Application of Hypermet-PC in PGAA

Summary Hypermet-PC has been developed in the mid-nineties at the Institute of Isotopes and Surface Chemistry based on a successful FORTRAN code from the seventies. With additional calibration routines and other helping features it has proved to be a very useful tool in quantitative analysis performed either with NAA or with PGAA. The sophisticated built-in peak-shape function allows the fitting of asymmetric peaks from large-volume germanium detectors over a very wide energy range needed for PGAA. The experience collected when evaluating several thousands gamma-spectra acquired for routine analysis and spectroscopic research, is summarized in the paper.     

Uses of PGAA at the Dalat reactor

A facility for neutron capture prompt -ray spectroscopy for activation analysis has been intstalled at the tangential beam tube of the 500 kW Dalat reactor. Using a single crystal of silicon for filtering the thermal neutron beam and the 73 cm³ HP-G detector shielded by common materials with flexible configurations suitable to various samples, LOD of nearly 30 elements were estimated. Applications of PGAA in the determination of elemental concentrations in biological, environmental, geological and industrial product samples are presented.     

Non-invasive PGAA,PIXE and ToF-ND analyses on Hungarian Bronze Age defensive armour

Non-invasive, archaeometric analyses on selected Hungarian Bronze Age defensive armour is presented here: three greaves, three helmets two shields as well as one vessel fragment were analysed with PIXE, PGAA and TOF-ND. The detected alloy elemental and phase composition as well as its intergranular or spatial concentration distribution reveals important insights into the alloys used and the manufacturing techniques applied c. 1200–950 BC, and allows to reconstruct the production techniques used during the Late Bronze Age.     

A New Gamma-Ray Spectrum Catalog for PGAA

A major obstacle to the use of the prompt gamma activation analysis (PGAA) method has so far been the lack of a suitable library. Therefore, new measurements have been performed at the PGAA facility at Budapest Research Reactor (BRR) in order to create a prompt -ray catalog for qualitative and quantitative analysis. Prompt -ray energies and associated k ₀-factors have been determined by internal standardization. The resulting catalog contains prompt -ray data from neutron capture and other reactions such as (n,), and decay -ray data from short-lived reaction products. Data have been measured for nearly all stable elements, from hydrogen to uranium. Generally, data for several isotopes are given, to enable isotopic analysis as well.     

Analysis of macro-constituents in steels by PGAA

The determinatin of the concentration of major steel forming elements in 2–5 g steel samples by PGAA and reference to synthetic standard or single comparator is presented. The relative standard deviation is approximately 5%. The analysis time is about 60 min per sample.     

Using k0 in PGAA: Perspectives

Prompt-gamma activation analysis (PGAA) differs from conventional neutron activation analysis in the set of elements measured, the irradiation conditions, and the nature of the gamma-ray spectra. Each of these affects the conduct of the measurements and interpretation of the data. In its recent development, the k ₀ standardization framework provides a solution to many of the problems of this analytical method, and may provide a bridge to greater certainty of analysis.     

Sampling and metrology

The result of a measurement refers in principle only to the amount of substance actually contributing to the analytical signal. However, an appropriate definition of the measurand must include a specification of the system for which the result of the measurement should apply. All systems being inherently heterogeneous, representativity assumes importance for the metrological quality of a measurement, and the process needed to ascertain representativity is sampling. The contribution from this characteristic must be included when expressing the uncertainty of the reported value of the measurand. Representative sampling of systems that are infinite or non-uniform was developed by Pierre Gy in his Theory of Sampling. Finite systems can achieve uniformity by mechanical treatment and mixing; the heterogeneity of these systems can be characterized by a sampling constant, expressed in units of weight, for each particular species being determined. Examples of the contribution of sampling to the uncertainty of analytical results are discussed for some biological materials. Presented at the 2nd International Conference on Metrology – Trends and Applications in Calibration and Testing Laboratories, November 4–6, 2003, Eilat, Israel.     

PGAA metals analysis in tailings in Zaida abandoned mine,high Moulouya,Morocco

The basin of Moulouya Oued is a region where mining industry has been developed early in the 20th century. As a consequence, residues generated from past mining activities over the years have been dumped as piles of tailings. Zaïda is one of the most affected region in this basin because of lead mine exploitation for long time. The aim of this study is to determine the amount of trace elements and the contamination of the river sediments. Analysis of collected samples has been achieved using the prompt gamma activation analysis method. The samples, in form of powders, were enclosed in Teflon sheets. The spectra were analyzed using HYPERMET PC software and the chemical composition is calculated using an Excel-macro that provides the concentrations as molar and weight percentages, as well as the corresponding masses of the oxides. The validation of the analytical method is demonstrated with the analysis of a reference material. The results show that the distribution of the studied metals (Pb, Zn, Cu, Cd, Cr Ni, and As) in the basin is dependent on location with a very significant contamination by Pb, Zn, Cu, Cd, Cr, and Ni close to the lead mine sites.     

