NSCL的回旋加速器气塞项目
The cyclotron gas stopper project at the NSCL
摘要：
气体阻止正在成为将通过射弹碎裂和飞行中分离获得的稀有同位素束转换为低能束的首选方法。这些光束允许ISOL类型的实验，如质量测量与陷阱或激光光谱学，以执行与弹丸碎片产品。目前用于高能束的气体塞系统是基于填充有0.1-1巴氦气的线性气室。虽然已经成功地用于实验，但发现在停止过程期间由氦原子的电离引起的空间电荷效应对可以使用的最大射束速率造成限制。此外，停止离子从这些装置的提取时间可能超过100毫秒，导致非常短寿命的同位素的大量衰变损失。为了避免这些限制，一种新型的气体塞子正在开发中的NSCL/MSU。新系统基于回旋加速器型磁体，该磁体具有填充有低压氦气缓冲气体的停止室。RF引导技术用于提取离子。空间电荷效应由于大体积以及由于停止区域和最高电离区域之间的分离而大大降低。本文研究了不同尺寸、不同磁场强度和磁场形状的回旋加速器气体塞系统。
英文摘要：
Gas stopping is becoming the method of choice for converting beams of rare isotopes obtained via projectile fragmentation and in-flight separation into low-energy beams. These beams allow ISOL-type experiments, such as mass measurements with traps or laser spectroscopy, to be performed with projectile fragmentation products. Current gas stopper systems for high-energy beams are based on linear gas cells filled with 0.1-1 bar of helium. While already used successfully for experiments, it was found that space charge effects induced by the ionization of the helium atoms during the stopping process pose a limit on the maximum beam rate that can be used. Furthermore, the extraction time of stopped ions from these devices can exceed 100 ms causing substantial decay losses for very short-lived isotopes. To avoid these limitations, a new type of gas stopper is being developed at the NSCL/MSU. The new system is based on a cyclotron-type magnet with a stopping chamber filled with Helium buffer gas at low pressure. RF-guiding techniques are used to extract the ions. The space charge effects are considerably reduced by the large volume and due to a separation between the stopping region and the region of highest ionization. Cyclotron gas stopper systems of different sizes and with different magnetic field strengths and field shapes are presently investigated.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
