An energy dispersive micro X-ray diffractometer based on a combined system of polycapillary optics

An energy dispersive micro X-ray diffractometer based on a combined system of two polycapillary X-ray lenses is designed. The polycapillary X-ray lens in the excitation channel is either a polycapillary parallel X-ray lens (PPXRL) or a slightly focusing polycapillary X-ray lens (SFPXRL). The polycapillary X-ray lens in the detection channel is a PPXRL. At 6.4 keV and 2θ = 141.5°, the total resolution of the diffractometer based on a SFPXRL in the excitation channel and a PPXRL in the detection channel in Δd/d is 4.8%.     

Identification of origin of single aerosol particles using polycapillary X-ray lens

A micro X-ray fluorescence (Micro-XRF) spectrometer based on a polycapillary focusing X-ray lens (PFXRL) and a laboratory X-ray source was designed to carry out the XRF analysis of single aerosol particles. The minimum detection limit (MDL) of this Micro-XRF spectrometer was 9 ppm for the Fe-Kα. The percentage of the particles of vehicle exhaust among aerosol particles was studied in Beijing, Chinese capital, during the test of odd-even driving restrictions for Beijing 2008 Olympics Games. This Micro-XRF spectrometer had potential applications in the analysis of single aerosol particles.     

一种针对组合材料研究的高通量X射线结构、成分表征方法

将X射线毛细管聚焦技术和能量色散X射线衍射技术相结合，提出了一种新的针对组合材料研究的高通量X射线结构、成分分析方法，并实际构建了一个样机，测试了样机的性能，验证了此方法的可行性及优缺点。     

The study of chemical composition and elemental mappings of colored over-glaze porcelain fired in Qing Dynasty by micro-X-ray fluorescence

It is very difficult to measure the chemical composition of colored pigments of over-glaze porcelain by X-ray fluorescence because it contains high concentration of Pb. One of the disadvantages of our polycapillary optics is that it has low transmission efficiency to the high energy X-ray. However, it is beneficial to measure the chemical compositions of rich Pb sample. In this paper, we reported the performances of a tabletop setup of micro-X-ray fluorescence system base on slightly focusing polycapillary and its applications for analysis of rich Pb sample. A piece of Chinese ancient over-glaze porcelain was analyzed by micro-X-ray fluorescence. The experimental results showed that the Cu, Fe and Mn are the major color elements. The possibilities of the process of decorative technology were discussed in this paper, also.     

Size-resolved source apportionment of aerosol particles using polycapillary X-ray lens with a plateau in its focal spot

A laboratory micro X-ray fluorescence spectrometer based on a special polycapillary X-ray lens (PXRL) was used to carry out the source apportionment of aerosol particles. In the curve of the distribution of the X-ray intensity in the focal spot of the special PXRL, there was a plateau with a diameter of 21.3 μm in which the distribution of the X-ray intensity was homogeneous. The gain in flux density in the plateau of the PXRL is 1490. The uniformity of this plateau was 2.9%. This was helpful for the quantitative X-ray fluorescence analysis of a single aerosol particle with smaller size than that of the plateau of the PXRL. The fingerprint database of aerosol particles with given sizes from various air pollution sources was established with the single particle analysis method. The size-resolved source apportionment of aerosol particles in haze in Beijing city was performed with this fingerprint database.     

Fine structures of divergence of polycapillary X-ray optics

The divergence of the beam focused by polycapillary X-ray optics (PXRO) varied at different distances from the exit of the PXRO. This distance dependence of the divergence of the PXRO was defined as the fine structures of the divergence of the PXRO. The fine structures of the divergence of the PXRO were presented in order to use them fully. There were main three types of the PXRO, such as polycapillary parallel X-ray lens (PPXRL), polycapillary focusing X-ray lens (PFXRL) and polycapillary slightly focusing X-ray lens (PSFXRL). For the PPXRL, the divergence decreased near its exit. The reason for this might be that the divergence near the exit of the PPXRL depended mainly on the X-rays traversing directly through the monocapillaries in the center of the PPXRL without total reflection. For the PFXRL and PSFXRL, they both had respectively a focal depth over which the beam sizes at different output distances remained acceptably small. For the 8 keV X-rays, the focal depth and divergence over the focal depth of the PFXRL were about 300 μm and 25.0 mrad, respectively. At the same energy of 8 keV, the focal depth and divergence over the focal depth of the PSFXRL were about 500 μm and 12.5 mrad, respectively. The divergence of the PFXRL and the PSFXRL depended mainly on the angles between axes of monocapillaries that composed them.     

