This book documents the design, construction process, and major scientific achievements of LHAASO, as well as the significant discoveries it has made. The Large High Altitude Air Shower Observatory (LHAASO), situated in Sichuan Province, China, aims to explore the origin of cosmic rays. As a new generation cosmic ray station, it boasts high altitude, all-weather operation, and large scale, making it currently the world's most sensitive gamma ray astronomy detection device. The book covers the basic theories of cosmic rays and related detection technologies, explaining how researchers investigate the high-energy universe through cosmic ray measurements. Additionally, the book highlights the remarkable progress of China's cosmic ray research, starting from zero, to becoming a leading force in the field. The book is an interesting read for researchers, engineers, students, and anyone involved in or interested in astronomical observation, particularly cosmic rays.

Cao Zhen is High-Energy Cosmic Ray Experimental Physicist, Academician of the Chinese Academy of Sciences, Researcher of the Institute of High Energy Physics of the Chinese Academy of Sciences, Professor and Doctoral Supervisor of the University of Chinese Academy of Sciences, Chief Scientist and Project Commander of the National Major Science and Technology Infrastructure LHAASO, Spokesperson of the LHAASO Collaboration, and Director of Tianfu Cosmic Ray Research Center. He is active in the field of cosmic rays and gamma ray astronomy both domestically and internationally, participating in multiple international cosmic ray experiments. He proposed and established the LHAASO, currently the world's most sensitive gamma ray astronomy detection facility, and achieved a series of significant breakthroughs regarding the origin of cosmic rays.
 
Bai Yunxiang is Senior Engineer at the Institute of High Energy Physics of the Chinese Academy of Sciences, and Executive Deputy Director of Tianfu Cosmic Ray Research Center. Bai Yunxiang participated in the development of China's First High-Energy Cosmic Ray τ Neutrino Telescope, and was involved in the construction of the "12th Five-Year Plan" National Major Science and Technology Infrastructure LHAASO, as well as the "13th Five-Year Plan" Science and Education Infrastructure Platform for Cosmic Ray Physics and Detection Technology. He also has been engaged in long-term research on high-energy physics experiments and the strategic research of large-scale scientific innovations.