A new PGAI-NT setup at the NIPS facility of the Budapest Research Reactor

Prompt gamma activation analysis (PGAA) is a well known tool for non-destructive bulk elemental analysis of objects. The measured concentrations are only representative of the whole sample if it is homogenous; otherwise it provides only a sort of average composition of the irradiated part. In this latter case one has to scan the sample to obtain the spatial distribution of the elements. To test this idea we have constructed a prompt gamma activation imaging — neutron tomograph (PGAI-NT) setup at the NIPS station of the Budapest Research Reactor, consisting of a high-resolution neutron tomograph and a germanium gamma-spectrometer. The samples are positioned relative to the intersection of the collimated neutron beam and the projection of the gamma-collimator (isocenter) by using an xyzω-moving table.     

Prompt gamma activation analysis and time of flight neutron diffraction on ‘black boxes’ in the ‘Ancient Charm’ project

The aim of the ‘Ancient Charm’ project is combining neutron tomography, prompt gamma activation analysis, time of flight neutron diffraction and neutron resonance transmission to generate elemental, and phase compositions of complex museum objects in 3D. To develop a protocol for such investigations, complex test samples were constructed and then analyzed by each method. The ‘black boxes’ are sealed iron and aluminum walled cubes, containing 2D or 3D arrangements of materials relevant for the compositions of archaeological samples. The experimental results obtained from bulk PGAA at BNC and TOF-ND at ISIS on two selected boxes are reported.     

Large sample neutron activation analysis of a ceramic vase

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.     

Three-dimensional micro-XRF investigations of paint layers with a tabletop setup

The non-destructive investigation of art and archaeological objects with depth sensitivity is now possible using 3D micro-XRF spectroscopy. More detailed answers for questions on painting techniques, on the pigment palette, on the production processes and indirectly on dating or provenancing of objects are accessible now. This was already illustrated by the investigation of Mughal miniatures with a confocal setup at the synchrotron source BESSY.In this paper we demonstrate the feasibility of 3D micro-XRF spectroscopy with a tabletop setup and discuss its sensitivity in comparison to the synchrotron-based setup. Investigated objects are glass standards and also prepared paint layers. Perspectives for other types of studies are proposed.     

Chemical characterisations of Carpathian obsidian sources by instrumental and epithermal neutron activation analysis

Obsidian samples from the Tokaj Mountains (Hungary) and from the neighbouring Zemplin Hills (Slovakia) were analysed by instrumental and epithermal neutron activation analysis for obtaining a “fingerprint” for discrimination of potential natural sources of raw material that would permit tracing the origin of archaeological obsidian artefacts. These techniques fully discriminate the Zemplin Hills sources (Carpathian I, eastern Slovakia) and the Tokaj Mountain sources (Carpathian II, north-eastern Hungary) as well as these Central European sources from those already studied of the Mediterranean basin and adjacent regions.     

Characterization of prehistorical glass beads excavated from Khao Sam Kaeo (Chumphon, Thailand) using PIXE and SEM–EDS

It was proved that non-destructive and non-sampling methods were used to analyze the composition of the archaeological glasses. Glass has been used in ornaments and decoration in Thailand for thousands of years. In this study, glass bead fragments found from the archaeological site at Khao Sam Kaeo, Chumphon Province, southern Thailand were analyzed by the proton induced X-ray emission spectroscopy (PIXE) and scanning electron microscope coupled with energy dispersive X-ray fluorescence spectroscopy (SEM?CEDS). The composition analysis showed that copper was mainly presence as the colorant. Titanium, common impurity in sand, was all present in the glass bead samples. Furthermore, this type of glass almost spread over the various sites in this region that demonstrated the long distance or exchange connections. Finally, PIXE and SEM?CEDS have been used to be the efficient techniques to analyze the archaeological objects, especially the glassy materials, to understand their characteristics and how they were produced in ancient times.     

The k 0 and relative INAA methods to determine elements in entire archaeological pottery objects

The advantages of instrumental neutron activation analysis applied to archaeological ceramics have been enhanced through the analysis of entire objects, using both the k ₀ method and the relative method, respectively, to determine the concentrations of chemical elements in aliquots of replicate objects used as comparators and in the sample object. Twenty-two chemical elements of archaeological importance were measured in mud figurines from Caral civilization (5000 year BC), irradiated inside a well-characterized radial channel facility of the nuclear research reactor at IPEN, Peru. The results showed less than 10 % of bias for most of the elements.     

