Effect of IRSL-BLSL-TSL reading modes combination on thermoluminescence (TL) response of BeO dosimeter.

The ultimate goal of this work is the study of the effect of luminescence stimulations and signals reading modes combinations on the thermoluminescence intensity and glow curve behaviour for the same X-ray irradiation dose. Three interesting stimulating and reading modes are considered, namely, infrared stimulated luminescence (IRSL), blue light-emitting diode stimulated luminescence (BLSL) and thermally stimulated luminescence (TSL). The studied stimulation and reading modes combination protocols are (Protocol 1) IRSL-TSL, (Protocol 2) IRSL-BLSL-TSL and (Protocol 3) BLSL-IRSL-TSL. Experiments are performed on beryllium oxide (BeO) dosimeter. Results demonstrate well that the combination of reading modes have direct impact on the TL signal in terms of intensity and glow curve shape. It was also found that when reading modes are correctly combined, particularly when IRSL is applied first, then BLSL and TL, it is possible to collect two or more exploitable signals of different stimulation types for the same irradiation that can be used for different purposes and final applications.

Three-dimensional control of alluvial fans by rock uplift in an extensional regime: Aydin Range, Aegean extensional province.

Tectonics imparts a first-order control on the overall morphology of alluvial fan systems in extensional settings by influencing sediment flux and accommodation space, while other factors such as climate, catchment lithology, and fault footwall characteristics are secondary. Previous alluvial fan modeling studies have focused on the link between the three-dimensional development of alluvial fans and rock uplift, however, despite the potential influence of tectonics on the overall three-dimensional morphology of alluvial fans, the controlling mechanisms, as well as their relative importance, remain largely unquantified in a natural setting with a targeted source-to-sink approach. Here, we examine 45 alluvial fans and their catchments along the southern mountain front of the Aydin Range, delimited by segmented normal faults in the western Anatolia Extensional Province, to quantify the role of rock uplift. We quantify river incision rates and catchment-wide erosion rates together with a series of topographic analyses across the southern flank of the Aydin Range as a proxy for rock uplift. Our results indicate that the spatial distribution of thicker and steeper alluvial fans fit well with higher rock uplift rates along the strike of the mountain front. In contrast, a lower uplift rate is responsible for prograding alluvial fans with decreasing thickness and gradients. Also, our data shows that alluvial fan thickness compared to other alluvial fan metrics strongly associated with the pattern of the rock uplift. This study demonstrates a field-based, quantitative linkage between three-dimensional alluvial fan morphology and rock uplift which has significant implications for improving alluvial fan models and understanding how alluvial fans respond to tectonics in extensional regions.

Thermally and optically stimulated luminescence properties of BeO dosimeter with double TL peak in the main dosimetric region.

Beryllium oxide (BeO), which has a widely known single main TL peak over the main dosimetric region, is an important luminescent material widely used in personal, medical, and environmental dosimetry fields. The thermal and optically stimulated luminescence properties (TL and OSL) of the BeO dosimeter, supplied by a private company in Turkey (BeOR) that yields a double peak in the main dosimetric region (100-300 °C; heating rate = 2 °C/s) were studied. The corresponding properties were compared to the commercially prevalent Thermalox 995 BeO (BeOT). Multiple characterization techniques including x-ray diffraction analysis (XRD), energy dispersive x-ray spectroscopy (EDX), scanning electron microscope (SEM) image and electron spin resonance (ESR) were used to detect possible differences in TL and OSL signals. It was hypothesized that the calcination and or sintering process applied during the manufacturing process might lead to a double peak in the main dosimetric region of BeOR TL signals. Moreover, dosimetric properties of this dosimeter such as reproducibility, dose-response, minimum detectable dose (MDD), thermal quenching, bleaching, and thermal stability in combination with annealing properties were comprehensively investigated. An analysis of the results shows that BeOR has lower detection limits in TL than BeOT. In contrast, BeOT exhibited lower detection limits in the OSL signal than BeOR. Although both dosimeters have dissimilarities in several aspects, both are appropriate for dosimetric research on health physics applications. Therefore, selecting the appropriate BeO dosimeter could be an important factor to consider when assessing accurate doses in studies. With this outline in mind and by investigating using different characterization methods, the available luminescence knowledge base of BeO dosimeters was expanded.

