The KATRIN neutrino experiment is located on the grounds of the Karlsruhe Institute of Technology in Germany. (KATRIN Photo)
Scientists from the University of Washington and other institutions around the world say they’ve reduced the upper limit for the mass of the neutrino by half.
Thanks to findings from the Karlsruhe Tritium Neutrino Experiment, or KATRIN, physicists now know to a 90% confidence level that the neutrino has a rest mass no greater than 1.1 electron volts, or 1.1 eV. The previous upper limit was 2 eV.
Nailing down the neutrino’s mass could solidify scientists’ grasp on the Standard Model, which describes the subatomic world in fine detail. It could also open a path to the mysterious realm beyond the Standard Model.
In this artistic rendering, a blazar is accelerating protons that produce pions, which produce neutrinos and gamma rays. One neutrino’s path is represented by a blue line passing through Antarctica, while a gamma ray’s path is shown in pink. (IceCube / NASA Illustration)
An array of detectors buried under a half-mile-wide stretch of Antarctic ice has traced the path of a single neutrino back to a supermassive black hole in a faraway galaxy, shedding light on a century-old cosmic ray mystery in the process.
The discovery, revealed today in a flurry of research papers published by the journal Science and The Astrophysical Journal, marks a milestone for the IceCube Neutrino Observatory at the National Science Foundation’s Amundsen-Scott South Pole Station.
It also marks a milestone for an observational frontier known as multi-messenger astrophysics, which takes advantage of multiple observatories looking at the sky in different ways. Thanks to IceCube’s alert, more than a dozen telescopes were able to triangulate on the neutrino’s source.
“No one telescope could have done this by themselves,” said IceCube lead scientist Francis Halzen, a physics professor at the University of Wisconsin at Madison.
