Curium-244 alpha-sources for space research

Special alpha-proton-X-ray spectrometric complexes (APXS) have been developed in order to perform chemical analyses of the Mars atmosphere and rock surface compounds by alpha back-scattering, alpha-proton measurements, and X-ray fluorescence. The sources were prepared by high temperature condensation of metal curium vapour onto silicon substrates. They are silicon disks with curium-244 fixed on their surfaces as a silicide. The sources have overall dimensions as follows: disk diameter 8 mm; thickness 0.3 mm; and 6 mm diameter active spot. The source activities are 5 ± 1 mCi and the alpha-line half-widths are equal to (1.7–2.5) and (2.9–4.5)% of full width at 10% of Maximum (Maximum is equal to 5.8 MeV). Thermovacuum (from 196 to 1000°C), mechanical, and resource tests were performed and demonstrated that the sources maintained their characteristics. The applicability of the sources for the above-mentioned analytical purposes was confirmed during NASA Mars Pathfinder mission.