NEUTRINOS IN PARTICLE PHYSICS AND ASTROPHYSICS

Neutrinos, first introduced for theoretical reasons, were discovered long ago, but their main properties have been established rather recently, especially by analyzing the so-called atmospheric and solar neutrinos. Now we know that there are three kinds of neutrinos that, in their propagation, get mixed among themselves through the mechanism of oscillations. In this paper we discuss this phenomenon and the main features of neutrinos; we mention also the neutrinos emitted by supernovae and the relic neutrinos. Neutrino telescopes represent a useful tool for investigating new phenomena both in particle physics and in astrophysics.