PIXEKLM-TPI. A software package for quantitative elemental imaging with nuclear microprobe

Complete text of publication follows. Production of true elemental images using PIXE and the scanning nuclear microprobe is a complex and still challenging problem. Ryan and his co-workers were the first who developed a software package (GeoPIXE) for quantitative mapping, which was the only available in this field [1]. It is based on a rapid matrix transform method called Dynamic Analysis which directly converts the spectrum vector (S) into the concentration vector (C) in terms of the matrix Γ: C = Q-1ΓS (Q is the accumulated charge). This linear equation system allows to produce true elemental images Mk(x; y) by incrementing each image k (at beam position x; y) by Γki ki for each event at channel i. Based on our Oxford-type scanning nuclear microprobe facility we realized a special μPIXE set-up consisting of an ultra thin windowed (UTW) and a Be windowed Si(Li) X-ray detectors a few years ago. Then with the modification of our PIXEKLM program package we solved the efficiency calibration of UTW detectors and quantitative analysis down to C-Kα line by PIXE. In this report we present our new method and software package (PIXEKLM-TPI) developed for true elemental imaging [2]. The method is based on the above-mentioned ideas and measuring system. The software allows off-line data processing from list mode files. The Γ matrix is calculated by the PIXEKLM program package for any sample composition and thickness from C to U for K, L and M characteristic X-ray lines. True elemental images are produced by a frame program called True PIXE Imaging (TPI). It allows advanced image processing and multivariate statistical analysis in order to help the interpretation and presentation of concentration data. Support from the 5FP projects NAS-MICRO-XRF and NANODERM (Contract Nos. G4RDCT-2000-00402 and QLK4-CT-2002-02678) is gratefully acknowledged. (author)