Ion/atom trap with use of superfluid helium

超流氦中的杂质离子由于电致伸缩作用形成了氦原子的微团簇。团簇的结构被认为是高度对称的，因此核心离子的自旋取向可能保持不变。这一特征对于应用于远离稳定性的不稳定核的光谱研究是很有吸引力的。我们研究了超富里氦作为离子陷阱的可行性和适用性。通过使用自旋极化的12B光束，确保了自旋极化的保持性。注入离子保留电荷的微团簇的形成几率高达注入离子的20%。在静电场作用下，进行了团簇的空间伸展运动。下一步是利用激光光泵进行偏振增强。研究了泵浦的困难。作为光谱研究的一个应用，观测到了17B的β延迟中子峰。通过测量与衰变中子符合的β射线不对称性，证明了17C激发态的个别自旋宇称归属是可能的。这种新方法对于奇异核的研究是非常有希望的。与氦离子陷阱的结合可能成为系统研究奇异核的一种新工具。

Alian ions in supefluid helium form a micro-clusters of helium atoms due to electrostriction. The structure of the cluster is thought to be highly symmetric and thus spin orientation of the core ion may be preserved. This feature is quite attractive for application to spectroscopic studies of unstable nuclei far from stability. We investigated feasibility and applicability of superfulid helium as an ion-trap.The preservation of spin polarization was ensured by using spin-polarized 12B beams. The formation probability of the micro-cluster in which the implanted ion preserves its charge was as high as 20 % of the implated ions. Spatial manupilation of the cluster under the electrostatic field was performed. Next step is a boostup of polarization by using laser optical pumping. Dificulties of the pumping have been investigated.As an application to the spectroscopic studies, beta-delayd neutron dacay of 17B has been observed. By measureing the beta-ray asymmetry in coincidence with the decaying neutrons, it was demonstrated that individual spin-parity assignment for the excited stated of 17C was possible. This new method is very promissing for the studies of exotic nuclei. Combination with the helium ion trap may serve as a new tool for the systematic studies of exotic nuclei.