A new method of evaluating the paleodose

On evaluating the paleodose in TL dating, there are two problems to be solved. The first is the supralinearity of TL response in the low dose range. The second is the sublinearity of TL response in the high dose (over 100 Gy) range. We surmised that these phenomena are concerned with the electron-trapping process. A competition model was used for the supralinearity phenomenon, and an ordinary saturation model was used for the sublinearity phenomenon. We proposed a new equation combining these two models. Furthermore, using this equation, the coefficients were decided directly from the experimental data without regressive error. Also, the change in TL sensitivity after annealing could be represented by the change of only one coefficient. This equation concerning these two phenomena offers well-fitting results with experiments from the low dose range to the high dose (2000 Gy) range. The annual dose rate is distributed in the range of 2.5 mGy/a. The age to which TL dating method is applicable, has been extended to about 106 years by using the equation. On three samples from the archeological sites in Miyagi Prefecture, by this method, the evaluated paleodoses range from 301.3 Gy to 626.5 Gy.