Analysis of lichen thin sections by PIXE and STIM using a proton microprobe

In order to better understand the distribution pattern of mineral elements in lichen tissues, thin sections (15 μm) of the foliose, vagrant soil lichen Xanthoparmelia chlorochroa were examined using proton microprobe Particle induced X-ray emission (PIXE). This technique was used to make two-dimensional scans, with 5 μm resolution, across tissue cross sections of the test species. Element maps for Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, and As have been prepared. Several elements are strongly localized in the element maps. PIXE data are complimented with STIM, light micrographs, and SEM images. Preliminary data suggest that nuclear microprobe techniques may be useful in elucidating element absorption and transport mechanisms in lichens.     

Forensic analysis of tempered sheet glass by particle induced X-ray emission (PIXE)

The elemental concentrations of five trace elements in tempered sheet glass fragments were determined using particle-induced X-ray emission (PIXE) spectrometry. The trace element concentrations for calcium, iron, manganese, strontium, and titanium are compared to those obtained by inductively-coupled plasma-atomic emission spectrometry (ICP-AES) following complete digestion by hydrofluoric acid. For these five elements, the absolute concentrations obtained by both methods are shown to agree well over a wide range of concentrations. The limits of detection for trace elements are typically lower for the ICP-AES method. However, we show that the concentrations of these five elements can be accurately measured by the PIXE method. Since PIXE is an entirely non-destructive method, there exists a niche for this technique to be used as a complement to the more sensitive ICP-AES technique in the forensic analysis of sheet glass.     

Combined PIXE and SEM study of the behaviour of trace elements in gel formed around implant coated with bioactive glass

Bioactive glasses are used as coating biomaterials to facilitate anchorage of metallic prostheses implanted into the body. The aim of this work is to study the behavior of gel formed in contact with alloys and BVA and BVH bioactive glasses implanted. Cylinders of metallic implants composed by Ti, Al and V, are coated with bioactive glass. Three sheep were implanted for different time length: 3, 6 and 12 months in the femoral epiphysis. Results obtained with particle induced X-ray emission and scanning electron microscopy show that BVA coating induces a better contact between the metallic implant and bone. On the other hand, BVH coating prevents corrosion from the metallic implant.     

Elemental investigation of Syrian medicinal plants using PIXE analysis

Particle induced X-ray emission (PIXE) technique has been employed to perform elemental analysis of K, Ca, Mn, Fe, Cu, Zn, Br and Sr for Syrian medicinal plants used traditionally to enhance the body immunity. Plant samples were prepared in a simple dried base. The results were verified by comparing with those obtained from both IAEA-359 and IAEA–V10 reference materials. Relative standard deviations are mostly within ±5–10% suggest good precision. A correlation between the elemental content in each medicinal plant with its traditional remedial usage has been proposed. Both K and Ca are found to be the major elements in the samples. Fe, Mn and Zn have been detected in good levels in most of these plants clarifying their possible contribution to keep the body immune system in good condition. The contribution of the elements in these plants to the dietary recommended intakes (DRI) has been evaluated. Advantages and limitations of PIXE analytical technique in this investigation have been reviewed.     

The new Cyclone 18/9 beam transport line at the CNA (Sevilla) for high energy PIXE applications

The Cyclone 18/9 cyclotron system at the Centro Nacional de Aceleradores (Sevilla, Spain) is commonly used to create short life radioisotopes for PET applications. Besides, an external beam transport line has been recently installed in one of the target ports with two major purposes: to study the effects of 18 MeV protons irradiation on the behaviour of electronic devices for space applications and to complement the analysis of materials using our 3 MV tandem accelerator with the PIXE measurements at high energy.In this work, the main elements of our beamline will be briefly described and the first PIXE application will be presented. The usual PIXE, in the analysis of archaeological metallic objects, using around 3 MeV protons requires having a shiny area. Our purpose is to obtain a deeper determination of the bulk composition bombarding with 18 MeV protons through the corroded samples surfaces, without polishing the ancient object. To check this methodology high energy PIXE has been performed on two fibulae of the Later Bronze Age and First Iron Age, coming from the area around Sevilla.     

