Standardization and application of internal monostandard NAA method using the Dalat research reactor
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Standardization and application of internal monostandard NAA method using the Dalat research reactor Tuan Anh Tran1 · Manh Dung Ho2 · Van Doanh Ho1 · Van Cuong Trinh1 · Duy Quang Nguyen1 · Thi Tho Nguyen1 Received: 29 December 2019 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The k0-based internal monostandard INAA method (IM-NAA) has been investigated for the determination of elemental concentrations in non-standard geometry samples at the Dalat research reactor (DRR). The experiments were implemented at the rotary specimen rack of the DRR which the thermal neutron flux was (3.61 ± 0.11) × 1012 n cm−2 s−1. In this work, the concentration analysis of Montana II Soil (SRM 2711a) and Brick Clay (SRM 679) have been used to validate the method. The elemental concentrations of Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Rb, Sb, Sm, Ta, Th, Yb, Zn have been analysed and to be in good agreement with certified values. The IM-NAA method has been applied to determine elemental concentrations in clay bricks and ceramics at the Cat Tien archaeological site. Keywords IM-NAA method · Non-standard geometry · Dalat research reactor
Introduction The k0-standardized neutron activation analysis has been successfully developed and applied in quantitative analysis of multi-element compositions in geological, biological, environmental samples. In this method, elemental concentrations are analyzed based on the specific activity of Au monitor which is simultaneously irradiated with analytical samples, neutron spectrum parameters α and f, as well as k0 factor [1]. Hence, the accuracy of obtained results strongly depends on these experimental values. In addition, the corrections for neutron self-shielding and gamma self-absorption effects must be required to take into account when applying the k0-based INAA on high neutron absorption materials and voluminous samples [2–6]. Several works have reported the calculations as well as experiments of these effects in volume samples. Chilian et al. [4] introduced a new iterative approach to correct the neutron self-shielding for cylindrical samples with unknown compositions. The measurement of the effect of neutron-absorbing samples * Tuan Anh Tran [email protected] 1
Dalat Nuclear Research Institute, 01 Nguyen Tu Luc, Dalat City, Vietnam
Center for Nuclear Techniques, 217 Nguyen Trai, Ho Chi Minh City, Vietnam
2
on nearby flux monitors was also carried out in Ref. [5]. Menezes et al. [6] used MATSSF and KayWin softwares to calculate the Gth, Gepi, efficiency and coincidence correction factors in 5 g soil sample. For the large sample up to kg size, the Monte Carlo simulation is used to calculate these corrections [7, 8]. Overwater et al. [7] presented the algorithms for correction of neutron self-shielding and γ-rays self-attenuation effects without information of sample compositions. Mandour et al. [8] calculated neutron and gamma correction factors using MCNP5 Monte Carlo code for unknown samples and calculated values could be obtained on tabulated data or graphs. The previous works h
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