Neutrino mass: the rest mass of Neutrino particles.
►Neutrinos are generated in radioactive processes (beta decay). Since they are therefore also produced in the sun and in other stars, a great many of them constantly flow through the universe. We, too, are hit by millions of neutrinos every second. Nonetheless, neutrinos are among the hardest elementary particles to observe, for they are extremely small and lightweight and have no electrical charge. This is why they can easily permeate heavy bodies, including whole planets.
The classic standard model of physics does not give us any information about whether neutrinos also have a rest mass in addition to the mass generated by their motion. Certain extensions of the standard model, however, do predict neutrino rest mass, since without it one kind of neutrino could not change into another. Due to the great number of existing neutrinos, neutrino rest mass — as small as it may be — could also contribute to ►dark matter.
Giant underground neutrino detectors that are insulated against all other types of particles have found some evidence in favor of a tiny amount of neutrino mass below 0.000002 GeV. However, further research is required for a more precise measurement of this quantity. To facilitate further experiments, in 2006 a neutrino beam was switched on at the CERN research center in Geneva, Switzerland, that is aimed through the Earth to the INFN Gran Sasso Laboratories some 730km away near Rome, Italy. There, scientists hope to be able to obtain more precise measurements of the neutrino mass based on the number of neutrino changes that occur on the route of the beam. Perhaps this will also bring as a little closer to solving the puzzle of dark matter.