High-Energy Heavy-Ion Reactions and Polarization in Matter

在高能重离子反应中产生的原子核预计将维持极化。这项研究的第一阶段是寻找具有较大偏振能力的放射性核。利用大阪大学和理研的回旋加速器、雷霍沃特的串列加速器和莱格纳罗的串列加速器来研究这种可能性。GSI的SIS-FRS系统也有效地应用于这一目的。在上述实验室中，实验测试了获得极化不明的快离子的可能性；从Legnaro串列加速器获得了重极化离子，并对其极化及其在固体材料中的保存进行了实验研究。成功地进行了液氦注入，并进一步研究了离子的行为和核极化。除了在雪球中保持核极化之外，还在研究以下事实。快离子在液氦中的阻止能力是双重的，一个成分与正常物质和流体中的成分相同，另一个成分表现在超流氦中，其作用范围比前者长得多。这可能是由于HeII中的集体流。测量是用放射性束流和β和α探测方法进行的。当离子在强电场中运动时，核极化可能会被破坏，从而避开雪球的包裹。这一现象将得到进一步的研究。

Nuclei produced in high-energy heavy-ion reactions are expected to sustaning polarization. The first stage of this research is to find radioactive nuclei sustaining large polarization. Cyclotrons of Osaka University and Riken, Tandem Accelerators of Rehovot and Legnaro were utilized to investigate the possibility. The SIS-FRS system at GSI was also effective to apply for such purposes.Possibilities of obtaining fast ions sustainig unclear polarization were tested experimentally at above laboratories ; the heavy polarized ions such as ^<93>Tc were obtained from the Legnaro tandem accelerator and the polarization and its preservation in a solid material were experimentally studied.The implantation into liquid helium was successfully carried out and the behavior of ions and nuclear polarization was further studied. In addition to the preservation of nuclear polarization in snowballs the folllowing facts are being studied. The stopping power of fast ions in liquid helium is double valued, one component as in normal matter and fluid, the other manifested in superfluid helium sustaining a range much longer then the former. This may be due to the collective flow in HeII.The measurements were carried out with radioactive beam and beta and alpha detection methods.The nuclear polarizaion may be destroyed when ions move in a strong electric field therefore evading the encapsulation in snowballs.The phenomenon will be further investigated.