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Monster antimatter particle slams into Antarctica

   March 13, 2021 12:55 AM
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by Rafi Letzter - Staff Writer

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SCIENCE Antarctica
This event was predicted in 1960, but never seen before in the real world.

The most remote particle detector on Earth has detected the most energetic antimatter particle ever: a single ultralight particle that smacked into the Antarctic ice with the (relatively) thundering energy of 6,300 flying mosquitos.

The collision occurred in 2016, but researchers only confirmed the details of the event March 10 in a paper published in the journal Nature. This antineutrino, an antimatter counterpart of the wispy, difficult-to-detect particles known as neutrino, collided with an electron somewhere in the ice of Antarctica at nearly the speed of light. That collision created a shower of particles detected by the buried IceCube Neutrino Observatory — a facility responsible for much of the important high-energy neutrino research of the last decade, as Live Science has reported. Now, IceCube physicists report that that particle shower included evidence of a long-theorized but never-before-seen event known as "Glashow resonance."

Back in 1960, the physicist Stephen Glashow, then a post-graduate researcher at the Nordic Institute for Theoretical Physics in Denmark, predicted that when a sufficiently high-energy antineutrino collided with an electron it would produce a heavy, short-lived particle known as a W boson. Glashow's prediction relied on the fundamental rules of the Standard Model of particle physics, a theory that dominates how researchers understand everything from the insides of atoms to light to antimatter.

Related: 5 elusive particles that may be lurking in the universe

Detecting Glashow's resonance is a powerful confirmation of the Standard Model. But it requires the neutrino to carry far more energy than any particle accelerator from 1960 — or 2021 — can produce: 6.3 petaelectronvolts (PeV).

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