Today at Berkeley Lab

Finding the Flavor of Neutrinos

neutrinoA Berkeley Lab researcher has done a new analysis of data from the IceCube observatory at the South Pole, showing that the high-energy astrophysical neutrino data collected from 2010 to 2013 is a mixture containing roughly equal components of the three types of neutrinos. Gary Binder, a Nuclear Science Division graduate student who works with Spencer Klein, studied a collection of energetic neutrinos and divided them up based on how they interacted in the detector. From this, he estimated the flavor ratios. The ratios are consistent with neutrinos that were produced by conventional acceleration processes—like what is expected in supernova remnants or around super massive black holes—and then traveled long distances. Exotic models, involving new phenomena like neutrino decay or sterile neutrinos are ruled out or constrained. The analysis appeared in a recent issue of Physical Review Letters.