IceCube Confirms the Glashow Resonance
Neutrinos are subatomic particles that rarely interact, but when they do it's often with electrons. They have no electric charge, and so must interact via the weak nuclear force. The weak force lives up to its name.
The IceCube Experiment is a massive particle detector perched atop the equally massive, Antarctic ice sheet. By drilling ice holes nearly a mile long (4920 ft), the experiment managed to dangle photon detectors to search for particle events via incoming cosmic, ultra high energy neutrinos.
What they're looking for is a trail of Cherenkov Radiation, associated with super high particles created by collisions with neutrinos. By recording that trail of light, they can reconstruct the underlying particle collision. (You can do this at home via Augmented Reality with your cell phone, via IceCube's mobile app.)
Neutrinos can collide with known particles in a variety of ways: they can kick atomic particles like an electron or a neutron. They can be absorbed into a nucleus. If the neutrino is coming in fast enough, they can even break apart a particle like a proton, creating a massive shower of other subatomic particles. This is the kind of event that everyone is talking about. This is the kind of event that IceCube was designed to look for.
The neutrino event physicists are freaking out about happened in 2016, but the folks at IceCube have finally managed to "confirm" that it was a very special kind of collision. The neutrino involved was moving with about 1000x times the energy that the LHC can accelerate a proton. At this level of energy, new kinds of collisions can occur, and in this case, folks are moderately sure that the W boson was formed.
In any case, it's the first known event consistent with the creation of a W boson - an collision event predicted by Nobel laureate Shelly Glashow some 60 years ago. Why is it exciting? Building neutrino detectors able to take data on these ultra high energy particles can tell us a lot about the distribution of antimatter in the universe. The Glashow Resonance requires anti-electron neutrinos.
To be fair, it's not yet clear that antineutrinos are distinct from neutrinos. The photon certainly isn't, but that's another matter for another experiment.
