|Schéma de désintégration|
This nucleus of radium-226, the ons discovered by Marie Curie, decays directly in 93 % of the case in a nucleus of radon by emitting an alpha. I, 7 % of the cases, the nucleus of radon is left in an excited state. Very rapidly, the excited nucleus get rid of this excess of energy, by emitting a gamma ray. Physicists have the habit of reprenting the various decays modes of a nucleus by decay charts similar to the one reprented on the right. The emission of gamma very often accompany the transformations of nuclei.