基于转移反应的丰中子核壳结构研究

迄今为止，大量丰中子核壳结构尚未被系统研究过。通常，人们相信转移反应是产生中重质量区丰中子核比较理想的反应机制。其中，单核子转移反应能布居一系列同宇称角动量为j的态，截面或谱因子最大的为j壳的主要成分。这样，利用单核子转移反应能强布居涉及壳结构的丰中子核关键激发态。但单纯的谱因子无法提供该态波函数的集体形变成分。尽管单粒子和集体成分为壳结构和壳坍塌提供了最直接的证据，成为热点和前沿课题。本课题利用溴化镧探测器测量此关键态退激特征γ射线。应用叠层塑料闪烁体对散射产物进行测量。在粒子-γ符合识别目标核的特征γ射线后，利用溴化镧和塑料闪烁体优越的时间性能，拟合粒子-γ时间谱获取目标能级的寿命。通过关键激发态寿命测量，可以同时确定球形单粒子和形变的集体转动在此态中的共存成分。最终认识壳结构和演化，理解核力在传统幻数消失、新幻数出现背后扮演的角色，探索壳坍塌后单粒子如何发展成集体运动。

Shell structures in many neutron-rich mass regions have so far not been investigated in detail. It is believed that the transfer reaction is the very ideal reaction mechanism to produce heavier neutron-rich nuclei. The reaction involving one-nucleon transfer directly measures the magnitude of j shell. This means that the one-nucleon transfer reaction can strongly populate the sub-shells. However, the obtained spectroscopic factors can’t provide the deformed components in such states. This project utilizes LaBr3 detectors to measure the de-exciting γ rays from such excited states, while one expects that the scattered particles are detected by the phoswich plastic scintillators. After identifying the characteristic γ rays by particle-γ coincidences, we will fit the particle-γ time spectra to obtain the lifetimes of aimed levels. Single-particle or collective properties can be determined from the measured lifetimes. Finally, we wish to understand the shell structure and evolution driven by the nuclear force and comprehend the deformed collectivity created by the spherical single-particle conspiracy after shell collapse.