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Development of Novel Experimental Method by Polarized Neutrons

极化中子新实验方法的发展

基本信息

批准号：
05044031
负责人：
ENDOH Yasuo
金额：
$ 6.4万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

When we initiated this project, we aimed construction of two main subjects : One is the so called a new version of neutron spin echo, and the other is the neutron polaritometry. Both were already developed at Institute Laue Langevin (ILL), but the High Flux Reactor of ILL have been shut down for long due to the replacement of the reactor vessel.Since Japanese neutron scattering scientists were eager to develop the experimental techniques utilizing polarized neutrons, it is a good opportunity to collaborate with the ILL scientists by inviting to this project of the technical development of polarized neutrons. We have been pushing hard two subjects and we could make at least one very successfully. We explain briefly the results what we have developed in the two years' period.The principle of the Neutron Spin Echo (NSE) method is that the Larmor precession of neutron spin around the steady magnetic field can be used as standard 'clock' besides 'velocity' of neutron flux. When polarized ne … More utrons pass through two magnetic channels in which the magnetic field is very identical through two channels. Then at the center of two channels, neutron spin rotation is forced to completely reverse. Eventually neutron polarization at just the outlet of the second magnetic channel is back to the same state of the polarization at the inlet of the first channel, which is called Echo. This principle was applied to the real NSE machine, with which we investigate the high resolution neutron spectroscopy combined with cold neutron source. Here we challenge a new version of NSE spectroscopy by using thermal neutrons as well as triple axis spectrometer. Since neutron velocity is larger and neutron path is not symmetric geometrically before and after the sample position, the echo condition is hard to realize. However the ILL scientists developed a number of new ideas but they had no chance to prove experimentally. In this project we both constructed a prototype NSE machine, which is set on the 3-axis spectrometer of PONTA (5G port of JRR3). and searched many points to be solved. Finally we have tested the performance of this NSE method and concluded the good sensitivity in energy resolution as well as the feasibility of the novel NSE technique itself.As for the neutron polaritometry, we have encountered unexpected difficulty of getting high quality polarizer, which have been installed at the triple axis spectrometer of TOPAN (6G port of JRR3). Therefore we have investigated how to improve neutron polarization mostly, from which we conclude now that the polarization can be improved as we aimed initially. Less

我们启动这个项目时，主要目标是建设两个学科：一个是所谓新版本的中子自旋回波，另一个是中子极化测量。两者均已在劳埃朗之万研究所（ILL）开发，但由于更换反应堆容器，ILL的高通量反应堆已长期关闭。由于日本中子散射科学家渴望开发利用极化中子的实验技术，因此邀请参加该极化中子技术开发项目是与ILL科学家合作的好机会。我们一直在努力推动两个课题，并且我们至少可以非常成功地完成一个课题。我们简单介绍一下我们两年来所取得的成果。中子自旋回波（NSE）方法的原理是，中子自旋绕稳定磁场的拉莫尔进动除了中子通量的“速度”外，还可以作为标准的“时钟”。当极化的ne… More utron穿过两个磁通道时，两个通道中的磁场非常相同。然后在两个通道的中心，中子自旋被迫完全反转。最终，第二磁通道出口处的中子极化回到与第一通道入口处的极化状态相同的状态，这称为回波。将该原理应用到真实的 NSE 机器中，我们研究了与冷中子源相结合的高分辨率中子谱。在这里，我们使用热中子和三轴光谱仪挑战新版本的 NSE 光谱。由于中子速度较大，且样品位置前后的中子路径在几何上不对称，因此回波条件很难实现。然而，ILL 科学家提出了许多新想法，但他们没有机会通过实验证明。在这个项目中，我们都构建了一台 NSE 原型机，该机器设置在 PONTA 的 3 轴光谱仪（JRR3 的 5G 端口）上。并搜索了许多需要解决的问题。最后我们测试了这种NSE方法的性能，得出了良好的能量分辨率灵敏度以及新颖的NSE技术本身的可行性。至于中子偏振测量，我们在获得高质量偏振器方面遇到了意想不到的困难，该偏振器已安装在TOPAN三轴谱仪（JRR3的6G端口）上。因此我们主要研究了如何改善中子极化，从中我们现在得出结论，极化可以像我们最初的目标那样改善。较少的