Sensitivity change of IRSL signal: model, predictions and tests

A model is introduced for explaining the sensitivity change of the infrared stimulated luminescence (IRSL) signal used for dating. The model involves the competitions of the two types of traps to capture the electrons created in the irradiation process, the sensitivity of the IRSL signal represents the response of the T, signal charges in the 'easy to bleach' trap to the irradiation dose and depends on the concentration of electron in the 'hard to bleach' traps. It predicts that the sensitivity of the IRSL signal can be increased, decreased or unchanged after laboratory bleaching. The sensitivity change is dependent on the degree of sunlight bleaching prior to deposition, the age of the sample and the conditions of laboratory bleach. The predictions by the model agree well with results reported in the literature. Further more, the model has been tested with a specially designed experiment. The implications to optical dating with regeneration method are discussed