Speaker
Description
Due to the difficulty of traditional high-energy particle detectors in simultaneously achieving large effective area and sub-microsecond time resolution, direct experimental evidence for the spatiotemporal evolution characteristics of high-energy radiation during lightning leader processes has long been lacking. The Large High-Altitude Air Shower Observatory (LHAASO) is located in Daocheng, Sichuan, a region with frequent lightning activity. Based on LHAASO data, this report presents an analysis of the detection of high-energy particles associated with two lightning leader processes during a thunderstorm on September 1, 2024.
During the observation period, both the WCDA and KM2A arrays of LHAASO recorded trigger events significantly higher than the background level, among which the count rate of KM2A increased by approximately 10 times, and that of WCDA increased by about 3 times. Through high-precision temporal correlation analysis, it is found that the high-energy particles recorded by the detectors correspond well in timing with the very-high-frequency (VHF) radiation pulses of lightning; however, it is worth noting that the signals of high-energy particles precede the breakdown pulses of lightning.
The two leader processes exhibit different temporal distribution characteristics on the detector array: events during the first leader show obvious clustering, while those during the second leader are relatively scattered. Moreover, the arrival directions of these high-energy particles are highly consistent with the localization results of lightning radiation sources.
Comprehensive observations of high-energy radiation from lightning leaders are conducted using LHAASO and VHF data, and a temporal relationship between high-energy particle radiation and the development of lightning leaders is identified. Such observations provide direct experimental evidence for in-depth studies of lightning physics, especially the generation mechanism of high-energy particles during thunderstorms.
