Study of Radioactive Snowballs in Superfluid Helium

超流氦中放射性雪球的研究

• 批准号: 03044093
• 负责人: TAKAHASHI Noriaki
• 金额: $ 5.76万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03044093/
• 关键词: Superfluid helium; Impurity ion; Snowball; Cluster; Radioactive nuclear beam; betaray detection; GSI; SIS; クラスタ-; 放射性核ビ-ム

Impurity ions introduced in liquid helium may behave as singly charged entities with effective mass of 50-100 He atoms, which are referred to as snowballs. A snowball is. therefore, an aggregate, a micro-cluster of helium atoms by means of electrostriction around an impurity core ion admitted in liquid helium. not only helium ions as first noticed but also other alien ions do form snowballs. The method used in the of study of polarization phenomena in heavy ion reactions enabled us to conceive renewed interests to approach individual snowballs though alpha- and beta-ray countings, which have been developed here.While the snowball has been thought of a highly paramount solid entity, there are still doubt whether all the existing evidences do decisively favor the picture of a solid core. The preservation of nuclear polarization in this research provided with an important clue to this issue, enabling us to test the inherent structure of snowballs directly as to peripheral problems of the above experiment.The radioactive nuclear beams from the SIS accelerator at GSI Darmstadt was examined and finally focussed for of snowball experiments. The intensity and focussing were enough for that purpose.The lifetime obtained for snowballs indicates the interaction responsible is not that with simple electrons but with basic excitations in liquid helium.The structure of snowball became clearly highly symmetric, as it was compared with the crystal structure composed of metal ion and hydrogen ions. This is an interesting point of view for understanding of maintaining nuclear polarization in the core ion trapped in a snowball.

液氦中引入的杂质离子可能表现为有效质量为 50-100 He 原子的单电荷实体，称为雪球。一个雪球就是。因此，通过电致伸缩围绕液氦中的杂质核心离子形成聚集体，即氦原子的微簇。不仅是最初注意到的氦离子，其他外来离子也确实形成了雪球。用于研究重离子反应中的极化现象的方法使我们能够重新产生兴趣，通过在这里开发的α射线和β射线计数来接近单个雪球。虽然雪球一直被认为是一种非常重要的固体实体，仍然怀疑所有现有证据是否确实有利于固体核心的图景。本研究中核极化的保存为解决这一问题提供了重要线索，使我们能够直接检验雪球的固有结构，以解决上述实验的外围问题。最后专注于滚雪球实验。强度和聚焦足以达到这个目的。雪球的寿命表明，相互作用不是与简单电子的相互作用，而是与液氦中基本激发的相互作用。与晶体结构相比，雪球的结构明显变得高度对称由金属离子和氢离子组成。对于理解雪球中捕获的核心离子中维持核极化的理解，这是一个有趣的观点。