Level Structure Of ¹²¹I

The atomic nucleus is a multibody system that can be excited in many kinds of quantum mechanics ways. The competition and interaction between the single particle movement and collective movement is the important factor which determines the nuclear structure. Nuclei in the mass A-130 region are predicted to be soft with respect toγdeformation. In this region, the proton Fermi level lies near the bottom of the h11/2 shell favoring prolate shapes (γ=0°, Lund convention), while the neutron Fermi surface is towards the top of the h11/2 shell, driving the nucleus towards a negative y shape. The deformation-driving properties of h11/2 neutrons and protons are therefore conflicting and a given nucleus may have either a prolate, oblate or triaxial shape depending on the configuration. It is a hot spot for the studies of the high-spin states which shows rich structural characteristics with the above features. In this thesis, by means of in-beam nuclear spectroscopy experiments, we focus on the studies of the odd-A nuclei,121I. All these nuclei areγsoft. They will show rich structural phenomena of various nuclear characteristics, since the shapes of these nuclei would be strongly influenced by the quasi-particles in various Nilsson orbitals. Through the study of these phenomena, you can deepen the understanding of these nuclides, enrich the systematics of nuclear spectroscopy of the whole A-130 high-spin states and contribute to the nuclear theory and improve further.The content of the thesis is divided into four parts:Introduction, the in-beamγspectroscopy experiments, offline data analysis and discussion.Introduction contains the following aspects:Firstly,briefly review of the course of development of nuclear physics, describe the development of technology and equipment in nuclear physics experiments. Elaborate the common nuclear model and the method of the system studies. At the last part, the background of the 121I research is described and further explain the original intention of this work and research purpose.The second part of the thesis introduces concepts and experimental methods of the in-beam y-ray spectroscopic techniques, such as the widely used methods to populate high spin states of atomic nucleus, the operating method of HI-13 tandem accelerator detector array, the electronic and data acquisition system, as well as the issues concerning on-line experimental value measuring and off-line data analysis. The experiment is completed in Beijing. The main purpose of the experiment is 122I high spin state and 121I belongs to a reaction road. The beam energy was selected in 65MeV, and experimental detection arrays comprised of 12 HPGe-BGO detector and a small plane detector. In data pre-handling stage, excitation function was calculated using cascade and pace2. In the last part of the two chapter, efficiency calibration for the detector array is carried out with standard radioactive source 133Ba and 152Eu, the two efficiency curves are normalized at the energy point of 400keV.In the third part of the thesis, the offline data analysis and experimental results are discussed. According to the y-y analysis, the original scheme was fixed. The highest spin of the yrast band is put to 55/2- with the[πh11/2g27/2]23/2-(?) [vh11/24]16 prolate configuration. The Iγ, DCO was calculated and the state of the each band was identification. The experimental B(M1)/B(E2) was taken from the band 2,5 and the ix-ωwas picked from band 2 to band 6. At the last, the shape coexistence, band terminate, i.e, are discussed.The fourth part of the thesis summarizes the already achieved results.