Alpha Radiation

Alpha particles are highly charged, heavy and slow moving (helium nuclei). Because of their high electrical charge and slow speed, alpha particles interact very strongly with the atoms through which they pass and therefore, they have a very limited range. Most alpha particles will not penetrate a sheet of paper nor will they penetrate the dead layer of skin. Because of this, alpha radiation does not cause an external radiation hazard. However, alpha radiation can be a serious internal radiation hazard and precautions must be taken to prevent internal uptake of alpha-emitting radioisotopes, particularly since they tend to accumulate in specific body organs and deliver high local doses.

Alpha decay results in monoenergetic alpha particles, meaning that all of the alpha particles emitted by a particular isotope, undergoing a particular nuclear transition, have the same energy. Alpha emission is common only from elements with a high atomic number (83 or higher) and is usually accompanied by one or more other types of radiation.

Common alpha-emitting isotopes are polonium-210, radium-226, radon-222, thorium, and uranium compounds.

Alpha emitters must be stored in such a way that leakage or other releases are avoided. This is accomplished by storing the alpha emitter in a container with a tight seal and opening it only in a fume hood. Alpha emitters should be stored in a fume hood, however, as with any storage, care must be taken to avoid disturbing the air flow into the fume hood by storing large containers near the entrance to the fume hood.

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