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A Maia detector array has been adapted and installed on the CSIRO-MARC Nuclear Microprobe. Maia uses an annular array of 384 silicon detectors to provide a solid-angle of 1.3 sr to improve the collection of X-rays induced by Particle Induced X-ray Emission (PIXE) using a micron focussed MeV proton beam. It features event-by-event data acquisition with dead-time correction and pileup rejection and a total count-rate capacity above 10 M/s, versatile stage and beam scanning modes (coupled to the DAQ-36 system described previously) to cater for a variety of sample configuration and experimental needs, precise measurement of transit time and integration of beam fluence per pixel, and spectral deconvolution of event data in real-time using the Dynamic Analysis method to provide element images during data collection. Here we demonstrate the system on thin sections made from geological samples extracted from active seafloor hydrothermal vents in the PACMANUS hydrothermal field in Papua New Guinea. [ABSTRACT FROM AUTHOR]

The Dynamic Analysis (DA) method in the GeoPIXE software provides a rapid tool to project quantitative element images from PIXE and SXRF imaging event data both for off-line analysis and in real-time embedded in a data acquisition system. Initially, it assumes uniform sample composition, background shape and constant model X-ray relative intensities. A number of image correction methods can be applied in GeoPIXE to correct images to account for chemical concentration gradients, differential absorption effects, and to correct images for pileup effects. A new method, applied in a second pass, uses an end-member phase decomposition obtained from the first pass, and DA matrices determined for each end-member, to re-process the event data with each pixel treated as an admixture of end-member terms. This paper describes the new method and demonstrates through examples and Monte-Carlo simulations how it better tracks spatially complex composition and background shape while still benefitting from the speed of DA. [ABSTRACT FROM AUTHOR]

Abstract: We report on a new FPGA based data acquisition system developed for the CSIRO Nuclear Microprobe (NMP) which is tightly integrated with both target positioning and beam transport. The data acquisition system called MicrodaQ is based on National Instruments Labview FPGA and numerous instrumentation modules spread over several PC’s. Beam transport uses a feedback control loop to optimise current on target for long unmanned experiments. These upgrades are discussed in detail and an example of the systems use for μ-Particle Induced X-ray Emission (PIXE) analysis on a Doriri apatite is briefly described. [Copyright &y& Elsevier]

Abstract: Application of nuclear microprobe event-by-event data acquisition approaches to synchrotron elemental imaging is at the heart of the design of a large energy-dispersive detector array called Maia, under development by CSIRO and BNL for SXRF elemental imaging on the X-ray microprobe. A new project is aimed at harnessing this development to provide high throughput PIXE imaging on the CSIRO Nuclear Microprobe. Maia combines a 1.2sr solid-angle 384 detector array, integrated scanning and real-time processing including spectral deconvolution of full-spectral data. Results using a Maia prototype demonstrate the potential using SXRF application data with elemental images of up 100M pixels. [Copyright &y& Elsevier]