G. Kaynak

Evaluation of radon concentration in well and tap waters in Bursa, Turkey

(222)Rn measurements in water samples collected from 27 wells and 19 taps that were supplied from the investigated wells were conducted using the AlphaGUARD PQ 2000PRO radon gas analyser at sites across several geologic formations within the city of Bursa, Turkey. The measured radon concentrations ranged from 1.46 to 53.64 Bq l(-1) for well water and from 0.91 to 12.58 Bq l(-1) for tap water. Of the 27 sites sampled, only 7 had radon levels above the safe limit of 11.1 Bq l(-1) recommended by the USEPA. In general, all determined concentrations were well below the 100 Bq l(-1) revised reference level proposed by the European Union. These values of radon concentrations in water samples are compared with those reported from other countries. Doses resulting from the consumption of these waters were calculated. The minimum and the maximum annual mean effective doses due to (222)Rn intake through water consumption were 0.02 µSv a(-1) and 1.11 µSv a(-1), respectively.

Measurements of radon concentration in drinking water samples from Kastamonu (Turkey)

Concentration of 222Rn was determined in selected natural spring and tap water samples collected during spring and summer seasons from Kastamonu, Turkey. The aim of this work was to produce a map of the radon concentrations in water sources of the province and to determine any potential radiological risk for the local population. Radon measurements were performed by an AlphaGUARD radon gas analyser. The average radon concentrations were found to vary from 0.39±0.02 to 12.73±0.39 Bq l−1 for natural springs and from 0.36±0.04 to 9.29±0.45 Bq l−1 for tap water in spring, from 0.50±0.09 to 19.21±1.00 Bq l−1 for natural springs and from 0.31±0.03 to 13.14±0.38 Bq l−1 for tap water in summer. Furthermore, the results are compared with international recommendations and concentrations reported for other countries. Doses resulting from the consumption of these waters were calculated. The effective dose equivalents due to the intake of the 222Rn present in these waters are expected to range from 0.93 to 32.54 μSv y−1 in summer and from 0.80 to 49.09 μSv y−1 in spring.

Giant Magneto–Impedance Effect in Thin Zinc Oxide Coated on Co-Based (2705 X) Amorphous Ribbons

ZnO film coated Co-based (2705 X) amorphous ribbons are prepared by the successive ionic layer adsorption and reaction technique. The influence of coating on giant magneto-impedance (GMI) has been investigated over a frequency range from 0.1 to 3.5 MHz and under a static magnetic field between -8 and +8 kA/m. The highest GMI ratio of 15.63% was obtained in the coated Co-based amorphous ribbons which is 80% higher than the sample without coating. The results indicate that the surface coating process plays an important role in the GMI effect.

Analytical Information on the Asphaltenes from a Few Standard Characterization Techniques

Abstract The asphaltene has been obtained from asphalt cement with penetration grade 60, which is extracted from crude Libya petroleum. The elemental composition and some structural properties of the asphaltene samples are determined by various methods, such as SEM, infrared spectroscopy, and X-ray analysis. Some experiments are performed on 1H dynamic nuclear polarization (DNP) in a number of asphaltene suspensions in organic solvents. The frequency dependence of the DNP enhancement under conditions of weak EPR saturation in a low magnetic field is obtained and interpreted as the EPR line shape of some free radicals present in the samples.

The variation of cross sections with energy for gamma rays in the atmosphere

Abstract It is known that for the study of low-energy gamma rays in the atmosphere, coherent scattering, incoherent scattering, photoelectric effect, and total coherent and incoherent cross-sections are needed. In this study, a number of interpolation functions are derived to relate energy to cross-section continuously.

Measurements of radon concentrations in waters and soil gas of Zonguldak, Turkey

The radon concentrations in soil-gas and water samples (in the form of springs, catchment, tap, thermal) used as drinking water or thermal were measured using a professional radon monitor AlphaGUARD PQ 2000PRO. The measured radon concentrations in water samples ranged from 0.32 to 88.22 Bq l(-1). Most of radon levels in potable water samples are below the maximum contaminant level of 11 Bq l(-1) recommended by the US Environmental Protection Agency. The calculated annual effective doses due to radon intake through water consumption varied from 0.07 to 18.53 µSv y(-1). The radon concentrations in soil gas varied from 295.67 to 70 852.92 Bq m(-3). The radon level in soil gas was found to be higher in the area close to the formation boundary thrust and faults. No correlation was observed between radon concentrations in groundwater and soil gas. Also, no significant correlation was observed between soil-gas radon and temperature, pressure and humidity. The emanation of radon from groundwater and soil gas is controlled by the geological formation and by the tectonic structure of the area.

