Some mineral substances such as fluorite store energy when exposed to ultraviolet or other ionising radiation. This energy is released in the form of light when the mineral is heated; the phenomenon is distinct from that of black body radiation. Fluorite (also called fluor-spar) is a mineral composed of calcium fluoride, CaF2. ... For other uses, see Ultraviolet (disambiguation). ... Ionizing radiation is radiation in which an individual particle (for example, a photon, electron, or helium nucleus) carries enough energy to ionize an atom or molecule (that is, to completely remove an electron from its orbit). ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ...
The amount of light given off is proportional to the dose of radiation received. In Thermoluminescence dating this can be used to date buried objects that have been heated in the past (eg pottery) since the dose received from radioactive elements in the soil, cosmic rays etc is proportional to age. Thermoluminescence (TL) dating is the determination by means of measuring the accumulated radiation dose of the time elapsed since material containing crystalline minerals was either heated (lava, ceramics) or exposed to sunlight (sediments). ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ...
This phenomenon is also used for Thermoluminescent dosimeters, to measure the radiation dose received by a chip of suitable material that is carried around by a person or placed with an object. A Thermoluminescent dosimeter is a small device used to measure radiation exposure by measuring the amount of visible light emitted from a crystal in the detector when the crystal is heated. ...
Literature
Thermoluminescence dating by M J Aitken, ISBN 0-12-046381-4
The Dating Game Scientific American June 11, 2001 page 2
Thermoluminescence (TL) dating is the determination by means of measuring the accumulated radiation dose of the time elapsed since material containing crystalline minerals was either heated (lava, ceramics) or exposed to sunlight (sediments).
As the material is heated during measurements, a weak light signal, the thermoluminescence, proportional to the radiation dose is produced.
Thermoluminescence dating presupposes a "zeroing" event in the history of the material, either heating (in the case of pottery or lava) or exposure to sunlight (in the case of sediments), that removes the pre-existing trapped electrons.
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