International Journal of PIXE

Determination of proton charge during in-air PIXE experiments can be hampered when analysing thick non-conductive samples. Several arrangements may be used for overcoming this problem, while in studies of historical documents a variant employing X-ray yield measurements on Ar in air is often used. At compact geometry, with a small distance from the exit foil to the sample (10 mm or less), and also with close location of the X-ray detector to the sample to increase the detector solid angle, the uncertainties in the experimental geometry directly influence the accuracy of the PIXE analysis. The factors affecting the accuracy when using Ar yields are estimated. The advantage of the other technique, measuring X-ray radiation from the exit foil, is elaborated.

A description of modifications in the variable energy cyclotron (VEC) Chandigarh along with the installation of Proton Induced X-ray Emission (PIXE) setup is presented. A new main magnet power supply of 400A/125V out put with ±10 ppm stability and a new stabilized solid state power supply for RF oscillator has improved the beam characteristics substantially. A new chamber has been designed to cater for Proton Induced Gamma Emission (PIGE) and Rutherford Back Scattering (RBS) along with PIXE measurements. The HPGe x-ray detector, the Ge(Li) γ-ray detector and a silicon surface barrier (SSB) detector can be mounted simultaneously in the chamber for this purpose. A Turbo-Molecular vacuum pump is provided to produce a clean vacuum of the order of 10^-8 mbar in the PIXE chamber. A remotely controlled stepper motor is provided to move the wheel having 12/24-position target holder. Beam size optimization along with the minimization of background has been done with the help of graphite collimators, thus making the setup suitable for practical applications. Preliminary experiments for the PIXE analysis of aerosol, gunshot residues and kidney stone samples are presented.

Stones removed from different patients of different ages were collected at Regional Institute of Medical Sciences, Imphal, North-eastern India. The stones were analyzed by PIXE with 3MeV protons. Ca was found to be the major constituent element. Light elements present in minor concentration were S, Cl and K. Again, Fe, Ni, Cu, Zn, Sr were observed in low concentration and most of them were detected in trace levels.

Human hairs of cirrhosis, acute viral hepatitis patients and healthy people in Ulaanbaatar, capital city of Mongolia, were analyzed for the presence of heavy elements by PIXE spectrometry using 2.5 MeV proton beam at the Tokyo Institute of Technology Van de Graaff Laboratory. The samples were dissolved in a mixture of nitric acid and hydrogen peroxide. Then a 20μl aliquot was dropped on a Nuclepore Track-etch Membrane. The IAEA Reference Hair IAEA-086 certified reference material was used in order to verify accuracy of the method and the results were in good agreement with the certified values. To determine the interaction among nine elements in hair, correlation coefficients were evaluated for several pairs of elements. In the group of healthy control, no correlation between elements was identified. Opposite to this, the strong positive correlations were observed for Zn and Ca or Fe; Mn and Ca or Ti; Sr and Zn or Fe in the patients hair. In the present study, the mean concentrations of Ca, Ti, As and Sr in Mongolian patients were higher than those in the hair of normal people in Japan, Mongolia, Iran and Indonesia. The levels of Cu, Zn and Mn concentration in hair of normal people were almost the same for all the cohorts.

A PIXE (Proton Induced X-ray Emission) analysis is applied for measuring the concentration of 21 major and minor trace metal elements (in the range of Z=13-53) for normal, adenoma and carcinoma human thyroid tissues. A 2.0 MeV proton beam was employed to excite the samples. The thyroid samples were obtained from 14 patients during surgical operations, with which normal and damaged parts are concerned as an aid to understand the mechanisms of formation of thyroid cancer and as a complementary diagnostic tool. Thirty samples were measured in total. Fourteen samples of them were in pairs, i.e.14 tumor samples with 14 corresponding healthy tissue specimens taken at a distance from the tumor. The statistical analysis of the results shows the lower levels of the mean value of iron and iodine in the carcinoma tissues than those in the normal tissues; especially iodine is about one tenth of the normal value. On the contrary, the elevation of the mean value for calcium and zinc in the carcinoma tissues in comparison with the normal ones is observed, while in the adenoma tissues copper is very lower than those in the normal thyroid. The concentration of iron in the adenoma is two times of normal tissues.

