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Types of Radiation

Fri, 03/06/2009 - 06:19 — admin

Radiation Penetration

Alpha Radiation
Alpha radiation is heavy, very short-range and is an ejected nuclei . Characteristics of alpha radiation are:
  • Does not penetrate human skin or clothing and is not an external hazard
  • Can be harmful to humans if the materials are inhaled, swallowed, or absorbed through open wounds.
  • Thin-window Geiger-Mueller (GM) probe can detect the presence of alpha radiation.
  • Cannot be detected through layers of water, dust, paper, or other material.
  • Travels only a short distance (a few cm) in air.


    • Examples of some alpha emitters: americium 241, radium, radon, uranium, thorium.

    Beta Radiation
    Beta radiation is a light, short-range and is an ejected electron. Characteristics of beta radiation are:

    • May travel a few metres in air and is moderately penetrating.
    • Beta radiation can penetrate human skin and prolonged exposure may cause skin injury.
    • Beta-emitting can be very harmful to humans if the materials are inhaled, swallowed, or absorbed through open wounds.
    • Can be detected with a thin-window GM probe, some beta emitters are very low-energy and are difficult to detect
    • Clothing provides moderate protection against beta radiation.

    Examples of some pure beta emitters: strontium-90, carbon-14, tritium, and sulfur-35.

    Gamma and X Radiation
    Gamma radiation and x rays are highly penetrating electromagnetic radiation. Characteristics of this radiation are:

    • Able to travel several metres in air and many centre metres in human tissue and are sometimes called "penetrating" radiation
    • Sealed radioactive sources and machines that emit this radiation are an external hazard to humans.
    • These electromagnetic radiations differ to light and radio waves only in the amount of energy they have.
    • Dense materials are needed for shielding, clothing provides little shielding but can prevent contamination of the skin by gamma-emitting materials.
    • Detected by GM probe and survey meters with a Scintillators such as sodium iodide.
    • Gamma radiation and/or characteristic x rays often accompany the emission of alpha and beta radiation during radioactive decay

      • Neutron Radiation
      Neutrons may be emitted during either spontaneous or induced nuclear fission, nuclear fusion processes, very high energy reactions such as in the accelerator-based neutron sources and in cosmic ray interactions.

    • Able to travel several metres through most materials
    • Sources and machines that emit this radiation are extremely hazard to humans.
    • Sometimes considered a more severe hazard due to neutron activation, the ability of neutron radiation to induce radioactivity in most substances it encounters
    • Dense materials are needed for shielding
    • Most commonly detected by with a Scintillators and other specialised equipment.
    • Neutrons also degrade materials; intense bombardment with neutrons creates dislocations in the materials, leading to embrittlement of metals and other materials.

      • Radiation Penetration