A new mapping acquisition and processing system for simultaneous PIXE-RBS analysis with external beam

The combination of ion beam analysis techniques is particularly fruitful for the study of cultural heritage objects. For several years, the AGLAE facility of the Louvre laboratory has been implementing these techniques with an external beam. The recent set-up permits to carry out PIXE, PIGE and RBS simultaneously on the same analyzed spot with a particle beam of approximately 20 μm diameter.A new mapping system has been developed in order to provide elemental concentration maps from the PIXE and RBS spectra. This system combines the Genie2000 spectroscopy software with a homemade software that creates maps by handling acquisition with the object position. Each pixel of each PIXE and RBS maps contains the spectrum normalised by the dose. After analysing each pixel of the PIXE maps (low and high energy X-ray spectra) with the Gupixwin peak-fitting software, quantitative elemental concentrations are obtained for the major and trace elements. This paper presents the quantitative elemental maps extracted from the PIXE spectra and the development of RBS data processing for light element distribution and thin layer characterization. Examples on rock painting and lustrous ceramics will be presented.     

用质子激发X荧光分析法测定肝硬化病人血清的微量元素含量——探讨中医治疗疗效

本文利用质子激发经X荧光分析法测量正常人和肝硬化病人血清中Zn、Cu、Fe、Br和Rb等元素的含量。结果表明,中医治疗前后,血清中微量元素含量有显著差异。治疗后,病人症状有明显改善,且微量元素的含量也向正常人靠近。     

On the accuracy of element concentrations and masses of micron sized samples determined with the Heidelberg proton microprobe

We have already tested the reliability of element-normalized PIXE (Proton Induced X-ray Emission) data on small (10–100 μm) particles that we routinely obtain with the Heidelberg proton microprobe. Thus, we here discuss the accuracy of quantitative results, i.e., absolute concentrations inferred from PIXE analyses of such particles. We investigated and reduced the effects of mechanical vibrations and of the instability of the electronic devices on the achievable minimum beam spot. We implemented into our computer code a mapping software for qualitative element distributions (PIXE) and quantitative mass images using STIM (Scanning Transmission Ion Microscopy). The STIM images determine the area density required to calculate from PIXE spectra the absolute element concentrations in thin samples. The accuracy of absolute PIXE concentrations is tested by measurements on 15 μm soda lime glass microspheres. Finally, the complete results of PIXE and STIM analyses of an interplanetary dust particle (IDP) are described.     

Study by PIXE method of trace elements transferred from prostheses to soft tissues and organs

Some metallic prostheses inserted in human hip undergo physico-chemical modification, a few years after their implantation. Tissues surrounding these prostheses are damaged by metallic element transfer. Surgeons in Clermont-Ferrand Hospital (France) recover tissues of abnormal coloration that were in contact with metallic implants. PIXE technique (particles induced X-ray emission) with a 400 μm proton beam and 3 MeV of energy is an efficient technique to analyze these tissues and to detect elements, which are transferred from prosthesis to tissues. PIXE analyses were carried at the CERI-CNRS Laboratory. We have applied this method to determine qualitatively and quantitatively trace elements migration from metallic implants to surrounding tissues and organs, like kidney, spleen, liver, lymphatic gland and lung.     

In situ analysis of human teeth by external PIXE

The elemental profiles of the enamel, cementum and caries of human teeth were analysed by the external proton induced X-ray emission studies. Ten elements namely P, Ca, V, Mn, Fe, Cu, Zn, As, Sr and Pb were estimated in the present study. P and Ca were found to be the major elements whereas all other elements were found in trace level. It was observed that the respective concentrations of elements namely P, Ca, Fe, Zn and Pb in enamel are more than those in cementum. Concentration of P ranged between 6.37% and 25% whereas Ca ranged between 12.94% and 43.36%.     

