Improvement of peak-to-background ratio in PIXE and XRF methods using thin Si-PIN detectors

This paper describes the peak-to-background ratio improvement that can be achieved in PIXE and XRF applications by the use of thin crystal detectors. This improvement becomes apparent in the presence of an intense gamma-ray source, which can be produced either during proton irradiation of a sample (PIXE) or in the deexcitation of the radionuclide in radioisotope-induced XRF analysis (RIXRF). In order to study theoretically the energy response of a silicon crystal in the x-ray energy region with respect to its thickness and the energy of the incident gamma-radiation, a Monte Carlo simulation was performed. Experimentally, two detectors having crystal thicknesses of 300 mum and 3 mm. were employed in specific analytical applications of PIXE, PIXE-induced XRF and RIXRF techniques. The peak-to-background ratios obtained for various characteristic x-rays were compared between the two detectors. The performances of the two detectors were also compared in the monochromatic XRF analysis of samples with low average atomic number matrix content. Copyright (C) 2003 John Wiley Sons, Ltd.