Ionizing Radiation

Ionizing Radiation

Ionizing (or ionising) radiation is radiation composed of particles that individually carry enough energy to liberate an electron from an atom or molecule, ionizing it. Ionizing radiation is generated through nuclear reactions, either artificial or natural, by very high temperature (e.g. the corona of the Sun), or via production of high energy particles in particle accelerators, or due to acceleration of charged particles by the electromagnetic fields produced by natural processes, from lightning to supernova explosions.

When ionizing radiation is emitted by or absorbed by an atom, it can liberate a particle (usually an electron, but sometimes an entire nucleus) from the atom. Such an event can alter chemical bonds and produce ions, usually in ion-pairs, that are especially chemically reactive. This greatly magnifies the chemical and biological damage per unit energy of radiation.

Ionizing radiation includes cosmic rays, alpha, beta and gamma rays, X-rays, and in general any charged particle moving at relativistic speeds. Neutrons are considered ionizing radiation at any speed. Ionizing radiation includes some portion of the ultraviolet spectrum, depending on context. Radiowaves, microwaves, infrared light, and visible light are normally considered non-ionizing radiation, although very high intensity beams of these radiations can produce sufficient heat to exhibit some similar properties to ionizing radiation, by altering chemical bonds and removing electrons from atoms.

Ionizing radiation is ubiquitous in the environment, and comes from naturally occurring radioactive materials and cosmic rays. Common artificial sources are artificially produced radioisotopes, X-ray tubes and particle accelerators. Ionizing radiation is invisible and not directly detectable by human senses, so instruments such as Geiger counters are usually required to detect its presence. In some cases it may lead to secondary emission of visible light upon interaction with matter, such as in Cherenkov radiation and radioluminescence. It has many practical uses in medicine, research, construction, and other areas, but presents a health hazard if used improperly. Exposure to ionizing radiation causes damage to living tissue, and can result in mutation, radiation sickness, cancer, and death.