Science Made Simple: What Is Beta Decay?

What Is Beta Decay?
Beta decay is the most common form of radioactive decay. It happens in one of two ways. In one type of beta decay, an unstable atomic nucleus emits an electron and an antineutrino while converting a neutron to a proton. In the second type, the unstable nucleus emits a positron (a positively charged electron, also called an antielectron) and a neutrino while converting a proton to a neutron. Positrons and electrons are beta particles. Scientists have observed beta decay in 97% of all known unstable isotopes. It occurs in nuclei with too many neutrons or too many protons.

Scientists have observed two main types of beta decay. The first is beta-minus decay. In this form, a nucleus emits an electron and an antineutrino (the antimatter form of a neutrino). This process changes a neutron in the nucleus into a proton. The second type of beta decay is beta-plus decay. In this form, the nucleus emits a neutrino and a positron (the antimatter form of an electron). This process changes a proton in the nucleus into a neutron.