The Second LHAASO Collaboration Conference in 2026 & The Academic Symposium for the 10th Anniversary of the LHAASO collaboration

LHAASO is located in Haizi Mountain, Daocheng County, Sichuan Province, which is an area with a high incidence of thunderstorms. Data analysis shows that the thunderstorm process will affect the overall operating state of the array. This study uses the trigger data of KM2A to find short-term Hit abnormal events, and combines WCDA data analysis to find TGF-like events. This method can be...

We present a search for gamma-ray emission from the Sun using data collected between 2021 and 2025 with the Water Cherenkov Detector Array (WCDA) of the Large High Altitude Air-shower Observatory (LHAASO). We apply an equal-zenith-angle background method and perform a spatial and spectral likelihood analysis using the WCDA detector response and point-spread function. For the cumulative bin0--6...

Terrestrial gamma-ray flashes (TGFs) are high-energy particle bursts originating from the Earth's atmosphere, typically accompanied by thunderstorm and lightning activity. The relativistic runaway electron avalanche (RREA) mechanism is widely considered responsible for the production of TGFs. In this work, Monte Carlo simulations are conducted with the CORSIKA package to investigate the RREA...

The initiation mechanism of lightning flash remains poorly understood in
modern atmospheric physics, despite decades of observational and theoretical efforts. Gurevich et al. proposed that abundant low-energy electrons produced during
relativistic runaway electron avalanche process (RREA) can utilize hydrometeors as "amplifiers" to form a high-conductivity region, thereby reaching the...

The Sun is an important source of high-energy gamma rays produced by interactions between Galactic cosmic rays and the solar atmosphere. However, discrepancies between theoretical predictions and observations suggest that the role of solar magnetic fields in gamma-ray production is not yet fully understood. In this work, we investigate the effects of localized solar magnetic structures on...

The LHAASO-WCDA array adopts 3-inch photomultiplier tubes (PMTs) for the small-PMT channels of its WCDA-2 and WCDA-3 sub-arrays. A total of 2,220 3-inch PMTs were fully installed in 2021 and have been in continuous operation for over five years. Notably, HZC Photonics, the original manufacturer of the deployed 3-inch PMTs, has terminated the production of this specific model. As a result,...

Accurate knowledge of atmospheric aerosol attenuation is essential for reconstructing the energy of air showers observed by the Wide Field-of-view Cherenkov Telescope Array (WFCTA) at LHAASO. We investigate whether the array’s existing laser calibration system can also be used to constrain the vertical distribution of aerosol optical depth. In this approach, WFCTA telescopes observe light...

LHAASO (4410 m a.s.l., Daocheng, Sichuan, China) is a new-generation hybrid ground-based detector array composed of three sub-arrays: KM2A, WCDA, and WFCTA, among which KM2A is used to measure electromagnetic particles and muons in cosmic ray air shower events. In the shower mode of the KM2A array, a shower event is recorded when the trigger condition is satisfied, i.e., at least 20 EDs or MDs...

Measurement of cosmic-ray component spectra with KM2A can be explored through template fitting as a practical route to studying the mass evolution of Galactic cosmic rays around the knee. In this work, the relative contributions of different mass groups are inferred by fitting the distribution of the muon-to-electromagnetic shower ratio in reconstructed-energy bins with a Markov Chain Monte...

We study the high-Galactic-latitude ultra-high-energy gamma-ray source J0956+4622 with LHAASO WCDA and KM2A. At a Galactic latitude of 50.8°, it is currently the only LHAASO source above 100 TeV with latitude greater than 20°. The source is extended, shows no clear variability, and has a spectral peak at 72.2 TeV, the third highest among LHAASO sources. No firm pulsar or 4FGL counterpart is...

Terrestrial gamma-ray flashes (TGFs) are brief bursts of high-energy gamma-ray emission associated with thunderstorms. In this study, electron and bremsstrahlung photon energy spectra are modeled within the framework of relativistic runaway electron avalanche (RREA) theory. Particle transport and detector response are simulated using G4KM2A, a Geant4-based simulation package for LHAASO-KM2A....

Quasi-periodic oscillations (QPOs) in blazar gamma-ray emission offer valuable clues to jet dynamics and central-engine activity. With its wide field of view and long-term monitoring capability, LHAASO-WCDA provides an opportunity to search for such variability at TeV energies. We investigate the long-term WCDA light curves of Mrk 421 and Mrk 501 and compare them with Fermi-LAT observations...

Energy reconstruction is a key component of gamma-ray spectral measurements with LHAASO-WCDA. While conventional methods use the number of triggered detector units, Nhit, as a proxy for shower size and primary energy, the spatial, timing, and charge information of individual hits can provide additional constraints. We develop a ParticleNet-based approach to event-level energy regression, using...