Beta Rays

Synonyms

Beta electrons

Definition

A beta ray is a stream of beta particles (electrons or positrons). In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted.

Overview

In the case of electron emission, the decay is referred to as beta minus (β⁻), while in the case of a positron emission as beta plus (β⁺). In beta minus decay, a neutron is converted to a proton, an electron, and an antineutrino; in beta plus decay, a proton is converted to a neutron, a positron, and a neutrino:

$$ n\to p+{\textrm{e}}^{-}+{\overline{\nu}}_{\textrm{e}} $$

$$ p\to n+{\textrm{e}}^{+}+{\nu}_{\textrm{e}} $$

If the proton and neutron are part of an atomic nucleus, these decay processes transmute one chemical element into another. Beta decay does not change the number of nucleons in the nucleus but changes only its charge. For example:

$$ {}^{90}\textrm{Sr}{\to}^{90}\textrm{Y}+{\textrm{e}}^{-}+{\nu}_{\textrm{e}} $$

The kinetic energy of beta particles has a continuous...