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

Abstract

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.

Keywords

• Gamma-Ray Spectroscopy
• Efficiency
• Self-Attenuation Effect
• Sample Container
• PHITS
• GESPECOR

References

1. Abd El Gawad, K., Zhijian, Z., & Hazzaa, M. H. (2020). Improving the analysis performance of gamma spectrometer using the Monte Carlo code for accurate measurements of uranium samples. Results in Physics, 17, 103145. doi:10.1016/j.rinp.2020.103145
2. Azbouche, A., Belgaid, M., & Mazrou, H. (2015). Monte Carlo calculations of the HPGe detector efficiency for radioactivity measurement of large volume environmental samples. Journal of Environmental Radioactivity, 146, 119-124. doi:10.1016/j.jenvrad.2015.04.015
3. Berger, M. J., Hubbell, J. H., Seltzer, S. M., Chang, J., Coursey, J. S., Sukumar, R., Zucker, D. S., & Olsen, K. (2010). XCOM: Photon Cross Section Database. Gaithersburg, MD. doi:10.18434/T48G6X
4. Bölükdemir, M. H., Uyar, E., Aksoy, G., Ünlü, H., Dikmen, H., & Özgür, M. (2021). Investigation of shape effects and dead layer thicknesses of a coaxial HPGe crystal on detector efficiency by using PHITS Monte Carlo simulation. Radiation Physics and Chemistry, 189, 109746. doi:10.1016/j.radphyschem.2021.109746
5. Gilmore, G. (2008). Practical Gamma-Ray Spectrometry. John Wiley and Sons.
6. Guerra, J. G., Rubiano, J. G., Winter, G., Guerra, A. G., Alonso, H., Arnedo, M. A., Tejera, A., Martel, P., & Bolivar, J. P. (2018). Modeling of a HPGe well detector using PENELOPE for the calculation of full energy peak efficiencies for environmental samples. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 908, 206-214. doi:10.1016/j.nima.2018.08.048
7. Hirayama, H., Namito, Y., Bielajew, A. F., Wilderman, S. J., & Nelson, W. R. (2006). The EGS5 Code System. Technical Report (SLAC-R-730) (KEK 2005-8), Stanford Linear Accelerator Center, Menlo Park, California.
8. Knoll, G. F. (2010). Radiation Detection and Measurement. John Wiley and Sons.

9. Lépy, M.-C., Altzitzoglou, T., Anagnostakis, M. J., Arnold, D., Capogni, M., Ceccatelli, A., De Felice, P., Dersch, R., Dryak, P., Fazio, A., Ferreux, L., Guardati, M., Han, J. B., Hurtado, S., Karfopoulos, K. L., Klemola, S., Kovar, P., Lee, K. B., Ocone, R., … Vidmar, T. (2010). Intercomparison of methods for coincidence summing corrections in gamma-ray spectrometry. Applied Radiation and Isotopes, 68(7-8), 1407-1412. doi:10.1016/j.apradiso.2010.01.012
10. Lépy, M. C., Thiam, C., Anagnostakis, M., Galea, R., Gurau, D., Hurtado, S., Karfopoulos, K., Liang, J., Liu, H., Luca, A., Mitsios, I., Potiriadis, C., Savva, M. I., Thanh, T. T., Thomas, V., Townson, R. W., Vasilopoulou, T., & Zhang, M. (2019). A benchmark for Monte Carlo simulation in gamma-ray spectrometry. Applied Radiation and Isotopes, 154, 108850. doi:10.1016/j.apradiso.2019.108850
11. Modarresi, S. M., Masoudi, S. F., & Karimi, M. (2017). A method for considering the spatial variations of dead layer thickness in HPGe detectors to improve the FEPE calculation of bulky samples. Radiation Physics and Chemistry, 130, 291-296. doi: 10.1016/j.radphyschem.2016.08.020
12. NIST, (2022). Composition of material. (Accessed: 01/10/2022) URL (https://physics.nist.gov/cgi-bin/Star/compos.pl)
13. Sato, T., Iwamoto, Y., Hashimoto, S., Ogawa, T., Furuta, T., Abe, S.-I., Kai, T., Tsai, P.-E., Matsuda, N., Iwase, H., Shigyo, N., Sihver, L., & Niita, K. (2018). Features of Particle and Heavy Ion Transport code System (PHITS) version 3.02. Journal of Nuclear Science and Technology, 55(6), 684-690. doi:10.1080/00223131.2017.1419890
14. Sima, O., De Vismes Ott, A., Dias, M. S., Dryak, P., Ferreux, L., Gurau, D., Hurtado, S., Jodlowski, P., Karfopoulos, K., Koskinas, M. F., Laubenstein, M., Lee, Y. K., Lépy, M. C., Luca, A., Menezes, M. O., Moreira, D. S., Nikolič, J., Peyres, V., Saganowski, P., … Yucel, H. (2020). Consistency test of coincidence-summing calculation methods for extended sources. Applied Radiation and Isotopes, 155, 108921. doi:10.1016/j.apradiso.2019.108921
15. Sima, O., & Arnold, D. (2002). Transfer of the efficiency calibration of Germanium gamma-ray detectors using the GESPECOR software. Applied Radiation and Isotopes, 56(1-2), 71-75. doi:10.1016/S0969-8043(01)00169-5
16. Sima, O., Arnold, D., & Dovlete, C. (2001). GESPECOR: a versatile tool in gamma-ray spectrometry. Journal of Radioanalytical and Nuclear Chemistry, 248(2), 359-364. doi:10.1023/a:1010619806898
17. Stríbrnský, B., Hinca, R., Farkas, G., Petriska, M., & Slugeň, V. (2022). Modeling and Optimization of HPGe Detector GC0518 Using MCNP5 Code. Radiation Protection Dosimetry, 198(9-11), 704-711. doi:10.1093/rpd/ncac123
18. Trang, L. T. N., Chuong, H. D., & Thanh, T. T. (2021). Optimization of p-type HPGe detector model using Monte Carlo simulation. Journal of Radioanalytical and Nuclear Chemistry, 327(1), 287-297. doi:10.1007/s10967-020-07473-2
19. Uyar, E., & Bölükdemir, M. H. (2022). The effect of front edge on efficiency for point and volume source geometries in p-type HPGe detectors. Nuclear Engineering and Technology, 54(11), 4220-4225. doi:10.1016/j.net.2022.06.009
20. Yücel, H., Solmaz, A. N., Köse, E., & Bor, D. (2010). Methods for spectral interference corrections for direct measurements of 234U and 230Th in materials by gamma-ray spectrometry. Radiation Protection Dosimetry, 138(3), 264-277. doi:10.1093/rpd/ncp239