Ionising radiation

Alpha particles are helium nuclei.
1. An alpha particle if 2 neutrons and 2 protons - The same as a helium nucleus.
2. They are relatively big, heavy and slow moving
  1. They therefore don't penetrate very far into materials and are stopped quickly, even when travelling through air.
    1. A piece of paper or 5cm of air will stop it.
3. Because of their size they are strongly ionising, which just means they bash into a lot of atoms and knock electrons off them before they slow down.
  1. This creates lots of ions - hence the term ionising.
Beta particles are electrons.
1. Beta particles are in between alpha and gamma in terms of their properties.
2. They move quite fast and are very small (the same size as a normal electron).
3. They are penetrate moderately into materials before colliding have a long range in air, and are moderately ionising too.
  1. A piece of aluminum 5mm thick or 1m of air will stop it.
4. For every beta particle emitted, a neutron turns into a proton in the nucleus.
5. A beta particle is simply an electron, with virtually no mass and a charge of -1.
Gamma rays have a very short wave length, they are essentially an electromagnetic wave.
1. Gamma rays are the opposite to alpha particles in terms of their properties.
2. They penetrate far into materials without being stopped and pass straight through air.
  1. Only 1m of concrete and no amount of air will stop it.
3. They are weakely ionising because they tend to pass through rather than collide with atoms. Eventually they do hit something and do damage.
4. Gamma rays have no mass and no charge.

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Ionising radiation

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	Created by jessica-gollop over 11 years ago