Study of Impurity Ions in Superfluid Helium and Their Nuclear Moments by Means of Beta-Ray Detection Method.

在液氦中引入的杂质离子可以表现为有效质量为50-100个He原子的单电荷实体，称为雪球。因此，雪球是一个聚集体，一个氦原子的微团簇，通过在液态氦中允许的杂质核心离子周围的电致伸缩来实现。不仅如第一次注意到的那样，氦离子，而且任何其他外星离子都会形成雪球。在研究重离子反应中的极化现象时所用的方法使我们重新产生了兴趣，通过这里开发的阿尔法和贝塔射线计数来接近单个雪球。虽然雪球一直被认为是一个非常重要的固体实体，但仍然存在疑问，是否所有现有的证据确实支持固体核的图景。这项研究中的核极化保存为这个问题提供了重要线索，使我们能够直接测试雪球的固有结构以及上述实验的外围问题。在本报告中，完成了核心离子^&lt；12&gt；B(T^&lt；1/2&gt；=20.4ms，β-放射性)的核极化保存和^8Li(T^&lt；1/2&gt；=832ms，β-和α-放射性)雪球寿命的测量。事实证明，与^&lt；12&gt；B相比，雪球的寿命要长得多，即雪球的半衰期为350ms。这一观察到的长寿命支持了雪球构成了在短寿命核心离子的整个生命周期中维持核极化的合适环境的观点，并为研究各种不稳定核的核矩开辟了道路。

Impurity ions introduced in liquid helium may behave as singly charl&ed 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 any other alien ions do form snowballs. The method used in the study of polarization phenomena in heavy ion reactions enabled us to conceive renewed interests to approach individual snowballs through 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 favour 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 well as to peripheral problems of the above experiment.Here, in this report, preservation of nuclear polarization of core ions ^<12>B (T^<1/2> = 20.4 ms, beta-radioacitve) and measurement of lifetime of ^8Li (T^<1/2> = 832 ms, beta- and alpha-radioactive) snowballs have been accomplished. It has been proved that the snowballs are far long-lived as compared to ^<12>B, namely, half-life of snowballs was obtained as 350 ms. This observed long lifetime supports the view that the snowballs constitute a suitable milieu for maintaining nuclear polarization of short-lived core ions throughout their lifetime, and the way is opened investigate nuclear moments of variety of unstable nuclei.