Alpha radiation

Alpha radiation (alpha rays) is one of the forms of ionizing radiation; is a stream of fast-moving, with considerable energy, positively charged particles (alpha particles).
The primary source of alpha-radiation are alpha-emitters - radioactive isotopesthat emit alpha particles in the process of disintegration. Feature of alpha radiation is its low penetration power. Mileage alpha-particles in matter (i.e. the way in which they produce ionization) is very short (a few hundredths of a millimeter in biological environments, 2,5-8 cm in air). However, along a short path alpha particles create a large number of ions, i.e cause large linear density of ionization. This provides expressed relative biological effectiveness, 10 times more than the influence of x-ray and gamma-radiation. When external irradiation of the body of alifatici are large enough absorbed radiation dose) to cause strong, although surface (short run) burns; when ingested through the mouth of long-lived alpha-emitters are posted on the body by the blood stream and are deposited in organs of the reticuloendothelial system and others, causing internal irradiation of the body. Alpha radiation is used to treat certain diseases. Cm. also alpha therapy, ionizing Radiation.

Alpha radiation is a stream of positively charged alpha-particles (nuclei of helium atoms).
The primary source of alpha-radiation are natural radioactive isotopes, many of which emit during the collapse of alpha-particles with energies from 3,98 to 8.78 MeV. Thanks energy, twice (in comparison with electron) charge and relatively small (compared with other types of ionizing radiation) speed (from 1.4·109 to 2.0·109 cm/s) alpha-particles create a very large number of ions, densely located on their way (up to 254 thousand pairs of ions). However, they quickly expend your energy is converted into ordinary helium atoms. The ranges of alpha-particles in the air under normal conditions - from 2.50 to 8,17 cm; in biological mediums - hundredth of a millimeter.
Linear density of ionization produced by the alpha particles reaches several thousand pairs of ions on 1 micron path in the tissues.
Ionization produced by the alpha-radiation, causes the number of features in those chemical reactions that take place in the substance, in particular in living tissue (the formation of strong oxidizing agents of free hydrogen and oxygen, and others). These radio-chemical reaction occurring in biological tissues under the influence of alpha-radiation, in turn, cause a special, more than other types of ionizing radiation, the biological effectiveness of alpha radiation. Compared to x-ray, beta and gamma radiation of the relative biological effectiveness of alpha radiation (RBE) equals 10, although in different cases it can vary widely. Like other types of ionizing radiation, A. research is used for the treatment of patients with various diseases. This section radiation therapy is called alpha therapy (see).
Cm. also ionizing Radiation, Radioactivity.