LHAASO

The Large High-Altitude Air Shower Observatory (LHAASO) opened the multi-TeV era in  γ-astronomy and cosmic ray physics. Since July 2021, LHAASO is fully operational and collecting high-quality data. A Nature paper in 2021, revealing 12 VHE new sources, was just the start of LHAASO science, revealing the huge scientific potential of this experiment.

LHAASO is a new generation multi-purpose experiment.

A detailed description of the system  and the main physics goals can be found in a dedicated chapter the LHAASO Science book  

LHAASO has been built at 4410 m a.s.l. on top of the Haizi mountain in the Sichuan region of China, covering an area of 1.3 km in diameter. In the middle of the array, a large Water Cherenkov Detector Array (WCDA) complex composed of three ponds covers an area of 78’000 m. The WCDA is segmented in 3120 square cells, with a side of 5 m separated by a black curtain to impede light cross-talk. The water level in the cell is 4.4 m above the ground. In each cell are installed 2 PMT of different sizes to accommodate a very large photon dynamic range. While in the WCDA-1 are installed 8" and 1.5" PMTs, in the other two ponds are installed 20" and 3" PMT in order to lower the energy threshold below the 100 GeV of the original design. The km-square array (KM2A), surrounding the WCDA complex, composed of 1171 Muon detectors (MD), arranged on a triangular grid with a spacing of 30 m, and 5195 electromagnetic detectors (ED) arranged on a triangular grid with a spacing of 15 m. The MD is a tank of 6 m in diameter with an height of 1.5 m buried under 2.5 m of dirt to shield it from muon of less than 1 GeV. In the center of the tank facing up under 1.2 m of water, a single PMT is installed. The installation is completed with the Wide Field of View Cherenkov telescope array (WCFTA),consisting of 18 telescopes with a field of view of 16 x 16 with a pixel size of approximately 5◦x5◦