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In Nuclear physics Beta decay (sometimes called
neutron decay) is a type of radioactive decay in which a
beta particle (an electron
or a positron) is emitted. In the case of electron emission, it is referred to as
"beta minus"(β- ), in the case of a positron, "beta plus"(β+ ).
In beta minus decay, a neutron is converted to a proton via the weak nuclear force and a beta minus particle (an electron) and an anti-neutrino are emitted:
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In beta plus decay, a proton is converted to a neutron via the weak nuclear force and a beta plus particle (a positron) and a neutrino are emitted.
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Examples at nuclear level:
- Beta minus decay
- Beta plus decay
The study of beta decay provided the first physical evidence of the neutrino.
The energies of electrons emitted by beta decay were observed to be non-discrete (some being more energetic than others). A
problem arose in trying to explain what happened to the missing energy if an electron was emitted with less than maximum energy
— the Law of conservation of energy
appeared to be violated. To solve this, Wolfgang Pauli proposed that
the "missing" energy was carried away by another yet undiscovered particle — the neutrino. This was analysed in more detail by Enrico
Fermi.
See also: beta particle, particle radiation, radioactive
isotope
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