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

为了通过自旋极化中子与氘核的弹性散射研究三核子相互作用的自旋依赖性，我们研制了一种高强度但廉价的自旋极化质子源。在这个方案中，通过与铷蒸气交换自旋产生极化氢原子束，然后用圆偏振激光器光泵将其极化，然后用ECR电离器电离。第一年主要研制了偏振铷蒸气产生系统，高强度激光的光谱宽度与铷蒸气的吸收相匹配是有效吸收激光功率的关键，因此可以同时实现高偏振和高蒸气压。虽然高强度半导体激光器在该光谱区域价格低廉，但其宽度通常为1太赫兹数量级，比1千兆赫的多普勒宽度宽1000倍，这导致吸收效率非常低。传统上非常昂贵的钛蓝宝石激光器用于此目的，采用光学调制器来扩大其极窄的宽度。虽然具有外腔的半导体激光器在商业上是可用的，但它们具有1兆赫的超窄宽度和几毫瓦的小功率，因为它们通常聚焦于光谱用途。因此，我们采用Fabry-Perot型外腔代替普通光栅型，开发了一种适合于光泵浦的激光系统，其宽度为100 MHz，功率为1 W。长期稳定波长的反馈系统与原子束系统并行发展。在学期的第二年，超导ECR离子源开始运行，并进行了各种改进，例如在光束提取部分和光束传输系统中，使用了重惰性气体。虽然目前还没有实现极化离子束的加速，但随着偏振光计的发展，该系统将在不久的将来完成。此外，通过举办几次研讨会，促进了与理论家的密切合作。少

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