A comparative study of the anomalous fading effects of TL and OSL signals of Durango apatite

The Thermoluminescence (TL), Blue Stimulated Luminescence (BSL) and Infrared Stimulated Luminescence (IRSL) properties of apatite (originating from Durango, Mexico) are studied. The TL dose response of Durango apatite is linear to an extended dose region whereas the BSL and IRSL dose responses are sublinear. The TL, BSL and IRSL signals are found to exhibit strong anomalous fading (AF). All experimentally obtained BSL and IRSL decay curves were transformed into pseudo-linear modulated (pseudoLM) ones. The resulting glow-curve shaped pseudo-LM curves were analyzed using a deconvolution analysis, similar to that used for the glow-curve deconvolution (GCD) of TL glow-curves. It was found that the pseudo-LM BSL and IRSL decay curves consist of two components termed fast and slow and their individual contributions were estimated. The AF of the remnant TL, BSL and IRSL signals as a function of storage time were fitted to the tunneling model equations and the fading rate g, in terms of percentage per decade was evaluated. According to the g values found the AF properties are ordered as following: The AF of the BSL and IRSL signals is stronger than that of the TL. The AF of the fast components of BSL and IRSL signals is almost the same. The stimulation by blue light causes strong bleaching of the TL signal and alterations in the glow-curve shape, whereas the IR light causes, only, a slight bleaching of the TL signal without changes in the glow-curve shape.