Simulation of optically‐stimulated luminescence of zircon

Abstract

PACS 78.55. Hx, 78.60.Kn, 87.66.Sq Mineral zircon, ZrSiO 4 , belongs to a class of materials that can be used as a chronological tool in geology and archaeology for measurements of the natural radiation dose and the sample age by optical methods. The model of optically stimulated luminescence developed earlier is used to investigate the applicability of the single-aliquot regenerative-dose method (SAR) for dating with zircon. Various implementations of the SAR method are considered and practical recommendations are formulated.1 Introduction Natural zircon grains are subjected to internal α-, β-and γ-irradiation due to radioactive decay of U and Th impurities [1]. Typically, the contribution of external irradiation from the surrounding materials and cosmic radiation is less than 10% of total dose rate [2]. A fraction of the radiation energy is stored in the crystal in the form of electrons and holes trapped at lattice defects. The luminescent light originates from recombination of electrons and holes released from traps during thermal or optical stimulation. This effect is used to estimate the radiation dose and the time elapsed since the sample was last heated or optically bleached. Zircon has a high signal-to-noise ratio; because, unlike other minerals (such as quartz), zircon is subjected to internal irradiation at a dose rate much higher than the dose rate from external sources. Hence, it is expected that zircon is especially suitable for dating of ultrayoung samples. Optically-stimulated luminescence (OSL) of zircon has not been studied systematically. Therefore, in this communication we investigate by computer simulation which OSL dating protocols should be used to minimize the errors in determination of the equivalent dose e D .