A NOVEL METHOD FOR CHARGE INTEGRATION IN EXTERNAL-BEAM TTPIXE - APPLICATION TO ANALYSES OF BIOLOGICAL-MATERIALS

An irradiation facility was developed for the elemental analyses of thick-target samples with particle induced X-ray emission (PIXE) spectroscopy. The samples were placed in air outside the cyclotron vacuum. The analyses were carried out with a beam of 6.4 MeV H-2(+)-ions giving rise to 3.2 MeV protons at impact on the vacuum foil. The integrated charge on the target was estimated utilizing measurements of light emission in air during irradiation of the target sample. The measured light intensity was used for normalizing the X-ray spectra obtained. Special attention was paid to the application of the thick-target PIXE (TTPIXE) technique to the analyses of biological materials. A commercial pelleting device was used for the preparation of composite target pellets with the biological sample pressed onto the surface of spectroscopically pure graphite. The TTPIXE method presented enables direct analyses of solid samples. The use of standard reference materials for calibration of TTPIXE analyses was tested. The accuracy and precision of the TTPIXE method are good for most elements.