PIXE measurements of Renaissance silverpoint drawings at VERA

Silverpoint drawings from the Renaissance are among the most precious and rarest treasures of graphical art. Our research group is particularly interested in the analysis of silverpoint drawings by Albrecht Dürer (1471-1528). A very sensitive and non-destructive analytical method, either spatially resolved synchrotron-radiation induced X-ray fluorescence (SY-XRF) or proton-induced X-ray emission (PIXE), is needed to determine the chemical composition of the very faint silver marks on such drawings. Dürer drawings from the collection of the Albertina, Vienna, were analyzed to amend existing data on Dürer drawings. For this purpose an external-beam PIXE setup was installed at the Vienna Environmental Research Accelerator (VERA). It allows to analyze a spot of ∼0.15 mm on the object in air with 3 MeV protons, and to detect the emitted X-rays that are characteristic for the chemical composition with very good sensitivity and without harming the precious objects. After successful measurements on artificial test samples, four original silverpoint drawings were investigated: two portraits from Albrecht Dürer’s very early period (self-portrait and portrait of his father) and two drawings from Dürer’s sketch book of his travel to the Netherlands 1520/21.     

毛细管X光透镜聚焦的微束X射线荧光谱仪的研发及应用

针对不同样品的分析需求,本文设计了几种不同类型的微束X射线荧光谱仪。用高精度激光位移传感器实时校正样品表面被测量点与毛细管透镜出端之间的距离,以减少形状不规则的古陶瓷样品测量时带来的误差;利用毛细管X光透镜传输能量高于25 keV的X射线效率低的特点,将其应用于高铅釉瓷器彩料的无损分析中;采用大功率X射线源,扫描分析了大米中K、Ca等元素分布;以人民币5角硬币为例,研究了能量色散的微束X射线衍射方法。研究结果表明,本文研发的微束X射线荧光谱仪在生物样品和文物样品的分析研究中有广泛的应用前景。     

Parametric X-rays generated by electrons in multilayer mirrors mounted inside a betatron

The measured characteristics of tunable, quasi-monochromatic X-rays from thin multilayer mirrors used as radiators mounted inside a 35 MeV betatron chamber are presented. Parametric X-ray radiation (PXR) was generated by 15-33 MeV electrons passing through two radiators consisted of a few hundreds of W/B4C bilayers with period of 14.86 and 18 A. Shifts of the PXR spectra were measured as the orientation of the multilayer radiators relative to the incident electron beam was changed. The PXR flux was determined by comparison with the yield of L fluorescence generated by electrons in the W layers of the multilayer.     

Accelerator-based trace element analysis of foods and agriculture products

An accelerator-based analytical method for measuring trace elements in foods and agricultural products was developed, optimized, validated and compared using reference standards. The method’s initial phase is a new, rapid and effective digestion process of a small mass analyte in an aqueous media containing H₂O₂. Digestion is initiated by radicals formed in water with pulsed UV (PUV) induced (laser) photolysis, which rapidly react with organic matter. After digestion, trace metals are pre-concentrated as carbamates and deposited as thin targets onto Teflon filters. Conventional particle induced X-ray emission (PIXE) or X-ray fluorescence (XRF) methods are then used to analyze elements in the sample. When foods and other agricultural commodities (i.e., soils, feeds) are analyzed, the combined method named pulsed UV (PUV)/PIXE results in enhanced detection of trace elements such as Fe, Co, Ni, Cu, Zn and Pb at ∼1 mg/kg (1 ppm) levels, without lengthy, acid-based digestions. It provides improvements in digestion kinetics and processing time enhancing analytical sensitivity and element recovery. Precision and recovery yields were confirmed with food reference standards. The analysis of edible foods from contaminated agricultural areas is also reported.     

