The Paper's trainee reporter Zou Jiawen and reporter Gao Wen
A huge cube shimmers on the 3,000-meter-deep seabed of the South China Sea, the action of ocean currents pushes it gently, and about a thousand cables planted between the cubes also dance slightly like algae.
Dark, quiet, focused, this is 2030. Seawater is its lens, and its gaze travels through the ocean at a depth of 3,000 meters, managing to capture high-energy neutrinos from the universe, the atmosphere, the motion or the silent demise.
This isn't the plot of a science fiction story, it's the "SeaBell Project" being led by Shanghai Jiao Tong University — a major project that seeks to explore the world of high-energy physics by studying neutrinos, hoping to build the first Chinese-led deep-sea neutrino telescope around 2030.
Once built, humans will have the opportunity to capture neutrinos from high-energy celestial bodies and explore the extreme universe through it.
Recently, the project has successfully taken the first step - successfully deployed several sets of self-developed experimental instruments in the predetermined sea area, not only collecting valuable data of more than 1TB of sea depth of 3500 meters in situ, but also scanning and testing the relevant properties of all-water deep seawater. After preliminary analysis, the feasibility of pre-selected sea area as a candidate site for neutrino telescopes is verified.
"The array has a slight dancing feeling under the action of ocean currents, and when the neutrino signal comes, if we observe the image with a romantic mindset, it is like an array of signals dialing bells, bringing us information from the depths of the distant universe, hence the name 'Sea Bell Project'." Xu Donglian, chief scientist of the project and a scholar of Li Zhengdao at Shanghai Jiao Tong University, said.
The "Sea Bell Project" Pathfinder project team recently completed various scheduled sea trial tasks and arrived in Shanghai safely. The pictures in this article are all courtesy of Shanghai Jiao Tong University
"Hailing Project": Monitoring more than 1 million Beijing Water Cubes in water bodies
The surging news reporter learned from the scientific research team that "Hailing" is a large grid array formed by about a thousand cables, and dozens of optical ball cabins are placed on each cable, and each ball cabin contains photodetectors.
The "Sea Bell" monitors more than 1 million Beijing "Water Cubes" in water bodies, and its engineering goal is to build an array of submarine neutrino telescopes that work continuously for 20-30 years, all-weather, and full-time operation.
Why is this huge device placed on the bottom of the sea?
According to the scientific research team, first of all, the seabed is high-pressure and less bubbles; secondly, the seabed can be shielded from atmospheric noise and a large number of cosmic rays, so that the detector can see more clearly in a quiet environment; in addition, the scattering absorption of light by seawater is very weak, and light can travel farther distances. "It can be said that seawater is the medium of neutrino reaction, and it can also be understood as an integral part of our telescope itself." Xu Donglian said.
The South China Sea belongs to the low latitude, and the "sea bell" in the South China Sea rotates with the earth, which can monitor a wider area of the sky, maintain sensitivity to the detection of the whole day, and sweep through the entire nearby universe. After the progress of neutrino research, the "sea bell" can further scan the earth's interior to understand the mysteries.
After mobilizing a large number of research data on the seabed and seawater, the scientific research team selected the South China Sea, an area where "seawater is like blue ink, and mud layers are as delicate as masks".
Through this sea test in the South China Sea, the team also basically determined that the South China Sea is suitable as a telescope "base". "It's so lucky that in our country, we can find such a place where we can build a device. The water depth is sufficient, the sea is calm and clean, and the seabed is flat, and these conditions are difficult to do without one. Xu Donglian introduced.
The team conducted a sea trial in the South China Sea, and the picture shows the "bottoming system".
The team conducted a sea trial in the South China Sea, and the picture shows the "four seasons submarine marker".
Recently, the "Hailing Project" Pathfinder project team completed various scheduled sea trial tasks and arrived in Shanghai safely, laying a solid foundation for the follow-up promotion of the "Hailing Project".
With Xu Donglian as the chief scientist and marine engineering scholar Tian Xinliang as the leader, more than 30 researchers and technicians from Shanghai Jiao Tong University, Peking University, Tsinghua University, University of Science and Technology of China, the Second Institute of Oceanography of the Ministry of Natural Resources and other institutions participated together.
The tiny particles contain great mysteries, and neutrino astronomy is in the ascendant
Why did project Hailing observe neutrinos?
According to Shanghai Jiaotong University, neutrinos are one of the basic units that make up the universe and the most numerous particles in the universe. It is not charged and interacts with matter extremely weakly, like a ghost, and extremely difficult to catch.
It is generally believed that because the cosmic rays in the interstellar spread are deflected by the magnetic field, their origin is still a mystery. Once the neutrinos generated by the cosmic ray reaction are detected, they can be traced back to the source, so the century-old mystery of the origin of cosmic rays can be solved by detecting the neutrino source of high-energy celestial bodies.
By building different detectors to study the oscillatory behavior of neutrinos (which can be converted to each other during the propagation of space-time, and transform the appearance of the momentary transformation in space-time), humans can partially glimpse the basic laws of the formation of matter in the universe, but the neutrinos themselves still have many unsolved mysteries, and the neutrinos are more deeply explored, or once again subvert our understanding of basic physical laws.
Shanghai Jiaotong University said that IceCube, the world's largest neutrino telescope, chose to build the detector array in the Antarctic ice layer at a depth of 2500 meters. In 2013, Ice Cube first detected a diffuse stream of high-energy neutrinos from beyond the earth, knocking on the door to high-energy neutrino astronomy. However, this neutrino stream shows no signs of agglomeration or explicitly points back to any known celestial source, suggesting that there are no celestial sources of high-energy neutrinos strongly radiating in the universe near Earth. To effectively find celestial sources of high-energy neutrinos, it is still necessary to improve the detection sensitivity of the next generation of neutrino telescopes.
At present, Europe, the United States and China are actively preparing to build a second-generation neutrino telescope with greatly optimized performance, which is expected to be completed around 2030, when a major breakthrough in the field of neutrino astronomy will be achieved.
Editor-in-Charge: Xu Xiaoyang