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

远离稳定性的奇异原子核结构正引起人们的极大兴趣，因为它们为我们对原子核的理解提供了严格的测试。我们提出了一种新的方法来确定远离稳定性的核激发态的自旋奇偶性。重要的一点是，我们观察到一个自旋极化的放射性原子核的β衰变各向异性与贝塔延迟粒子相符合。我们将把这一方法应用于11Li，以研究在非常丰富的中子核中N=8中子幻数的消失。这项研究方案已经在加拿大TRIUMF的ISAC设施上获得高度优先的批准，这是一座最先进的放射性核束设施。2001年和2002年，我们完成了以下准备工作：(1)实现高偏振11Li束流，(2)建造专用束线，(3)建立β射线、β延迟中子和伽马射线探测系统，所有工作将于2002年4月准备就绪，实验计划于2002年5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 will be ready by April, 2002, and the experiment is scheduled in May 2002.