Study of photonuclear reactions in the DELTA-resonance region using a polarized ^3He target

本研究计划旨在利用极化^3He靶，通过光核反应研究^3He中的核子-核子关联。极化靶是通过极化碱金属原子与靶原子之间的自旋交换反应得到的，作为制备极化^3He靶的第一步，我们尝试用圆偏振激光光泵浦的方法制备极化铷原子。我们采用0.5W钛-蓝宝石激光器作为光源，为了防止产生的极化原子与泵浦池壁碰撞而产生退偏，我们在池壁涂上了二甲基二氯硅烷。为了寻找最佳的生产条件，需要对产物的极化和厚度进行快速精确的测量。我们研制了一套高速测量系统，可以测量法拉第旋转角，测量精度小于0.01 °，并成功地制备了极化度为0.4，厚度为10 ~ 10<14>原子/厘米~ 2的极化铷原子。

This research project aims to investigate nucleon-nucleon correlations in ^3He by means of photonuclear reactions using a polarized ^3He target. The polarized target is obtained by a spin exchange reaction between a polarized alkaline atom and a target atom.As a first step to make the polarized ^3He target, we tried to produce polarized rubidium atoms using an optical pumping method with a circularly polarized laser light. We have used a 0.5W titanium-sapphire laser as the source, and, in order to prevent the depolarization due to the collision between produced polarized atoms and the pumping cell wall, we have coated the wall with dimethyldichlorosilane.A search for the most optimum condition for the production needs a quick and precise measurement of the polarization and the tthickness of the products. We have developed a high speed measuring system, which enable to measure the Faraday rotation abgle with the precision less than 0.01 deg.Finally we have succeeded to produce a polarized rubidium atoms having the polarization of 0.4 with the thickness of 10^<14> atoms/cm^2.