Dating by thermoluminescence
When scientists pull pottery from the ground, they use heat or lasers to de-excite these electrons out of their trap states back to their original state. Scientists measure the amount of light to get the total measured radiation dose (TMRD).They divide this by an assumed radiation dose rate (RDR) to estimate the pottery’s age. It is an absolute dating method, and does not depend on comparison with similar objects (as does obsidian hydration dating, for example). The thermoluminescence technique is the only physical means of determining the absolute age of pottery presently available.Luminescence dating (including thermoluminescence and optically stimulated luminescence) is a type of dating methodology that measures the amount of light emitted from energy stored in certain rock types and derived soils to obtain an absolute date for a specific event that occurred in the past.
However, problems arise from assuming a uniform radiation dose rate over any significant period of time and assuming that the TMRD resulted from the object or artifact being in a strictly constrained environment identical to that in which it was found.When we receive your sample we must first prepare it for measurement.Powder samples (from pottery and bronze cores) are mixed with acetone and allowed to settle, so that fine grains, approximately 1/100mm. These grains are deposited and dried onto aluminium discs (for fine-grain analysis) or rhodium (for pre-dose analysis).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.