HCP track calculations in Lif:Mg,Ti: 3D modeling of the "track – escape" parameter

The conceptual framework of the track interaction model (TIM) was conceived in the 1970s and mathematically formulated in the 1980s to describe heavy charged particle TL fluence response supralinearity. The extended track interaction model (ETIM) was developed to include saturation effects due to overlapping tracks and has been applied to both proton and alpha particle TL fluence response. One of the parameters of major importance in the TIM is the "track – escape" parameter, defined by Ne/Nw, where Ne represents the number of electrons which escape the parent track during heating, and Nw is the number of electrons which recombine within the parent track to produce a TL photon. Recently a first attempt was carried out to theoretically model escape parameters calculated in 2D geometry as a function of particle type and energy using trapping center (TC), luminescent center (LC) and competitive center (CC) occupation probabilities calculated from track segment radial dose distributions and optical absorption (OA) dose response. In this study, the calculations are extended to 3D geometry using a Monte Carlo approach which samples the point of creation of the charge carriers according to the TC occupation probabilities and then estimates Nw by sampling the chord length to the track exterior. Charge carriers which escape the irradiated track volume contribute to Ne. This more sophisticated 3D calculation of Ne/Nw is expected to increase the reliability of the modeling of heavy charged particle TL fluence response in the framework of the ETIM and enhance our understanding of “track effects” in Heavy Charged Particle (HCP) induced TL.