International Journal of PIXE

Detection limit for thin backing films is formulated. A polyvinyl formal film of ~ 0.14µm was bombarded with 3 MeV protons and continuos backgrounds were measured with a Si(Li) detector. A large constant background of a high energy region (≥6 keV) was interpreted as the Compton tail due to the 440 keV γ-rays from the excited state of ²³Na which contaminated the surface of a carbon collimator placed just in front of a target. The detection limits of this thin film, under the condition of the beam spot size 6 mmϕ without collimator, are estimated for the elements of atomic number Z=10~55 and the minimum detection limit is calculated to be 4×10⁻¹²g for Z=28~34.

Samples of atmospheric aerosol particles collected at three sites of Debrecen city, were analyzed with respect to 15 elements by PIXE method. The center of the city has higher concentration values for most of the trace elements than the other places, indicating that the human activity plays an important role in increasing the total particulate mass of atmospheric aerosol. The concentrations measured are compared to some other results in published literatures.

Constitutional elements of head hair of mouse (Mus musculus) were investigated by Particle-Induced X-ray Emission (PIXE) analysis. The high peaks of S, K and Ca, and the low peaks of several other elements were observed in PIXE spectra of all the specimens from the used strains. The result clearly indicates that the ratios of these elemental contents are different among the coat colors of mice. Further, we observed strain difference even in the same color.

Particle induced x-ray emission (PIXE) measurements were applied to analyze constituent elements in ancient earthenware (middle Jomon period) excavated at Teramae site in Fukushima prefecture. Quantitative analyses of the earthenware and clay obtained near the site show difference in contents of the constituent elements between them.

A method of quantitative analysis of bone samples by simultaneous measurements of proton induced X-ray emission (PIXE) and Rutherford backscattered (RBS) spectra is described. The method is used for the evaluation of the data collected during proton microprobe irradiation. The RBS spectra are used for the determination of the sample thickness. The sample matrix is regarded as a mixture of collagen and hydroxyapatite. The unknown proportion of both compounds at each irradiated point is adjusted until the Ca concentration determined by PIXE is in accordance with the value calculated on the basis of the assumed matrix composition. For quantitative analysis, the calculation of the absolute yield using the thick target PIXE formula was applied. The sources and ranges of systematic errors are discussed.

As sample preparation technique for PIXE analysis of brain tumor, “homogenizing method” and “chemical ashing method” have been studied and developed. It is concluded that chemical ashing method is quite appropriate for biological sample preparation. By taking samples of surgically removed brain tumor (meningioma) and brain tumor cell line (rat glioma and human glioblastoma), elemental constitution of brain tumor is compared with that of normal brain, and remarkably high concentration of Zn is found in brain tumor.

Effects of one human-dose (30 µmol/kg) of calcium salt of diethylenetriaminepentaacetic acid (Ca-DTPA) on the urinary excretion of essential metals and on their concentration in several tissues were studied in rats by particle induced X-ray emission (PIXE). Ca-DTPA enhanced the urinary excretion of manganese, iron, copper and zinc, while their concentration in the liver, kidneys, brain and thigh bone remained unchanged. These results suggest that urinary loss of these metals caused by Ca-DTPA can be compensated by homeostatic mechanisms in the body under the treatment schedule of one human-dose per day.

A new apparatus is made to prepare a uniform and thin target for PIXE analysis by atomizing sample solution hydrolyzed with nitric acid at 105ºC for 2 hrs. When concentration of NIST Bovine Liver (SRM 1577b) is determined, values of almost all elements heavier than Na, except for Cl and Br, which are volatile under acidic condition, are roughly same as those certified by NIST.