21、23F中集团结构的实验研究

Clustering structures have been predicted along the neutron drip-line by different nuclear theories. Such features only have been confirmed in very little neutron-rich isotopes experimentally. Anti-symmetrized molecular dynamics (AMD) model predicts that the normally compact F isotopes become highly clustered at the neutron drip-line, but no experimental results to prove it. In this project, we will study the directly breakup reactions of 21,23F experimentally, to prove such clustering structures in neutron-rich F isotopes. The excitation spectrum, around the cluster decay threshold, can be reconstructed by coincident measurements of the reacted fragments. Clustering structures can be tested in neutron-rich F isotopes by comparing of the cross sections of different reaction channels, and then compared with theoretical results. The formation mechanics and development of these α+N structures can be described by systematically study of the F isotopes. The obtained excitation spectrum can be confirmed by coincident measurements of γ spectrum and neutron emissions. . With the accomplishment of this project, the intrinsic understanding of nuclear nature will be greatly improved, and also invoke the clustering structures experimental studies in China. The modern nuclear theory can also be tested.

丰中子滴线附近核内存在有核子集团结构被很多理论模型都预言了。但只有很少的丰中子核中的核子集团结构被实验得到了确认。AMD模型计算表明在丰中子F同位素中也存在这种核子集团结构，但没有实验验证。为了验证丰中子F同位素中的这种核子团结构，本项目对21F、23F进行直接碎裂反应的实验研究。通过对反应碎片的关联测量，可以重建碎裂前核子集团衰变阈附近的激发能谱；对不同反应道截面对比研究，可以得出丰中子F同位素内部是否存在核子集团结构，并与理论结果进行比较。通过对同位素链这种系统性的研究，对这种α＋N集团结构的形成机制及发展趋势进行描述。结合γ能谱的符合测量与发射中子关联测量，还可以对重建的激发能谱进行确认与验证。.通过本项目,对于原子的内在规律的认识将进一步提高，并可带动国内相关关于核内多核子集团结构的实验研究，并对现有原子核理论进行检验。

为了验证丰中子F同位素中的核子集团结构，本项目拟对21F、23F进行直接碎裂反应的实验研究。通过对反应碎片的关联测量，可以重建破裂前核子集团衰变阈附近的激发能谱；对不同反应道截面的对比研究，可以得出丰中子F同位素内部是否存在核子集团，并与理论计算结果进行比较。.实验基本上按照设想来进行，但因为目标实验时间的延迟，目前只是对探测装置进行了测试。从前期实验的初步结果来看，17C和15B的结团激发能谱可以被重构，说明本实验方法对于核内结团结构研究没有任何问题。并且根据目前的实验数据分析，对将来实验手段的改进提出了建议。