The Maia Detector Journey: Development, Capabilities and Applications

Abstract

The development of the Maia detector was motivated by the desire for high throughput synchrotron fluorescence element mapping with images beyond 100 M pixels, which capture both fine detail and extended spatial context. It achieves this by using a large planar silicon detector array together with event-mode data acquisition, where each detected X-ray event is tagged with position in the scan, thus avoiding the readout overheads of a "step and acquire" style of mapping. The sample stage moves continuously and the stage encoders are read by the FPGA based real-time processor to provide coordinates for each event, which provides great freedom in scan speed or transit time per map pixel [1]. The large detector array, with 384 independent detector channels, each with its own charge amplification and pulse capture electronics, implemented using custom ASICs, enables cumulative count-rates exceeding 10 M/s to be achieved with low pile-up probability, which enables adequate counting statistics to be acquired per pixel in transit times as short as 50 µs [2,3]. The array uses a back-scatter, annular configuration, which combines a 1.3 sr solid-angle detection geometry with complete freedom in sample size and scanning range. This has enabled applications to extend from the initial focus on synchrotron X-ray microanalysis, with µm sized pixels and scan ranges up to a few centimeters, to macro-scale mapping using synchrotron or laboratory X-ray sources, with scan ranges up to ~1 m. Synchrotron XRF mapping using Maia has been applied to studies in the earth, planetary, environmental, medical, biological, chemical and material sciences as well as cultural heritage (see refs cited in [1]). Methods and quantitative imaging techniques developed for Maia, which exploit event acquisition tagged by two or three axis coordinates, include large area, high definition, high throughput