Conduction band/valence band kinetic modeling of the LiF:Mg,Ti system incorporating creation of defects in the irradiation stage

A conduction band/valence band kinetic model is described for the irradiation stage of the thermoluminescent LiF:Mg,Ti system. Unlike previous investigations the model incorporates creation of fluorine vacancies via irradiation and their subsequent partial filling by electrons in the relaxation stage leading to the creation of F centers. The radiation induced vacancies thus operate as additional competitors to the 4 eV electron trapping center (TC) associated with composite glow peak 5 in the glow curve of LiF:Mg,Ti. With the appropriate choice of parameter-values the model successfully predicts the experimentally measured, linear/exponentially saturating dose response of the optical absorption (OA) bands of the 4 eV TC and the 5.45 eV competitive center (CC) which serves as well as the recombination stage competitor. The increased competition due to the creation of negative ion vacancies during irradiation is found to lead to changes in the population dose response characteristics of the various centers taking part in the TL mechanism. The implication of these changes on the relative thermoluminescence (TL) efficiency following heavy charged particle (HCP) irradiation is discussed.