Physics with Radioactive Microclusters in He II

这个项目的目的是对超流氦中杂质的贡献有一个基本的了解。由于离子施加的电致伸缩，杂质离子在其周围形成一团氦原子。与裸离子或中性原子相比，这种团簇的迁移率非常小。这里研究的特点是利用放射性杂质来检测各种杂质。从研究中可以清楚地看到，这种杂质是通过注入高速放射性核束在超流氦中产生的，带电杂质可以在电场中输运。因此，这种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下来。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。中性粒子不具有偏振守恒。根据我们独特的研究收集的事实，将利用GSI Darmstadt的SIS和FRS系统的放射性核束，与GSI等机构合作，培育出一个新的物理学分支--核物理和凝聚态物理。放射性核的核结构和光谱远离强调控制核自旋的稳定线，处于前者的领域。团簇结构和杂质与块体超流氦的相互作用属于后者。值得一提的是，这些探测方法使星团“雪球”的探测效率提高了好几个数量级。放射性核的捕获也是一个有趣的课题，这将在核物理和粒子物理的广泛领域中得到应用。

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.