Attenuation Effect of Sample Container in Radioactivity Measurement by Gamma-ray Spectroscopy

The measurement of radioactivity in environmental samples containing natural radionuclides such as 238U, 232Th, and 40K in gamma-ray spectrometry is the most common application. One of the most widely used sample containers for environmental radioactivity measurements is volumetric sample containers of certain sizes in cylindrical geometry. These cylindrical containers can be made of materials with different densities and thicknesses. In this intention, in this study, the effect of the sample container, which is one of the many parameters affecting the detector efficiency, was investigated. For this purpose, acrylic and polypropylene materials with of different densities were examined. IAEA RGU-1, IAEA-RGTh-1 and IAEA-RGK-1 standards containing uranium, thorium and potassium environmental radionuclides analyzed in gamma-ray spectrometric measurements were used as samples for these sample containers with different densities. Additionally, since the spectra in cylindrical geometry are taken by placing them on the detector endcap, the effect of the bottom thickness was investigated by changing the bottom thickness of these materials. Different material and bottom thickness evaluations were made using PHITS and GESPECOR Monte Carlo simulation programs. Compatible results were obtained with a difference of <5% between the PHITS and GESPECOR programs. From the outcome of this study, it can be concluded that when choosing the container material, the density should be as low as possible and especially the bottom thickness should be thin.