Spatial distribution studies of thermoluminescence using a high-gain image intensifier

Abstract

Thermoluminescence (TL)—the light emitted when a previously irradiated material is heated—is normally studied by heating the material under a photomultiplier (PM). This measures the total light emitted within the acceptance angle of the PM, but provides no information on the spatial distribution of the TL. The dating of archaeological specimens by means of their naturally acquired TL is a common application of this method. While such a spatially-averaging technique is acceptable in studying TL from homogeneous materials, problems can arise when it is applied to inhomogeneous materials, such as certain natural calcites¹, where TL emissions may be correlated with internal irradiation dose rates. As we shall demonstrate, a high-gain image intensifier (IIT) can be successfully used to investigate the spatial distribution of TL from such materials at light levels where even fast photographic emulsions fail to record any emission. So far as we are aware this is the first time that high-gain image intensification techniques have been used in such studies.