Z. Yegingil

Fission track dating obsidians in Central and Northern Anatolia

Twenty obsidian samples from Central and North Anatolia were dated by the fission track method. Split samples analyzed in two different laboratories give consistent results. Data presented refer to three volcanic fields and are summarized as follows: Orta-Sakaeli (Northern Anatolia) obsidians with ages from 21–23 Ma; Göllü Dagi dome complex near Çiftlik (Central anatolia) has given ages between 1.33–0.98 Ma; Acigöl caldera (Central Anatolia) shows three age groups: (1) Eruptions of precaldera (Bogazköy) obsidians with ages 0.18–0.15 Ma; (2) Formation of the large intracaldera dome Kocadag-Taskesiktepe at about 0.08 Ma (uncorrected “apparent” age of 0.075 Ma); and (3) Acigöl peripheral obsidian domes with plateau ages of 0.020 and 0.019 Ma, and an additional uncorrected age of 0.018 Ma form a distinct age group. This fission track parameters discriminate between the various obsidian sources of prehistoric obsidian artifacts.

The analysis of thermoluminescent glow peaks of CaF2: Dy (TLD-200) after β-irradiation

Variable dose (VD), Tm–Tstop, initial rise (IR), variable heating rate (VHR), peak shape (PS) and computerized glow curve deconvolution (CGCD) methods are used to determine the number of peaks, the order of kinetics (b), the activation energy (Ea) and attempt-to-escape frequency (s) associated with the glow peaks in CaF2 : Dy (TLD-200) after β-irradiation between the dose level 0.1 and 110 Gy. The Tm–Tstop procedure indicates that the glow curve of this crystal consists of at least nine glow peaks. The dose variation experiment indicates that seven of them, namely peaks 1–6 and 8, are of first-order kinetics and peaks 7 and 9 are of general-order kinetics. However, the Tm–Tstop procedure and the CGCD method have indicated that peak 6 has general-order kinetics too. The activation energy found with the IR, VHR, PS and CGCD methods for peak 4 yield very close values. For all other peaks, there is no agreement between the results of all the applied methods. This work also indicates that the post-irradiation annealing and the heating rate have pronounced effects on the evaluated kinetic parameters of all glow peaks.

The analysis of dosimetric thermoluminescent glow peak of -Al2O3 : C after different dose levels by -irradiation

The variable dose (VD), Tm?Tstop, initial rise, variable heating rate, peak shape and computerized glow curve deconvolution (CGCD) methods were used to determine the number of peaks, the order of kinetics (b), the activation energy (Ea) and attempt-to-escape frequency (s) associated with the dosimetric glow peak of ?-Al2O3?:?C after ?-irradiation at a dose level between 0.02 and 288?Gy. The Ea?Tstop and CGCD methods indicated that the dosimetric peak of this crystal is the superposition of at least two components (peak?2a and?2b). When the dose level reaches and exceeds saturation point, a third peak (peak 2c) is also evident on the low temperature side of the dosimetric peak. The VD and CGCD methods indicated that both components of the dosimetric peak have general-order kinetics that change with doses. The dose responses of peak?2a follow linear, supralinear, saturation and sublinear patterns, whereas peak?2b does not exhibit supralinear behaviour. They are saturated at different dose levels, peak?2a at D = 10?Gy and peak?2b at D = 5?Gy. Ea?Tstop plots obtained at two different dose levels (D = 10 and 1?Gy) indicated that the efficiency of thermal quenching effect on this sample is highly dependent on the dose level and decreases with increasing dose level, which also has pronounced effects on the evaluated kinetic and thermal quenching parameters of the dosimetric peak.

A survey of distribution of terrestrial radionuclides in surface soil samples in and around the Osmaniyeprovince, Turkey

The purpose of this survey was to determine the distribution of terrestrial radionuclides ((238)U, (232)Th and (40)K) in surface soil samples collected from different locations in and around Osmaniye and assess the radiological implications of outdoor external exposure. The activity concentrations of (238)U, (232)Th and (40)K in soil samples ranged from 2.6 to 38.1 Bq kg(-1) with a mean of 10.4±0.7 Bq kg(-1), 3.7-40.5 Bq kg(-1) with a mean of 12.2±0.7 Bq kg(-1) and 30.0-639.7 Bq kg(-1) with a mean of 243.4±12.8 Bq kg(-1), respectively. The concentrations of these radionuclides, presented in this article, were compared with those obtained from similar studies related to Turkey reported in the literature as well as earths crust average values. The results of the activity concentrations were used to assess the external absorbed gamma dose rate (GDR) in outdoor air and the annual effective dose (AED). The outdoor absorbed GDRs fluctuate from 5.2 to 53.6 nGy h(-1) with a mean of 22.4±9.5. The corresponding mean AED is found to be 0.03 mSv.

The fission-track analysis : An alternative technique for provenance studies of prehistoric obsidian artefacts

Abstract Comparison of fission-track parameters- age and track densities - is an alternative tool for correlating obsidian artefacts with their potential natural sources. This method was applied by different fission-track groups in various regions and results were compared with those obtained using the more popular provenance identification techniques based on chemical composition studies. Hundreds of analyses prove that fission-track dating is a complementary technique which turns out to be very useful, specially when the chemical composition does not fully discriminate different sources. Archaeologically significant results were obtained applying the fission-track analysis in various regions of earth.

