Abstract Gas-filled stopping cells are used at accelerator laboratories for the thermalization of high-energy radioactive ion beams. Common challenges of many stopping cells are a high molecular background of extracted ions and limitations of extraction efficiency due to space-charge effects. At the FRS Ion Catcher at GSI, a new technique for removal of ionized molecules prior to their extraction out of the stopping cell has been developed. This technique utilizes the RF carpet for the separation of atomic ions from molecular contaminant ions through their difference in ion mobility. Results from the successful implementation and test during an experiment with a 600 MeV/u 124Xe primary beam are presented. Suppression of molecular contaminants by three orders of magnitude has been demonstrated. Essentially background-free measurement conditions with less than 1 % of background events within a mass-to-charge range of 25 u/e have been achieved. The technique can also be used to reduce the space-charge effects at the extraction nozzle and in the downstream beamline, thus ensuring high efficiency of ion transport and highly-accurate measurements under space-charge-free conditions.

中文翻译：

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使用 RF 地毯通过离子迁移分离原子和分子离子

摘要 加速器实验室使用充气停止室来热化高能放射性离子束。许多停止池的共同挑战是提取离子的高分子背景和由于空间电荷效应导致的提取效率限制。在 GSI 的 FRS 离子捕集器中，开发了一种在离子分子从停止池中提取之前去除离子分子的新技术。该技术利用 RF 地毯通过离子迁移率的差异将原子离子与分子污染物离子分离。展示了在使用 600 MeV/u 124Xe 主光束进行实验期间成功实施和测试的结果。已经证明可以将分子污染物抑制三个数量级。已经实现了在 25 u/e 质荷比范围内背景事件少于 1% 的基本无背景测量条件。该技术还可用于减少提取喷嘴和下游光束线的空间电荷效应，从而确保在无空间电荷条件下离子传输的高效率和高精度测量。