丰中子核{56,58}V的低激发态谱学研究

The low-energy level structures of 56V and 58V will be investigated through both the beta decay of the respective 56Ti and 58Ti parent nuclei and the gamma decays from isomeric states in 56V and 58V. The experiment will be performed at the Heavy Ion Research Facility in Lanzhou (HIRFL). The neutron-rich nuclei of interest (beta-decay parents {56,58}Ti and excited {56,58}V) will be produced by projectile fragmentation of a 76Ge primary beam on a 9Be target, and then selected and separated using the Radioactive Ion Beam Line in Lanzhou (RIBLL1). Based on the experimental measurements, the low-lying excited states in {56,58}V will be established in this project and, in particular, the isomeric states and their halftimes will be searched and measured, aiming to complete the isomer systematics in odd-odd nuclei in this region. Thus, the theoretical predictions of shape coexistence around {56,58}V and shape evolution along the V isotopic chain can be studied systematically. By comparing experimental results with theory calculations, we can extract the spin-flip interaction between the protons in the f5/2 orbital and the neutrons in the f7/2 orbital, and analyze the possible influence of the neutron g9/2 and d5/2 intruders which play an important role to explain the existence of isomers.

拟通过{56,58}Ti的beta衰变和{56,58}V的同核异能态衰变两种实验方法研究{56,58}V的低激发态能级结构。实验将在兰州重离子加速器上开展，感兴趣的丰中子核（beta衰变母核{56,58}Ti和处于激发态的{56,58}V）可以通过76Ge初级束轰击9Be靶引起的弹核碎裂反应产生，然后由放射性束流线RIBLL1进行分离和传输。基于实验测量结果，本项目将建立{56,58}V的低激发态能级结构，着重寻找这两个核中的同核异能态，并测量寿命，从而完善该核区双奇核中已发现的同核异能态的系统性。这样，就可以对理论预言的{56,58}V中的形状共存和V同位素中的形状演化进行系统的研究。通过与理论计算结果的比较，可以提取处于f7/2轨道的质子和处于f5/2轨道的中子之间的自旋反转相互作用，并分析在同核异能态的形成中起主要的作用的中子g9/2和d5/2闯入轨道的影响。

With the advent of radioactive beams and sensitive detector systems, the domain of nuclides accessible for spectroscopic study has increased drastically during the last two decades. Nuclei far from the beta-stability line are thus in the focus of the nuclear structure physics community at present. .In this work, on neutron-rich side, excited states in 63,65,67Mn were studied via in-beam -ray spectroscopy; level schemes of these three nuclei were established, the first time for 65,67Mn. The data on the low-lying excited states of odd-mass Mn provide a textbook example of nuclear structure evolution from weak coupling through decoupling to strong coupling along a single isotopic chain. The manuscript has been finished, and is ready to be submitted to PRL..On the proton-rich side, excited states in 117Ba have been observed for the first time using the recoil-decay tagging technique. Through the analysis of the gamma-gamma coincidence relationships, a high-spin level scheme consisting of t