Ionizing radiation
Quantity Detector CGS units SI units Other units
Disintegration rate curie becquerel
Particle flux Geiger counter , proportional counter , scintillator counts / cm · second counts / metre · second counts per minute , particles per cm per second
Energy fluence thermoluminescent dosimeter , film badge dosimeter MeV / cm joule / metre
Beam energy proportional counter electronvolt joule
Linear energy transfer derived quantity MeV / cm Joule / metre keV / μm
Kerma ionization chamber , semiconductor detector , quartz fiber dosimeter , Kearny fallout meter esu / cm gray roentgen
Absorbed dose calorimeter rad gray rep
Equivalent dose derived quantity rem sievert
Effective dose derived quantity rem sievert BRET
Committed dose derived quantity rem sievert banana equivalent dose
Measurement
The table below shows radiation and dose quantities in SI and non-SI units . The relationships of the ICRP dose quantities are shown in the accompanying diagram . Graphic showing relationships between radioactivity and detected ionizing radiation
Ionizing radiation (ionising radiation) is radiation, traveling as a particle or electromagnetic wave, that carries sufficient energy to detach electrons from atoms or molecules, thereby ionizing them. Ionizing radiation is made up of energetic subatomic particles, ions or atoms moving at high speeds (usually greater than 1% of the speed of light), and electromagnetic waves on the high-energy end of the electromagnetic spectrum. [citation needed]
Gamma rays, X-rays, and the higher ultraviolet part of the electromagnetic spectrum are ionizing, whereas the lower ultraviolet part of the electromagnetic spectrum and all the spectrum below UV, including visible light (including nearly all types of laser light), infrared, microwaves, and radio waves are considered non-ionizing radiation. The boundary between ionizing and non-ionizing electromagnetic radiation that occurs in the ultraviolet is not sharply defined, since different molecules and atoms ionize at different energies. Conventional definition places the boundary at a photon energy between 10 eV and 33 eV in the ultraviolet (see definition boundary section below). Typical ionizing subatomic particles found in radioactive decay include alpha particles, beta particles and neutrons. Almost all products of radioactive decay are ionizing because the energy of radioactive decay is typically far higher than that required to ionize. Other subatomic ionizing particles which occur naturally are muons, mesons, positrons, and other particles that constitute the secondary cosmic particles that are produced after primary cosmic rays interact with Earth's atmosphere. Cosmic rays are generated by stars and certain celestial events such as supernova explosions. Cosmic rays may also produce radioisotopes on Earth (for example, carbon-14), which in turn decay and produce ionizing radiation. Cosmic rays and the decay of radioactive isotopes are the primary sources of natural ionizing radiation on Earth referred to as background radiation. Ionizing radiation can also be generated artificially by X-ray tubes, particle accelerators, and any of the various methods that produce radioisotopes artificially.