Ionizing radiation From Wikipedia, the free encyclopedia Jump to: navigation, search Ionizing radiation hazard symbol 2007 ISO radioactivity danger symbol. The red background is intended to convey urgent danger, and the sign is intended to be used in long-term radioactive waste depositories, which might survive into a distant future where other danger symbols may be forgotten or misinterpreted. Ionizing (or ionising) radiation is radiation composed of particles that individually carry enough kinetic energy to liberate an electron from an atom or molecule, ionizing it.[1] Ionizing radiation is generated through nuclear reactions, either artificial or natural, by very high temperature (e.g. plasma discharge or the corona of the Sun), 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 an atomic particle (typically an electron, proton, or neutron, 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 because chemical bonds will be broken in this process. If the atom were inside a crystal lattice in a solid phase, then a hole would exist where the original atom was. Ionizing radiation includes both subatomic particles of matter moving at relativistic speeds and electromagnetic waves on the short wavelength end of the electromagnetic spectrum, which act like energetic particles. Common particles include alpha particles, beta particles, neutrons, and various other particles such as mesons that constitute cosmic rays.[2][3][1] Electromagnetic waves are ionizing if their wavelength is short enough that the photons have enough energy to ionize. Gamma rays, X-rays, and the upper vacuum ultraviolet part of the ultraviolet spectrum are ionizing, while the lower ultraviolet, visible light (including laser light), infrared, microwaves and radio waves are considered non-ionizing radiation.[1][3] 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.
Posted on: Sat, 26 Oct 2013 12:14:06 +0000