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radioactive decay

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absolute dating

Overview page. Subjects: Archaeology — Environmental Science.

A range of methods for determining the absolute age of an object or material, for example using radiometric dating which measures the decay product produced by radioactive decay in...

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alpha decay

Overview page. Subjects: Earth Sciences and Geography — Ecology and Conservation.

The decay of a radionuclide (radioactive nuclide) by the spontaneous emission from its nuclei of alpha particles. An alpha particle is composed of two protons and two neutrons and has a...

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beta decay

Overview page. Subjects: Science and Mathematics.

Some unstable atoms decay by emitting a negatively charged beta particle (negatron) from the nucleus, often accompanied by the emission of radiant energy (gamma rays). Beta decay may be...

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closure age

Overview page. Subjects: Earth Sciences and Geography.

The time at which diffusion within a mineral or rock of a daughter product of a radioactive decay system becomes negligible compared to accumulation, so that the system becomes ‘closed’,...

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closure temperature

Overview page. Subjects: Earth Sciences and Geography.

The temperature at which a rock that is cooling ceases to exchange the products of radioactive decay with the surrounding material. It is the temperature at which the rock becomes a closed...

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dating methods

Overview page. Subjects: Environmental Science.

During the last century geologists constructed a relative time-scale based on correlation of palaeontological and stratigraphic data. Depositional rates of sediments have also been employed...

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decay constant

Overview page. Subjects: Ecology and Conservation — Earth Sciences and Geography.

Radioactive decay involves only the nucleus of the parent atom, and thus the rate of decay is independent of all physical and chemical conditions (e.g. pressure, temperature, etc.). The...

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decay curve

Overview page. Subjects: Earth Sciences and Geography — Ecology and Conservation.

A graphic representation of the rate of decay of a radioactive isotope of an element. Radioactive disintegration is exponential. If half the parent nuclide remains after one time increment,...

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decay series

Overview page. Subjects: Ecology and Conservation — Earth Sciences and Geography.

Radioactive decay of a parent nuclide through a sequence of radioactive daughter nuclides to a final, stable daughter nuclide. Uranium has three naturally occurring isotopes: 238U, 235U,...

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far-field barrier

Overview page. Subjects: Earth Sciences and Geography.

In the disposal of radioactive waste, a structure with geological and hydrological characteristics which make it impermeable to radionuclides and thus ensure that it will provide permanent...

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Frederick Soddy

Overview page. Subjects: Science and Mathematics.

(1877–1956)

British chemist, who worked with Ernest Rutherford in Canada and William Ramsay in London before finally settling in Oxford in 1919. His announcement in 1913 of the...

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gamma radiation

Overview page. Subjects: Science and Mathematics.

Ionizing radiation in the range 10-14 to 10-10 meters wavelength; very high-energy, penetrating, biologically active, ionizing radiation, emitted by radioactive substances and during very...

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geothermal field

Overview page. Subjects: Earth Sciences and Geography.

An area of the Earth characterized by a relatively high heat flow. The anomolously high rate of heat flow may be due to present, or fairly recent, orogenic or magmatic activity, or to the...

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growth curve

Overview page. Subjects: Earth Sciences and Geography.

In microbiology, a curve showing the change in the number of cells in a growing culture as a function of time.

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isotope geochemistry

Overview page. Subjects: Earth Sciences and Geography.

The study of the abundance ratios of isotopes (both stable and radioactive) of major and trace elements in rocks (e.g. Rb/Sr, Pb/U, etc.), to elucidate a number of geologic problems and...

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isotopic dating

Overview page. Subjects: Earth Sciences and Geography — Biological Sciences.

Means of determining the age of certain materials by reference to the relative abundances of the parent isotope (which is radioactive) and the daughter isotope (which may or may not be...

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lead loss

Overview page. Subjects: Earth Sciences and Geography.

Loss of daughter lead nuclides during the radioactive decay of uranium to lead, in which 238U decays to 206Pb, and 235U decays to 207Pb (see decay series). These lead isotopes, together...

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nuclear reactor

Overview page. Subjects: Physics.

A device in which nuclear fission may be initiated, maintained, and controlled to produce energy, conduct research, or produce fissile material for nuclear explosives. Known in the USA as a...

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parent element

Overview page. Subjects: Environmental Science.

An isotope (parent) that is transformed into a different (daughter product) isotope by radioactive decay.

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planktonic geochronology

Overview page. Subjects: Ecology and Conservation.

The use of planktonic organisms (e.g. globigerinid foraminiferids or microscopic algae) to provide a relative dating of sediments deposited in marine waters. Radioactive-decay methods...

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