Characterization of Maya pottery by INAA and ICP-MS

A total of 81 pottery and 25 clay samples from the archaeological site and hinterland areas of Blue Creek in northwest Belize were analyzed by instrumental neutron activation analysis and inductively-coupled-plasma mass-spectrometry at the University of Missouri Research Reactor. Data generated for this study offers insight into local clay-resource variability and movement of pottery in the transition from Early (A.D. 250–600) to Late Classic (A.D. 600–850) occupation. Comparison of data generated by the two analytical techniques demonstrates the relative strengths and weaknesses of each method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Design and development of a neutron/X-ray combined computed tomography system at Missouri S&T

A new method for non-destructive analysis has been developed using a combined neutron/X-ray imaging system at the Missouri Science & Technology Reactor (MSTR). The interactions of neutrons and X-ray photons with matter produce differing characteristic information, resulting in distinctly different visual images. In order to obtain a more comprehensive picture of the structural and compositional data for a desired object, a prototype imaging system has been designed which utilizes neutron and X-ray imaging simultaneously without obstructing the beam geometry for each imaging mechanism. The current system is optimized for the imaging of small to medium sized objects of 0.5–50 mm. This new imaging capability in place at the MSTR promises great advances in the field of non-destructive testing, especially for nuclear engineering, nuclear medical science, and material science research. In an imaging object, a range of atomic number values and thermal cross-sections may be present. Where multiple materials having similar atomic number and differing thermal cross-section or vice versa may be present, exclusive neutron or X-ray analysis may exhibit shortcomings in distinguishing interfaces. However, fusing the neutron image and X-ray image into a combined image offers the strengths of both and may provide a superior method of analysis. In this paper, a novel combined X-ray and neutron imaging system will be introduced for superior analysis of certain imaging objects. Design details of experimental set-up and examples of preliminary imaging tests from individual modality will be detailed.     

Development of a micro-X-ray fluorescence system based on polycapillary X-ray optics for non-destructive analysis of archaeological objects

A new micro-X-ray fluorescence (micro-XRF) system based on rotating anode X-ray generator and polycapillary X-ray optics has been set up in XOL Lab, BNU, China, in order to be used for analysis of archaeological objects. The polycapillary X-ray optics used here can focus the primary X-ray beam down to tens of micrometers in diameter that allows for non-destructive and local analysis of sub-mm samples with minor/trace level sensitivity. The analytical characteristics and potential of this micro-XRF system in archaeological research are discussed. Some described uses of this instrument include studying Chinese ancient porcelain.     

Analyse par activation et numismatique

In this communication we show that two nuclear methods permit a non-destructive determination of major, minor and trace elements in three important “archaeological” metals: gold, silver, copper and alloys. With the first one, neutron activation analysis with a²⁵²Cf neutron source, we can perform a fast and accurate determination of three important elements of the coin's composition, viz. gold, silver and copper. With the second one, proton activation analysis, we can determine trace elements at ppm level in gold, silver and copper metals. Using these two techniques of activation analysis two important numismatic problems can be studied: the evolution of the fineness; characterization or differentiation by the trace elements the metal used to mint the coin. One example of each numismatic problem is also given.      

Non-destructive examination of roman silver coins by neutron activation analysis

The detection of “plated” specimens (ancient falsifications consisting of a copper core with a silver outer layer) amidst a great collection of silver coins was performed by non-destructive neutron analysis. The “plating” can be detected by measuring the Ag/Cu ratio. In practice it is more convenient to determine the Au/Cu ratio which is proportional to it, A short activation in a low thermal neutron flux is sufficient for this purpose. Consequently the induced activity of the long-lived^110mAg is small. The necessary correction for self-absorption on the measured ratio is small. A series of 2000 coins was analysed in this way.     

Multi-element standard for routine instrumental activation analysis of trace elements in rocks and tectites

The use of high-resolution Ge(Li) detectors in non-destructive instrumental neutron activation analysis (INAA) of mineral materials makes possible the simultaneous determination of a number of trace elements. In routine applications of INAA the use of a multi-element standard (MES) has proved to have advantages over a set of standards for each determined element. An MES has been prepared containing 8 trace elements mixed in a suitable proportion and giving, after neutron activation, long-lived γ-emitters, the γ-ray lines of which regularly occur in the γ-ray spectra of silicate mineral materials. This method has been used in the determination of Sc, Cr, Co, Rb. Cs, Eu, Hf and Th in samples of standard rocks and moldavites.     

14 MeV neutron activation analysis of gold jewellery

Samples of nominal 18 carat and 21 carat gold jewelleries from the local market were non-destructively bulk analyzed using neutron activation analysis. Neutrons of 14 MeV energy were used with a fast pneumatic sample transfer system. The actual gold contents, as well as the composition of the base metals in these samples were determined. The fast neutron activation was found to be an efficient, quick and accurate method of characterizing the precious metal objects routinely in bulk, with a large sample throughput. The results demonstrate the commercial availability of the technique for non-destructive bulk analysis of precious metal objects.     

