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Gamma Decay

In a gamma decay, an excited nucleus comes down to a less excited (lower energy, more stable) state by emitting a gamma ray.


Wize Tip
This is very similar to photon emission of the atomic orbitals.


Since the basic structure of the nucleus does not change, the element stays the same. Therefore both the atomic number ZZ and the mass number AA are the same.exciting

The decay equation is:

 ZAX  ZAX+γ \boxed{ \ _Z^A X^*\to \ \ _Z^A X+\gamma \ }






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Wize Concept
  • After a nucleus has undergone alpha or beta decay, it can still be excited, and it will emit gamma photons to return to the ground state.
  • The nucleus can get excited by being bombarded with photons, or at high temperatures.


Exam Tip
Remember that gamma rays aren't particles but waves, so they have no mass or charge. They are the kind of electromagnetic radiation with the highest energy, and move at the speed of light.


Wize Concept
Since gamma rays have no mass, they have the highest energy of the different types of decay.

A few inches of lead or a meter of concrete will be needed to stop most gamma rays!