| The atomic nucleus is a complex quantum multi-body system that consists of a number of protons and neutrons. The behaviour of nuclei is generally interpreted as governed by effective interactions between the nucleons, however, many of the nuclear characteristics and the detail mechanism behind the nuclei are not fully understood. Many models have been developed to explain the phenomena observed in the experiments. This thesis contains two nuclear phenomena, i.e. multi-phonon ?-vibrational bands and octupole correlation.Gamma spectroscopy has been applied in this thesis to study the nuclear structure of105 Nb,138Nd and147,152 Ce. For neutron-rich nuclei105 Nb and147,152 Ce, prompt ?rays coming from spontaneous fission of252 Cf have been measured to build the level schemes. For neutron-deficient nucleus138 Nd, the excited states have been populated through heavy-ion fusion evaporation reaction and in-beam ? rays have been measured.In the whole Segr`e chart, one-phonon ?-vibrational bands have been observed in many nuclei, however, two-phonon ?-vibrational bands are mainly reported in the mass number A = 100 and 160 regions. And multi-phonon ?-vibrational bands are very scarce in oddmass nuclei. For odd-Z nucleus105 Nb, it is the fifth case of multi-phonon ?-vibrational bands reported in the whole Segr`e chart. In the study of105 Nb nucleus, three side bands have been built for the first time. Multi-phonon ?-vibrational bands have been proposed in105 Nb nucleus based on the systematics of g factor, moment of inertia, the ratio of band head and triaxial projected shell model calculations. For138 Nd nucleus, it lies in the mass number A = 130 transitional region. In this region, the fermi level of proton lies at the bottom of h11/2subshell, while the fermi level of neutron lies at the top of h11/2subshell.The protons drive the nuclei to have prolate shape, while the neutrons drive the nuclei to have oblate shape. Many interesting phenomena have been observed in this region because of the interplay between the collective motion and unpaired single particles, such as prolate bands, oblate bands, shape coexistence, signature inversion, chiral doublet bands and so on. Many Nd isotopes have been reported with 1? band, however, the study of two-phonon ?-vibrational bands in138 Nd is the first case in the A = 130 mass region.In138 Nd nucleus, the 1? band was extended and the 2? band was proposed for the first time. The assignment of multi-phonon ?-vibrational bands agrees with the systematics and triaxial projected shell model calculations. It was predicted by theory the existence of octupole deformation island in Z = 56, N = 88 region. In152 Ce nucleus, a negative side band was built for the first time, which forms the octupole correlation structure together with the yrast band with s = +1. The assignment of octupole correlation in152 Ce agrees with the systematics and the calculations based on reflection asymmetry relativistic mean field theory. The identification of octupole correlation in152 Ce extended the region of octupole deformation island. In147 Ce nucleus, the yrast band and the negative band(2)were extended in our work, which form the octupole correlation structure with s = +i.A new side band was built. The systematic comparisons and reflection asymmetry shell model calculations further support our assignment of octupole correlation in147 Ce. |
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