Selected number of anti-diabetic medicinal plant leaves has been characterized by accelerator based particle-induced X-ray emission (PIXE) technique. Validity of the technique was assured by analyzing certified plant reference materials (CRMs). A large number of trace elements like Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr and Pb are found to be present in these studied leaf samples with variable proportions. The concentrations of elements like K and Ca are quantified in percentage level whereas other elements are found to be in parts per million levels. Among the studied samples, the leaves of Methi are found to be containing maximum amount of trace elements.

H2 receptor antagonist (H2RA) and proton pump inhibitor(PPI) are often used to treat gastric ulcers, in addition to the zinc-L-carcino-complex which is commonly adopted for such therapies. However, there have been no previous reports detailing the levels and distribution of zinc in human gastric mucosa. The aim of our current study is to clarify the relationship between Helicobacter pylori infection and trace elements such as zinc in gastric mucosa using particle induced X-ray emission (PIXE). Forty gastric ulcer patients were chosen as subjects of this study and divided into two groups. One is a new ulcer patients group(twenty nine cases). And the other, eleven of these patients had been prescribed zinc-L-carcino-complex (polapreZinc^®), at a dose of 150mg/day for periods ranging from 16 to 20 weeks. The zinc levels in the gastric ulcer group were found to be significantly less than those of the control group and the concentrations of zinc in gastric mucosa were observed to increase following the administration of treatments containing this element.

A program was started to create a new medical scientific field, which involves radiation oncology and nuclear medicine, utilizing advanced accelerator and ion beam technology. An in-air micro-PIXE analyzer system, which is among the most important technical aspects of the program, was upgraded to improve the accuracy of elemental mapping for samples with thickness variation in the scope of microbeam scanning. In order to address important bio-medical problems in cancer, the intracellular dynamics of trace elements according to the development mechanism of diseases were studied using this system. This paper outlines the program, showing correction of micro-PIXE elemental map by STIM analysis and the preliminary application results.

Two types of bleached mutant strains were isolated from a culture of wild-type Euglena gracilisZ strain. These mutant strains formed yellow and white colored colonies, named Y₁ZSmL and W₁ZSmL, respectively. The losses of chlorophyll a in both mutant strains were found from the evaluation of chlorophyll a concentrations. To elucidate physiological effects due to the chlorophyll a loss, cell growth and the amounts of trace elements (Al, P, S, K, Ca, Fe, Cu, and Zn) in each strain were studied. The obtained data for mutant strains were compared with those for wild-type Z strain. Cell growth of each strain differed and the abundances of cells were consequently high, decreasing in the order of Z, Y₁ZSmL, and W₁ZSmL. The amounts of all elements except S in mutant strains were significantly lower than those in the Z strain. Differences between Y₁ZSmL and W₁ZSmL were found only in the amount of Cu. Copper, therefore, would be one of the factors causing differences in the color of the colonies and the growth of cells between both mutant strains.

Particle-induced X-ray emission (PIXE) was applied for the determination of heavy metals accumulated in natural phytoplankton. We selected four Japanese marine sites to collect phytoplankton: Toni Bay and Kamaishi Bay (Kamaishi, Iwate) as non-polluted areas; and Shimotsu port (Shimotsu, Wakayama) and Toyama new port (Shinminato, Toyama) as polluted areas. After removing the zooplankton and visible dust by passing the seawater through an NXX13 plankton net (95-μm mesh aperture), the phytoplankton were collected on a polycarbonate filter (25 mm diameter, 1.0 μm pore size) by suction filtration. The filter was dried and subjected to scanning electron microscopy (SEM) and a PIXE analysis. The phytoplankton consisted of diatoms, dinoflagellates and coccolithophores were observed by SEM analysis on the filter prepared from 100 ml of Toni Bay seawater. Heavy metals (Pb, Ni, Cu, Cr, Zn, Mn, Hg and As) could be detected by the PIXE analysis in almost all the cases tested, in which 50-200 ml each of respective seawater sample was filtered. There was a linear relationship between the amount of heavy metals on the polycarbonate filter (ng cm^-2) and the volume of seawater (25-200 ml) filtered (i.e. the amount of phytoplankton collected on the filter). Likewise, the PIXE analysis revealed that significant differences in heavy metal contamination between the polluted and non-polluted areas, and also among sampling sites in a polluted area depending on the location and seawater movement. These results indicate that a multi-element analysis of marine phytoplankton by PIXE would be a promising technique for biologically assessing and monitoring heavy metal pollution in the first link of the aquatic food chain.

