Visible light, radio waves, infrared and ultraviolet radiations, X-rays are carried by tiny electromagnetic waves: the photons. The higher the energy of these waves is, the shorter their wavelength. In Nature, photons are emitted and absorbed by atoms. Photons are also emitted by nuclei in an excited state. These are the gamma photons (γ) whose energy, the largest of naturally occurring photons, can be of the order of 1 million electronvolts.

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Gamma Rays (γ)