On-site test system for LHAASO-KM2A muon detector

The Muon detector (MD) of LHAASO-KM2A (Large High-Altitude Air Shower Observatory 1km2 Array) [1] is a water Cherenkov detector with an effective area of ~36 m2. The 2.5 m thick overburden soil is used as a shield to prevent low energy electromagnetic particles from reaching water. Each MD must be well tested before the covering process of the thick soil. In this case, the on-site test system is designed and manufactured, consisting of a telescope and a data acquisition system. The telescope is a combination of two vertically placed scintillator detectors covered by 4cm thick lead each. Charge resolution and time resolution are estimated by analysing the test data. In addition, waveforms of the MD signal are recorded each second, which will serve to evaluate the water quality of MD.