质子激发X射线荧光分析法测定头发、肾和肝中的微量元素

本文使用质子激发X射线荧光分析法(PIXE)测定正常人发、肝和肾组织中的微量元素。详细介绍了样品的采集制备、实验测定和定量方法,并且使用标准参考物质小牛肝(NBS)、马肾(IAEA)和比对粉末发样检查校正测量系统的准确性。报道了三种器官组织中近二十种微量元素的含量,初步探讨了人体自身器官组织中微量元素含量分布之间的相互关系。     

Analysis of atmospheric aerosols by PIXE: the importance of real time and complementary measurements

Particle-Induced X-ray Emission (PIXE) has been used for more than 30 yr in many urban and background air pollution studies. The technique has certainly contributed to the understanding of source-receptor relationship for aerosol particles as well as to aerosol physics and chemistry. In the last few years, where aerosol issues were strongly linked to global climate change through the relationship between aerosol and atmospheric radiation points to new challenges in atmospheric sciences, where PIXE could play an important role. Also the recognition for the inter-relationship between aerosol and liquid and gas phases in the atmosphere makes important to integrate PIXE aerosol analysis with other complementary measurements. The use of Nephelometers and Aethalometers to measure scattering and absorption of radiation by aerosol particles can be done in parallel with particle filter collection for PIXE analysis. Parallel measurements of trace gases using traditional monitors as well as with new techniques such as Differential Optical Absorption Spectroscopy (DOAS) that can provide concentration of O₃, SO₂, NO₃, NO₂, HCHO, HNO₃, Benzene, Toluene, and Xylene, is also important for both urban and remote aerosol studies. They provide information that allows a much richer interpretation of PIXE data. Recently developed instruments that provide real time aerosol data such as the Tapered Element Oscillating Microbalance (TEOM) PM₁₀ monitor and automatic real time organic and elemental carbon analyzers provide extremely useful data to complement PIXE aerosol analysis. The concentrations of trace elements measured by PIXE comprise only 10–30% of the aerosol mass, leaving the organic aerosol characterization and measurement with an important role. The aerosol source apportionment provided by PIXE analysis can be extended with other aerosol measurements such as scattering and absorption, estimating for example, the radiative impact of each discriminated aerosol source. The aerosol bulk PIXE measurements can be complemented with soluble concentrations provided by Ion Chromatography (IC) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Recent developments in remote sensing techniques and products also enhance significantly regional aerosol studies. Three-dimensional air mass trajectories should be integrated in aerosol studies for urban and remote areas. The applications of these techniques to study urban aerosols from São Paulo and Santiago de Chile have broadened extensively the scientific scope of these studies.     

Nuclear microprobe analysis of U-doped (Bi,Pb)2Sr2Ca2Cu3Oy/Ag superconducting tapes

Superconducting (Bi,Pb)₂Sr₂Ca₂Cu₃O_y/Ag tapes are doped with uranium compounds to introduce flux pinning defects from neutron-induced fission. The composition and distribution of elements in cross sections of the tapes were probed with a scanned 3 MeV proton microbeam using proton induced X-ray emission (PIXE). Distributions of the constituent elements were found to be heterogeneous on a scale of 10 μm. By combining the PIXE analysis with Rutherford backscattering spectrometry, the stoichiometry of the superconductor within the tape was measured, including oxygen from elastic scattering, revealing a departure from the desired 2223 composition. In one of the tapes, PIXE elemental maps of the Ag distribution showed diffusion of Ag into the superconductor from the enclosing jacket. Crystals of the same material, not fabricated into tapes, did not contain the contaminants and had a more ideal stoichiometry. Correlation maps between the constituent elements, deduced from the elemental maps, indicate the presence of secondary or unreacted phases.     

