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Ionizing radiation

Ionizing radiation

Radiation that carries enough energy to liberate electrons from atoms or molecules

Ionizing radiation (inaccurate synonym with a broader meaning - radiation) - streams of photons and other elementary particles or atomic nuclei capable of ionizing matter.

Ionizing radiation does not include visible light and ultraviolet radiation, which can ionize matter in certain cases. Infrared radiation and radiation in the radio bands are not ionising radiation, as their energy is not sufficient to ionise atoms and molecules in the ground state


Paints using uranium and other radioactive materials were in use long before our era, but their radiation was so low that it could not be detected. A major step in the discovery of radioactivity was made by the German chemist Martin Heinrich Klaproth in 1789. He obtained a dark, unknown substance from tarry ore and named it Uranus, though in time it turned out that it was not pure uranium, but its oxide. In 1804, the chemist Adolph Gehlen discovered light sensitivity of uranyl chloride solution in ether, he was interested in the effect but had no real explanation, so the discovery remained unnoticed in the scientific community at that time[8]. The proof of ionising radiation was the discovery in the 1860s of cathode rays (streams of electrons accelerated in a vacuum tube by high voltage). The next discovered type of ionising radiation was X-rays (Wilhelm Röntgen, 1895). In 1896 Henri Becquerel discovered another type of ionising radiation - invisible rays emitted by uranium, which pass through a solid, opaque substance and light up the photoemulsion (in modern terminology - gamma rays). Further research into the phenomenon of radioactivity led to the discovery (Ernest Rutherford, 1899), that radioactive decay emitted alpha-, beta- and gamma rays, differing in a number of properties, in particular, in electric charge. Subsequently, other types of ionising radiation arising from the radioactive decay of nuclei have also been discovered: positrons, conversion and Auger-electrons, neutrons, protons, fission fragments, clusters (light nuclei emitted during cluster decay). In 1911-1912, cosmic rays were discovered.

The nature of ionising radiation

The following types of ionising radiation are the most significant:

Shortwave electromagnetic radiation (high energy photon flux):


gamma rays.

Particle fluxes:

Beta particles (electrons and positrons);


protons, muons and other elementary particles;

ions, including alpha particles, fission fragments (produced by nuclear fission), clusters (light nuclei emitted during cluster decay).


Further Resources


Ionizing Radiation



June 29, 2021

What is ionizing radiation?


November 16, 2016

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