Alpha Particle X-Ray Spectrometer
An Alpha Particle X-Ray Spectrometer is a device that analyses the chemical element composition of a sample from the scattered alpha particles, and fluorescent X-rays after the sample is irradiated with alpha particles and X-rays from radioactive sources. Since there are faster methods available which do not use radioactive material to analyse the elemental composition of a sample, this compact and low power method is most often used on space missions. A variation is the Alpha Proton X-Ray Spectrometer, such as on the Pathfinder mission, which also detects protons. The common abbreviation is APXS.