Study On The Shape Phase Transition And Wobbling Motion Of Odd-mass Nucleus Within The Microscopic Core-quasiparticle Coupling Model

In recent years,with the construction and operation of a new generation of large-scale radioactive nuclear beam device in the world,many novel phenomena or motion modes have been found in unstable and exotic nuclei,such as quantum shape transition,shape coexistence,(anti)magnetic rotation,chiral rotation and wobbling motion.However,in the study of these novel phenomena or motion modes,the traditional nuclear theory based on the development of stable nuclear properties has obvious limitations and needs to be improved or put forward.Covariant density functional theory can describe the ground state properties of nuclei in almost the whole nuclide diagram in a micro,self-consistent and unified way.In order to describe the low-lying spectrum and new phenomena of exotic nuclei,our group developed the micro collective Hamiltonian model based on the covariant density functional theory,and further constructed the micro core-quasiparticle coupling(CQC)model by coupling the quasiparticle and collective motion,which was successfully applied to describe the odd-A low-lying spectrum and the quantum shape transition of Eu isotopesIn this paper,we study the spectral properties of odd-A nuclei,the coupling of single particle motion and collective motion,and the novel motion modes by using the microscopic core quasiparticle coupling model based on the covariant density functional theory.The details are as follows:1)we study the low excitation structure of the odd-neutron Sm isotopes,give the axially symmetric potential energy curves of even-even cores,and reproduce the low-lying spectrum of Sm isotopes,the evolution regular of the order parameters such as the two-neutron separation energies,the ground state charge isotope shifts and the quadrupole shape invariants,are discussed A rapid transition is found at N=90,which further confirms that there is a first-order phase transition in the Sm isotopes,and no obvious core shape polarization effect is observed in the odd A nucleus;2)the wobbling motion of the 105Pd is studied.The low-lying spectrum,B(E2)and B(M1)of 105Pd are calculated,and the characteristics of transverse wobbling motion:energy spectrum spacing,B(M1)out/B(E2)in and B(E2)out/B(E2)in are discussed.The influence of the spectrum of cores on the wobbling motion is further analyzed.In general,although the theoretical calculation reproduces the spectrum of wobbling motion,the agreement quite bad for the measured electromagnetic transition ratio.It is expected to give a more reasonable description by extending the model to include multi-quasiparticle excitation.