gamma radiation

gamma radiation

gamma radiation, high-energy photons emitted as one of the three types of radiation resulting from natural radioactivity. It is the most energetic form of electromagnetic radiation, with a very short wavelength (high frequency). Wavelengths of the longest gamma radiation are less than 10-10 m, with frequencies greater than 1018 hertz (cycles per sec). Gamma rays are essentially very energetic X rays; the distinction between the two is not based on their intrinsic nature but rather on their origins. X rays are emitted during atomic processes involving energetic electrons. Gamma radiation is emitted by excited nuclei (see nucleus) or other processes involving subatomic particles; it often accompanies alpha or beta radiation, as a nucleus emitting those particles may be left in an excited (higher-energy) state. The applications of gamma radiation are much the same as those of X rays, both in medicine and in industry. In medicine, gamma ray sources are used for cancer treatment and for diagnostic purposes. Some gamma-emitting radioisotopes are also used as tracers (see radioactive isotope). In industry, principal applications include inspection of castings and welds. Data from artificial satellites and high-altitude balloons have indicated that a flux of gamma radiation is reaching the earth from outer space, thus opening up the field of research known as gamma-ray astronomy.
Gamma (uppercase Γ, lowercase γ; Γάμμα) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. It was derived from the Phoenician letter Gimel . Letters that arose from Gamma include the Roman C and G and the Cyrillic letters Ge Г and Ghe Ґ.

In Modern Greek, it represents either a voiced velar fricative /ɣ/ or a voiced palatal fricative /ʝ/. In Ancient Greek, it represented a voiced velar stop /ɡ/. Before velars, it represents a velar nasal /ŋ/ in Modern as well as Ancient Greek, and a double gamma represents a prenasalized voiced velar stop (/ŋɡ/).

Gamma combinations

The gamma can be combined with other letters or itself.

  • A double gamma (γγ) is pronounced like the ng in "jumping"
  • A gamma with xi (γξ) is pronounced roughly like the nx in "Sphinx"
  • (γχ) is pronounced like the nkh in "ankh"
  • A gamma combined with kappa (γκ) is pronounced like the nk in "banker"

Use as a symbol or a term

Gamma is often used to denote a variable in mathematics and physics. In certain areas it has a specific meaning, such as representing gamma radiation in nuclear physics and the Lorentz factor in theory of relativity. In mathematics, there is a gamma function (usually written as Γ-function.)

See also

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