X. R. Li

Calibration and monitoring of LHAASO-KM2A muon detectors with muon decay events

The Large High Altitude Air Shower Observatory (LHAASO) will be constructed at 4400 m asl in Daocheng, Sichuan Province, with the aim of discovering sources of ultra-high energy cosmic rays and studying cosmic ray physics. The whole array includes 1171 muon detectors (MDs), constituting the largest muon detector array in the world. The special high altitude and wide-field environment requires simple and stable calibration as well as monitoring method of MDs. In this paper, the muon decay events will be selected for calibrating the charge and monitoring the water level of each MD. In the prototype muon detector, the simulation and experiment results reveal that the charge of the decay electron is approximately 0.147 times that of the vertical equivalent muon for a standard MD, and the QVEM/Qe shows a linear correlation with the water level.

Study of Water Cherenkov muon detector parameters and performances for LHAASO

In the Large High Altitude Air Shower Observatory project, about 1146 water Cherenkov muon detectors will be built to discriminate cosmic ray species. Each muon detector has a 6.8 m diameter Tyvek bag containing 1.2 m height pure water in it. In the summer of 2014, a water Cherenkov muon detectors prototype was installed at YBJ, both data analysis and simulation has been performed. The detector performances strongly depend on detector parameters, especially the Tyvek reflectivity and water attenuation length. MD prototype signals are simulated by using Geant4 with different parameters, while the detector parameters are determined by comparing simulation to data. The MD performances, such as NPE and the relationship of effective attenuation length with water absorption length, Tyvek reflectivity and time ranges are studied.