Radiation Protection

A 4He nucleus, a helium isotope that contains two protons and two neutrons. The term alpha is reserved for 4He nuclei emitted during radioactive decay or as an ejectile in a nuclear reaction. The name alpha was coined by Rutherford in 1897.

Decay by emission of a beta particle. Three types of beta decay are common in nuclei: Neutron rich nuclei tend to decay by emitting a β- particle. An antineutrino is also emitted in this type of b decay and the it results in the nucleus converting a neutron into a proton. Neutron deficient nuclei tend to decay by positron emission or electron capture. Positron emission refers to the emission of a positron (β+), which is the antiparticle of the electron. A neutrino is emitted in the process and this results in the nucleus converting a proton into a neutron. Electron capture is usually classified as a type of beta decay and involves an orbital electron being absorbed by a nucleus, effectively converting a proton into a neutron.

The nuclide produced in radioactive decay.

A series of nuclides linked in a chain by radioactive decay. Each nuclide in the chain decays to the next until a stable nuclide is reached.

Heat produced through radioactive decay. It is especially important for fission products.

A particular type of radioactive decay. Examples include β- decay, β+ decay, a decay, internal transition, and spontaneous fission.

Electromagnetic radiation emitted by a nucleus with a very short wavelength. These radiations result from the de-excitation of an excited state in a nucleus. Individual gamma-ray quanta are also known as photons. Gamma rays were first observed by Villard in 1900.

Energy released by radioactive decay, through a nuclear reaction, or in the course of nuclear fission.

The energy released in a nuclear reaction or in radioactive decay as calculated from the difference in total energy (including rest mass) of the products (product nuclei and ejectiles) and reactants (target nuclei and projectiles). When applied to radioactive decay, the target nucleus is the parent nuclide, the daughter nucleus is the product nuclide, and there is no projectile.

Having the capacity to undergo spontaneous disintegration by the emission of radiation. The term applies to an atom, a collection of atoms or an object.

Spontaneous emission by a nucleus of photons or particles. The spontaneous transformation of one nuclide into another by emission of particles, absorption of an orbital electron, or by fission. It also refers to gamma-ray and conversion electron emission that only reduces the excitation energy of the nucleus.