The low-lying electric dipole strengths in proton-rich nuclei 17F and 17Ne, which can be produced at HIRFL-CSR in Lanzhou, are investigated. In the framework of the covariant density functional theory the self-consistent relativistic Hartree Bogoliubov model and the relativistic quasiparticle random phase approximation with the NL3 parameter set and Gogny pairing interaction are adopted in the calculations. A pronounced dipole peak appears below 10 MeV in17Ne, but does not occur in 17F. The prop erties of this low-lying E1 excitation in 17Ne are studied, which may correspond to a proton pygmy resonance with different characteristics from those of giant dipole resonance.
MA ZhongYu1,2 & TIAN Yuan1 1 China Institute of Atomic Energy, Beijing 102413, China
Radioactive decay of super heavy nuclei via the emission of α-particles has been studied theoretically in the preformed cluster model (PCM). The nucleus-nucleus (NN) potential is obtained by double folding the density distributions of the α-particle and the daughter nucleus with a realistic effective interaction. The M3Y effective interaction, supplemented by a zero-range pseudo-potential for exchange term, is used to calculate the NN potential. The α decay half-lives for 317 nuclei at Z=102 120 are performed in the PCM framework with the theoretical Q values extracted from the MSller-Nix-Kratz and Liran-Marinov-Zeldes mass tables and are compared with the experimental data. The calculated results are also compared with those obtained by using Q values from the Muntian-Hofmann-Patyk-Sobiczewski and Myers-Swiatecki mass estimates.
Some special issues of the random phase approximation(RPA) in the relativistic approach are reviewed. A full consistency and proper treatment of coupling to the continuum are responsible for the successful application of the RPA in the description of dynamical properties of finite nuclei. The fully consistent relativistic RPA(RRPA) requires that the relativistic mean filed (RMF) wave function of the nucleus and the RRPA correlations are calculated in a same effective Lagrangian and the consistent treatment of the Dirac sea of negative energy states. The proper treatment of the single particle continuum with scattering asymptotic conditions in the RMF and RRPA is discussed. The full continuum spectrum can be described by the single particle Green's function and the relativistic continuum RPA is established. A separable form of the paring force is introduced in the relativistic quasi-particle RPA.
MA Zhong-yu1,2,YANG Ding1,TIAN Yuan1,CAO Li-gang2,3(1 China Institute of Atomic Energy,Beijing 102413,China