Impact and Application: Fast Electron Ejection in Atomic Collisions Studied with the ARGOS Multi-Detector

Three-Electron Auger Process from Beam-Foil Excited Multiply Charged Ions

“…Auger electron emission from the fast projectile takes place with energies in the laboratory frame well above 10 000 eV so that it is impos-sible that target Auger electrons could obscure the spectra. The experiment was performed with a beam of C 3 (22:7A MeV) traversing thin carbon foils (thickness 21, 49, and 90 g=cm 2 ) at the superconducting cyclotron CS at LNS (Catania) in the large scattering chamber CICLOPE with the ARGOS multidetector [11,12]. Fast scintillation detectors of the ''phoswich'' type (a BaF 2 crystal covered with a plastic scintillation foil mounted on a photomultiplier tube) allow identifying ionic particles (protons, deuterons, heavy ions), neutrons, energetic photons ( or x rays) and electrons.…”

“…The velocity of the particle can be measured by the time-of-flight method since the ion beams delivered by the cyclotron are pulsed with a small pulse width of typically below 1 ns and the distance between target and detector (typically about 1-4 m) can be measured with great precision. For about the past ten years, ARGOS, initially designed for studying nuclear heavy ion reactions [11], was used to measure electron emission in atomic collisions [12]. This detection system has several advantages compared to electrostatic or magnetic electron spectrometers such as accurate measurement of absolute cross sections, the possibility to study electronelectron coincidences, and an important ''dynamics'' concerning the measurement of doubly differential yields.…”