| One can make separate detectors for electronic, muonic and tauonic neutrinos, because they take part in different reactions. Given a flux of neutrinos, e.g. coming from the Sun or from a nuclear reactor, one can use the different kinds of neutrino detectors to estimate the total flux and the fractions of the three kinds. With another set of detectors put somewhere else, at a great distance along the direction of propagation of the neutrino flux, i.e. where those neutrinos arrive later, one can measure again the fractions of the total flux. If one measures different fractions, and knowing the propagation time between the 2 locations, one can conclude that oscillations exist and measure the frequency of the oscillations. Nonetheless, this is much easier said than done, All neutrino experiments have extremely poor signal-to-noise ratios and all their results are affected by great uncertainties. The theory about the existence of the neutrino oscillations had been originally proposed as an explanation for the fact that the flux of neutrinos coming from the Sun was about 3 times smaller than predicted by the modelling of the fusion reactions inside the Sun. Later, experimental results from measuring the fractions of the different neutrino kinds at distant locations appeared to support the oscillation hypothesis. |