“LACT consists of 32 imaging Cherenkov telescopes with a diameter of 6 meters each, strategically positioned within the LHAASO array. Leveraging spatial stereoscopic tracking observation technology, LACT achieves a remarkable high angular resolution better than 0.05°. The groundbreaking advancements made by LHAASO have opened a new window in the field of 'ultra-high-energy gamma astronomy', leading to the discovery of over 40 ultra-high-energy gamma-ray sources. Each source exhibits complex structures, encompassing multiple cosmic-ray origin candidate celestial bodies.
However, the angular resolution of LHAASO is limited to approximately 0.3°, constraining the precise measurement of internal fine structures of sources and hindering the effective differentiation of which celestial body within the source region emits the ultra-high-energy gamma rays. Currently operational imaging Cherenkov telescopes such as HESS, MAGIC, VERITAS, CTA-LST, etc., exhibit significantly lower sensitivity in detecting ultra-high-energy gamma rays from these sources compared to LHAASO's sensitivity.
Focusing on this forefront scientific demand, we propose the LACT project. LACT aims to match the detector sensitivity of LHAASO for ultra-high-energy gamma sources while improving the angular resolution by more than 5 times. This enhancement allows for high-resolution clear imaging measurements of these sources, enabling the identification of the celestial bodies from which ultra-high-energy gamma rays originate. LACT, once completed, will be the most sensitive and highest angular resolution stereoscopic tracking observation device for ultra-high-energy gamma-ray sources in the northern hemisphere, leading to groundbreaking achievements in cosmic-ray origin studies.”
