What is beta decay?

Beta decay comes in two main forms: beta-minus decay, where a neutron becomes a proton and emits an electron and an antineutrino, and beta-plus decay, where a proton becomes a neutron and emits a positron and a neutrino. The process was key to understanding the weak interaction and the need for neutrinos, which were proposed in 1930 and detected directly only in 1956. Beta decay changes one element into another, so it is important in nuclear physics and some forms of medical imaging and therapy. It also plays a major role in the natural radioactivity of certain isotopes.