Variation in the radon concentrations and outdoor gamma radiation levels in relation to different geological formations in the thermal regions of Bursa, Turkey.

Spring waters used as spas and their region may contain significant amounts of natural radionuclides. The main sources of exposure are the inhalation of radon and its decay products released from the water and soil and terrestrial gamma-radiation. In order to evaluate the potential risk of thermal regions in Bursa, located in the impact area of the NAF (North Anatolian Fault), radon and thoron concentrations in soil gas, radon concentrations in thermal waters and outdoor gamma radiation levels were measured in thermal regions that have different geological formations. The radon and thoron concentrations in soil-gas were found to vary from 2272  ±  121 to 245196  ±  3455 Bq m-3 and from 999  ±  218 to 178 848  ±  17 742 Bq m-3, respectively. The radon concentrations in thermal waters ranged from 0.99  ±  0.21 to 226.74  ±  2.51 Bq l-1 in the rainy season and from 0.26  ±  0.10 to 178.03  ±  12.86 Bq l-1 in the dry season. The measured outdoor gamma radiation levels varied from 38 to 180 nGy h-1. The gamma dose rates were found to be strong positively correlating with the radon and thoron concentrations in soil-gas. The radon and outdoor gamma radiation levels were observed to be a function of the geological formations of the area.

The investigation of radionuclide distributions in soil samples collected from Bursa, Turkey.

The distributions of (226)Ra, (232)Th, (40)K and (137)Cs activity concentrations were determined using a high-purity germanium detector in uncultivated surface soil samples collected from Bursa. The range of (226)Ra, (232)Th, (40)K and (137)Cs activity concentrations varied from 10±1 to 61±3 Bq kg(-1) (mean value 25±3 Bq kg(-1)), from 12±1 to 50±2 Bq kg(-1) (mean value 26±3 Bq kg(-1)), from 257±5 to 1010±11 Bq kg(-1) (mean value 435±44 Bq kg(-1)) and from 1.01±0.07 to 48.97±0.54 Bq kg(-1) (mean value 8.52±2.59 Bq kg(-1)), respectively. In addition, the mean outdoor absorbed dose rates in air, annual effective dose equivalent, radium equivalent activity and external hazard index were found to be 45 nGy h(-1), 56 μSv y(-1), 96 Bq kg(-1) and 0.26, respectively. The gross beta activity concentrations were determined using a Tennelec LB 1000-PW detector. The range of gross beta activity concentrations varied from 46±9 to 1199±113 Bq kg(-1) with a mean value of 541±19 Bq kg(-1).

Calculation of angular distribution of 662 keV gamma rays by Monte Carlo method in copper medium.

This paper presents results on the angular distribution of Compton scattering of 662 keV gamma photons in both forward and backward hemispheres in copper medium. The number of scattered events graph has been determined for scattered gamma photons in both the forward and backward hemispheres and theoretical saturation thicknesses have been obtained using these results. Furthermore, response function of a 51 x 51 mm NaI(Tl) detector at 60 degrees angle with incoming photons scattered from a 10mm thick copper layer has been determined using Monte Carlo method.

Electrical properties of photodiodes based on p-GaSb/p-GaInAsSb/N-GaAlAsSb heterojunctions

We have studied the electrical characteristics of photodiodes based on p-GaSb/p-GaInAsSb/N-GaAlAsSb heterojunctions and investigated the mechanisms of current transfer in these heterostructures at various temperatures. A comparison of the theoretical results and experimental data showed that the tunneling charge transfer mechanism dominates at low temperatures (T < 150 K) under both forward and reverse bias conditions. The tunneling current becomes a determining factor at an electric field strength in the p-n junction of no less that 105 V/cm, which is related to a small bandgap width of the materials studied and low effective masses of electrons and holes.