Optically stimulated luminescence dating wiki
Two forms of luminescence dating are used by archaeologists to date events in the past: thermoluminescence (TL) or thermally stimulated luminescence (TSL), which measures energy emitted after an object has been exposed to temperatures between 400 and 500°C; and optically stimulated luminescence (OSL), which measures energy emitted after an object has been exposed to daylight.To put it simply, certain minerals (quartz, feldspar, and calcite), store energy from the sun at a known rate.The OSL signal is reset by exposure to sunlight, so the signal is reset to zero while the sand is being transported (such as in a glacial meltwater stream). Once the sand grain has been buried and it is no longer exposed to sunlight, the OSL signal starts to accumulate. Testing an approach to OSL dating of Late Devensian glaciofluvial sediments of the British Isles. Materials of geological origin will have absorbed considerable quantities of radiation since their formation, so any human-caused exposure to heat or light will reset the luminescence clock considerably more recently than that since only the energy stored since the event will be recorded.The way you measure energy stored in an object that you expect has been exposed to heat or light in the past is to stimulate that object again and measure the amount of energy released.The energy released by stimulating the crystals is expressed in light (luminescence).The intensity of blue, green or infrared light that is created when an object is stimulated is proportional to the number of electrons stored in the mineral's structure and, in turn, those light units are converted to dose units.
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