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 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
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.