Dating Uncertainties with Thermoluminescence
Larry A. DeWerd
Thermoluminescence is the emission of light from a solid material that has received a dose from radiation. This phenomenon can be used to date pottery and volcanic eruptions, since the luminescence increases as it is irradiated with time to the point of saturation. The amount of radioactivity in the vicinity of the sample has to be measured, which can be one of the potential sources of error, since any change in the radioactivity of the past can affect the proposed date. The date obtained is dependent on the environment of the site where the sample is located. Other characteristics of the thermoluminescence process can affect the date obtained. The mechanism of thermoluminescence will be described using an alkali halide, LiF:Mg,Ti, as an example of potential sources of error. Alkali halides have been studied extensively for their use as a dosimeter in the medical radiation field. Careful control of the thermoluminescence can result in good accuracy. The thermoluminescence of quartz will be discussed. The criteria and assumptions necessary for the dating process and the potential problems will be described. The uncertainty of the process will be explained and how it may affect the date. Thermoluminescent measurements, when all uncertainties or the process are accounted for, show dates less than 6000 years. A review of the thermoluminescence process shows that this is a useful area of research for the creation scientist.
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