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Yayın TL and OSL response of turquoise for dosimetric application(University of Aegean, 2010) Subedi, Bhagawan; Afouxenidis, Dimitrios; Polymeris, George S.; Tsirliganis, Nestor C.; Paraskevopoulos, Konstantinos M.; Kitis, GeorgeTurquoise is one of the amongst first gem stones used in jewelry and possessing cultural value since 2000 BC (at least). This work attempts characterize this stone scientifically using both thermally (TL) and optically stimulated luminescence (OSL) techniques. The experimental investigation included 1) the study of the natural TL and OSL signals, 2) the reproducibility of TL sensitivity over repeated irradiation and TL readout cycles, 3) dependence of sensitivity on annealing temperatures and 4) the TL and OSL dose response curves. The potential use of the TL and OSL techniques in determination of provenance, accidental dosimetry and probably to authenticity and dating purposes are then discussed.Yayın Component resolved OSL dose response and sensitization of various sedimentary quartz samples(Elsevier Ltd, 2007-02) Güneç Kıyak, Nafiye; Polymeris, George S.; Kitis, GeorgeThe structure of the linearly modulated optically stimulated luminescence (LM-OSL) signal was studied for four sedimentary quartz samples, collected from different sites around Istanbul, Turkey. Applying a computerized deconvolution analysis to the LM-OSL curves, at least six individual components of first-order kinetics were identified and photoionization cross-section of each component was evaluated. The OSL dose-response curve of each component for each quartz sample was obtained, showing a remarkable differentiation from component to component. The behavior of a highly dosed sample to successive LM-OSL measurements was also studied showing a stable recuperation signal in the position of the "slow" and "medium" components and high resistance to OSL bleaching of the "slow" component. The individual sensitivity of each component as a function of the activation temperature was obtained. The sensitivity of each component was normalized over the respective sensitivity of the glow-peak at 110 degrees C of quartz in order to investigate the ability of the 110 degrees C glow-peak to act as a correction factor for all components of the LM-OSL curves examined.Yayın A comparative morphological, compositional and tl study of tenedos (Bozcaada) and Sile aeolianites, Turkey(Univ Agean, 2012) Polymeris, George S.; Erginal, Ahmet Evren; Güneç Kıyak, NafiyeAeolianites are carbonate-cemented deposits of coastal dune sands, mostly of Quaternary age. Even though aeolianite exposures on the coasts of the Mediterranean Sea are frequent, very few records have been documented from the coasts of either the Aegean or the Black Sea. The present study deals with evaluating and comparing both compositions and thermoluminescence (TL) ages of two recently reported samples of coastal aeolianites. Both were recovered at the Turkish coasts of Tenedos (Bozcaada) island, Aegean Sea and Şile, Western Black Sea. In the latter case, being the first record for the specific coastal area, the oldest age obtained was dated at 158±25 ka while the youngest age yielded was 108±14 ka. These values imply that both deposition and cementation occurred during the high sea stand of marine isotope stage 5 (MIS 5). In the case of Tenedos, the aeolianites were deposited between the early stage of the oxygen isotope stage 2 period (OIS 2) and the very late phase of the oxygen isotope stage 3 period (OIS 3). These latter TL results are in excellent agreement with a previous study of the same complex after applying OSL. Besides the ages, a number of luminescent features and properties in conjunction with compositional data suggest the dissimilarity for the quartz samples extracted from the aeolianites recovered at these two sampling sites, excluding thus any transport from one sampling site to the other, despite the short distance of the two sampling sites and the meteorological data regarding the preferable wind directions between them.Yayın Investigating the thermally transferred optically stimulated luminescence source trap in fired geological quartz (vol 62, pg 60, 2014)(Pergamon-Elsevier Science Ltd, 2014-08) Koul, Dileep K.; Patil, Pravinkumar G.; Oniya, Ebenezer O.; Polymeris, George S.[No abstract available]Yayın The firing temperature of pottery from ancient Mesopotamia, Turkey, using luminescence methods: a case study for different grain-size fractions(Wiley-Blackwell, 2014-10) Polymeris, George S.; Güneç Kıyak, Nafiye; Koul, Dileep K.; Kitis, GeorgeThe assessment of the firing temperature of a prehistoric pottery sample collected from ancient Mesopotamia, Turkey was studied using luminescence techniques. The methods for this estimation involved the observation of the thermal and pre-dose sensitization with various re-firing temperatures for both TL and the OSL signals. In the former case, the 110 degrees C TL peak and the rest of the glow curve were used as proxies in this study. In the framework of a first attempt to investigate the impact of grain-size dependence on the sensitization of the luminescence signals, the aforementioned study was performed with four different pottery grain-size fractions: (i) less than 60m, (ii) 60-90m, (iii) 90-180m and (iv) 180-250m. The results clearly demonstrated the firing temperature mark of approximate to 500 degrees C in for the grain size of 90-180m, whileas in the case of the lower grain-size fractiona third proxy, the ratio of the pre-dosed to the thermal sensitization, was seen to indicate the firing temperature. The remaining two grain-size fractions failed to provide any meaningful results with regard to the firing temperature estimation. The dependence of the TL characteristics on the grain size was explained in the framework of the mixed