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Abstract  

Neutron activation laboratories worldwide are at a turning point at which new staff has to be found for the retiring pioneers from the 1960s–1970s. A scientific career in a well-understood technique, often characterized as ‘mature’ may only be attractive to young scientists if still challenges for further improvement and inspiring new applications can be offered. The strengths and weaknesses of neutron activation analysis (NAA) are revisited to identify opportunities for innovation. Position-sensitive detection of elements in large samples, Monte Carlo calculations replacing the use of standards, use of scintillator detectors and new deconvolution techniques for increasing the sensitivity are examples of challenging new roads in NAA. Material science provides challenges for the application of NAA in both bulk samples, ultrathin layers and ultrapure materials.

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Abstract  

Large Sample Neutron Activation Analysis (LSNAA) was applied to perform non-destructive elemental analysis of a ceramic vase. Appropriate neutron self-shielding and gamma ray detection efficiency calibration factors were derived using Monte Carlo code MCNP5. The results of LSNAA were compared against Instrumental Neutron Activation Analysis (INAA) results and a satisfactory agreement between the two methods was observed. The ratio of derived concentrations between the two methods was within 0.7 and 1.3. Estimation of the activity level decay with time showed that the vase could be released from regulatory control at about 3 months post-irradiation. This study provided an analytical procedure for bulk sample analysis of precious and archaeological objects that need to be preserved intact and cannot be damaged for sampling purposes.

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Abstract  

Instrumental neutron activation analysis (INAA) was applied to assess element concentrations in eleven samples of mineral supplements/multivitamins acquired in drugstores and pharmacies in São Paulo city, SP, Brazil. Concentrations of Ca, Co, Cr, Cu, Fe, K, Na, Se and Zn were determined. A comparison was made between the results obtained with the labels of the mineral supplents. Certified reference materials, NIST SRM1400 Bone Ash and NIST SRM 1633b Coal Fly Ash were analyzed for quality control of the analytical results.

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Abstract  

A benchmark experiment was performed for Neutron Activation Analysis (NAA) of a large inhomogeneous sample. The reference sample was developed in-house and consisted of SiO2 matrix and an Al–Zn alloy “inhomogeneity” body. Monte Carlo simulations were employed to derive appropriate correction factors for neutron self-shielding during irradiation as well as self-attenuation of gamma rays and sample geometry during counting. The large sample neutron activation analysis (LSNAA) results were compared against reference values and the trueness of the technique was evaluated. An agreement within ±10% was observed between LSNAA and reference elemental mass values, for all matrix and inhomogeneity elements except Samarium, provided that the inhomogeneity body was fully simulated. However, in cases that the inhomogeneity was treated as not known, the results showed a reasonable agreement for most matrix elements, while large discrepancies were observed for the inhomogeneity elements. This study provided a quantification of the uncertainties associated with inhomogeneity in large sample analysis and contributed to the identification of the needs for future development of LSNAA facilities for analysis of inhomogeneous samples.

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Abstract  

Different modes of epithermal neutron activation analysis are described. The principles and examples are given for each.

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Abstract  

Neutron activation analysis (NAA) remains an excellent technique to introduce undergraduate students to nuclear science and engineering coming from different academic areas. The NAA methods encompass an appreciation of basic reactor engineering concepts, radiation safety, nuclear instrumentation and data analysis. At the Nuclear Engineering Teaching Lab at the University of Texas at Austin we have continued to provide opportunities through outreach programs to Huston-Tillotson University in Austin and Florida Memorial University in Miami Gardens, both Historically Black Colleges and Universities, and Southwestern University in Georgetown, Texas. Furthermore, in the past four years we have established a strong educational collaboration with the École Nationale Supérieure d’Ingénieurs de Caen (ENSICAEN), France. Undergraduate students at ENSICAEN are required to have an internship outside of France. While many of the students stay in neighboring European countries others have chosen the United States. The cornerstone of these programs is to secure a relationship with each institution through clear educational and research objectives and goals.

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Abstract  

Main achievements towards improved quality of measurements results obtained by neutron activation analysis (NAA) at the TRIGA Mark II reactor of the Jožef Stefan Institute during its 45 years of continuous operation are reviewed from a historical perspective; emphasis is on the features specific for NAA. The development of radiochemical neutron activation analysis for characterising reference materials is described in detail in the first part. Several approaches specific for the method such as the determination of long-lived radionuclides, the simultaneous determination of several elements using double irradiation and the internal standard method are presented in more detail. Several interesting approaches such as combination with liquid scintillation counting detection and combination with radiometric measurements are outlined. Then, the development of instrumental neutron activation analysis, specifically the k 0-NAA based method is discussed. The contribution towards methodological development of uncertainty assessment is outlined, and the importance of the nuclide-specific and neutron fluence-specific approach is emphasised. Throughout the paper, the importance of neutron activation analysis and contributions of measurements results obtained by this method to characterising (candidate) reference materials is shown.

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Abstract  

Instrumental neutron activation analysis (INAA) was applied to determine Ca, Cl, Mg, Mn, Na, Sr and Zn in human dentin and enamel tissues from carious and sound teeth. Comparisons were made between the results obtained in carious and sound dental tissues for dentin and enamel. The findings obtained were also compared with the published data. Accuracy and precision of the results were evaluated by analyzing certified reference material.

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Abstract  

Mice genetically selected for high antibody responsiveness (HIII) were immunized against different Bothrops species snake venoms from distinct region of Brazil. The Neutron Activation Analysis technique was used to evaluate the whole blood concentrations of elements of clinical relevance [Ca, Cl, K, Mg and Na] in order to establish a potential correlation between antibody response and blood constituents after Bothrops venom administration for clinical screening of envenomed patients.

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Abstract  

In the Egyptian society, it is usual until now that females wear extensively gold jewelry since their birth. The present work is carried out to determine gold content in scalp hair samples from some selected female donors of various ages. Instrumental Neutron Activation Analysis, with gamma ray spectrometry was applied for this study. The obtained data are compared with the available published data for analysis of hair samples from other countries. The correlation between age and gold concentration in hair samples is discussed. Interpretation of the influence of other factors which possibly may affect the contents of gold in the analyzed hair samples is also presented.

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