Speakers
Description
Macro-X-ray fluorescence (MA-XRF) scanners with two detectors are used, with their signals normally summed to improve the signal-to-noise ratio and the difference between them neglected. We show that this difference, plus one extra measurement, scanning the same painting again with the canvas tilted forward, is enough to characterise the instrument, with no dedicated calibration measurements fully. Tilting the canvas changes the paths that fluorescence photons take to each detector, but leaves the detectors themselves unchanged. Comparing the two scans, therefore, splits the observed differences into two parts: detector properties, which do not depend on tilt, and geometric effects, which change with tilt in a predictable, energy-dependent way. From two routine scans of one painting, we obtain per-element efficiency ratios with uncertainties, the effective viewing angle of each detector, and a flat-field correction map, and we measure how sensitive the element maps are to canvas positioning. The result is an energy-weighted fusion of the two detectors that outperforms simple summing, and a practical estimate of the error caused by imperfect mounting.