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.The method is a direct dating technique, meaning that the amount of energy emitted is a direct result of the event being measured.The older the pottery, the more radiation it has absorbed and the brighter the pottery sample glows.By measuring the TL, we can calculate how much radiation has been absorbed and use this information to calculate the approximate age of the pottery.This energy is lodged in the imperfect lattices of the mineral's crystals.Heating these crystals (such as when a pottery vessel is fired or when rocks are heated) empties the stored energy, after which time the mineral begins absorbing energy again.Any remaining powder is dried and used for radioactivity measurements to complete the dating calculation. When the glue is dry, they are cut into slices 1/4mm thick with a fine diamond blade. Each slice is soaked in acetone after cutting to remove the glue. The remaining core is crushed and used for radioactive analysis to complete the dating calculation.We have 3 fully automated, computer operated Riso Minisys TL readers for measuring the TL.
To put it simply, certain minerals (quartz, feldspar, and calcite), store energy from the sun at a known rate.The presence of rubidium and cosmic radiation generally play a lesser but contributory roll, and the total radiation dose delivered to the TL phosphor is modified by the presence of water.The period since deposition is therefore measured by determining the total amount of stored TL energy, the palaeodose (P), and the rate at which this energy is acquired, the annual radiation dose (ARD).TL Age = Palaeodose (P) _____________ (ARD) TL samples may be collected in open ended or opaque PVC tubes approximately 12cm in length and 6cm in diameter.Whilst it advisable to protect the sample from direct sunlight there is no need to sample at night and the orientation of the specimen is not important.