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Beta radiation is a form of ionizing radiation
emitted by certain types of radioactive nuclei such as cobalt-60.
This radiation is in the form of beta (β) particles, which are high-energy electrons or positrons ejected from a nucleus in a process known as beta decay. There are
two forms of beta decay, β− and β+, which respectively give rise to the electron and
positron.
In β−-decay, a neutron is converted into a proton, an electron and an electron-type antineutrino (the antiparticle of the neutrino):
In β+-decay—observed in proton-rich nuclei—a proton is converted into a neutron, a positron and an
electron-type neutrino:
Due to the presence of the neutrino, the atom and the beta particle do not usually recoil in opposite directions. This observation is in fact what led Wolfgang Pauli to postulate the existence of neutrinos in order to prevent violation of conservation of
energy and momentum laws. Beta decay is mediated by the weak nuclear force.
Beta particles generally have a range about ten times as far as alpha
particles and an ionizing power about a tenth of that of alpha particles. They are
stopped completely by a few millimeters of aluminium.
The electron gun inside a television tube could also be considered a source
of beta radiation, which is absorbed by the phosphor coating inside the tube to
create light.
see also alpha particle, gamma rays, radioactivity, radiation, nuclear physics, list of particles
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