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Marine site found for the neutrino observatory



A reconnaissance trip to the South China Sea succeeded in finding a suitable location for the construction of a deep-water neutrino observatory that would be the first such facility in China, Shanghai Jiao Tong University said.

Plans for the Hai-Ling, or Sea Bell, project call for the observatory to be built 3,000 meters below the sea surface by 2030 to detect astrophysical neutrinos, elementary particles that are electrically neutral and have a mass much smaller than other known ones. elementary particles.

As high-energy astronomical messengers, neutrinos provide information to probe the most violent astrophysical sources, such as star explosions, gamma-ray bursts, and cataclysmic phenomena involving black holes and neutron stars.

Earlier this month, a team of Chinese scientists and engineers traveled to the South China Sea to assess the feasibility of building a next-generation neutrino telescope array, and project scientists have said preliminary data reported from the trip had shown positive results.

“The water here is very clear and the current is gentle. It is an ideal candidate site,” said project chief scientist Xu Donglian, a researcher at the university’s Tsung-Dao Lee Institute.

“The construction of a deep-water neutrino observatory closer to the Earth’s equator will complement the global networks of multi-messenger observatories.”

Because neutrinos interact weakly, they are difficult to observe. The existence of neutrinos was first postulated in 1930, but they were not detected until 1956.

Since then, several neutrino observatories have been built to capture the elusive particle in order to study astronomical objects, such as the core of the Sun and supernovas inaccessible to optical telescopes.

The Hai-Ling Deep Sea Telescope will be made up of hundreds of cables draped to the bottom of the sea, and around 20 to 30 optical sensor modules will be attached to each cable to detect weak light in the deep sea from particles. charged from collisions of neutrinos and water near the detector.

The idea of ​​detecting neutrinos using a large volume of transparent water was proposed by Soviet physicist Moisey Markov in 1960, but the first generation of these neutrino observatories was not large enough to have a sufficient sensitivity to efficiently capture neutrinos.

The Hai-Ling project aims to build a network of telescopes several kilometers long and wide while extending approximately 1 km deep from 2,500 to 3,500 meters below sea level, like a rice paddy. seaweed planted on the seabed.

The world’s largest neutrino telescope, IceCube, measures one cubic kilometer and was built over 1,500 meters deep in the ice of the South Pole in 2010. It made the world’s first observation of cosmic neutrinos in 2013.

“The Hai-Ling will be a much bigger ‘net’ for scientists to capture neutrino particles,” Xu said, adding that building next-generation water-based neutrino observatories, including the Cubic kilometer neutrino telescope, or KM3NeT, at the bottom of the Mediterranean Sea and the Baikal Gigaton volume detector in Lake Baikal in Russia, the world’s largest freshwater lake, are also expected to be completed during the decade.

“The neutrino telescope has the potential to make groundbreaking scientific discoveries, such as identifying the origins of cosmic rays,” she said. “The project can also advance interdisciplinary studies between particle physics, astrophysics and marine geology.”

Tian Xinliang, associate professor at the university’s State Key Laboratory of Ocean Engineering, said the project poses great challenges for engineering, as the telescope will occupy more than 10 cubic kilometers of water and is expected to operate stably for 20 to 30 years old.

“How to design, install and maintain this largest deep-water scientific infrastructure in human history requires a lot of innovation and cooperation between different areas of expertise,” he said. “Fortunately, our university has unique strengths in shipbuilding, ocean engineering, materials and electronics, and we are confident that we will overcome these challenges.”