Comparative PGAA and NAA results of geological samples and standards

Concentrations of major and trace elements in volcanic rock and soil samples, including geological standard reference materials, were determined by neutron activation analysis (NAA) and prompt gamma activation analysis (PGAA), both using the k ₀-standardization method. The paper highlights the different experimental procedures, such as sample preparation, data collection and spectrum evaluation. In geological samples, PGAA gives precise results for major elements (Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K and—as a unique method—for H), for some of the light trace elements as B and Cl, as well as for Sc, S, Cr, Co, Ni, Cd, Nd, Sm and Gd. NAA is sensitive for the rare earth elements, and for many major (Ti, Al, Fe, Mn, Mg, Ca, Na, K) and trace elements (e.g.: Sc, V, Cr, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Zr, As, Sb, Ce, Ba, Hf, Ta, W). For most major elements the results obtained by the two methods show good agreement. The comparison of the results obtained for trace elements is not always possible, since PGAA is less sensitive and concentrations are often below its detection limits. Nevertheless, the complementarity of NAA and PGAA allows nearly panoramic analysis of geological materials.     

Gamma-ray background at the Budapest PGAA facility

Summary The gamma-ray background components of the Budapest PGAA-NIPS facilities have been extensively studied. Sources and production processes for the background gamma-rays have been identified and collected in tables. The data obtained here may help to identify background components at other PGAA or slow neutron capture facilities, and can be useful at any facility where neutrons are present and produce background gamma-radiation.     

Ceramic glaze analysis by simultaneous in-beam PGAA and XRFS

Twenty-one ready-to-use hobby glazes, of which 18 were labeled safe for food containers (SFFC), were analyzed for Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Gd, Hf, K, Mn, Na, Pb, Si, Sm, Sr, Ti, Zn, and Zr by neutron capture prompt -ray activation analysis (PGAA). Simultaneously, Pb was also determined by X-ray fluorescence spectrometry (XRFS) using Pb K X-rays induced by the -ray component of the neutron beam. The XRFS limits of detection were 200–400 g Pb·g^–1 (dry weight), a factor of 100 better than those for PGAA. Pb concentrations (by dry weight; with weight losses ranging from 28 to 49% after air-drying) found were 0.16–27.2% in the SFFC glazes and 0.86–32% in the other glazes. The SFFC glazes contained from <0.6 to 202 g Cd·g^–1, and Co, Cr, and Cu (elements which may enhance Pb leaching from fired glazes) were found in concentrations up to 1.2, 2.7, and 5.6%, respectively. Method accuracy was demonstrated with the analysis of soil, fly ash, and glass standard reference materials.     

A new gamma-ray spectrum catalog and library for PGAA

New measurements have been performed at the PGAA facility at the Budapest Research Reactor (BRR) in order to create a prompt -ray catalog for qualitative and quantitative analysis. The measured spectra were accurately analyzed by HYPERMET-PC. Prompt -ray energies and associated -ray production cross-sections have been determined by internal standardization. The resulting catalog contains prompt -ray data from neutron capture and other reactions such as (n,), and decay -ray data from short-lived reaction products. Data have been measured for nearly all stable elements, from hydrogen to uranium. Generally, data for several isotopes are given, to enable isotopic analysis as well. The whole library, including elemental spectra, will be available as a book.     

Maple syrup analysis for137Cs,K, and B,using a low-background counting system and PGAA

Fifteen maple syrups were analyzed for¹³⁷Cs and K (via⁴⁰K) by using a low-background -ray counting system, and for B and K by using neutron capture prompt -ray activation analysis (PGAA). For low-background -ray counting, 3 limits of detection (24-hour counts) were 0.03 Bq¹³⁷Cs/kg and 10 mg K/kg for 3.5-L portions and 0.08 Bq¹³⁷Cs/kg and 20 mg K/kg for 1.0-L portions. K concentrations determined by the two methods (using 2-g portions for PGAA) were in excellent agreement. The products were obtained in 1991, with one produced in Maryland, three in New York, four in Pennsylvania, two in New Hampshire, and five in Canada. The average activity concentration for Canadian syrups (2.8 Bq¹³⁷Cs/kg) was nearly a factor of 20 greater than the average (0.15 Bq¹³⁷Cs/kg) for the other syrups, but all¹³⁷Cs activity concentrations were at least 100 times lower than those for which controls would be recommended according to Federal Radiation Council guidance. The data exhibited distinct groupings related to the sources of the products when the ratios of¹³⁷Cs activity to K content (Bq_Cs/mg_K) were plotted vs. B concentrations.     

