The Beta decay reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Beta decay

Nuclear processes

Radioactive decay processes Alpha decay Beta decay Electron capture Gamma radiation Neutron emission Positron emission Proton emission Spontaneous fission Nucleosynthesis Neutron Capture The R-process The S-process Proton capture: The P-process

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:

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.

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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