Monte Carlo characterization of materials for prosthetic implants and dosimetric validation of Pinnacle TPS

In external beam radiotherapy the calculation of dose distribution for patients with hip prostheses is critical. Metallic implants not only degrade the image quality but also perturb the dose distribution. Conventional treatment planning systems do not accurately account for high-Z prosthetic implants heterogeneities, especially at interfaces. The materials studied in this work have been chosen on the basis of a statistical investigation on the hip prostheses implanted in 70 medical centres. The first aim of this study is a systematic characterization of materials used for hip prostheses, and it has been provided by BEAMnrc Monte Carlo code. The second aim is to evaluate the capabilities of a specific treatment planning system, Pinnacle³, when dealing with dose calculations in presence of metals, also close to the regions of high-Z gradients. In both cases it has been carried out an accurate comparison versus experimental measurements for two clinical photon beam energies (6 MV and 18 MV) and for two experimental sets-up: metallic cylinders inserted in a water phantom and in a specifically built PMMA slab. Our results show an agreement within 2% between experiments and MC simulations. TPS calculations agree with experiments within 3%.     

Late Bronze Age hoard studied by PIXE

The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising four socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni, and Ag has been determined using this ion beam technique. The high tin content alloy and the high purity of the metals from the Freixanda hoard are characteristic of the Portuguese and Spanish Late Bronze Age metallurgy, supporting the idea of a regional production.     

用质子激发X荧光分析技术鉴别玉器种类

质子激发Ｘ荧光分析中以测定玉器的主量、次量及微量元素的成分和含量,因而可以将那些外形及颜色相近的玉器因其化学组分的不同而清楚地分开,并得知其真实的材料种类。对于主要化学组分一致的同类玉器,如果产于不同的地方,则由于其成矿地区地球化学环境的不同,它们的微量元素种类及含量也将有所不同,因而这一方法也可用来判定玉器的产地。     

PIXE and XRF analysis of particulate matter samples: an inter-laboratory comparison

PIXE and XRF are very effective techniques in atmospheric aerosol investigation, therefore they are extensively used by the authors. In this work an inter-laboratory comparison of the results obtained analysing several samples (collected on different substrata) with both techniques is presented: the samples were analysed by PIXE (in Florence, at the 3 MV Tandetron accelerator of LABEC laboratory) and by XRF (in Genoa and Milan, where two Oxford XRF instruments are operational). The results of the three sets of measurements are in good agreement for all the analysed samples.The aim of this work was also to compare PIXE and XRF performance in atmospheric aerosol analysis with the routine set-up currently in use at the three laboratories, to determine the best technique to be applied depending on the substratum used for aerosol sampling and the main elements of interest for each specific research project. Results of the comparison between the minimum detection limits of both techniques will be shown for all the measured elements, for different substrata (Teflon, polycarbonate and cellulose mixed esters).     

M-shell X-ray production cross sections for PIXE applications

M-shell X-ray production cross sections by protons of energies 0.1–4.0 MeV are reported for the most intense M_β(M_4,5N_6,7), M_γ(M₃N_4,5) and M₃O_4,5 M-X ray transitions appearing in PIXE spectra. The cross sections have been measured systematically for selected heavy elements between Ta and Th (Z₂=73–90). Measured M-X-ray production cross sections were found to be universal with respect of M-shell scaled velocity ξ_M. The data are compared with available theoretical calculations of M-shell ionization by charged particles based on the plane-wave Born approximation (PWBA) and the semiclassical approximation (SCA), as well as the ECPSSR theory and relativistic RPWBA-BC which are going beyond the first order treatment. Simple parameterization of experimental proton induced M-X-ray cross sections is proposed for PIXE applications. This parameterization, being accurate within ±5%, can be used for precise determination of heavy metal concentrations by PIXE technique.     

PIXE analysis of trace elements in northern fur seal teeth

Trace elements in teeth of northern fur seal Collorhinus ursinus were analyzed by PIXE and micro-PIXE (μ-PIXE). Trace elements such as Mn, Fe, Zn, Cu, As, Br, Sr, and Pb were detected in the teeth, which were composed of hydroxyapatite crystals. Among these elements, the concentrations of Fe and Zn were relatively higher in winter and lower in summer and also Zn varied along with growth of individuals. These elemental fluctuation seems to correspond to the life history of the northern fur seal. It suggests that the PIXE analysis will make a powerful tool to reconstruct the life history.     

