A tiny electron anti-neutrino has traveled incredible cosmic distances at almost the speed of light, colliding with an electron on the ice of Antarctica. This interaction created a W-boson, one of the carrier particles for weak nuclear energy (such as photon electromagnetic energy carrier particles).
This interaction first theoretically proposed 60 years ago, and now it has observed for the first time. The discovery published in the journal Nature. Now, some background for this remarkable discovery. Let us start with neutrinos. Neutrinos are elementary particles with the smallest mass and have no electrical charge. This makes them very fast and they do not really like to interact with other particles. These come in three types or “flavors”: electronic neutrino, muon neutrino and tau neutrino.
Neutrinos contain antimatter – antineutrinos. It is difficult to study how these particles stubbornly reject interaction. Every second, 100 trillion neutrinos pass through our bodies. Physicists use giant detectors to try to capture rare moments when a neutrino hits another particle – and it happened inside an ice cube. If the neutrino slammed into one of those large particles, the observer could catch it. In 1960, Sheldon Glashow, working at the Neil Bohr Institute in Copenhagen, suggested in a research paper that an electron in contact with electrons could form new particles if the new molecule gained the correct energy of neutrino. This process became as Glasgow Resonance.
The particle in question, the W-boson, discovered in 1983 – but the energy required producing it by Glasgow resonance is beyond what humans can produce. The Large Hadron Collider should have about a thousand times the energy of the energy-neutrinos that we can give particles. However, natural particle accelerators can do much better than we can. A supermassive black hole in another galaxy probably accelerated a large number of particles with incredible energy, including an anti-neutrino. This traveled an interplanetary space until an electron thrown into the ice.
Principal investigator of IceCube professor Francis Halzen, from the University of Wisconsin-Madison, said in a statement, “When Glashow was Neil Bohr’s postdoc, he never imagined that his conventional proposal for W-boson production would be realized by antineutrino from distant galaxies wrecked in the Antarctic ice.” The ice cube is more than a decade old, and since 2013, it has regularly reported to detected neutrinos outside the solar system – including a black hole that ripped through a star. This newly reported identification – which actually happened in December 2016 – is the first time researchers have been able to confirm that the event caused by an anti-neutrino.
“Previous measurements were not sensitive to the difference between neutrinos and antineutrino, so this result is the first direct measurement of an antineutrino component of astrophysical neutrino flux,” explained Dr. Lu Lu, a professor at the University of Wisconsin.
