在CSR外靶实验终端上研究29S的结构性质

Intermediate- and high-energy Coulomb excitation measurement is an effective method to study deformation and collective of exotic nuclei. At present, the studies in this topic focus on neutron-rich isotopes, and some interesting results were already got in the region of N=20 and N=28 nulei. Shell model calculations suggest that the states of 29S are connected by strong E2 tran.sitions characteristic of well-deformed nuclei. Intermediate- or high-energy Coulomb excitation measurement would quantify the extent of deformation in this isotope. But the measurements of the proton-rich nuclei in the sd shell are almost a gap. In present work, the high-energy 29S beam obtained by HIRFL-CSR main storage ring will be used to bombard a gold target, cross sections and γ energies to the different excited states will be measured by the External Target Facilities (ETF) at HIRFL-CSR. The reduced transition probability B(E2) and the deformation parameter β2 will be obtained by the experiment. Comparing with the calculating results of the shell model, this measurement would confirm the rotational nature of 29S isotope.

中、高能库仑激发反应是研究奇异核四级形变和集体运动性质的有效手段。目前国际上相关研究主要集中在丰中子核区域，并已在N=20和N=28区域系统性的取得了有意义的结果,但对于sd壳丰质子核的集体运动性质研究较少。目前，壳模型计算预言29S的低级发能级具有较强的E2跃迁强度，而这一现象又与核的形变紧密相关。本项目拟利用HIRFL-CSR主环提供的高能放射性束29S轰击Au靶，通过外靶实验终端探测器测量符合γ能谱以及各个能级的反应截面，定量的测定相应能态的约化跃迁概率B（E2）和形变参量 β2。对比壳模型理论计算结果，研究29S的集体运动性质，为该区域丰质子核的壳模型计算提供可靠的实验数据。

如今，中高能放射性束物理实验已经成为研究非稳定核的重要工具。本项目系统研究了用于外靶放射性束物理实验的伽马球探测器的能量重建方法及探测效率。并针对外靶核反应实验特点研制了一套多重望远镜探测器，并利用束流研究了该探测器的离子鉴别能力和CsI(Tl)探测器刻度方法。所得研究成果对于未来将要进行的CSR外靶实验积累了宝贵的经验。最终，利用CSR外靶实验终端提供的305 MeV/u的14O束流轰击碳靶开展了14O敲出反应的实验研究，实验结果表明Eikonal反应模型可能对于这种反应过程不再适用。