Glossary of terms used on this site
All
| Term | Definition |
|---|---|
| Electromagnetic spectrum |
All electromagnetic radiations displayed as a continuum in order of increasing frequency or decreasing wavelength. |
| Electromagnetic wave |
See electromagnetic radiation. |
| Electron |
An elementary particle with low mass, 1/1836 that of a proton, and unit negative electric charge. Positively charged electrons, called positrons, also exist. See also beta particle. |
| Electron volt |
Unit of energy employed in radiation physics. Equal to the energy gained by an electron in passing through a potential difference of 1 volt. Symbol eV. 1 eV = 1.6 × 10-19 joule approximately. |
| Element |
A substance with atoms all of the same atomic number. |
| Emergency reference level |
One of a dual set of doses likely to be averted by the introduction of countermeasures to protect the public from ionising radiation after a nuclear or other serious accident. |
| EMF |
Electromagnetic field. Not to be confused with the initials for electromotive force. |
| Enriched uranium |
Uranium in which the content of the isotope uranium-235 has been increased above its natural value of 0.7% by weight. |
| ERL |
See emergency reference level of dose. |
| Erythema |
Reddening of the skin caused by dilation of blood vessels. |
| Excitation |
A process by which radiation imparts energy to an atom or molecule without causing ionisation. Dissipated as heat in tissue. |
| Fallout |
The transfer of radionuclides produced by nuclear weapons from the atmosphere to earth; the material transferred. |
| Fast neutrons |
Conventionally, neutrons with energies in excess of 0.1 MeV. Corresponding velocity of about 4 × 106 m s-1 |
| Fast reactors |
See nuclear reactor. |
| Fission |
Nuclear fission. A process in which a nucleus splits into two or more nuclei and energy is released. Frequently refers to the splitting of a nucleus of uranium-235 into two approximately equal parts by a thermal neutron with emission of other neutrons. |