Study of the Ultracold and Ultrafast Beam-Cooling with a Superconducting Electron Cooler

超导电子冷却器超冷超快束流冷却研究

基本信息

批准号：
08504002
负责人：
TANABE Tetsumi
金额：
$ 29.7万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08504002/
关键词：
Accelerator Electron Cooling Superconducting Magnet Atomic Physics Atomic Collisions Dissociative Recombination

项目摘要

An electron cooling method has widely been used in the atomic physics research as well as accelerator technology. The cooling time and the final accuracy in experiments are determined by the electron temperature. The electron beam has initially an energy width (or temperature) of about 100 meV,since electrons are emitted from a hot cathode. However, electron temperature can be reduced to a level less than the cathode temperature by expanding the electron beam adiabatically in a gradually decreasing solenoid field. This method is called 'adiabatic expansion method' and the electron temperature decreases in inverse proportion to an expansion factor. Based on this principle, we modified the existing electron system to the adiabatic expansion type. In the fiscal 1996, we designed and constructed an superconducting electron cooler with a magnetic field of 3.5 T and realized an expansion factor of 100 resulting in an electron temperature of 1 meV for the first time in the world. The supercon … More ducting magnet is liquid-helium free, which realized a compact design and a simple operation. The cooler opened the way to the super-fast beam cooling and extremely high-accuracy experiments. In the fiscal 1996-1997, highly accurate atomic collision experiments have been performed with this cooler. Dissociative recombination (DR) of molecular ions is one of the important processes in the upper atmosphere and the outer space. The DR of HeH^+ isotopes were studied with the extremely low-temperature electron beam of the order of 1 meV produced by the superconducting electron cooler at the storage ring TARN II.The DR spectra show a fine new structure and a clearisotope dependence in the low energy region. Those features are well reproduced by the theoretical calculations based on a multichannel quantum-defect theory. According to the theory, the newly observed structure is an evidence of a new indirect mechanism. These results on the cooler and the physics experiments have been presented at the domestic conferences in Osaka and at Kobe, and the foreign conferences in Vancouver, Vienna and Heidelberg. We also started the feasibility study of atomic collision experiments with the new cooler on many other ions. Less

一种电子冷却方法已被广泛用于原子物理学研究和加速器技术。实验中的冷却时间和最终精度由电子温度确定。由于电子是从热阴极发出的，因此电子束最初的能量宽度（或温度）约为100 meV。但是，通过在逐渐降低电磁阀场中的绝热扩展电子束，可以将电子温度降低到低于阴极温度的水平。该方法称为“绝热膨胀方法”，电子温度与扩展因子成比例降低。基于这一原则，我们将现有的电子系统修改为绝热膨胀类型。在1996财年，我们设计并构建了一个超导电子冷却器，磁场为3.5 t，并实现了100个膨胀因子，导致电子温度在世界上首次达到1 MeV。 SuperCon…更多的管道磁铁是无液态的，它实现了紧凑的设计和简单的操作。冷却器为超快速光束冷却和极高的精确实验开辟了道路。在1996 - 1997财年，使用该冷却器进行了高度准确的原子碰撞实验。分子离子的解离重组（DR）是上层大气和外层空间中的重要过程之一。 Heh^+同位素的Dr是研究的，其极低温度的电子束在存储环Tarn II处由超导电子冷却器产生的1 MEV阶，DR Spectra谱图显示出良好的新结构，并且在低能区域中依赖清洁剂。这些特征通过基于多通道量子缺陷理论的理论计算很好地复制了。根据该理论，新观察到的结构是一种新的间接机制的证据。这些结果是在大阪和科比的家庭会议上以及温哥华，维也纳和海德堡的外国会议上提出的。我们还开始对许多其他离子的新冷却器进行原子碰撞实验的可行性研究。较少的