4.2.2 Types of Radiation

Types of Nuclear Radiation

Alpha Radiation (α)

• Description:
• An alpha particle is emitted from the nucleus.
• Composed of 2 neutrons and 2 protons (same as helium).
• Large and can travel around 5 cm in the air before they collide with air particles and stop.
• Penetration:
• Stopped by a single sheet of paper.
• Ionisation:
• Very strongly ionising.

Beta Radiation (β)

• Description:
  • A beta particle is an electron which is ejected from the nucleus at a very high speed.
  • Formed inside the nucleus when a neutron spontaneously changes into a proton and an electron.
  • Travels about 15 cm in the air before stopping.
• Penetration:
  • Stopped by a few millimetres of aluminium.
• Ionisation:
  • Quite strongly ionising.

Gamma Radiation (γ)

• Description:
  • Electromagnetic radiation from the nucleus.
  • Travels several meters in air before stopping.
• Penetration:
  • Absorbed by thick sheets of lead or meters of concrete.
• Ionisation:
  • Weakly ionising compared to alpha and beta radiation.