Experimental evidence for these objects was first obtained by Project Spectre at Savannah River by Cowan and Reines. Proposed because two-body collisions cannot in general conserve both momentum and kinetic energy, one type of these also conserves lepton number in beta decay. Postulated by Pauli in 1930 and named by Fermi, these elementary particles were initially thought to be massless, but this was undermined experimentally in the 1990's, with evidence of oscillation among their flavors. FTP, 
Experimental evidence for these objects was first obtained by Project Spectre at Savannah River by Cowan and Reines. Proposed because two-body collisions cannot in general conserve both momentum and kinetic energy, one type of these also conserves lepton number in beta decay. Postulated by Pauli in 1930 and named by Fermi, these elementary particles were initially thought to be massless, but this was undermined experimentally in the 1990's, with evidence of oscillation among their flavors. FTP, name these uncharged leptons denoted nu, many of which are emitted by the sun, but very few of which react with matter.
Experimental evidence for these objects was first obtained by Project Spectre at Savannah River by Cowan and Reines.
neutrinos [prompt on nus]