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

引入液氦的杂质离子可能表现为有效质量为50-100个He原子的单chared实体，称为雪球。因此，雪球是一种聚集体，一种氦原子的微团簇，通过电伸缩围绕在液态氦中允许的杂质核心离子周围。不仅是最初注意到的氦离子，其他的外来离子也会形成雪球。在重离子反应极化现象的研究中使用的方法使我们对通过α和β射线计数来接近单个雪球产生了新的兴趣，这是在这里发展起来的。虽然雪球被认为是一个非常重要的固体实体，但是否所有现有的证据都决定性地支持固体核的观点，仍然存在疑问。本研究中对核极化的保存为这一问题提供了重要线索，使我们能够直接测试雪球的内在结构以及上述实验的外围问题。本文完成了^<12>B核心离子（T^<1/2> = 20.4 ms， β -放射性）的核极化保存和^8Li （T^<1/2> = 832 ms， β -和α -放射性）雪球的寿命测量。实验证明，这些雪球的半衰期远比^<12 b> B长，即雪球的半衰期为350 ms。这一长寿命的观察结果支持了雪球构成了短寿命核离子在其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途径。

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.