An ENAA and PGAA comparative study of anoxic Black Sea sediments

A comparative study performed by means of both epithermal neutron activation analysis (ENAA) and prompt gamma neutron activation analysis (PGAA) concerning the distribution of 9 elements (Na, Al, Cl, K, Ca, Ti, Mn Fe and Sm) in unconsolidated sediments collected from the Black Sea anoxic region is presented. Principal component analysis (PCA) was used as a supplementary method in interpreting experimental data. The final results have shown that eight of them (Na, Al, Cl, K, Ti, Mn, Fe and Sm) have concentrations which differ by less than 30% from the corresponding concentrations of Upper Continental Crust (UCC), confirming the continental origin of sediments. At the same time, Ca concentration was about six times higher than that of UCC, this significant enrichment being due to the presence of the neighbouring oxygenated zone of considerable deposits of shell debris, characteristic of the Western Black Sea Continental Platform. Excepting Na and Mn, the concentrations of all other elements involved in this intercomparison were coincident within one standard deviation which attests the accuracy of this test. At the same time, PCA revealed the presence of five clusters, which could be put into concordance with the mineralogical composition of sediments, each of them consisting in equal proportions of elements determined by both methods.     

Conceptual thinking and metrology concepts

In introducing the term ‘concept’, the authors of the 2008 International vocabulary of metrology ‘Basic and general concepts and associated terms’ (VIM, 2008) recognize that in order to operationalize a globally accepted set of metrology terms, one requires to deal with a higher level of abstraction. Concepts are obviously not specific to metrology–handling complex tasks in any domain of knowledge that requires conceptual thinking abilities. In this short white paper, we discuss how to assess and develop conceptual thinking of professionals in service, business, and industrial environments. The approach builds on a proven methodology called MERLO that has been developed in the last 15 years by experts in psychology and education with adaptation to new interactive technologies such as clickers and internet-based formative assessments. MERLO pedagogy can be used to assess individuals’ inherent conceptual thinking abilities and train them to enhance their competence in analyzing complex conceptual situations. This is pertinent to the education of metrology, quality, and statistical thinking. We suggest that MERLO can be considered as a complementary enabler to VIM, so that this fundamental work can enhance its impact and applicability.     

Chemical metrology, chemistry and the uncertainty of chemical measurements

Chemical results normally involve traceability to two reference points, the specific chemical entity and the quantity of this entity. Results must also be traceable back to the original sample. As a consequence, any useful estimation of uncertainty in results must include components arising from any lack of specificity of the method, the variation between repeats of the measurement and the relationship of the result to the original sample. Chemical metrology does not yet incorporate uncertainty arising from any lack of specificity from the method selected or the traceability of the result to the original sample. These sources of uncertainty may however have much more impact on the reliability of the result than will any uncertainty associated with the repeatability of the measurement. Uncertainty associated with sampling may amount to 50–1000% of the reported result. Chemical metrology must be expanded to include estimations of uncertainty associated with lack of specificity and sampling. Received: 29 May 2001 Accepted: 17 December 2001     

Fundamentals of fluctuation metrology

The possibility in principle of extending metrological concepts to the characteristics of complex objects, the primary information about the state or structure of which is presented in the form of complex chaotic dependences and cannot be expressed using standard metrological images such as directly measured time and length and other dimensional values, is shown. To correctly characterize the dynamic state of such complex objects, including states of objects during nonstationary evolution, or the special features of structures formed under the conditions of external actions of various intensities, it is necessary, first, to introduce autocorrelation dependences averaged over time or spatial intervals on the basis of measured dynamic variables and, next, to use these dependences to find sets of information parameters, which can be presented as metrological characteristics of the dynamic state under study or spatial image to be analyzed. The phenomenological basis of the corresponding analysis is provided by flicker-noise spectroscopy with its possibilities of developing procedures and algorithms that can be used to obtain metrological characteristics over various frequency (time and spatial) ranges of the signals analyzed. This is the basis on which unity of metrological characteristic measurements with a determined uncertainty (error) in measurements can be achieved, standards and reference samples of fluctuation metrology can be created, and methods for the transfer of standard parameters from standards to reference samples and then to working measurement instruments can be developed. This opens up the possibility for solving many practical problems of microelectronics, energetics, nanoindustry, chemical technology, which include standardization of the state of complex systems and articles of various functional purposes, and the quality of products created.