Spectroscopic Study of Neutron-Rich Nuclei with Spin-Polarized Radioactive Nuclear Beams

远离稳定核的奇异结构为我们理解原子核提供了严格的检验，因而引起了人们极大的兴趣。本文提出了一种确定远离稳定核激发态自旋宇称的新方法。其实质是，我们观察到的β衰变各向异性的自旋极化放射性核与β延迟粒子的巧合。我们将把这种方法应用到11Li中，以研究N=8中子魔数在非常丰中子核中的消失。在2001年和2002年，我们完成了以下准备工作：（1）获得高极化的11Li束流，（2）建造专用束线，（3）建造β射线、β缓发中子和γ射线探测器系统，所有这些工作都在2003财年年底完成。原定于2003年6月的束流时间因加速器故障而推迟。试验定于2004年7月进行。

The exotic structure of nuclei far from the stability are attracting much interest because they provide stringent tests for our understanding of nuclei. We propose a new method to determine the spin-parities of excited states of nuclei far from the stability. The essential point is that we observe the beta-decay anisotropy from a spin polarized radioactive nucleus in coincidence with beta-delayed particles. We will apply this method to 11Li in order to investigate the disappearance of the N=8 neutron magic number in very neutron rich nuclei.The research proposal has been approved with high priority at ISAC facility of TRIUMF in Canada, which is a state-of-the-art radioactive nuclear beam facility. In 2001 and 2002, we achieved the following preparatory works :(1)Achieving highly polarized 11Li beam,(2)Constructing a dedicated beam-line(3)Constructing detector systems for beta-rays, beta-delayed neutrons, and gamma-rays.All have been done by the end of FY2003. The scheduled beam time in June 2003 was postponed due to accelerator trouble. The experiment is scheduled in July 2004.