China is a step closer in its quest to measure elusive particles called neutrinos with the installation of a massive subterranean sphere detector in the country’s south.
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The sphere is about 35 metres (115 feet) in diameter and is a central element of the US$376 million Jiangmen Underground Neutrino Observatory, or Juno, project in Jiangmen, Guangdong province.
It will be filled with 20,000 tonnes of a “liquid scintillator” and suspended in 35,000 tonnes of pure water 700 metres below ground to try to measure the mass of different types of neutrinos produced by two nearby nuclear power plants.
Neutrinos are elementary particles that are very difficult to detect because they have no electrical charge, very little mass and move at near light speed.
Although almost all of the particles will pass through the detection liquid without a trace, some will interact with the liquid, triggering two flashes of light which will then be recorded by thousands of light-detecting phototubes.
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State broadcaster CCTV reported on Friday that the sphere had been installed, and work was under way on assembly of its outer metal shell and the phototubes.