Neutrinos

Neutrinos represent a new "window" to the Universe, spanning a large range of energy. We discuss the science of neutrino astrophysics and focus on two energy regimes. At "lower" energies (approximate to 1 MeV). studies of neu trinos born inside the sun, or produced in interactions of cosmic rays with the atmosphere, have allowed the first incontrovertible evidence that neut rinos have mass. At energies typically one thousand to one million times hi gher, sources further than the sun (both within the Milky Way and beyond) a re expected to produce a flux of particles that can be detected only throug h neutrinos.