Study of the spin-dependence of three-nucleon interactions by developing a high-intensity polarized neutron beam

通过开发高强度偏振中子束研究三核相互作用的自旋依赖性

基本信息

批准号：
17340064
负责人：
OKAMURA Hiroyuki
金额：
$ 8.77万
依托单位：
Osaka University (2006)Tohoku University (2005)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

In order to study the spin-dependence of three-nucleon interaction via elastic scatterings of spin-polarized neutron off deuteron, we have developed a highly intense but inexpensive spin-polarized proton source. In this proposal, an atomic beam of polarized hydrogen is produced by exchanging spins with Rubidium vapor, which is polarized with optical pumping by a circularly polarized laser, and then ionized by an ECR ionizer. In the first year of the term, mainly the polarized Rubidium vapor generating system has been developed It is crucial to match the spectral widths between the high-intensity laser and the absorption of Rubidium vapor so that the laser power is efficiently absorbed and accordingly a high polarization and a high vapor pressure can be achieved at the same time. Although high-intensity semiconductor lasers are available at low prices in this spectral region, their widths are usually of order of 1 THz, which is thousand times broader than the Doppler width of 1 GHz, res … More ulting in very poor absorption efficiency. Conventionally very expensive Ti-Sapphire lasers are used for this purpose, employing optical modulators to broaden their extremely narrow widths. Although semiconductor lasers with external cavities are commercially available, they have 1 MHz super-narrow widths and a few mW small powers, as they are usually focused to spectroscopic use. Thus we have developed a laser system suitable for optical pumping, with a broader width of 100 MHz and a high power of 1 W, by employing a Fabry-Perot type external cavity instead of the ordinary grating type. A feedback system for stabilizing the wavelength in a long term and an atomic beam system has been developed in parallel. In the second year of the term, the superconducting ECR ion source started operation and various improVements have been made, e.g., in the beam extraction part and in the beam transport system, by using heavy noble gases. Although the acceleration of polarized ion beam has not been achieved in the term, the system will be completed in the near future, together with the development of polarimeters. Also closer collaboration with theoreticians has been promoted by holding several workshops. Less

为了通过氘核中自旋极化中子的弹性散射来研究三核子相互作用的自旋依赖性，我们开发了一种高强度但廉价的自旋极化质子源。在该提案中，产生了极化氢原子束。通过与铷蒸气交换自旋，铷蒸气通过圆偏振激光的光泵浦进行偏振，然后通过 ECR 电离器电离。已开发出偏振铷蒸气发生系统关键是高强度激光与铷蒸气吸收之间的光谱宽度相匹配，以便激光功率被有效吸收，从而在同时，尽管在此光谱区域可以以低廉的价格获得高强度半导体激光器，但它们的宽度通常为 1 THz，比 1 GHz 的多普勒宽度宽数千倍。传统上，采用光学调制器来拓宽其极窄的宽度，从而导致吸收效率非常差。以及几毫瓦的小功率，因为它们通常专注于光谱用途，因此我们开发了一种适合光泵浦的激光系统，具有 100 MHz 的更宽宽度和 1 的高功率。 W，通过采用法布里-珀罗型外腔代替普通光栅型，用于长期稳定波长的反馈系统和原子束系统在本学期的第二年并行开发。 ECR离子源开始运行，并通过使用重惰性气体在束流提取部分和束流传输系统中进行了各种改进，尽管尚未实现偏振离子束的加速。短期内，该系统将与旋光计的开发一起完成，并且通过举办几次研讨会也促进了与理论家的更密切合作。