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Test and Development of New Production Method for Ultracold Neutrons

超冷中子生产新方法的试验与开发

基本信息

批准号：
10554006
负责人：
ASAHI Koichiro
金额：
$ 8.26万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10554006/
关键词：
untracold neutrons electric dipole moment weak interaction magnetic moment adiabatic fast passage method magnetic deceleration pulsed neutron source alternating magnetic field

项目摘要

Neutrons provide an important experimental opportunities in fundamental physics researches through, e.g., searches for an electric dipole moment, studies of beta decays, and observations of quantum interference phenomena. In such studies, the availability of neutrons at energies below EィイD2crィエD2 0.25 【similar or equal】μeV (ultracold neutrons, or UCN) is essential, because the spatial confinement of neutrons in a bottle for experiment is only possible for such low energies. In the present work we proposed a new method for the production of UCN, investigated its performances through computer simulations, and developed techniques for the testing and realization of its concepts.The method comprises the deceleration of neutrons through the interaction of a neutron magnetic moment and an external magnetic field. The deceleration effect is accumulated by repeating the spin flip at high- and low-field positions during the flight by means of the adiabatic passage nuclear magnetic resonance tec … More hnique. The deceleration effect is varied according to the time of flight of neutrons from a pulsed neutron source, so that the final kinetic energies converge into narrow region below EィイD2crィエD2.Computer simulations were performed for a designed setup consisting of 160 sections of superconducting magnets which implement a field alternating from 0.59 T to 4.95 T along the neutron flight path. The result shows that an about 70 times higher UCN density compared to the best density presently available in the world will be realized.Then a prototype section with a normal-conducting magnet and an rf coil for the spin flip was constructed. Solid state neutron detectors with a ィイD17ィエD1Li converter foil in front were developed for the UCN detection. Using low-energy neutron beams from the super-mirror turbine facility at Kyoto University Research Reactor Institute, an experimental study is in progress to test validity of the proposed deceleration method and to develop techniques required for it. In the runs performed up to now we have suceeded in obtaining neutrons monochromafized in a velocity range v = 4.27-5.48 m/s with a counting rate of 0.52 mcps. This result suggests that the detection of the deceleration effect will be realized with a planned setup change in the upstream neutron duct. Less

中子为基础物理研究提供了重要的实验机会，例如，研究电偶极矩，研究β衰变，观察量子干涉现象。在这样的研究中，能量低于E D2cr D2 0.25 μeV（超冷中子，UCN）的中子的可用性是必不可少的，因为只有在这样低的能量下，才有可能将中子空间限制在实验用的瓶子里。在目前的工作中，我们提出了一种新的方法来生产UCN，通过计算机模拟研究其性能，并开发了测试和实现其概念的技术。该方法包括通过中子磁矩和外部磁场的相互作用来减速中子。利用绝热通道核磁共振技术，在飞行过程中，通过在高场和低场位置重复自旋翻转来积累减速效应。 ...更多信息 hnique。减速效果根据来自脉冲中子源的中子的飞行时间而变化，对一个由160段超导磁体组成的装置进行了计算机模拟，沿中子飞行路径施加沿着从0.59 T到4.95 T的交变磁场，计算结果表明，在160段超导磁体的作用下，中子的最大动能集中在E_（max）D_（2cr）D_（2cr）D_（2cr）D_（2cr与目前世界上最好的密度相比，将实现大约70倍的高密度UCN。然后，构造具有正常导电磁体和用于自旋翻转的RF线圈的原型部分。研制了用于UCN探测的固体中子探测器，探测器前装有一个转换箔，转换箔为1000 D17，转换箔为D1 Li。使用来自京都大学研究反应堆研究所超镜涡轮机设施的低能中子束，一项实验研究正在进行中，以测试所提出的减速方法的有效性并开发所需的技术。在迄今为止进行的运行中，我们成功地获得了速度范围v = 4.27-5.48 m/s的单色化中子，计数率为0.52 mcps。这一结果表明，减速效应的检测将实现与上游中子导管中的计划设置的变化。少