Development of treatment planning for scanning irradiation at HIMAC

In order to utilize an intensity-controlled raster scan method at the new treatment facility in HIMAC, we have developed, as a first step, a research version of a treatment planning tool. In this tool, treatment plans are produced according to the following steps: (a) import a planned target volume (PTV) delineated on a CT data set, (b) determine the primary treatment parameters, (c) convert the PTV in the CT system to the one in the water equivalent system, (d) choose beam positions within the PTV, (e) optimize the scan trajectory, (f) determine the particle numbers for each pencil beam and (g) produce the beam steering file. As an example, a treatment plan was produced for the data of a patient treated at HIMAC in this paper. The reliability of the tool was confirmed with irradiation experiments according to the obtained beam steering file.     

Use of silicon drift detectors for the detection of medium-light elements in PIXE

In order to fully exploit in PIXE the superior performance of silicon drift detectors especially for the detection of low- and medium-energy X-rays, avoiding in particular the negative effects of backscattered particles, we developed a custom spectrometer based on a 10 mm² chip with a thermoelectric Peltier cooler and home-designed front-end electronics, coupled to a weakly focusing polycapillary lens.This paper briefly describes the detector + lens assembly and reports the results of first tests carried out at an external beam line of the LABEC laboratory in Florence. Excellent energy resolution is achieved under real operating conditions in a PIXE run (measured FWHM at 1 keV is 81 eV with a count-rate of 480 cps) and also the lineshapes are very good (FW1/10M over FWHM ratio is 2.1). As a whole, our preliminary tests gave encouraging results and also helped to point out some aspects which it is worthwhile to investigate further (e.g. how X-ray peak intensity ratios may be affected by inaccurate lens alignment), in order to profit fully from such a good performance of the spectrometer.     

L-subshell ionization of heavy elements by S ions with energy of 0.4-3.8 MeV/amu

The L-shell X-ray production cross sections have been measured for sulphur ions in the energy range of 12.8-120 MeV for Au and Bi elements. The experimental L X-ray spectra were analyzed using the method that takes into account the multiple ionization in outer shells. The L-subshell ionization cross sections have been obtained from measured X-ray production cross sections for resolved Lα_1,2 Lγ₁ and Lγ_2,3 transitions using the L-shell fluorescence and Coster-Kronig yields modified by the multiple ionization effects in the M and N shells. The results are compared with the predictions of ECUSAR theory, which is the modified ECPSSR approach describing both direct ionization and electron-capture processes and the semiclassical approximation (SCA) calculations for direct ionization. These approaches were modified by the L-subshell coupling effects within the “coupled-subshell model” (CSM). Both modified approaches are in good agreement with the data. Remaining discrepancies are discussed in terms of the L-shell decay rates modified for the multiple ionization effects.     

Assessment of DNA damage of Lewis lung carcinoma cells irradiated by carbon ions and X-rays using alkaline comet assay

DNA damage and cell reproductive death determined by alkaline comet and clonogenic survival assays were examined in Lewis lung carcinoma cells after exposure to 89.63 MeV/u carbon ion and 6 MV X-ray irradiations, respectively. Based on the survival data, Lewis lung carcinoma cells were verified to be more radiosensitive to the carbon ion beam than to the X-ray irradiation. The relative biological effectiveness (RBE) value, which was up to 1.77 at 10% survival level, showed that the DNA damage induced by the high-LET carbon ion beam was more remarkable than that induced by the low-LET X-ray irradiation. The dose response curves of “Tail DNA (%)” (TD) and “Olive tail moment” (OTM) for the carbon ion irradiation showed saturation beyond about 8 Gy. This behavior was not found in the X-ray curves. Additionally, the carbon ion beam produced a lower survival fraction at 2 Gy (SF2) value and a higher initial Olive tail moment 2 Gy (OTM2) than those for the X-ray irradiation. These results suggest that carbon ion beams having high-LET values produced more severe cell reproductive death and DNA damage in Lewis lung carcinoma cells in comparison with X-rays and comet assay might be an effective predictive test even combining with clonogenic assay to assess cellular radiosensitivity.     

