Gamma Decay

Gamma decay is a type of nuclear decay in which an unstable atomic nucleus emits a gamma ray – a high-energy electromagnetic wave.

When a nucleus undergoes gamma decay, its atomic and mass numbers do not change, and it does not become a different isotope or element. The nucleus changes from a higher-energy state to a lower-energy state.

Gamma decay takes its name from the third letter of the Greek alphabet, γ. The symbol for a gamma ray is γ. Gamma rays are also called gamma radiation.

An Example of Gamma Decay

Cobalt-60 is an isotope of cobalt that undergoes beta decay to nickel-60. The resulting nickel nucleus is in an excited state, and releases a gamma ray in order to reach a lower-energy state. The nuclear equation below represents this process.