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γ ray
A synonym for gamma ray.

Ga
A symbol for gallium.

gadolinium
A chemical element with atomic number 64. Gadolinium was discovered independently by two scientists. In 1880, Jean-Charles Marignac isolated the metallic oxide of gadolinium from the mineral samarskite. In 1886, Paul-émile Lecoq de Boisbaudran was able to isolate the element in fairly pure form. The two scientists agreed to name the element gadolinium in recognition of the Finnish chemist, Johan Gadolin.

Symbol: Gd.
Related to cerium earths.
Related to lanthanides.
Related to rare earths.


gallium
A chemical element with atomic number 31. Gallium was discovered by spectral analysis in 1875 by Paul émile Lecoq de Boisbaudran. The name gallium is derived from Gallia, Latin for Gaul, ancient France.

Symbol: Ga.

gamma radiation
A synonym for gamma ray.

gamma ray
Electromagnetic radiation emitted by a nucleus with a very short wavelength. These radiations result from the de-excitation of an excited state in a nucleus. Individual gamma-ray quanta are also known as photons. Gamma rays were first observed by Villard in 1900.

Reference: P. Villard. CR Acad. Sci. (Paris) 130, 1010, 1178 (1900).
Symbol: γ.
Synonym: γ ray.
Synonym: gamma photon.
Synonym: gamma radiation.
Synonym: gamma-ray photon.
Related to alpha particle.
Related to beta particle.
Related to electromagnetic radiation.
Related to x-rays.


gap
The space between a fuel pellet and the cladding in a fuel rod.

Related to fuel element.
Related to fuel pellet.


gas-cooled reactor
A nuclear reactor design which uses gas as a coolant.

Acronym: GCR.
Synonym: high temperature gas-cooled reactor.


gas counter
A synonym for ionization detector.

gaseous diffusion
A process of separating isotopes as gases by their slight difference in velocity. Lighter isotopes diffuse faster through a porous membrane or vessel than do heavier isotopes.

Related to isotopic abundance.

gaseous diffusion plant
A facility for separating isotopes or enriching the isotopic abundance of one isotope using gaseous diffusion.

Acronym: GDP.

gas-filled detector
A synonym for ionization detector.

gas flow counter
A gas ionization detector that does not have a window between the sample and the detection medium. Samples are placed inside the detector and the detection volume is flushed with a suitable detection gas.

GCR
An acronym for gas-cooled reactor.

Gd
A symbol for gadolinium.

GDP
An acronym for gaseous diffusion plant.

Ge
A symbol for germanium.

Geiger counter
A synonym for Geiger-Müller detector.

Geiger-Müller counter
A synonym for Geiger-Müller detector.

Geiger-Müller counter tube
A synonym for Geiger-Müller detector.

Geiger-Müller detector
A gas ionization detector. Geiger-Müller detectors consist of a tube containing a detection gas and electrodes. Radiations enter the tube through a thin window. The Geiger-Müller detectors operate at a high electrical potential, allowing accelerated ions to produce the maximum secondary ionization. The ionization process is quenched when the extensive secondary ionization distorts the electric field. This results in an easily detectable pulse for even the weakest of radiations.

Synonym: Geiger counter.
Synonym: Geiger-Müller counter.
Synonym: Geiger-Müller counter tube.
Synonym: GM counter.
Synonym: GM counter tube.
Synonym: GM detector.
Related to detection gas.
Related to quench.
Related to secondary ionization.
Related to window.


germanium
A chemical element with atomic number 32. Germanium was discovered in 1886 by Clemens Alexander Winkler. The name germanium was given in honor of Germany.

Symbol: Ge.
Related to metalloids.


giga
A unit prefix equivalent to 109.

gigawatt
A unit of power equivalent to 1 billion watts.

Symbol: GW.
Related to watt.


gigawatt hour
One billion watt-hours.

Related to watt-hour.

GM counter
A synonym for Geiger-Müller counter which is a synonym for Geiger-Müller detector.

GM counter tube
A synonym for Geiger-Müler counter tube which is a synonym for Geiger-Müller detector.

GM detector
A synonym for Geiger-Müller detector.

gold
A chemical element with atomic number 79. Gold has been known from antiquity.

Symbol: Au.
Synonym: aurum.
Related to transition metals.


graphite
A naturally-occurring form of crystalline carbon. Graphite is an excellent neutron moderator because carbon has a very low neutron capture cross section and a moderate scattering cross section.

Related to neutron capture cross section.
Related to scattering cross section.


gray
An SI unit of absorbed radiation dose. One gray is equivalent to an energy absorption of 1 J/kg. It has replaced the rad, an older standard. One gray is equivalent to 100 rad.

Symbol: Gy.
Related to absorbed dose.
Related to roentgen absorbed dose.
Related to sievert.
Reference: 10CFR10; NUREG-0544, Rev. 4.


GW
A symbol for gigawatt.

Gy
A symbol for gray.
Reference: 10CFR20.1004; 10CFR34.3; DOD 3150.8-M; DOE-HDBK-1106-97; USACHPPM TG 204.
 
 
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