The Maia Mapper Story

Maia Mapper was designed and built at CSIRO as an Advanced Resource Characterisation Facility infrastructure project funded by the Science and Industry Endowment Fund (SIEF). But the story really started nearly 20 years earlier with the early development of the Maia detector array. Conceived as a solution to achieving high count-rates for detailed X-ray fluorescence imaging at synchrotron X-ray microprobe beamlines, Maia was developed as a collaboration between CSIRO and Brookhaven National Laboratory in New York with funding from ARC LIEF, CSIRO and the Australian Synchrotron. It exceeded expectations, expanding the detail in synchrotron XRF images, in terms of the number of pixels, by around 1000 times. It became the mainstay of the XFM beamline at the Australian Synchrotron and was awarded an R&D100 Award in 2011 and the CSIRO Research Achievement Medal in 2012.

However, access to these facilities is in high demand and typically even the best science merit proposals gain access only a couple of times per year for a few days. Fortunately, advances in laboratory X-ray sources and focussing systems permitted conceiving of a Maia XRF system for the laboratory, which then would allow 24/7 access all year round. The Maia Mapper project brought together the high brightness laboratory X-ray source from Excillum in Sweden called the Metal Jet D2, which outperforms other options in terms of brightness and incidentally also was awarded an R&D100 Award in 2011. For focussing, a high efficiency polycapillary optic from XOS in the USA was chosen, matched to the X-ray spectrum from the Metal Jet. Finally, harnessing years of experience in robotics control at CSIRO, a sample stage system was added to the concept, closely integrated with Maia for imaging and building on the experience of honing Maia at the synchrotron. The combined system is a great match, providing XRF count-rates on geological samples up to 5 million counts per second over images sizes up to 60 million pixels at a spatial resolution of 30 microns and with excellent control over dwell time per pixel and spectral quality. And the best thing is that this is available 24/7 in the lab for larger project runs and fast turn-around analysis.

The Technical Details
Maia Mapper is a laboratory µXRF mapping system for efficient elemental imaging of drill core sections serving minerals research and industrial applications. It targets intermediate spatial scales, with imaging of up to ~80 M pixels over a 500 x 150 mm² sample area. It brings together (i) the Maia detector and imaging system, with its 1.3 steradian solid-angle, event-mode operation, millisecond pixel transit times in fly-scan mode and real-time spectral deconvolution and imaging, (ii) the high brightness 70 kV, 250 W Metal Jet D2+ liquid metal micro-focus X-ray source from Excillum, and (iii) an efficient XOS polycapillary lens with a flux gain ~15,900 at 21 keV into a ~32 µm focus, and (iv) a sample scanning stage engineered for standard drill-core sections. Count-rates up to ~5 M/s are observed on drill core samples with low dead-time up to ~2%. Automated scans are executed in sequence with display of deconvoluted element component images accumulated in real-time in the FPGA based Maia detector controller.