非束缚核~9He的实验研究

Experimental Investigation of Unbound Nuclei^9He

简要介绍了目前有关非稳定核9He的实验和理论研究现状.现代壳模型理论计算表明9He的基态自旋宇称为1/2+,而不是1/2-,即存在自旋宇称翻转现象.到目前为止,实验上虽然观测到了9He的几个共振态,但还不能确认其基态的能量和自旋宇称值.利用新的实验技术———逆运动学弹性共振散射,对9He核进行研究,给出了共振态的自旋宇称可能的取值范围.在ISOL型次级束装置上的实验有望能给出9He核能级的精确测量.

The status of theoretical and experimental investigations on unbound nucleus()^(9)He is briefly introduced. The results of modern shell model suggest that the ground state of^(9)He should be 1/2^(+) instead of 1/2^(- )as expected by the normal shell ordering. Therefore, it means that the parity inversion which was well known in^(11)Be occurs also in^(9)He ground state. Recently, some resonance states were observed in transfer reactions and final-state reaction, but their spin-parities cannot be exactly determined and the ground-state cannot be uniquely identified. New technique, which is elastic resonance scattering in inverse kinematics, has been used in recent experiments with radioactive ion beam. We expect that the new results on^(9)He energy levels will be obtained in ISOL type second-beam line experiments.