In order to obtain high time-resolution, i.e., chemical data of atmospheric particulate matter (PM) at one-hour intervals, we carried out direct analysis of suspended particulate matter (SPM) on hourly spot samples on a new type of PTFE ultra-membrane filter-tape mounted in an automated beta-ray absorption mass monitor by conventional PIXE. Analysis of hourly SPM spot samples revealed 20 elements (Na, Mg, Al, Si, S, Cl, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Sr and Pb) in total. Therefore, we are convinced that the chemical information that is obtained from high time-resolution PM spot samples on a PTFE membrane filter-tape mounted in an automated beta-ray absorption mass monitor will lead to new developments in PM research. Furthermore, elemental data obtained by the high time-resolution along with data for ionic species compositions, and SO₂, NO_X and other gaseous air pollutants at the same level, will make possible the analysis of detailed air pollution phenomenon.

Particle induced X-ray emission (PIXE) technique developed at Variable Energy Cyclotron, Panjab University Chandigarh has been used for the detection of trace elements in the aerosol samples collected from relatively clean and industrially polluted city in northern India. Aerosol samples were collected from Jammu City of Jammu and Kashmir State, which is supposed to have a clean environment and from Mandi-Gobindgarh, one of the most polluted steel city of Punjab. The results from the analysis of these samples show some basic differences in the trace element profile of the two cities. The results further suggest a long term aerosol sample analysis to segregate anthropogenic and natural sources of air pollution. The mean concentration levels of different trace elements in PM₁₀ (Particulate matter with aerodynamic diameter less than 10 μm) from these two cities of northern India are compared with some of the prominent cities of India.

Biological monitoring through higher plants should be more than just a second choice for air-quality assessment in polluted or dry areas that happen to be devoid of lichens and/or bryophytes. Provided that some of their specifics are accounted for, vascular plants could indeed stand for an actual alternative to lower epiphytes, if not featuring some real advantages – technical, economical and ecological – over them. As a contribution to an evaluation of such an alternative, olive trees (Olea europaea Linn.) have been sampled for their outer bark across two separate areas of mainland Portugal, in a total of 53 collection locations. After suitable procedures, bark samples were put through proton-induced X-ray emission (PIXE) and analyzed for their elemental contents. Nonparametric coefficients (Kendall's) for the spatial variation of S, Ni, Cu and Pb are significant beyond any reasonable, statistical level. There is also a good spatial agreement – sometimes, an excellent one – with lichen trends as an external reference, but for lead, that may suffer from spectral interference though. Further research on material cleansing and pelletising procedures is advisable, especially in what concerns the homogeneity of bark samples for PIXE analysis.

Polycrystalline ingots of CuInSe₂ and CuIn₃Se₅ were synthesized by melt-quench technique starting from the stoichiometric mixture of constituent elements. X-ray Diffraction (XRD) studies confirmed the single-phase nature of the materials. Compositional analysis by Particle Induced X-ray Emission (PIXE) showed that the compounds are near stoichiometric. Thin films of CuInSe₂ and CuIn₃Se₅ were grown from pre-synthesized CuInSe₂ and CuIn₃Se₅ powders. The films were polycrystalline, single-phase and near stoichiometric in nature, as indicated by Transmission Electron Microscopy (TEM) and PIXE studies.

Proton-Induced-X-Ray-Emission (PIXE) is a suitable technique for the elemental analysis of ancient metallic artifacts, without any deterioration of the samples. Metallography was used to determine the manufacture technique of ancient metallic artifacts. These techniques were applied to study 12 copper artifacts collected, from burial offerings of a "Señor Tarasco", discovered by Eduardo Pareyon, in "El Portal de Matamoros", Uruapan, Michoacán, in 1957.

Bismuth (Bi) content of electrum from Mongolian artisanal/small-scale mining sites was determined by micro-PIXE at CSIRO. This is to provide artisanal/small-scale miners information on the valuable trace element in electrum which they recover from quartz veins. The analysis was done using a 3 MeV micro-beam (30 micrometer in diameter) with an aluminum filter of 125 micrometer thickness. The result showed that electrum grains from the study area contains Bi with a range from 0 to 2,530 ppm.