A code XANTHO for fitting X-ray spectra induced by photons or charge particles was developed as a Lazarus application. Background subtraction is performed by iterative filtering (brushing) of the ...source spectrum, based on the adapted Kolmogorov-Zurbenko approach. For comparison, a code with top-hat filtering was also developed. Critical comparison was made for a glass standard at PIXE analysis. XANTHO is intended for accurate fitting of individual spectra during analytical work and for sequential fitting at mapping experiments.
Physics beyond PIXE Šmit, Ž.
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
08/2020, Letnik:
477
Journal Article
Recenzirano
The paper reveals geometrical effects that govern the accuracy of PIXE measurements: distinction between thin and thick targets, misorientation of the sample, surface roughness and contribution of ...the invisible matrix. It shows an importance of the mean X-ray production distance and its application in differential measurements. It further reviews the data base needed for thick target calculations and the importance of developing more accurate theoretical models based on the semiclassical picture and coupled channel approach. An example of transitions in a perturbed harmonic oscillator demonstrates that the united atom limit does not exist at adiabatic collisions and that the cross section likely exhibits an oscillatory behaviour.
In this paper, the chemical analyses of forty-two samples of glassware from the sixth to early seventh century AD Byzantine settlement of Gradina on Jelica, Serbia are reported, completing the ...previous study of forty windowpane samples from the same site. Apart from a single plant ash glass, all other glasses are natron-based, classified as Foy 2.1 (thirty-four), Foy 3.2 (six), and Roman (two). The ten colourless glasses from the assemblage are decolourised with manganese. Five glasses are intentionally coloured blue with cobalt and copper, one black with iron. Four blue glasses are opacified, one with antimony, one perhaps with tin. Some Jelica glass finds classified as Foy 3.2 are specific for having magnesium levels above those characteristic for série 3.2. Jelica glasses assigned to Foy 2.1 group were further divided into low iron (twenty), high iron (four), and very high iron (six) subgroups. The overall compositional pattern of Jelica samples identified as Foy 2.1 suggest that different sands with different heavy mineral suites and sources of lime were used in their making, as well as different levels of recycling. Our findings indicate that the reasons for the compositional blurring of Foy 3.2 and Foy 2.1 are not limited to technological reasons such as recycling, but also include variations in the sand minerals. The results support the picture of the dominance of Foy 2.1 and Foy 3.2 types of glass in central and eastern Balkans and on the Macedonian-Thracian coast during the sixth century AD. Our findings, together with the apparent absence of Levantine glass from this region reported until now, suggest that different trade routes were supplying these regions with Eastern Mediterranean raw glass from those supplying Adriatic Sea coasts.
A series of 25 Greek coins from the 6th to 4th centuries BC was studied by PIXE for their trace element composition, with an aim to discover the origin of their silver ore. The procedure revealed a ...counterfeited coin, and then concentrated on distinguishing the coins minted from the ore of Laurion on the Attica peninsula and the coins minted from other sources. Linear discriminant analysis based on the impurities and alloying elements of copper, gold, lead and bismuth revealed that discrimination is indeed possible according to a single canonical variable.
•Our external beamline has been upgraded to achieve beam focusing and provide in-air PIXE imaging.•Lateral resolution of 50 μm was achieved using magnetic quadrupole lenses and ultrathin Si3N4 exit ...window.•Quantitative concentration maps of a longitudinal section of a whole thick wheat grain have been determined.
The existing external beamline at the Microanalytical Centre of the Jožef Stefan Institute (JSI) in Ljubljana has been upgraded in order to extend the capabilities towards in-air PIXE imaging across relatively large sample surface area (∼1 cm2) with lateral resolution of sub 100 µm. For that purpose, a doublet of magnetic quadrupole lenses was installed on the beamline together with the newly designed exit nozzle with a 200 nm Si3N4 exit window resulting finally in ∼ 50 × 50 μm2 lateral resolution. Additionally, an in-vacuum beam chopper was installed before the exit nozzle to measure the proton dose deposited on the sample. The beam characterization results are presented together with the first application from the field of biology, namely quantitative concentration maps of a longitudinal section of a whole thick wheat grain.
The combined PIXE–PIGE method was used for the analysis of 43 glass fragments from the archaeological site Tonovcov grad in western Slovenia, with 10 of these additionally being analysed by ...LA-ICP-MS. The glass objects were attributed to the Late Antique production of the 4th–7th c. AD, with two examples of early Roman glass and three glass beads, one of them presumably of oriental origin. The analysis showed typical natron-type glass, produced in the Levantine region around the river Belus, and a few examples of HIMT glass, which could be recognized also in several other recycled objects. Only one glass bead, found in Early Medieval context, was made of the ash of halophytic plants.
A series of 74 small silver Celtic coins discovered on the territory of the present Slovenia and classified in 7 different types were analyzed using the methods of proton-induced X-ray emission ...(PIXE) and prompt gamma activation analysis (PGAA) to determine the silver and copper concentrations on the surface and in the bulk, respectively. The aim of the research was to determine the purity of the metal and the trace element content in relation with the coin type. Though no classification could be performed according to the concentrations of trace elements in the surface layer as determined by PIXE, the bulk analysis showed a two-tailed distribution of low- and higher-grade silver. This means that the base metal was supplied through two different distribution centers or that the basic alloy suffered a gradual decrease of fineness as a consequence of inflationary movements.
Analysis of metals with luster: Roman brass and silver Fajfar, H.; Rupnik, Z.; Šmit, Ž.
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
11/2015, Letnik:
362
Journal Article
Recenzirano
Non-destructive PIXE analysis using in-air proton beam was used for the studies of earliest brass coins issued during the 1st century BC by Greek cities in Asia Minor, Romans and Celts, and for the ...studies of plated low grade silver coins of the 3rd century AD. The analysis determined the levels of zinc and important trace elements, notably selenium, which confirms spread of selenium-marked copper from the east. For plating, combined tinning and silvering was identified by the mapping technique for the mid 3rd century AD, which evolved into mere plating by 270 AD.
Garnets (62 individual stones) originating from the Migration Period cemeteries and hilltop settlements in Slovenia were analyzed by the combined PIXE/PIGE method for their chemical composition. ...Typologically, the analyzed stones may be classified as almandines originating from the sites in India, belonging to types I and II according to Calligaro. A smaller group of pyraldines intermediate between almandines and pyropes was also determined; identified as type III, their source is most likely in Sri Lanka. No garnets from Bohemia (Czech Republic) have been discovered, which may be related to important political changes in the 7th c. AD, induced by Slavic and Avaric migrations.
Analysis of Roman glass from Albania by PIXE–PIGE method Šmit, Ž.; Tartari, F.; Stamati, F. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
02/2013, Letnik:
296
Journal Article
Recenzirano
A series of 31 Roman glasses dated to the 1st–4th c. AD from the present Albania was analyzed by the combined PIXE–PIGE method. The analysis shows typical natron-based glass of the Roman period, ...though statistical treatment using principal component analysis and bivariate plots reveals four distinct groups, which are qualified by increased levels of potassium, magnesium and titanium–manganese–iron oxides, respectively. MgO content may exceed 2% and reach the level commonly accepted for halophytic plant-ash glass. The groups are formed on account of mineral impurities in the sand, which gives support to the thesis of multiple production centers of raw glass in the imperial age.
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