What information is obtained from radioactive dating
Much stoneware is not so hard as porcelain and may be sampled by drilling.The clay cores from lost wax metal castings may readily be tested. By comparing this light output with that produced by known doses of radiation, the amount of radiation absorbed by the material may be found. Most mineral materials, including the constituents of pottery, have the property of thermoluminescence (TL), where part of the energy from radioactive decay in and around the mineral is stored (in the form of trapped electrons) and later released as light upon strong heating (as the electrons are detrapped and combine with lattice ions). General references Links to other useful sites BACK TO HOME PAGE HOW DOES THERMOLUMINESCENCE DATING WORK?In all, close to two dozen physical quantities must be accurately measured to establish the relationship between doses of different kinds of radiation and light output, and to compute dose rate.
Among the reasons for this is the small amount of material that may be taken for testing.
The TL laboratory at Daybreak was established in 1977 to make TL available to the art community in general. Studies at Oxford back in the 70s on Romano-British pottery indicated that when all quantities entering the age equation are measured, the TL date of a single potsherd will typically fall within 15 per cent of the known date.
When dates of a number of sherds associated together are averaged, the error is reduced typically to 7-10 per cent. The succeeding 30 years, and increased understanding of the dosimetry, have not brought much improvement.
It was employed in the 1950's as a method for radiation dose measurement, and soon was proposed for archaeological dating.
By the mid-1960's, its validity as an absolute dating technique was established by workers at Oxford and Birmingham in England, Riso in Denmark, and at the University of Pennsylvania in the U. The Research Laboratory for Archaeology at Oxford, in particular, has played a major role in TL research.
This is adequate for the purposes of authentication where the question is whether the piece was fired in antiquity or recently; it will not differentiate, say, between a classic Greek terra cotta and a Roman copy.