BEXCO - Room F(201/202/203/204)
[GA037] A way to calibrate the time of LHAASO-WCDA detectors with the air shower signals
The Water Cherenkov Detector Array (WCDA), which is one of the main components of the Large High Altitude Air Shower Observatory (LHAASO), functions as surveying the northern sky for high-energy gamma ray sources at the energy range around 100 GeV--30 TeV. Aiming a good observation, the accuracy of the time offsets among detector cells is required to be less than 0.2 ns. Besides the dedicated time calibration system, the time information from air shower particles recorded in each detector can be used to calibrate the time offsets too. Borrowing the idea of the trigger scheme and the cluster-wised hardware calibration system of the WCDA, with the help of a simulation, the shower events restricted in every overlapped 144 cells are investigated. The analysis results are presented, the time window required for a valid calibration is postulated. This method can be employed as a cross-check to the hardware calibration system frequently, guarrantteeing a robust and steady performance of the WCDA.