Advances in Dynamic Analysis PIXE imaging: Correction for spatial variation of pile-up components

The Dynamic Analysis matrix transform facilitates generation of real-time quantitative elemental proton induced X-ray emission (PIXE) images. However, samples with strongly varying sample composition can lead to significant spatially varying concentration errors due to strong matrix effects or the overlap of pile-up lines that change in nature across the sample. The elements responsible for the highest count rate X-ray lines may change spatially, which means that the nature of the 'pile-up element' changes across the sample. This is a non-linear effect, related to the product of X-ray intensities for the dominant elements in each pixel. However, both matrix and pile-up effects are related to composition variation. Hence, it is possible to determine all these in a self-consistent fashion. This paper describes treatment for these pile-up effects in the GeoPIXE software and illustrates their application to imaging in geology