What are alpha, beta, and gamma radiations?

Alpha, beta, and gamma radiations are types of ionising radiation emitted by radioactive substances.

Alpha radiation, or alpha particles, are made up of two protons and two neutrons, essentially a helium nucleus. They are positively charged and relatively large, which makes them highly ionising but not very penetrating. They can be stopped by a sheet of paper or a few centimetres of air. Alpha particles are typically emitted by heavy, proton-rich unstable nuclei. The alpha decay process transforms a nucleus into a new element, reducing the atomic number by 2 and the atomic mass by 4.

Beta radiation, on the other hand, consists of high-speed electrons (beta-minus) or positrons (beta-plus) ejected from the nucleus. Beta-minus decay occurs when a neutron in the nucleus transforms into a proton, an electron, and an electron antineutrino. Beta-plus decay is the opposite, with a proton transforming into a neutron, a positron, and a neutrino. Beta particles are smaller and faster than alpha particles, making them less ionising but more penetrating. They can be stopped by a few millimetres of aluminium.

Gamma radiation is a form of electromagnetic radiation, similar to X-rays but with higher energy. It is emitted by the nucleus during radioactive decay or nuclear reactions. Unlike alpha and beta particles, gamma rays are not particles but waves, and they carry no charge. This makes them the least ionising but the most penetrating type of radiation, capable of passing through several centimetres of lead or metres of concrete. Gamma decay usually occurs after alpha or beta decay, when the remaining nucleus is in an excited state and needs to lose energy.

In summary, alpha, beta, and gamma radiations are all products of radioactive decay, but they differ in their composition, charge, ionising ability, and penetrating power. Understanding these differences is crucial for managing radiation safety and harnessing the power of nuclear energy.