Karabidak, S.M.; Cevik, U.

The counting systems consisting of electronic devices are used for detection of radiation due to X or gamma rays. The dead time of the counting system is based on time limitations of these electronic devices. The dead time causes counting losses. Determination of counting rate losses in quantitative and qualitative analysis become a vital step for correction of analysis. Therefore, compensating for counting rate losses is of great importance. These counting rate losses are due to piled up reject time, paralyzable or non-paralyzable system dead time or a combination of these mechanisms. Paralyzable and non-paralyzable models are well-known and frequently used for correction of counting rate losses dependent on the system dead time. However, these two models do not provide enough correction at medium and high counting rates. Therefore, the new models for corrections of counting rate losses are needed. For this reason, both an alternative approach is proposed and a simulation program is coded for counting rate losses in this study. A good agreement is obtained between theoretical model and simulation program.

Damla, N.; Cevik, U.; Kobya, A. I.; Celik, A.; Celik, N.; Yildirim, I.

In this study the distribution of natural radionuclides ((226)Ra, (232)Th, (40)K) in brick and roofing tile samples commonly used as building materials in Turkey was measured by using gamma spectrometry. The activity concentrations, radium equivalent activities (Ra(eq)), representative level index, indoor absorbed dose rate in air values and annual effective dose due to the intake of the above-mentioned radionuclides in the brick and roofing tile samples were estimated to assess the radiation hazard for people living in dwellings made of the materials studied. The measured average activity concentrations of (226)Ra, (232)Th and (40)K were 34 +/- 14, 34 +/- 13 and 462 +/- 175 Bq.kg(-1), respectively, for brick samples. For roofing tile, the average activity concentrations of (226)Ra, (232)Th and (40)K were measured to be 34 +/- 14, 33 +/- 12 and 429 +/- 161 Bq.kg(-1), respectively. The concentrations for these natural radionuclides were compared with the reported data of other countries. The Ra(eq) values of all samples were lower than the limit of 370 Bq.kg(-1), equivalent to a gamma dose of 1.5 mSv.a(-1) recommended by OECD. This study shows that the measured brick and roofing tile samples do not pose any significant source of radiation hazard and are safe to be used as building materials. Moreover, the experimental mass attenuation coefficients (mu/rho) of brick and roofing tile samples were determined in the energy range 80-1332 keV using the gamma ray transmission method. The experimental mass attenuation coefficients were compared with theoretical values obtained using XCOM. It was found that the computed values and the experimental results of this work are in good agreement with those reported in the literature. The chemical compositions and structural analysis (XRD) of the brick and roofing tile samples are also presented. (C) 2011 Elsevier Ltd. All rights reserved.

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.