PARTIAL AND TOTAL CROSS-SECTIONS FOR SINGLE-ELECTRON CAPTURE BY AR8+ FROM HE IN THE 400-2400-EV ENERGY-RANGE

Charge-exchange processes in 400-2400 eV Ar8+-He collisions are investigated: high energy resolution ion beam spectroscopy is performed with a recoil ion source (RIS) built in GANIL, total and partial cross sections for single-electron capture are measured using retarding field and energy gain techniques. Comparison with previous experimental results for total charge-exchange cross sections shows a rather good agreement and confirms the independence of these cross sections on the collision energy in the studied range. In contrast partial charge-exchange cross sections are shown to depend strongly on the collision energy. The experimental data are compared with theoretical results in the semi-classical impact parameter frame and with predictions made by other authors using the Landau-Zener model.