Duran, S.U.; Küçükömeroğlu, B.; Çevik, U.; Çelik, N.; Taskin, H.; Ersoy, H.

Background: The aim of this study is to measure the level of radon gas in the thermal springs of the four seasons in the Black Sea Region and to determine the gamma activity levels in the soils around them. Materials and Methods: Indoor radon activity concentrations of four spa facilities, namely Ladik, Havza, Ilıcaköy, and Ayder, were measured using CR-39 passive radon dosimeters and active radon monitoring AlphaGUARD for all four seasons. Radon activity concentrations in the soil in the vicinity of these spa facilities were measured using AlphaGUARD. Radionuclides in the soil samples collected from the spa regions were also determined using gamma-ray spectroscopy. Results: The highest radon value in the air environment in the spa facility was measured in swimming pools. Indoor radon levels in the spa's swimming pool vary within a wide range, (30-2118) Bq·m−3. The average radon gas levels in the soil around the Ayder, Havza, Ladik and Ilıcaköy hot springs were measured as 38±1 kBqm-3, 9±1 kBq m-3, 50±3 kBqm-3, 955±5 kBqm-3, respectively. Conclusion: The annual effective doses due to indoor radon sources changed from 0.6 mSv to 13.4 mSv for workers, and from 1 x10 -4 mSv to 3x10-1 mSv for patients. The annual effective dose equivalents from the soils around the spa were calculated to be between 82-558 µSv y-1. The results were compared with those of other measurements performed in different parts of the world.

Çelik, N.; Özen, S.A.; Demirtaş, Ö.F.; Çevik, U.

The effect of energy resolution of two detection systems, HPGe and NaI(Tl), was determined by Monte Carlo (MC) calculation on mass attenuation coefficients of magnesium (Mg) and tungsten (W). In order to reveal the energy resolution effect, the detectors' collimator diameters were changed from 2 mm to 20 mm while sending collimated photon beams to the absorber material. It was observed that mass attenuation coefficients were increased with increasing collimator diameters. The performances of HPGe and NaI(Tl) detectors were quantified. The calculated results were compared with experimental results for Mg at energy of gamma rays 662 keV for different collimator diameters using both HPGe and NaI(Tl). It was observed that the MC calculation results were in a good agreement with the experimental data within the relative error from around 4% to 8%.

Çelik, N.; Çevik, U.; Küçükömeroğlu, B.

Variation of virtual point detector (VPD) position inside HPGe detector as a function of source photon energy for the energy range from 26.6 to 1,332 keV was investigated. Although VPD concept was well established for HPGe detectors from 59.5 to 10 MeV, a new attempt was made to obtain VPD positions for photon energies below 59.5 keV. It was found that VPD position shows different functional behavior for the energy ranges 26.6-59.5 keV and 59.5-1,332 keV. The VPD position decreases with increasing energy for 26.6, 31.7, 36.4, and 37.3 keV and increases with the energy until it reaches a plateau. The functional behavior of VPD position for the energy range 26.6-59.5 keV was attributed to the dead layer thickness of the Ge crystal. Monte Carlo simulations were performed to investigate the behavior of VPD position with various dead layer thickness ranging from 100 to 800 μm. It was seen that VPD position increases with increasing energy for 31.7, 59.5, and 80.1 keV more significant at relatively lower energies, but constant for the energies 661-1,332 keV.

Karabidak, S. M.; Kaya, S.; Çevik, U.; Çelik, A.

Reducing count losses and pile-up pulse effects in quantitative and qualitative analysis is necessary for accuracy of analysis. Therefore, the proper peaking time for particular detector systems is important. The characteristic X-rays emitted from pure some elements were detected by using an Ultra-LEGe detector connecting a Tennelec TC 244 spectroscopy amplifier at different peaking time modes. Overall pulse widths were determined by an HM 203-7 oscilloscope connecting amplifier. The proper peaking time for Ultra-LEGe is determined as 3.84 mu s. (C) 2011 Elsevier Ltd. All rights reserved.