International Journal of PIXE

Information on the elemental constituents of atmospheric aerosols is of basic importance in studying atmospheric processes for a detailed understanding of the physics and chemistry of the atmosphere. Environmental pollution and its impact can be tested in the same way, too.

In the present review we survey the main research fields in aerosol analytics that can be investigated with the application of the PIXE method. The nature of emission sources, emission inventories, aerosol transport and its tracing, arctic aerosols and climatic influences are mentioned along with methodological features of the present-day PIXE technique and its combined applications with other tools of instrumental analytics.

An approach to define cancer is proposed and our work is reviewed. We have tried to localize (or mark) a malignant tumor from its benign environment by injecting a small amount of a lanthanide into a tumor-bearing nude mouse to see how a lanthanide can localize in a tumor. In order to see a contrast from its environment, we measured a trace element distribution in several organs or tissues of a nude mouse also. We have tried to enhance the effectiveness of a lanthanide with hematoporphyrin derivatives, and have extended our animal experiment to analyze an elemental distribution in human brain tumors. We have found the particle induced X-ray emission (PIXE) analysis a convenient and practical method for our purpose. A mathematical model for a human glioma growth is introduced and a dynamical model, a generalized predator prey model, is proposed. Some significant features of our findings in each topic are discussed in the respective section.

A charge-division, position-sensitive proportional counter with a carbon-fiber anode and its associated signal processor has been developed. This counter is very small in volume with a simple structure and vacuum proof. The spatial resolution of 0.36 mm was achieved under a gas pressure of 1.7×10⁵ Pa. A correlation factor between the position and the channel number was measured to be 0.97, indicating good linearity of the system. The detector was combined with a crystal spectrometer in order to measure spectra of particle-induced characteristic X rays. Energy resolutions measured at Si K_α (1.74 keV) and Fe K_α (6.4 keV) X rays are 4 and 34 eV, respectively.

K X-ray spectra have been obtained from Platinum-Group Element (PGE) minerals using 40 MeV Proton-Induced X-ray Emission. It is possible to resolve all four component X-ray lines for the PGEs. In cases where there is more than one PGE present, some K X-ray lines may overlap, but in all cases, there were single lines available for quantitative analysis.

The spectrum obtained from the sperrylite during exposure to the proton beam beam contained Au X-rays. The presence of the Au can be attributed to (p,xn) reactions with Pt, induced by proton bombardment of the sample. The intensity of Au X-ray lines in the spectrum is proportional to the amount of Pt in the sample and the cross-section for (p,xn) reactions between Pt and Au at 40 MeV.

The measurement of rock varnish cation-ratios [(K+Ca)/Ti] and barium is evaluated by analyzing the same varnish scrapings with PIXE, inductively coupled plasma, neutron activation and wavelength dispersive electron microprobe. Results among these different methods are generally similar for ratios, but absolute concentrations differ in part due to uncertainties associated with weighing small samples. Barium concentrations are typically less than 1 % by weight; higher concentrations can be found in varnishes with depressions eroded into the varnish by fungi and lichens, and later infilled with aeolian detritus often including barium sulfate. Since these infilled hollows are known to produce anomalous varnish cation ratios, high barium values can, therefore, be used as an indicator that a sample is inappropriate for cation-ratio dating. The glacial chronology at Pine Creek, California, is revised in light of new data and a better understanding of variables influencing varnish chemistry.

The objective of this research is to determine whether there is a difference in the Ca, P, Fe, F, Mg, and Sr concentrations in teeth from children with and without cystic fibrosis (CF) as a function of age, sex of the child, maternal smoking habit, maternal drinking habit, and fluoridation of water supply. The nuclear analytical methods used were Proton-Induced X-Ray Emission (PIXE) and Proton-Induced Gamma Emission (PIGE). The findings are: (1) the concentration of Mg is higher in the teeth of children with cystic fibrosis who took antibiotics other than tetracycline (CF+NT) than in non-cystic fibrosis (NCF) teeth for the “female” category; (2) P concentration is less in (CF+NT) teeth for the “age greater than ten” group; (3) Fe concentration is greater for females in the NCF group; (4) Ca and Fe concentrations are lower for CF than for NCF in the “mother smokes” group; (5) F and Sr concentrations for CF+NT are higher for the “mother drinks” group than for the “mother does not drink” group; (6) “mother smokes” shows a depletion of Ca and Fe compared to “mother does not smoke” for CF+NT. (7) “fluoridation of water supply” shows an increase in F, except for NCF teeth.