mineralogy.Yayın New quartz technique for OSL dating of limestones(2010) Liritzis, Ioannis; Drivaliari, N.; Polymeris, George S.; Katagas, Christos G.The equivalent dose De determination of limestone-made ancient constructions by thermoluminescence (TL) prevents accurate measurements and requires plateau test of bleached curves. Optical stimulated luminescence (OSL) of quartz and feldspar minerals for surface dating is routinely applied for De but not for limestones. Here the OSL of present traces of such minerals removed with powder from surface limestone bleached by sunlight overcomes this issue and offers an alternative way for De. This is verified with further test examples.Yayın Thermally assisted OSL from deep traps in Al2O3:C(Pergamon-Elsevier Science Ltd, 2010-03) Polymeris, George S.; Raptis, Spyridoula; Afouxenidis, Dimitrios; Tsirliganis, Nestor C.; Kitis, GeorgeThe present work suggests an alternative experimental method in order to not only measure the signal of the deep traps in Al2O3:C without heating the sample to temperatures greater than 500 degrees C, but also use this signal for high dose level dosimetry purposes as well. This method consists of photo transfer OSL measurements performed at elevated temperatures using the blue LEDs (470 nm, FWHM 20 nm) housed at commercial Riso TL/OSL systems, after the sample was previously heated up to 500 degrees C in order to empty its main TL dosimetric trap. The influence of this procedure on specific features such as glow curve shape and sensitivity of the main TL glow peak was also studied.Yayın IRSL dating of a deep water core from Pylos, Greece; comparison to post ir blue OSL and TL dating results(Univ Agean, 2011) Polymeris, George S.; Kitis, GeorgeThe 'double SAR' protocol procedure permits the determination of two equivalent dose (De) values for each polymineral aliquot; an IRSL De resulting mostly from feldspars along with a post-IR OSL De for a mixed signal for quartz (mostly) and feldspar grains. The objective of the present study is to test for the first time its usefulness for polymineral, coarse silt, closely-spaced deep-sea sediment samples. A new, 'double SAR' IRSL dataset is presented for the sedimentation ages of a deep-sea sediment core of the Hellenic Trench, drilled from a water depth of 4 km, near the deepest site of the Mediterranean Sea, outside Pylos, Greece. Post IR quartz-based optical dating was previously proved to be consistent with AMS radiocarbon ages, obtained from planktonic foraminifera from the same core. IRSL De values are, with one exception, always much greater than the corresponding (post-IR) OSL results. This result suggests that for the present study 'double SAR' protocol procedure was proved to be extremely effective method for separating the luminescence signals from quartz and feldspars. Furthermore, De values obtained after infra-red stimulation and thermoluminescence generally agree within errors. This quantitative equivalence of those two sets of De values implies that as in the case of IRSL, TL signal is also feldspar-dominated. IRSL ages vary between 3.5 and 7.8 ka with associated errors up to 9%. Application of 'double SAR' protocol to coarse silt, closely-spaced deep-sea sediment samples seems advisable, despite the fact that the post-IR blue OSL signal is the most stable signal, and is preferred for dating.Yayın Investigation of the OSL signal from very deep traps in natural quartz(Univ Agean, Dept Mediterranean Stud, 2010) Kitis, George; Güneç Kıyak, Nafiye; Polymeris, George S.; Pagonis, VasilisIt has been recently reported by several studies that a thermally transferred optically stimulated luminescence (TT-OSL) signal from quartz grains can be used to extend the dating range for quartz samples. The TT-OSL signals are believed to consist of a recuperated OSL (ReOSL) component and a basic-transferred OSL (BT-OSL) component. In the present work the TT-OSL signals from several types of unfired quartz samples were studied. A special protocol was used, which allowed the measure the OSL from very deep traps (VDT) as a function of the OSL stimulation temperature. It was found that all quartz samples exhibit TT-OSL signals, which are depended on sample and on the OSL stimulation temperature. The activation energy of the process was evaluated and the influences of the TT-OSL on the ReOSL dating protocol are discussed.Yayın Reconstruction of thermally quenched glow curves in quartz(Pergamon-Elsevier Science Ltd, 2012-04) Subedi, Bhagawan; Polymeris, George S.; Tsirliganis, Nestor C.; Pagonis, Vasilis; Kitis, GeorgeThe experimentally measured thermoluminescence (TL) glow curves of quartz samples are influenced by the presence of the thermal quenching effect, which involves a variation of the luminescence efficiency as a function of temperature. The real shape of the thermally unquenched TL glow curves is completely unknown. In the present work an attempt is made to reconstruct these unquenched glow curves from the quenched experimental data, and for two different types of quartz samples. The reconstruction is based on the values of the thermal quenching parameter W (activation energy) and C (a dimensionless constant), which are known from recent experimental work on these two samples. A computerized glow-curve deconvolution (CGCD) analysis was performed twice for both the reconstructed and the experimental TL glow curves. Special attention was paid to check for consistency between the results of these two independent CGCD analyses. The investigation showed that the reconstruction attempt was successful, and it is concluded that the analysis of reconstructed TL glow curves can provide improved values of the kinetic parameters E, s for the glow peaks of quartz. This also leads to a better evaluation of the half-lives of electron trapping levels used for dosimetry and luminescence dating.
