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

为了研究自旋极化中子在氘核外的弹性散射引起的三核子相互作用的自旋依赖性，我们研制了一台高强度、低成本的自旋极化质子源。在这个方案中，极化氢原子束通过与铷蒸汽交换自旋而产生，铷蒸汽通过圆偏振激光的光泵浦而极化，然后通过ECR电离器电离。在本学期的第一年，主要开发了偏振铷蒸气发生系统。关键是使高强度激光和铷蒸气吸收之间的光谱宽度匹配，以便有效地吸收激光功率，从而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中可以以低价格获得，但是它们的宽度通常为1 THz的量级，这比1 GHz的多普勒宽度宽数千倍，分辨率为1000。 ...更多信息 导致非常差的吸收效率。传统上非常昂贵的钛蓝宝石激光器用于此目的，采用光学调制器来加宽其极窄的宽度。虽然具有外腔的半导体激光器在市场上有售，但它们具有1 MHz的超窄宽度和几mW的小功率，因为它们通常专注于光谱用途。因此，我们已经开发出一种适合于光泵浦的激光系统，具有更宽的100 MHz和高功率为1 W，通过采用法布里-珀罗型外腔代替普通的光栅型。同时开发了用于长期稳定波长的反馈系统和原子束系统。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，在射束引出部分和射束传输系统中，通过使用重惰性气体。虽然极化离子束的加速还没有实现，但随着极化仪的研制，该系统将在不久的将来完成。还通过举办几次讲习班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