Ion-trapping properties of SCRIT: Time evolutions of 138Ba charge state distributions

Abstract

We aim at evaluating time evolutions of charge state distributions of target ions in internal targets formed by the self-confining RI ion target (SCRIT) technique. The charge state distribution of the target ions is important for optimizing the SCRIT performance, because the number of target ions escaping from the SCRIT is increasing with decreasing the mass-to-charge ratio (A/q) of the target ions. To quantitatively evaluate the charge state distribution, we developed the E-scanning method that separates target ions by their A/q using a fixed magnetic field and a scanning electric field in the E×B velocity filter. Results in the measurements with 138Ba ions, the 138Ba1+∼7+ ions trapped in the SCRIT were identified clearly, and their time evolutions were observed for the first time at a trapping time of 30 ∼ 300 ms.