A kinetic model of zircon thermoluminescence

Abstract

Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. AbstractA kinetic model of zircon thermoluminescence (TL) has been constructed to simulate the processes and stages relevant to thermoluminescent dating such as: filling of electron and hole traps during the excitation stage both for natural and laboratory irradiation; the time dependence of fading after laboratory irradiation; TL experiments both after laboratory and natural irradiation. The goal is to inspect qualitative behavior of the system and to unravel the processes and determine the parameters controlling TL phenomena of zircon. The input parameters of the model, such as types and concentrations of the TL centers and energy distributions of the hole and electron traps, were obtained by analyzing the experimental data on fading of the TL-emission spectra of samples from different locations. EPR data were used to establish the nature of the TL centers. Glow curves and 3D TL emission spectra are simulated and compared with the experimental data on time-dependent TL fading. Theoretical dating curves for combined natural plus laboratory irradiation have been calculated for as-irradiated, faded and preheated samples. Ó

Protocol for TL dating with zircon: Computer simulation of temperature and dose rate effects

“…Additional background centers (Bgr) that trap holes were introduced into the model to account for the TL intensity distributed over a wide spectral range observed at low temperatures. Three types of luminescent centers are sufficient to describe simultaneously the time-dependent fading of the TL from g-irradiated zircon samples [3] and the annealing behavior of the EPR signal associated with Dy 3þ and Tb 4þ ions [5]. The other centers, i.e.…”

“…The temperature dependence of the recorded TL intensity, I ðT Þ, shows the typical form of a glow curve. The TL intensity is defined as a rate at which photons are emitted due to recombination of electrons with holes trapped at luminescent centers Equations (1)-(5) were solved numerically using the material parameters presented in [3]. Two types of simulated samples have been prepared:…”

“…In this communication we consider mineral zircon, which has important advantages over other minerals [1,2]. To investigate the possible application of zircon for dating purposes we have formulated a kinetic model for the production of radiation damage [3]. Computer modeling has shown that differences in the TL data of zircon after natural and laboratory irradiation can be explained by the presence of high concentrations of shallow electron and hole traps, as well as by complex redistribution effects of the charge carriers in the trap system during heating and=or long-term storage [3].…”

“…To investigate the possible application of zircon for dating purposes we have formulated a kinetic model for the production of radiation damage [3]. Computer modeling has shown that differences in the TL data of zircon after natural and laboratory irradiation can be explained by the presence of high concentrations of shallow electron and hole traps, as well as by complex redistribution effects of the charge carriers in the trap system during heating and=or long-term storage [3]. In this communication we model the dating procedures and consider the possibility how to reproduce the dose dependence of the TL signal of samples irradiated under natural conditions by using a combination of short-term laboratory irradiation and additional postirradiation treatments such as fading and preheats.…”

Gamma radiation effects on TL and EPR on natural zircon

“…Karaly [3] produced zircon in laboratory doped with Pr, Sm, Eu, Gd, Dy, Ho, Er and Yb and found TL peaks in the range 25 to 675 K. Each rare earth has characteristic light emission. Turkin [4] attributed the 150 o C TL peak emission to Dy and Tb. Hutton and Troups [5] reported an EPR spectrum due to Gd 3+ in natural zircon; Barker and Hutton [6] found g x =2.0016, g y =2.0076 and g z =2.0036 in ZrSiO 4 :Y, assuming that this result is due to the paramagnetic center SiO 4 3-, which compensates the charge difference due to substitution of Zr 4+ by Y…”