Chemical characterisations of Anatolian obsidians by instrumental and epithermal neutron activation analysis

Obsidian is a volcanic glass which is generally black, sometimes grey, brown, red or green in colour and characterised by a glassy appearance and conchoidal fractures. It is formed by the sudden cooling of the molten, generally acid magma with high water content. Obsidian was widely used for tool-making during prehistoric times. This work concems the chemical characterisation of obsidian occurrences from Northem, Central and Eastem Anatolia by Instrumental and Epithemal Neutron Activation Analysis for obtaining an accurate “fingerprint” for discrimination of potential natural sources of raw material that would permit tracing the origin of archaeological obsidian artefacts.

Evaluation of potential exposure risks of natural radioactivity levels emitted from building materials used in Adana, Turkey

In this paper, the natural radioactivity levels in a total of 117 samples of 14 different building materials collected from building construction sites and from the retailers in Adana were studied by means of gamma-ray spectrometer with HPGe detector. The mean activity concentrations of 226Ra, 232Th and 40K measured in the studied building material samples ranged from 2.1 to 88.2 Bq kg−1, 1.8 to 52.7 Bq kg−1 and 68.1 to 847.5 Bq kg−1 for 226Ra, 232Th and 40K radionuclide, respectively. The external and internal index, the indoor absorbed dose rate and the corresponding annual effective dose were evaluated for potential exposure risks from the usage of the building material samples. The evaluated values of the external and internal index were below the recommended upper level. All the values of effective annual dose determined were lower than recommended exemption level of 0.3 mSv. The results suggest that the use of the studied building material samples in the construction of buildings is unlikely to give rise to any significant radiation exposure to the residents.

Thermoluminescence properties of annealed natural quartz after beta irradiation

Here we investigated the effects of annealing, heating rate and fading (after annealing at 800 °C) on the thermoluminescence (TL) glow curves of natural quartz (NQ). All of the samples were annealed at different temperatures between 100 °C and 800 °C and then irradiated with a beta dose of about 34 Gray (Gy), in order to determine the effects of annealing treatments on TL peaks of natural quartz. TL glow curves of the samples were recorded. It was observed that the intensities of TL peaks were strongly sensitive to annealing temperatures at 800 °C. The heating rate and fading effect of TL peaks of natural quartz were examined for the annealed samples at 800 °C for 30 min. It was observed that the intensities of the TL peaks were differently affected from heating rate and fading. Additionally, TL kinetic parameters (activation energy, frequency factor and order of kinetics) of all peaks were determined for annealed samples using a computerized glow curve deconvolution (CGCD) method and Mathematica software. Copyright

INVESTIGATION OF THE ACTIVITY LEVEL AND RADIOLOGICAL IMPACTS OF NATURALLY OCCURRING RADIONUCLIDES IN BLAST FURNACE SLAG

The activity level and possible radiological impacts of naturally occurring radionuclides on the health of workers and members of the public, as a result of utilisation of blast furnace slag (BFS) samples as a substitute for aggregate in road construction were investigated by using a gamma-ray spectrometer and potential exposure scenarios given in Radiation Protection 122. The mean activity concentrations of the (226)Ra, (232)Th and (40)K in BFS samples were found to be 152.4, 54.9 and 183.1 Bq kg(-1), respectively. These values are compared with typical values measured in BFS samples from the European Union countries, which are 270, 70 and 240 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The values of radium equivalent activity index calculated for BFS samples were within the recommended safety limits. The highest total annual effective doses evaluated as 0.9 and 0.4 mSv y(-1) for members of the public and workers, respectively, were lower than the annual limit of 1 mSv y(-1).

Environmental evaluation of natural radioactivity in soil near a lignite-burning power plant in Turkey

Natural radionuclides are released into the environment together with fly ash from the coal-burning power plant and cause an increase in the natural radioactivity in environmental samples. The study concerns to the evaluation the influence of Kangal lignite-burning power plant (LBPP) with a power of 457 MWe, which has been in operation since 1989, on natural radionuclide a concentration in surface soil samples around it. Activity concentrations of natural radionuclides (226Ra, 232Th, 40K and 222Rn) in the soil samples, and emanation coefficient (EC) and mass (ERM) and surface (ERS) exhalation rate of radon were determined by using a gamma-ray spectrometer with an HPGe detector. The average values of 226Ra, 232Th, 40K and 222Rn, EC, ERM and ERS were found as 37±5, 17±3, 222±30Bqkg-1 and 9±1kBqm-3, 12%, 12.1 µBq kg-1 s-1 and 7.1mBqm-2 s-1, respectively. Absorbed gamma dose rate in outdoor air and the corresponding effective dose rate from external exposure and excess lifetime cancer risk were estimated to evaluate radiological hazards for human population. The results revealed that the Kangal LBPP has caused a small increment in 226Ra concentration in the studied area. No influence was observed for 232Th and 40K.