Ionoluminescence technique for nuclear microprobes

Ionoluminescence (IL) produced by MeV/amu particles in the Nuclear Microprobe carries rich information on the nature of the chemistry and physics in the various types of materials, such as the molecular structure and ion's valence, etc. IL/PIXE methods offer unique ways to study the general luminescence phenomenon by directly relating the trace element information provided by PIXE to IL spectroscopic results. The IL can also be used to identify the organic molecular structure, hence, the combination of the IL data with the PIXE elemental data provide a new tool for biology and medicine studies. One example is the epidermis from the human skin, which exhibits a clear IL. IL is very sensitive to the local chemical environment conditions of the excitation point, therefore, it can be very effective to study the beam modification and beam damage effects. The beam damage problem in the Nuclear Microprobe applications is discussed.     

Conversion from Tooth Enamel Dose to Organ Doses for Electron Spin Resonance Dosimetry

Conversion from tooth enamel dose to organ doses was analyzed to establish a method of retrospective individual dose assessment against external photon exposure by electron spin resonance (ESR) dosimetry. Dose to tooth enamel was obtained by Monte Carlo calculations using a modified MIRD-type phantom with a teeth part. The calculated tooth enamel doses were verified by measurements with thermo-luminescence dosimeters inserted in a physical head phantom. Energy and angular dependences of tooth enamel dose were compared with those of other organ doses. Additional Monte Carlo calculations were performed to study the effect of human model on the tooth enamel dose with a voxel-type phantom, which was based on computed tomography images of the physical phantom. The data derived with the modified MIRD-type phantom were applied to convert from tooth enamel dose to organ doses against external photon exposure in a hypothesized field, where scattered radiation was taken into account. The results indicated that energy distribution of photons incident to a human body is required to evaluate precisely an individual dose based on ESR dosimetry for teeth.     

Trace element analysis of blood samples from mentally challenged children by PIXE

The accelerator based ion beam analysis method of proton induced X-ray emission (PIXE) has been used for analysing up to 14 elements in the blood serum of patients, collected from rehabilitation centres for the mentally retarded and from Medical College Hospital, Coimbatore, Tamil Nadu, India. The experimental subjects of the different groups displayed significant variations in their levels of certain trace elements such as zinc, iron, copper, phosphorus, chlorine, and rubidium. The results are compared with those of healthy control subjects and are discussed in detail in this paper. Hence, PIXE as a method of trace element analysis can be used to determine trace element content in mentally challenged patients.     

Fluorine analysis of human enamel around fluoride-containing materials under different pH-cycling by μ-PIGE/PIXE system

The caries preventive effect of fluoride-containing materials (FCMs) might depend on the caries risk of the individuals. Two pairs of demineralizing and remineralizing solutions of pH-cycling were prepared for simulating low and high caries risk. The purpose of this study was to determine fluorine (F) uptake into human enamel around FCMs under different pH-cycling using the in-air μ-PIGE/PIXE system. Fluoride-containing glass ionomer cement (Fuji IX_GP FAST CAPSULE (FN)), and composite resin (BEAUTIFIL II with FLUORO BOND SHAKE ONE (BS)) were used in this study. The pH-cycling (pH 6.8-4.5) was carried out for 5 weeks. After pH-cycling, the caries progression was analyzed using transverse micro-radiography (TMR). The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the PIGE/PIXE system. From TMR analysis, there was a difference in caries risk between the two kinds of pH-cycling. Although the caries preventive effect of BS and FN was confirmed at low risk, the effect at high risk was confirmed for FN only. From the analysis of the fluorine uptake in the outer 200 μm of the lesion we concluded that there was no significant difference between the pH-cycling solutions. However, we found different fluorine concentrations in the enamel for the two FCMs. The decreased caries progression under high risk for FN indicated that an adequate amount of fluorine supplied from the material is required at higher caries risk. It was confirmed that the caries preventive effect of FCM depends on the caries risk. The fluorine analysis of teeth under various pH-cycling conditions gives information to evaluate the caries preventive effect of fluoride-containing materials according to the caries risk.     

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.     

