Thermoluminescence dating definition, a method of dating archaeological specimens, chiefly pottery, by measuring the radiation given off by ceramic materials as they are heated. See more. Websters Dictionary – Online Edition is an excellent reference for classical literature, Bible studies, history papers, and the reading of America's national documents.
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Where there is a dip a so-called " electron trap" , a free electron may be attracted and trapped. The flux of ionizing radiation—both from cosmic radiation and from natural radioactivity —excites electrons from atoms in the crystal lattice into the conduction band where they can move freely.
Most excited electrons will soon recombine with lattice ions, but some will be trapped, storing part of the energy of the radiation in the form of trapped electric charge Figure 1.
Depending on the depth of the traps the energy required to free an electron from them the storage time of trapped electrons will vary as some traps are sufficiently deep to store charge for hundreds of thousands of years. In practical use[ edit ] Another important technique in testing samples from a historic or archaeological site is a process known as Thermoluminescence testing, which involves a principle that all objects absorb radiation from the environment.
This process frees electrons within elements or minerals that remain caught within the item. Thermoluminescence testing involves heating a sample until it releases a type of light, which is then measured to determine the last time the item was heated.
In thermoluminescence dating, these long-term traps are used to determine the age of materials: When irradiated crystalline material is again heated or exposed to strong light, the trapped electrons are given sufficient energy to escape.
In the process of recombining with a lattice ion, they lose energy and emit photons light quanta , detectable in the laboratory. The amount of light produced is proportional to the number of trapped electrons that have been freed which is in turn proportional to the radiation dose accumulated.
In order to relate the signal the thermoluminescence—light produced when the material is heated to the radiation dose that caused it, it is necessary to calibrate the material with known doses of radiation since the density of traps is highly variable. 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.
Therefore, at that point the thermoluminescence signal is zero. Merrian-Webster Ed. Darien, CT: Federal Street Press. All students need access to a print source dictionary. This dictionary can be used for any class. There are several dictionaries but this is the most up to date and this includes frequently used words unlike other dictionaries. The purpose of this dictionary is to be a reference tool for any student needing a quick definition to frequently used words.
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