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

β射线探测法研究超流氦中的杂质离子及其核矩。

基本信息

批准号：
01460019
负责人：
TAKAHASHI Noriaki
金额：
$ 3.97万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01460019/
关键词：
Superfluid Helium Impurity Ion Snowball Micro-cluster Radioactive Beam beta -Ray Detection Method alpha -Particle Detection Method Nuclear Moment マイクロクラスタ-ベ-タ放射性核不安定核ビ-ム

项目摘要

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.

在液氦中引入的杂质离子可以表现为具有50-100个He原子的有效质量的单电荷艾德实体，其被称为雪球。因此，雪球是一种聚集体，一种氦原子的微团簇，通过电致伸缩围绕着液氦中允许的杂质核心离子。不仅氦离子，而且任何其他外来离子都能形成雪球。在重离子反应中极化现象的研究中所使用的方法使我们重新产生了通过α射线和β射线计数来研究单个雪球的兴趣。虽然雪球被认为是一种非常重要的固体实体，但仍然怀疑所有现有的证据是否都决定性地支持固体核的图像。在这项研究中，核极化的保持为这个问题提供了一个重要的线索，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<12>B（T^<1/2> = 20.4 ms，β-放射性）和^8Li（T^<1/2> = 832 ms，β-和α-放射性）雪球寿命的测量。结果表明，雪球的半衰期<12>为350 ms，比^ B长得多，这一长寿命的观测结果支持了雪球构成了短寿命核离子在其整个寿命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.