Trace elements concentration in sediments of Orontes River using PIXE technique

Proton induced X-ray emission (PIXE) has been used to measure trace elements in sediments of Orontes River. Measurements were carried out using a 2 MeV proton beam produced from of the 3 MV tandem accelerator. Sediment samples were collected from 11 sites covering the important potential pollution sources at the river. The accuracy of the experimental procedure was verified using a certified sediment reference material (IAEA-SL1) and was found to be less than 10%. The results have shown that Pb and As were within the natural levels. In contrast, high concentrations of other elements like Cr, Cu, Ni and Zn have been found at different sites and explained by local human and industrial activities.     

Non-destructive analysis and appraisal of ancient Chinese porcelain by PIXE

This paper reports the results of the PIXE analysis on ancient Chinese blue and white porcelain fired at Kuan Kiln (Jingdezhen, Jiangxi province) during 13–19th century. The major, minor and trace element of porcelain body, white glaze and blue glaze were determined by PIXE. In this paper the chemical compositions of porcelain body, white glaze and blue glaze measured from Yuan (AD 1206–1368), Ming (AD 1368–1644) and Qing (AD 1616–1911) blue and white porcelain are present. The cobalt blue pigment used in Yuan, Ming and Qing are also discussed.     

STIM evaluation in GeoPIXE to complement the quantitative dynamic analysis

The GeoPIXE software for quantitative PIXE trace element imaging and analysis is a well established package for evaluation of characteristic X-ray data for both PIXE and SXRF. For the case of microbeam applications on semi-thick samples knowledge of the local areal density distribution is important for precise quantification. A technique is reported to achieve this using the measurement of beam particle energy loss as it traverses the sample, as in scanning transmission ion microscopy (STIM). New functionality is added to the GeoPIXE code through integration of routines for STIM sorting of event-by-event data to create elemental maps of the mean energy after traversing the sample. Integration of stopping powers for a given sample matrix then permits the measured energy loss to be related to the local areal density. In a further step, this information is used for X-ray absorption corrections made directly to the PIXE analysis results.As a complement, user-written plugins operating on single STIM spectra have been used to compare the estimated areal density from chosen spots with the corresponding values calculated with the new GeoPIXE routines. The additions made to the code allow a more precise quantification to be done on inhomogeneous, semi-thick samples.     

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.     

PIXE and the nuclear microprobe: Tools for quantitative imaging of complex natural materials

The 40 year history of nuclear microscopy has seen sustained progress in the development of technology needed to improve PIXE analysis and trace element imaging performance. Focussing systems have been developed for improved spatial resolution, detector systems have evolved to collect more signal, full-spectral scanning data acquisition approaches have been devised. The complexity of PIXE spectra has driven the development of techniques for fitting numerous overlapping components in spectra for quantitative analysis, methods have been developed for specialized problems in geology, such as the analysis of fluid and melt inclusions in minerals, and techniques for the deconvolution of elemental components in full-spectral scanning data sets have been developed to produce accurate element images. The future of nuclear microscopy using PIXE is promising. Lens system approaches have evolved and point towards ‘full bore’ acceptance, optimal matching to accelerator emittance, high current density and sub-μm spatial resolution using many nA beam currents. Detector arrays and integrated data acquisition and scanning systems are emerging that can collect all events across a large solid-angle collection area and process these events for element image display in real-time. The combination of these advances provides a path to greatly enhanced sensitivity for PIXE analysis and imaging and a more productive user experience. The emergence of detector array approaches for scattered particles and reaction products, and the development of software tools for coupled PIXE-RBS data reduction, suggest a path towards complementary RBS and NRA tools. The stage is set for an exciting and productive future for PIXE imaging on the nuclear microprobe.     

