Large High Altitude Air Shower Observatory

The Large High Altitude Air Shower Observatory (LHAASO) is a gamma-ray and cosmic-ray observatory in Daocheng, in the Garzê Tibetan Autonomous Prefecture in Sichuan, China. It is designed to observe air showers triggered by gamma rays and cosmic rays. The observatory is at an altitude of 4410 m above sea level. Observations started in April 2019.

The observatory covers an area of some 145 ha. It has three underground observing pools, each “more than triple the size of the Water Cube (National Aquatic Center) in Beijing”. One of the pools is designed to contain 100000 tonne of water. The pools will contain 12 telescopes to capture high-energy photons. Cherenkov radiation detectors are used. Research teams from Australia and Thailand will participate in the project directly, with others expressing interest.

The observatory works essentially as the CASA-MIA observatory did but with a bigger surface array, better muon detectors, improved designed layout and at higher altitude.

Scientific results
On 17 May, 2021, LHAASO Discovers a Dozen PeVatrons and Photons Exceeding 1 PeV including one at 1.4 PeV.

On 26 February, 2024, LHAASO reported the discovery of "a giant ultra-high-energy gamma-ray bubble structure in the Cygnus star-forming region." It contains multiple photons exceeding 1 PeV and at least one reaching 2.5 PeV, leading scientists to identify the presence of a "super cosmic ray accelerator" within the structure.