordering of neutrinos on the background, veto strategy and effective volume cut. [Methods] This study utilized the earliest photon arrival time and charge information from the photomultiplier tube signals to construct a charge-weighted least squares time equation. Through simulation studies and parameter adjustments, this method can be successfully applied to large water Cherenkov detectors. Using the JUNO (Jiangmen Underground Neutrino Experiment) detector as a case study, Geant4 simulations were performed to optimize parameters. [Results] The method ultimately achieves muon track reconstruction in the water layer, with a spatial resolution better than 12 cm, an angular resolution better than 0.4 degrees, and a reconstruction efficiency of approximately 97%. [Conclusions] This result can help JUNO to further reduce the background, which plays an important role in the sensitivity analysis of JUNO in the future.