China and U.S. race to study neutrinos — 'ghost particles' of the universe
China is building a facility to measure neutrinos — mysterious subatomic particles. It's the first of three neutrino observatories expected to open worldwide in the next decade.
GOLDEN ROOSTER TOWN, Kaiping, China — In a granite cavern deep beneath the forested hills of southern China, workers will soon complete a 600-ton sphere that could crack open some of the deepest mysteries of modern physics.
The plexiglass sphere is the centerpiece of the Jiangmen Underground Neutrino Observatory, or JUNO, a $300 million facility designed to measure neutrinos, the smallest subatomic particles known to physicists.
Sometimes called “ghost particles,” neutrinos are invisible and nearly massless, and they travel at close to the speed of light. They come in three mass states, the biggest of which is estimated to have one-millionth the mass of an electron. Neutrinos can pass through the Earth and other matter without interacting with it, which is a large part of the reason they have thus far remained elusive for physicists.
Understanding them could help unravel a puzzling imbalance at the heart of the Big Bang theory: According to the standard model of physics, that event should have produced equal amounts of matter and antimatter. But the former is much more abundant, and scientists don’t know why.
The goal for JUNO and other neutrino observatories expected to come online in the coming years is to measure differences among the masses of neutrinos. Because the particles are so small, it’s difficult to do that precisely. JUNO has been built 2,300 feet below the Earth’s surface, therefore, to shield the neutrinos under study from the interference of cosmic rays.
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