The high-altitude cosmic ray observation station "cable" was completed in 4 years.
Our reporter Lu Chengkuan
On October 24, the reporter learned from the Institute of High Energy Physics of the Chinese Academy of Sciences that the National Major Science and Technology Infrastructure High Altitude Cosmic Ray Observation Station "LHAASO" (LHAASO) has officially passed the performance process acceptance recently, which indicates that the cable has been completed and officially Enter the stage of scientific operation.
It is expected that by the end of this year, the cable will complete the required procedures for national acceptance.
After the project site inspection, the process acceptance expert group believes that the construction unit has completed various construction tasks approved by the National Development and Reform Commission in a timely, comprehensive and high-quality manner, including the ground shower particle array, the water Cherenkov detector array, and the wide-angle cut The three major arrays including the Lenkov telescope array, the clock distribution and data acquisition system, the data processing platform, and the corresponding general purpose, civil engineering and supporting facilities, etc.; the performance indicators of all the detector arrays and process systems of the cable meet the design requirements, and the three major arrays The overall performance of the cable is better than the acceptance index. Among them, the sensitivity of the cable in the ultra-high energy gamma-ray band is significantly better than that of the existing and under construction detection devices in the world. The overall performance of the detection device is reliable and has the ability to operate stably and scientifically for a long time.
Cao Zhen, chief scientist of Lasso and researcher of the Institute of High Energy of the Chinese Academy of Sciences, said that Lasso’s core scientific goal is to explore the origin of high-energy cosmic rays and related cosmic evolution, evolution of high-energy celestial bodies, and dark matter research. High-energy cosmic ray cases and more than 2 billion very high-energy cosmic ray cases.
During the cable construction process, the project team conquered a series of key core technologies.
The expert group believes that through independent innovation, the Lasso project team has completed a number of key core technology research, and for the first time the large-scale use of a new type of silicon photoelectric tube in the large-field imaging Cherenkov telescope has completely changed this type of telescope that cannot be used on moonlit nights. The traditional observation mode of work has realized the double increase of effective observation time; the development of large-area, multi-node, high-precision clock synchronization technology based on the "little white rabbit" technology, adapted to the high-altitude field conditions above 4000 meters, has improved The technology has a long-distance synchronization accuracy of 5 times to 0.2 nanoseconds; it uses a domestically made 20-inch ultra-large photomultiplier tube, and increases the time response by 3 times, breaking the international technology monopoly; the observation threshold can be reduced from 300 GeV (ten Billion electron volts) to 70 GeV, greatly expanding the observation capability; significant progress has been made in mass data acquisition technology, the development and realization of "no trigger" data acquisition, and the realization of "zero" for cosmic ray cases with a data volume of up to 4GB/s. Dead time" observation; using special data screening technology, lossless compression of massive data, real-time data transmission from Haizishan to High Energy Institute.
At the same time, the expert group believes that the cable makes full use of the high-altitude geographical advantages of the roof of the world to become the world's largest and most sensitive ultra-high energy gamma-ray survey telescope and the world's leading cosmic ray observatory with the broadest energy coverage; Exceeding the detection sensitivity of existing and under-developed gamma-ray telescopes in the world, the cable has achieved major breakthrough scientific results during its initial operation, discovered the widespread existence of electron volt accelerators in the Milky Way, and opened up ultra-high-energy gamma-ray observations window.
The cable is located in Haizi Mountain at an altitude of 4410 meters in Daocheng County, Sichuan Province. It is jointly built by the Chinese Academy of Sciences and the Sichuan Provincial People's Government. The Chengdu Branch of the Chinese Academy of Sciences and the Institute of High Energy Physics jointly undertake the construction period of 4 years and the total investment is about 1.2 billion yuan.
The observation station covers an area of 1.3 square kilometers with an average elevation of 4,410 meters.
The main cable construction project started in November 2017. In April 2019, 1/4 scale construction was completed and put into scientific operation; in July 2021, the full array construction was completed and put into operation.