Biomedical research at LIPSION - Present state and future developments

Since its commissioning in 1998 the high energy ion nanoprobe LIPSION has been developed into a versatile tool for a variety of applications in biomedical research. It includes quantitative trace element analysis with sub-micron spatial resolution and 3D-element imaging, as well as 2D- and 3D-microscopy of density distributions. The analytical methods base on particle induced X-ray emission spectrometry (PIXE) and PIXE-tomography, Rutherford backscattering spectrometry (RBS), as well as scanning transmission ion microscopy (STIM) and STIM-tomography.The continuous developments led to improved capabilities for trace element analysis. For sub-micron analysis the spatial resolution could be improved to 0.3 μm for high resolution work and to 0.5 μm for routine analysis. On the other hand, LIPSION was optimized for high sample throughput in quantitative element imaging maintaining a lateral resolution of 1-2 μm. Recently the methods of PIXE- and STIM-tomography of biological specimens have been extended to limited angle tomography to avoid the complicated preparation of free-standing samples.Besides its analytical applications, the nanoprobe is also used for targeted irradiation of living cells with counted single ions for radiobiological research. It is capable of irradiating up to 20,000 cells per hour. Furthermore, we have developed a technique to achieve confined cell growth based on the proton beam writing technique (PBW) and agar. The paper presents an overview of the current biomedical research fields at LIPSION and gives an outlook on prospective developments.     

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.     

Characterisation of ferromagnetic magnetic storage media surfaces by complementary particle induced X-ray analysis and time of flight-energy dispersive elastic recoil detection analysis

Thin (10 nm–1 μm) films of ferromagnetic material constitute an important class of materials that are difficult to analyse by conventional ion beam analytical (IBA) techniques because they are based on the ferromagnetic elements (Co, Fe, Mn, Ni, and Cr). The similar or overlapping isotope masses makes it difficult to separate the elemental signals using time of flight and energy dispersive elastic recoil detection (ToF-E ERD). In this exploratory study we have investigated the use of Particle Induced X-ray Emission (PIXE) measurements to refine the mass dispersive depth profile information from ToF-E ERD. The surfaces of two commercial magnetic media were investigated. One sample was a double density diskette with a coating of ferrite particles in an organic binder. The other sample was a complex C/Co/Cr/Ni–P/Al multilayer structure taken from a standard hard disc. The Lund nuclear microprobe with a 2.55 MeV proton beam was used for PIXE analysis. ToF-ERD measurements were carried out using a 55 MeV ¹²⁷I¹⁰⁺ ion beam incident at 67.5° to the surface normal. The time of flight and kinetic energy of recoils ejected at 45° to the ion beam direction was measured in a detector telescope. The findings demonstrate that by detailed analysis of the PIXE spectra it is possible to remove the ambiguities in mass assignment of the ToF-ERD data associated with the ferromagnetic elements.     

GIC4117串列加速器外束PIXE/PIGE分析系统

本文介绍在北京师范大学GIC4117串列加速器上建立的外束PIXE/PIGE分析系统,和基于此系统的薄样品外束PIXE/PIGE定量分析方法。给出了2010年Teflon滤膜采集的361个气溶胶样品外束PIXE分析得到的各元素平均探测限和最低探测限,并同真空PIXE分析探测限进行了比较。利用标准样品给出了激发曲线不同坪区薄样品外束PIGE分析F和Na的探测限,通过测定¹⁹F(p, p′γ)¹⁹F激发的197 keV γ射线得到的F的探测限可达73.9 ng•cm^-2,Na的探测限可达198.9 ng•cm^-2。     

Beam charge integration in external beam PIXE–PIGE analysis utilizing proton backscattering with an extraction window

In this study,we present a new method for the indirect integration of beam charges in external beam proton-induced X-ray emission and proton-induced c-ray emission(PIXE–PIGE) analysis.We recorded proton spectra backscattered by a Kapton film extraction window in different sample situations and under different beam currents.We also simulated backscattering spectra using the simulation of backscattering spectra program(SIMNRA).We determined that in a specific geometrical arrangement,different sample situations did not significantly affect factor C_Q(the ratio between integral backscattering proton counts and integral beam charges).We also studied the reproducibility and beam current dependence of factor C_Q.The statistic factor of C_Q was28.95 ± 0.6 kilo counts/l C,with a relative standard deviation of 2.0 %.Significantly,in external beam PIXE–PIGE analysis,we were able to calculate beam charge integration from the integral backscattering proton counts in an energy region.