Beta decay

In nuclear physics, beta decay or a is a type of radioactive decay in which a beta particle (an electronpositron) is emitted. In the case of electron emission, it is referred to as beta minus (β^⁻), while in the case of a positron emission as beta plus (β⁺). Kinetic energy of beta particles has continuous spectrum ranging from 0 to maximal available energy (Q), which depends on parent and daughter nuclear states participating in the decay. Typical Q is around 1 MeV, but it can range from a few keV to a few tens of MeV. Like the equivalence of energy of the rest mass of electron is 511 keV, the most energetic beta particles are ultrarelativistic, with speeds very close to the speed of light.