A gigantic and sophisticated telescope that aims to capture one of the most elusive forms of matter in the universe—neutrinos—was lowered into the waters of Russia’s Lake Baikal, the deepest lake on Earth, on Saturday.
Scientists deployed the Baikal Gigaton Volume Detector (Baikal-GVD), a neutrino observatory that stretches across half a cubic kilometer and extends to depths between 750 and 1,300 meters beneath the surface of this iconic Siberian lake over the weekend. The observatory is made up of glass orbs with a delightful sci-fi aesthetic, attached to vertical tethers that plunge deep into the clear and chilly water.
Developed by Russia’s Joint Institute for Nuclear Research (JINR), the new observatory is a significant upgrade of the Baikal Deep Underwater Neutrino Telescope (BDUNT), which has been operating within Lake Baikal for more than two decades. Eventually, the JINR team plans to extend the observatory to encompass a full cubic kilometer within Lake Baikal.
“Lake Baikal is perhaps the only lake where a neutrino telescope can be deployed because of its depth,” Bair Shoibonov, a scientist at the Joint Institute for Nuclear Research, told AFP. “We need the greatest possible depth—over a kilometer.”
Neutrinos are the lightest known particles in the universe; so light, in fact, that the question of whether they had any mass at all was debated for decades. The discovery that these bizarre entities actually do have a tiny bit of mass—equal to about a millionth the mass of an electron—earned the 2015 Nobel Prize for Physics.
Given that they are fundamental (yet enigmatic) subatomic particles, scientists think neutrinos are key to unlocking many secrets of the universe, from the evolution of matter to the exact mechanisms behind the pyrotechnic deaths of large stars.
These weird “ghost” particles, as they are sometimes called, are created by common processes such as stellar nuclear fusion and radioactive decay, making them by far the most plentiful particles in the universe: about 100 trillion of them pass through your body every second. Most of these particles are produced locally by the Sun, but some of them are high-energy particles that originate in ancient supernovae and other exotic cosmic sources.
But despite their abundance, the incredible lightness of neutrinos allows them to easily travel through matter, such as Earth, without slowing down from their usual light-speed clip, or interacting with matter in any significant way.
This ethereal quality makes neutrinos extremely difficult to detect, which is a real scientific bummer considering how much we can learn from these entities.
For this reason, scientists around the world have devised all manner of wildly imaginative observatories, typically in extreme environments, for capturing these spectral particles. For instance, the IceCube Neutrino Observatory, operated by the University of Wisconsin-Madison is the largest neutrino observatory on Earth, with tendrils that delve 2.5 kilometers (1.5 miles) into the South Pole in Antarctica.
Baikal-GVD is now the largest neutrino observatory in the Northern Hemisphere, according to the JINR team. The underwater telescope is built around vertically arranged arrays of hundreds of glass orbs, known as optical modules, that are anchored to the lakebed and stabilized by a system of buoys. The modules are packed with equipment to sense high-energy neutrinos, and they have to number in the hundreds (and eventually, thousands) to boost the odds that any single orb will capture one of the subtle particles.
Neutrino detectors work best when buried under remote ice, like IceCube, or submerged in freshwater, like Baikal-GVD, because these environments provide a clear medium that is ideal for spotting the signatures of neutrinos as they collide with subatomic particles inside atoms. These detectors search for the bluish glow that these reactions produce, known as Cherenkov radiation.
In addition to hunting neutrinos and their sources, Baikal-GVD will also investigate candidates for dark matter, an unidentified non-luminous substance that accounts for most matter in the universe, and will conduct environmental studies of Lake Baikal, which is undergoing rapid change as a result of warming global temperatures.
Though JINR heads the project, the telescope is a collaboration between researchers from Russia, the Czech Republic, Germany, Poland, and Slovakia.
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