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Fig. 13.5 This is what neutrino oscillation looks like. Left panel for atmospheric
neutrinos and right panel for Kamland reactor neutrinos
oscillations from accelerators, discussed below. The observation of atmospheric
neutrino oscillations is depicted in Fig. 13.5. These oscillations were then
confirmed in laboratory experiments using neutrinos from accelerators.
13.7 Neutrino Oscillations Confirmed by
Accelerator and Reactor Neutrinos
The Ray Davis experiment as well as the GALLEX, SAGE, Super-K, and
SNO experiments used naturally born neutrinos in the Sun, and the SuperK also used the neutrinos born in atmospheric particle collisions to confirm
the neutrino oscillations. The first five experiments confirmed the oscillations
of electron neutrinos to other species, i.e. ν e to ν μ , ν τ , whereas the Super-K
experiment using atmospheric neutrinos confirmed the oscillation of muon
neutrinos ν μ to ν τ and some to ν e . This meant that there is a force (mass
mixing) connecting all three known neutrinos, making the oscillations happen,
and that meant that the neutrinos are not massless, a fundamental new piece
of information about the neutrino.
These experiments were confirmed using neutrinos generated in accelerators. First, a word about how neutrino beams are created in the laboratory:
one starts with proton–proton collisions, which via strong forces produce
mesons, such as pions, along with two protons since the baryon number