Thermoluminescence dating using fine grains from pottery
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.
Different materials vary considerably in their suitability for the technique, depending on several factors.
Subsequent irradiation, for example if an x-ray is taken, can affect accuracy, as will the "annual dose" of radiation a buried object has received from the surrounding soil.
Six ceramics and two baked soil samples collected from the famous Xian Terracotta Army Site have been dated by using fine grain (2–8 μ) TL technique.
Five samples of pottery sherds exhibited peak TL at about 275°C and 395°C gave the TL age ranged from 2.13 ± 0.14 ka to 2.25 ± 0.14 ka and a mean TL age of 2.20 ± 0.15 ka, with a good plateau in the range of 290–400°C.
Thermoluminescence dating is used for material where radiocarbon dating is not available, like sediments.
Its use is now common in the authentication of old ceramic wares, for which it gives the approximate date of the last firing.Optically stimulated luminescence dating is a related measurement method which replaces heating with exposure to intense light.The sample material is illuminated with a very bright source of green or blue light (for quartz) or infrared light (for potassium feldspars).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 a crystalline material is heated during measurements the process of thermoluminescence starts.The Radiation Dose Rate - the dose accumulated per year-must be determined first.