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Properties of Radiation

Different radiations have different properties, as summarized below:

Radiation Type of Radiation Mass (AMU) Charge Shielding material
Alpha Particle 4 +2 Paper, skin, clothes
Beta Particle 1/1836 1 Plastic, glass, light metals
Gamma Electromagnetic Wave 0 0 Dense metal, concrete, Earth
Neutrons Particle 1 0 Water, concrete, polyethylene, oil

In summary, the most common types of radiation include alpha particles, beta and positron particles, gamma and x-rays, and neutrons. Alpha particles are heavy and doubly charged which cause them to lose their energy very quickly in matter. They can be shielded by a sheet of paper or the surface layer of our skin. Alpha particles are only considered hazardous to a persons health if an alpha emitting material is ingested or inhaled. Beta and positron particles are much smaller and only have one charge, which cause them to interact more slowly with material. They are effectively shielded by thin layers of metal or plastic and are again only considered hazardous if a beta emitter is ingested or inhaled.

Gamma emitters are associated with alpha, beta, and positron decay. X-Rays are produced either when electrons change orbits within an atom, or electrons from an external source are deflected around the nucleus of an atom. Both are forms of high energy electromagnetic radiation which interact lightly with matter. X-rays and gamma rays are best shielded by thick layers of lead or other dense material and are hazardous to people when they are external to the body.

Neutrons are neutral particles with approximately the same mass as a proton. Because they are neutral they react only weakly with material. They are an external hazard best shielded by thick layers of concrete. Neutron radiation will be discussed in more detail in the discussion of nuclear power.