Gamma Decay of Cobalt 60 nuclide
In gamma decay, a nucleus changes from a higher energy state to a lower energy state through the emission of electromagnetic radiation (photons).
The number of protons (and neutrons) in the nucleus does not change in this process, so the parent and daughter atoms are the same chemical element. In the gamma decay of a nucleus, the emitted photon and recoiling nucleus each have a well–defined energy after the decay. The characteristic energy is divided between only two particles.
Gamma decay is composed of electromagnetic rays. It is distinguished from x–rays only by the fact that it comes from the nucleus. Most gamma rays are somewhat higher in energy than x–rays and therefore are very penetrating. It is the most useful type of radiation for medical purposes, but at the same time it is the most dangerous because of its ability to penetrate large thicknesses of material.