Nuclear asrophysics with low energy beams of short-lived nuclei

短寿命原子核低能束的核天体物理学

基本信息

批准号：
62540206
负责人：
SHIMODA Tadashi
金额：
$ 1.22万
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 (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62540206/
关键词：
Ion-Trapping In Liquid Helium Long Lifetime Of Trapping Ion-Source For Beams Of Radio-Active Nuclei Small Beam Emittance Thermo-Nuclear Reactions Via Radioactive Nuclei 液体ヘリウム中のイオンイオンの閉じ込め閉じ込め効率取り出し効率天体熱核反応

项目摘要

We have investigated the possible use of liquid helium as an effective ion-source for beams of radio-active nuclei, which open up studies of nuclear synthesis via reactions associated with unstable nuclei under environments of very high temperature and high density such as in novae. An ion introduced into the liquid helium gathers many helium atoms around itself due to the electrostriction and the ion is trapped in the cluster of helium atoms. This charged cluster is referred to as "snowball" When the ions of radioactive nuclei produced in nuclear reactions are stopped and trapped in very low temperature liquid helium, the extracted beams from the liquid will have very small emittance.The feasibility of such ion-source relies on achieving (i) the high efficiency in forming the snowball, (ii) long lifetime of the snowball and (iii) high efficiency in extracting the ions from the liquid. We have examined the characteristics of the snowball in the following experiments; ions of ^<14>N with energy of 90 MeV are implanted into the liquid helium, and the ion currents have been measured under the electric fields applied in correlation with the beam pulse. The results we obtained are as follows:(1) The lifetime of the snowball was found to be about 700 ms, which is much longer than in the other methods of ion trapping.(2) The ion current depended much on the electron density around the ion in the liquid. This implies that the efficiency in forming the snowball may be increased by decreasing the implantation energy of the ions and by increasing applied field.(3) The mobility of the snowball was much larger in the superfluid helium than in the normal helium. Therefor more rapid control of the snowball is possible in the superfluid. In summary the liquid helium ion-source for the radio-active nuclear beams is quite promising.

我们研究了液氦作为放射性核束的有效离子源的可能性，这开启了通过与在极高温度和高密度环境（例如新星）中的不稳定原子核相关的反应进行核合成的研究。引入液氦的离子由于电致伸缩而在其周围聚集许多氦原子，并且该离子被捕获在氦原子簇中。这种带电团簇被称为“雪球”。当核反应中产生的放射性原子核的离子被停止并被捕获在极低温度的液氦中时，从液体中提取的束流将具有非常小的发射度。这种离子源的可行性依赖于实现（i）形成雪球的高效率，（ii）雪球的长寿命和（iii）从液体中提取离子的高效率。我们在以下实验中研究了雪球的特性；将具有90MeV能量的^ 14 N离子注入液氦中，并在与束脉冲相关的施加的电场下测量离子电流。我们得到的结果如下：(1) 雪球的寿命约为 700 ms，比其他离子捕获方法长得多。(2) 离子电流很大程度上取决于周围的电子密度。液体中的离子。这意味着形成雪球的效率可以通过降低离子的注入能量和增加施加场来提高。(3)雪球在超流氦中的迁移率比在正常氦中大得多。因此，在超流体中可以更快速地控制雪球。总之，用于放射性核束的液氦离子源是非常有前途的。