Gamma radiation


Unstable nuclei seek their equilibrium in different ways. One way is to emit gamma radiation. Gamma rays are waves of pure energy, without mass. Like all electromagnetic waves, they move at the speed of light: 300.000 kilometres/second. Their energy is determined by their frequency, which is the number of waves per second.

Gamma rays have a very high penetrating power in the surrounding matter and can only be stopped by a dense material like iron, concrete or lead. The thickness of material required can be anything from a few centimetres to a few metres, depending on the intensity of the radiation. Gamma radiation can pass through hundreds of metres of air without any appreciable loss of energy.

Alpha and beta radiation

Alpha and beta rays are not waves. They are high-energy particles that are expelled from unstable nuclei.

In the case of alpha radiation, the energy particles are relatively large and heavy (they are helium atoms consisting of two protons and two neutrons). As a result, alpha rays are not very penetrating and are easily absorbed. A sheet of paper or a 3-cm layer of air is sufficient to stop them. The particles leave the nucleus at a speed of 16.000 kilometres/second.