Speaker
Description
The interaction between secondary particles from cosmic ray air showers and electric fields in thundercloud is one of the hottest topics in high-energy atmospheric physics. Owing to the large active area and high-altitude location with frequent thunderstorms, LHAASO is suitable to study the correlation between thunderstorms and variations in cosmic rays. Based on the experiment data with LHAASO-KM2A in Shower mode, and combined with Monte Carlo simulations, the cosmic ray air shower variations are studied. During thunderstorms, the shower rate changed significantly. The variation amplitude is found to be related to the electric field intensity, and also strongly dependent on the primary zenith angle. With nearby lightning flashes, the shower rate variations are terminated sharply. During a thunderstorm occurred on 16 June, 2022, the downward TGF-like events, in coincidence with strong lightning strikes, are detected by LHAASO-KM2A. To improve the accuracy of the reconstructed shower’s primary information and understand the shower rate variations during thunderstorms, changes of characteristic parameters (such as shower size, temporal structure and lateral distribution) are studied. At the same time, the performance of LHAASO-KM2A operating in Scaler mode is studied, and the variations of counting rates with different multiplicities during thunderstorms are analyzed. Due to the acceleration/deceleration and deflection by the electric field in thundercloud, the cosmic ray variations are easily to understand.
