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neutrino
subject			fact

neutrino	has antiparticle antineutrino
	has definition An electrically neutral, very weakly interacting particle, with a rest energy which is either zero or very small. The particle was predicted in 1931 as a means of reconciling the measurements of beta decays with the conservation of energy, but it was not directly detected until 1956.
	has definition Chargeless species of particle, subject only to the weak force.
	has definition An electrically neutral, massless particle of spin-1/2, which interacts only by the weak force and gravity. It was first postulated by Pauli in 1930 to ensure conservation of energy and angular momentum in nuclear β decay. Three different types of neutrinos are known to exist corresponding to the three massive leptons: νe, νµ and ν τ.
	has definition A fundamental elementary particle with no electric charge and very small if any rest mass. Believed to be exceedingly abundant in the universe. The neutrino has a very low cross-section for interaction with matter and is almost impossible to detect, hence the uncertainty over its rest mass. The Sun produces neutrinos from thermonuclear reactions in its core, and a large flux of neutrinos carries away most of the energy, of a supernova. Neutrinos are one candidate for Dark Matter. Experiments to detect cosmic neutrinos involve large masses of "stopping" material and indirect detection of the effects of neutrino absorption.
	has definition A stable particle with no charge, a rest mass of zero, and a spin of 1/2, that carries away energy in the course of nuclear reactions. Its main characteristic is the weakness of its interactions with all other particles. Since the wavelengths of neutrinos at the energies at which they are normally emitted from unstable nuclei are only a few thousandths of an angstrom (compared with the wavelength of a light photon which is several thousand angstroms), they have negligible probability (10-19 that of a light photon) of interacting with matter and escape at the speed of light. Neutrinos arise only in the energy-producing regions of stars and therefore, unlike light photons, provide direct evidence of conditions in stellar cores. There are two types of neutrinos, those associated with electrons (ve) and those associated with muons (vµ).
	is a kind of lepton
	is a kind of neutral particle
	is a kind of massless particle
lepton	has spin 1/2
massless particle	has mass 0
neutral particle	is not accelerated by electric or magnetic fields
	has charge 0
fermion	has quantum behavior Fermi-Dirac statistics
	obeys exclusion principle
particle	obeys uncertainty principle
	has frequency inversely proportional to the wavelength
	has wavelength inversely proportional to its momentum
physical object	has location or center of gravity
	has angular momentum
	has velocity
	has momentum
	has temperature
	has volume
	has extent
	has material

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