Contributions of pre-exposure dose and thermal activation in pre-dose sensitizations of unfired and annealed quartz

This work was undertaken to determine the separate contributions of pre-exposure dose and subsequent thermal activation in sensitisations of 110 °C Thermoluminescence (TL) peak in attempt to further unravel the complex nature of quartz luminescence properties. Two sets of quartz samples were used. Each of the two sets was divided into two parts; the first was unfired while the second part was annealed at 900 °C for 1 h. The TL measurements were carried out on each aliquot using an automated RISØTL/OSLreader(model-TL/OSL-DA-15) utilizing different heating rates. Pre-dose sensitization in unfired samples was observed to be predominantly derived from thermal activation while it was pre-exposure dose that majorly contributed to that of annealed samples. This indicated opposite mode of pre-dose sensitizations in the two categories of samples. The findings in the present work revealed that pre-dose technique is not appropriate for unfired sample but rather ideal for fired/annealed quartz samples. All the observed modes of sensitization were explained under the framework of existing models. Effect of sensitization resulting from TL readout and radiation histories in respect of mass normalization in TL/OSL dating procedures was stressed.