What is radiation?
Radiation (science term for ionizing radiation) is the flux of photons, elementary particles or atomic nuclei that can ionize matter.
The ionizing radiation does not include visible light and ultraviolet radiation, which in some cases can ionize a substance. Infrared radiation and radio-frequency radiation are not ionizing, because their energy is not enough to ionize atoms and molecules in the main state.
The most significant types of ionizing radiation are:
1) Short-wave electromagnetic radiation (high-energy photon flux):
- x-ray radiation;
- gamma radiation.
2) Particle flows:
- beta particles (electrons and positrons);
- protons, muons and other elementary particles;
- ions, including alpha particles, fission fragments (arising in nuclear fission), clusters (light nuclei which emitted during cluster decay).
Natural sources of ionizing radiation:
- Spontaneous radioactive decay of radionuclides.
- Thermonuclear reactions, for example, on the Sun.
- Induced nuclear reactions as a result of entry into the nucleus of high-energy elementary particles or nuclear fusion.
- Cosmic rays.
Artificial sources of ionizing radiation:
- Artificial radionuclides.
- Nuclear reactors.
- Accelerators of elementary particles (X-ray apparatus, as a kind of accelerators, generates X-ray bremsstrahlung).