what is β-decay?

Beta decay is the radioactive decay in which an electron or a positron is emitted by the nucleus of an atom. When a neutron converts into a proton and an electron is emitted with some kinetic energy we call it a beta minus decay.

Example:

₁₅P³² ---> ₁₆S³² + _-1e⁰

When a proton is converted into a neutron and a positron is emitted we call it beta plus decay.

Example:

₆C¹¹ ---> ₅B¹¹ + e⁺

In a beta decay the atomic number of the new nucleus is more than the original nucleus but there is no change in mass number. The emitted particles have a continuous range of kinetic energy with the speed of some particles very close to the speed of light.