Pop science
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 thundering energy of 6,300 flying mosquitos.
The collision occurred in 2016, but researchers only confirmed the details of the event in March 2021.
This antineutrino, an antimatter counterpart of the wispy, difficultto-detect particle known as a neutrino, collided with an electron 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. Now IceCube physicists report that the particle shower included evidence of a long-theorised but neverbefore-seen event known as Glashow resonance.
Back in 1960, the physicist Sheldon Glashow, then a postgraduate 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 aW 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 inside of atoms to light to antimatter. Actually detecting Glashow resonance is a powerful confirmation of the Standard Model. But it requires the neutrino to carry far more energy than any particle accelerator can produce: 6.3 pet a electron volts(PeV ).
It’s usually difficult to wrap your mind around the numbers involved in high-energy particles. A single neutrino has a mass of about 2 billion-billion-billion-billionths of a gram, and thousands of lowenergy neutrinos from the Sun pass through your body every second of the day without noticeable effects. But a neutrino with 6.3 petaelectronvolts of energy is another beast entirely.
To put it into perspective, a teraelectronvolt (TeV) is equivalent to the energy of a single mosquito flying at one mile per hour. 6.3 PeV is 6,300 TeV, so turn that single mosquito into a swarm of 6,300 – or accelerate the single mosquito to Mach 8.2, more than four times the top speed of an F-16 – and you’ve got the energy of the single infinitesimal particle required for Glashow’s resonance.
There’s another way to think of 6.3 PeV: it’s 450 times the maximum energy that the Large Hadron Collider, CERN’s 17-milelong multi-billion-dollar accelerator, responsible for the detection of the Higgs boson, should be able to produce by the late 2020s following ongoing upgrades.
RAFI LETZTER