Sublinear dose dependence of thermoluminescence as a result of competition between electron and hole trapping centers.

This paper presents a model of sublinearity of thermoluminescence (TL) dose response, based on the competitive interaction between active electron trapping centers and deep hole centers during excitation and heating of a phosphor. It is shown by analytical and numerical calculations that the sublinear response is observed at low doses, when the trap occupancy is far from saturation. It is found that the linearity index of TL dose response depends on the concentration of the deep hole traps, and on the coefficient of non-radiative electron recombination. The TL dose response is derived in parametric form. A new analytical expression is derived for the threshold doses, at which the TL response changes from a sublinear growth to an almost linear behavior. This phenomenon of a sublinear TL response changing into a linear behavior, is explained by the deep traps filling up to saturation. The dependence of the linearity index on the model parameters is found by numerical methods. [ABSTRACT FROM AUTHOR]