Quartz luminescence dating
We measure this emitted light (the luminescence) and this is the first stage towards measuring the sample age. We then give our sand sample a range of laboratory radiation doses and measure the luminescence that each dose produces to develop a calibration curve. When these quartz or feldspar minerals are exposed to the ionising radiation emitted by the radioactive isotopes in zircons, electrons within the crystals migrate and become trapped in their crystal structure. The number of trapped electrons depends on the total amount of radiation that the mineral has been exposed to. This is because water attenuates (scatters) the radiation, reducing the total radiation dose that the sample has been exposed to. In addition to radiation from the surrounding sediment, OSL samples are affected by a cosmic dose rate, which reduces as the amount of sediment the sample is buried under increases. From this curve we can calculate the dose that our sample must have received to produce the amount of light that we measured first. We call this measurement our “equivalent dose”, because it is equivalent to the dose that the sample received in nature.
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.
Particularly, the "post-infrared infrared stimulated luminescence", known as p-IRIR not only compensates for the problems associated with quartz but also saves all benefits of feldspar dating, such as intense signals under laboratory stimulation and considerably higher saturation levels, and additionally deals with the problem of anomalous fading.