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The radiation dose rate is calculated from measurements of the radioactive elements (K, U, Th and Rb) within the sample and its surroundings and the radiation dose rate from cosmic rays.
The dose rate is usually in the range 0.5 - 5 grays/1000 years.
The radiation causes charge to remain within the grains in structurally unstable "electron traps".
It uses various methods to stimulate and measure luminescence.The problem with this technique is that the operator does not know the individual figures that are being averaged, and so if there are partially prebleached grains in the sample it can give an exaggerated age .In contrast to the multiple-aliquot method, the SAR method tests the burial ages of individual grains of sand which are then plotted.Heating the substance at temperatures of about 450° C (842° F) and higher enables the trapped electrons to return to their normal positions, resulting in the release of energy.The intensity of the emission can be correlated to the length of time that a given substance was exposed to radiation; the longer the time allowed for the radiation to build up an inventory of trapped electrons, the greater the energy released.
The minerals that are measured are usually either quartz or potassium feldspar sand-sized grains, or unseparated silt-sized grains.