Detection of the neutrino

The neutrino, a nearly undetectable particle proposed to exist two decades earlier, was observed using nuclear fission reactors. More specifically, it's antiparticle the antineutrino was observed, and neutrinos themselves were later detected in solar radiation.
 Frederick Reines and Clyde Lorrain Cowan United States 1956 Detection of the neutrino

The neutrino, a nearly undetectable particle proposed to exist two decades earlier, was observed using nuclear fission reactors. More specifically, it's antiparticle the antineutrino was observed, and neutrinos themselves were later detected in solar radiation.