质子激发X荧光法测定西太平洋海域雨水的微量元素组成

用质子激发Ｘ荧光分析法测定了西太平洋海域海面上雨水中微量元素的组成和浓度，并通过富集因子的计算，表明海面上雨水中的地壳元素和污染元素主要来自陆地长距离输送的尘土粒子及人为排放污染物。     

Present and future role of ion beam analysis in the study of cultural heritage materials: The example of the AGLAE facility

The application of IBA to cultural heritage mostly relies on the use of PIXE because of its high sensitivity and its ease of implementation at atmospheric pressure. The need for depth information not easily available with this technique has conducted to associate RBS also in external beam mode. We have progressively developed a set-up that permits such a combination of techniques either simultaneously or sequentially. The set-up is currently further improved to permit NRA measurement (depth profiles of light elements) in addition to PIXE and RBS. The coupling of all these techniques provides a wealth of information on cultural heritage objects, not easily attainable with any other single method.     

Thick-target Pixe analysis of chromium, copper and arsenic impregnated lumber

Chromium, copper and arsenic (CCA) have for decades been used for wood preservation. Of these elements especially arsenic is very toxic. As CCA impregnated wood is still today used for many construction purposes, a monitoring of these metal ions is of great environmental importance. Thick-target PIXE is a powerful method for the determination of trace metals in wood. The TTPIXE method enabled study of variations of the elemental concentrations in lumber treated with CCA impregnation solution. Distribution patterns were obtained for both naturally occurring elements and elements introduced in the treatment process. During the impregnation process a desorption of e.g. alkali metal ions takes place from the wood. The sensitivity of the method is improved by dry ashing of the samples prior to PIXE analysis. The TTPIXE method was calibrated and validated using international certified reference materials (CRM) based on wood material.     

Characterization of human fingernail elements using PIXE technique

PIXE technique was employed in the determination of the major, minor and trace elemental concentrations in finger-nails of 62 healthy young adults (30 females and 32 males), aged between 20 and 37 years. The elemental concentrations in the nails of the analyzed population provide good reference data set for further health studies. The PIXE measurements were carried out using 1.8 MeV collimated proton beam from the 2.5 MV AN-2000 Van de Graaff accelerator at INFN, LNL, Legnaro (Padova), Italy. The results show the presence of twenty elements. Their metabolic roles in humans are presented and discussed. The comparison of our results with those of other authors are also presented.     

Elemental micro-PIXE mapping of hypersensitive lesions in Lagenaria sphaerica (Cucurbitaceae) resistant to Sphaerotheca fuliginea (powdery mildew)

Genotypes of the Southern African cucurbit, Lagenaria sphaerica, that are resistant to powdery-mildew (Sphaerotheca fuliginea) exhibit foliar hypersensitive (HS) lesions on inoculation with this fungal pathogen. Elemental distributions across radially symmetrical HS lesions, surrounding unlesioned leaf tissue and uninoculated leaf tissue, were obtained using the true elemental imaging system (Dynamic Analysis) of the NAC Van de Graaff nuclear microprobe. Raster scans of 3 MeV protons were complemented by simultaneous PIXE and BS point analyses. The composition of cellulose (C₆H₁₀O₅) was used as constant matrix composition for scans, and the sample thickness was found from BS spectra. Si and elements heavier than Ca contributed to matrix composition within HS lesions and the locally elevated Ca raised the limits of detection for some trace metals of interest. In comparison to uninoculated tissue, inoculated tissue was characterised by higher overall concentrations of all measured elements except Cu. Fully developed, 6 day-old HS lesions and the surrounding tissue could be divided into five zones, centred on the fungal infection site. Each zone was characterized by distinct local elemental distributions (either depletion, or accumulation to potentially phytotoxic levels).     

微束背散射分析元素微区分布的研究

微束背散射分析元素微区分布的分析方法使上海原子核研究所的质子微探针能在微区内综合使用质子激发Ｘ射线荧光和背散射等多种核效应，为样品由轻元素到重元素的全面无损、双微（微区、微量）分析提供了依据。应用该方法还测量了Ｓｉ３Ｎ４／ＳｉＣ复合陶瓷材料，证明了该分析方法的可靠性。