Application des echangeurs d'ions et des filtres inorganiques au dosage du selenium et du tellure dans le cuivre

Selenium and tellurium isotopes formed by thermal neutron irradiation have longer half-life than the copper isotope. The non-destructive analysis fails even after the complete decay of copper because of the other radioisotope present. The radioisotopes were separated by ion exchange chromatography on Dowex 1X8 (200–400 mesh) and “Pertitanic” resins in order to obtain a highly sensitive analysis. The limits of detection of 5 ppb for tellurium and 0.5 ppb for selenium were obtained.      

Instrumental activation analysis for determining the composition of micro-ingots of multi-constituent alloys

A procedure for the instrumental neutron activation analysis of micro-ingots of alloys containing In, Sb, Au, Ga, Ni, Sn and Bi is proposed. The non-destructive analysis of the irradiated samples is performed by γ-spectrometry techniques including one-crystal scintillation detectors, dual-crystal sum-coincidence scintillation detectors and Ge(Li) semiconductor detectors. As a result, the cumbersome operations of radiochemical separation can be eliminated. The sensitivity of quantitative determinations using scintillation detectors in alloys of the above composition is 10⁻¹⁰ g for indium, gold, antimony and gallium and 10⁻⁶ g for nickel and tin. The use of semiconductor detectors yields sensitivities of 10⁻¹⁰ g for indium and gold and 10⁻⁹ g for gallium and antimony.     

Neutron activation analysis of large volume samples: The influence of inhomogeneity

A large sample neutron activation analysis (LSNAA) facility is under development at GRR-1 research reactor, NCSR ‘Demokritos’, to perform multi-element, non-destructive, contamination-free analysis of large volume samples. Correction algorithms have been derived to account for thermal neutron and gamma-ray self-attenuation in macroscopically homogeneous samples, as well as the photon detection efficiency to voluminous samples, based on no prior knowledge of the sample matrix composition. In the present study Monte Carlo simulations were performed to estimate the influence of inhomogeneities of major (matrix) and trace element on the accuracy of the technique. Types of inhomogeneities that can lead to severe errors in the analysis were depicted. The potential of including inhomogeneity tests in the measuring procedure to ensure the method’s applicability was examined.     

Neutron activation analysis of impurities in gallium phosphide

Gallium phosphide is a new type of semi-conductor material. Although this substance becomes highly radioactive after neutron irradiation, because of the nature of its component elements (gallium and phosphorus) the chances were that the great sensitivity of the neutron activation technique would at least partly solve this very difficult trace analysis problem. The possibilities of non-destructive analysis of long lived elements (Co−Sb−Sc−Zn−Fe...) were investigated first. To extend this method to the determination of medium-life elements, different methods of radiochemical separation plan was worked out. Finally the method developed gives quantitative analysis of fourteen elements (Ag−As−Au−Ba−Co−Cr−Cu−Fe−Ir−Na−Rb−Sb−Sc−Zn) amounting very often less than one ppb.     

μ-XRF analysis of glasses: a non-destructive utility for Cultural Heritage applications

This paper presents a μ-XRF analytical approach for a non-destructive study of Cultural Heritage glass finds. This technique can be used for quantitative analysis of small volumes of solid samples, with a sensitivity that is superior to the electron microprobe but inferior to an ICP-MS system. An experimental set-up with natural and synthetic glass standards is proposed here for the quantitative analyses of major and trace elements on glass objects which cannot be sampled such as small archaeological or historical artefacts from Cultural Heritage. The described method, performed by means of the commercial μ-XRF Eagle III-XPL, was applied to Islamic glass specimens of Sasanian production (III-VII century A.D.) previously analyzed by ICP-MS and SEM-EDS techniques (P. Mirti, M. Pace, M. Negro Ponzi and M. Aceto, Archaeometry, 2008, 50(3), 429-450; P. Mirti, M. Pace, M. Malandrino and M. Negro Ponzi, J. Archaeol. Sci., 36, 1061-1069; and M. Gulmini, M. Pace, G. Ivaldi, M. Negro Ponzi and P. Mirti, J. Non-Cryst. Solids, 2009, 355, 1613-1621) and coming from the archaeological site of Veh Ardasir in modern Iraq. Major elements (Na, Mg, Al, Si, K, Ca, Fe) of glass specimens show an accuracy better than 5%. Trace elements (Cr, Mn, Sr and Zr) display an accuracy better than 5% when the checked elements have a concentration >100 ppm by weight, whereas it is around 10% with a concentration <100 ppm by weight. μ-XRF is, therefore, a suitable elemental analysis technique for the non-destructive study of small glass finds due to its relatively good accuracy, reproducibility and low detection limits (～tens ppm).