Physics with Radioactive Microclusters in He II

本项目旨在对超流氦中杂质的贡献获得基本认识。杂质离子由于离子施加的电致伸缩而在其周围形成氦原子团。与裸离子（如果存在的话）或中性原子相比，这种团簇的迁移率非常小。这里的研究的具体特点是使用放射性杂质来实现对各种杂质的检测。从我们的研究中可以看出，这些杂质是通过注入高速放射性核束在超流氦中产生的，并且带电杂质可以在电场中传输。因此，这些杂质的捕获是可以实现的。包裹在雪球中的杂质的核极化被保留。如果电场很强，离子可能会从周围的团簇壳层中自由迁移，极化似乎会消失。中性粒子没有极化守恒。根据我们独特的研究所收集的事实，我们将与GSI和其他机构合作，利用GSI达姆施塔特SIS和FRS系统的放射性核束，培育核物理和凝聚态物理的新物理分支领域。远离稳定线的放射性核的核结构和谱学属于前者，强调对核自旋的控制。团簇的结构和杂质与超流氦的相互作用属于后一个领域。可以强调的是，探测效率的团簇“雪球”变得更灵敏的许多数量级通过这里开发的检测方法。捕获的放射性核也是一个有趣的主题，这将在核物理和粒子物理的广泛领域中应用。

This project aims at obtaining basic understanding on the contribution of impurities in superfluid helium.An impurity ion forms a cluster of helium atoms around itself, owing to the electrostriction exerted by the ion. The mobility of such a cluster is extremely small as compared to a bare ion, if it exists at all, or a neutral atom.The specific features of the research here is to use radioactive impurities to enable detection of various kinds of impurities.From out studies, it has become clear that such impurities are produced in superfluid helium by implantation of high-speed radioactive nuclear beams, and the charged impurities can be transported in the electric field. Thus trapping of such impurities is realizable.Nuclear polarization of impurities encapsulated in snowball is preserved. If the electric field is quite strong ions may migrate free from the surrounding cluster shell and the polarization seems to be lost. Neutrals have no polarization conserved.Based on the facts, gathered from our unique research, a new field of physics branching on nuclear physics and condensed-matter physics will be cultivated by using a radioactive nuclear beams from the SIS and FRS system of the GSI Darmstadt in cooperation with GSI and other institutions. The nuclear structure and spectroscopy of radioactive nuclei far from the stability line stressed on the control of nuclear spin is in the former field. Structure of clusters and the interaction of impurities with the bulk superfluid helium belongs to the latter field. It can be emphasized that the detection efficiency of clusters "snowballs" became by many orders of magnitude more sensitive by the detection methods developed here.The trapping of radioactive nuclei is also an interesting subject and this will be applied in a wide field of nuclear and particle physics.