Düzgün, İ.; Küçük, M.A.; Kaya, S.; Çelik, N.

Low-cost NaI(Tl) detectors are practical for gamma-ray spectrometry but their limited energy resolution can introduce systematic errors in mass attenuation coefficient measurements when scattered photons are included in the peak region. This study proposes a machine-learning correction framework that maps NaI(Tl)-derived attenuation coefficients to XCOM-based HPGe-equivalent reference values through a dimensionless correction factor. An EGS4/XCOM dataset of 756 model-development configurations, covering 18 atomic numbers, six monoenergetic photon energies, and seven collimator radii, was used to train twelve regression models and evaluate them over 60 randomized train–validation–test cycles. Sodium and Bismuth were withheld for external material-wise validation. Gaussian Process Regression with a Matérn 5/2 kernel provided the best overall testing performance. For the withheld materials, the correction reduced the mean deviation from XCOM references from 3.07% to 0.83%, supporting its use as a practical correction layer for low-cost attenuation measurements.

İncele

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.

AtıfScopus3·WoS3

İncele

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%.

AtıfScopus8·WoS7·OpenAlex7

İncele

Çelik, N.

The virtual point detector (VPD) concept for an HPGe detector with 55% relative efficiency was confirmed for bulky sources having different diameters and heights. After reproducing experimental data, Monte Carlo simulation was used to investigate the dependence of VPD location on photon energy for various source diameters and heights in the energy range from 60 keV to 2 MeV. The simulations were confirmed using a soil reference source prepared by International Atomic Energy Agency (IAEA). It was seen that increasing photon energy makes significant changes in VPD location up to 600 keV. It was observed that VPD locations increase with increasing source diameter and height. It was also seen that VPD locations were approximately linearly dependent on source diameters and heights.

AtıfScopus5·WoS5·OpenAlex6

İncele

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.

AtıfScopus4·WoS3·OpenAlex3

İncele