External scanning micro-PIXE for the characterization of a polycapillary lens: Measurement of the collected X-ray intensity distribution

We developed a PIXE detection system for the analysis of medium-light elements which exploits a weakly focusing polycapillary lens for the transmission of the X-rays emitted from the target material to a Silicon Drift Detector. The polycapillary lens efficiently collects X-rays, while prevents back-scattered protons from impinging on the detector chip, thus avoiding electronics perturbation and consequent quality loss of PIXE spectra. The system is optimized for the detection of X-rays in the energy range 1–10 keV, when the emission from the target is induced by MeV proton beams with size of the order of a few hundreds of micrometers.This work reports the results of the lens characterization in terms of X-ray collection spot, i.e. the area of the sample actually “seen” by the lens, and its dependence on the X-ray energy. The lens properties have been measured using the external scanning microbeam facility of the Tandetron accelerator at LABEC-INFN in Florence. The detection system was used to detect X-rays from a set of pure elemental standards with an incident 3 MeV proton beam focused to a size of about 30 μm scanning an area of 1.9 × 1.6 mm². By measuring the spatial distribution of characteristic X-rays from each given material, the collection profile of the lens at the corresponding X-ray energy was obtained. Using several standards, the behaviour throughout the range 1–10 keV was examined. The sensitivity of the lens collection profile on the lens-sample out-of-focus distance was also investigated.     

Aerosol-induced lung injuries observed by synchrotron radiation X-ray phase-contrast imaging technique

Adverse health effects are associated with the inhalation of a variety of atmospheric particles. To study the lung injuries caused by aerosol PM_2.5, synchrotron radiation (SR) X-ray phase-contrast imaging technique was used. Nude mice were inoculated with PM_2.5 samples collected from suburban area (JD), industrial area (BS) and traffic tunnel (DPQ) of Shanghai. From X-ray phase-contrast images of lung tissues, apart from blood vessels and structures of alveoli, even hemorrhage spots of several microns caused by the inflammation were clearly observed. The studies showed that the PM_2.5 samples collected from the traffic tunnel (DPQ) produced higher level of lung injury, followed by the aerosol samples collected from industrial area (BS) and suburban area (JD). Our studies also helped us to understand the process of lung injuries caused by aerosol particles.     

微束X射线荧光分析系统的建立及其在考古学中的应用

文章报道一种新型基于X光透镜的微束X射线荧光分析系统的结构、性能和特点及其在考古学中的应用。X光透镜将旋转阳极X射线发生器产生的X射线束聚成直径为几十微米的光束，可用于考古样品的无损微区分析。为检验微束分析系统的可行性，分析了1片明代青花瓷残片中青花部位的元素分布。分析结果表明：青花中Mn和Co元素的含量与青花颜色的深浅相一致。相关性分析表明：Mn和Co呈现良好线性相关；Mn和Co的含量或比值对青花的产地和真伪的辨别有重要意义。     

Effect of swift heavy ion irradiation on hydrothermally synthesized hydroxyapatite ceramics

The effect of swift heavy ion irradiation on hydroxyapatite (HAp) ceramic - a bone mineral was investigated. The irradiation experiment was conducted using oxygen ions at energy of 100 MeV with three different fluences of 10¹², 10¹³, 10¹⁴ ions/cm². The irradiated samples were characterized by glancing angle X-ray diffraction (GXRD), atomic force microscopy (AFM), dynamic light scattering (DLS), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). GXRD confirmed incomplete amorphisation of HAp with increase in fluence. There was considerable reduction in particle size on irradiation leading to nanosized HAp (upto 53 nm). PL studies showed emission in the visible wavelength region. The irradiated samples exhibited better bioactivity than the pristine HAp.     

Quality assessment system for curved crystal X-ray optics

Doubly curved crystal X-ray optics provide intense focused monochromatic beams from laboratory X-ray tube sources. These optics are employed in crystallography and X-ray fluorescence systems and may find application to imaging. It is increasingly important to understand how optic defects impact performance for these systems. A simulation model was developed to assess the effects of misalignment and optic defects on system parameters such as intensity, beam size and resolution. Simulation results were compared to optics measurements. Rapid reproducible measurements of optics quality are important both for performing systematic studies of optics defects and for assessing individual optics. A simple operator-independent alignment technique was developed that was also beneficial in ensuring optimal beam intensity in analysis systems. The measurements and simulations were in good agreement and provided insight into essential optics parameters.