Production of highly-charged recoil-ion beams at very low energy

Abstract An apparatus for production of an intense, charge-state separated, recoil-ion beam of very low energy and good collimation has been constructed. In a test experiment, in which 30 MeV C1 5+ projectiles were used to produce recoil ions, the feasibility of the method was demonstrated. The mass to charge ratio of the beam is selected by means of a Wien-filter, and the beam energy can be varied between 2 q eV and 1q keV with a constant charge-state resolution. Presently, the angular definition of the beam is 2.5°, but it can be impoved by at least a factor of 2. Very low energy Ar-ion beams, of intensities usable for secondary slow collision experiments, can be created for charge states ranging from one to nine. For example, beams of Ar 4+ and Ar 6+ of intensities 2.5 × 10 4 and 5 × 10 3 s −1 , respectively, can be furnished at energies of 10 q eV, while the corresponding numbers for 2 q eV beams ar approximately five times lower.