Determination of trapping parameters in BeO ceramics in both quenched as well as reconstructed thermoluminescence glow curves using various analysis methods.

The trapping parameters of BeO thermoluminescence peaks 2 and 3 (with delocalization temperatures of 192 and 308°C respectively, obtained with heating rate of 1K/s) have been calculated using various analysis techniques, including the peak shape methods, isothermal decay, variable heating rates, the fractional glow technique and de-convolution. However, as BeO has been reported to undergo thermal quenching, both intensity as well as trapping parameters are affected, because the glow curve is distorted. Therefore, trapping parameters were calculated for both quenched and unquenched data of the aforementioned thermoluminescence peaks. The unquenched glow curves were determined by reconstructing the corresponding quenched; the following thermal quenching parameters were adopted: W = 0.60eV and C = 1.3 × 106 for peak 2 and W = 0.80eV and C = 1.2 × 107 for peak 3. The obtained activation energies and frequency factors before and after reconstruction were compared both for every method and also to previous studies. This study emphasizes the importance of reconstruction process on trapping parameters for peak 3, as this peak lies within a special temperature range where the efficiency gets values < 0.54. The main dosimetric peak is mildly affected by thermal quenching; thus before and after reconstruction the corresponding values do not yield significant variations. The average values for the activation energy and frequency factor after reconstruction were calculated as 1.14 ± 0.07eV and 9.9 × 1010 ± 0.4 × 1010 s-1 for peak 2; the corresponding values for peak 3 are 1.34 ± 0.08eV, 6.9 × 1011 ± 0.6 × 1011 s-1 respectively. Both peaks are described by first order of kinetics even after reconstruction has occurred. Individual peculiarities of each analysis technique has been both presented and discussed.

TL and OSL dose response and stability properties of various commercially glass samples obtained from Turkey for dosimetric purposes in the UV emission spectral region.

This paper reports Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) dose response characteristics of ten different commercial glass samples collected from Turkey. Nowadays, glass samples are widely used mostly in objects of everyday life. The study focuses to both TL and OSL dose responses, through a dose region within 1 and 512Gy. Lowest detectable dose limit (LDDL) as well as the respective linearity features of the corresponding dose response curves were studied for both TL and OSL. Moreover, signal reproducibility and fading behaviors have also been studied in detail. For specific samples, the lowest detectable dose was yielded at 2Gy, making thus these samples appropriate for retrospective dosimetry applications. Nevertheless, based on the features reported in the present study, the majority of the samples could be possibly used effectively for dosimetric applications of higher doses in the UV region emission.

Thermoluminescence properties of irradiated commercial color pencils for accidental retrospective dosimetry.

Color pencils are widely used mostly in kindergartens, in schools and could be found in all houses with families having young children. Their wide spread use in modern times as well as their chemical composition, consisting mostly of Si and Al, constitute two strong motivations towards exploiting their use as accidental retrospective thermoluminescent dosimeters. The present manuscript reports on the study of colored pencils manufactured by a commercial brand in China which is very common throughout Turkey. The preliminary results discussed in the present work illustrated encouraging characteristics, such as the presence of a trapping level giving rise to natural TL in a temperature range that is sufficiently high. Specific thermoluminescence features of this peak, such as glow peak shape and analysis, anomalous fading, thermal quenching, reproducibility, linearity and recovery ability to low attributed doses were studied. The results suggest that the color pencils could be effectively used in the framework of retrospective thermoluminescent dosimetry with extreme caution, based on multiple aliquot protocols.