We present a quantitative study of the role played by different components characterizing the nucleon-nucleon interaction in the evolution of the nuclear shell structure. It is based on the spin-tensor decomposition of an effective two-body shell-model interaction and the subsequent study of effective single-particle energy variations in a series of isotopes or isotones. The technique allows to separate unambiguously contributions of the central, vector and tensor components of the realistic effective interaction. We show that while the global variation of the single-particle energies is due to the central component of the effective interaction, the characteristic behavior of spin-orbit partners, noticed recently, is mainly due to its tensor part. Based on the analysis of a well-fitted realistic interaction in sdpf-shell model space, we analyze in detail the role played by the different terms in the formation and/or disappearance of N=16, N=20 and N=28 shell gaps in neutron-rich nuclei.
One of the common methods used to investigate the nuclear structures of atomic nuclei is the nuclear shell model. Similar to the placement of atomic electrons into orbits, in the nuclear shell model, protons and neutrons are thought to fill the orbits within the nucleus, following the principle of Pauli's exclusion. These orbits are grouped together to form shells, which are said to be closed if all possible places in a shell are full. Atomic nuclei with closed shells are very stable and valence nucleons that are more than these nuclei are included in the nuclear shell model calculations. In t…
Applications of configuration mixing methods for nuclei near the proton and neutron drip lines are discussed. A short review of magic numbers is presented. Prospects for advances in the regions of four new "outposts" are highlighted: $^{28}$O, $^{42}$Si, $^{60}$Ca and $^{78}$Ni. Topics include: shell gaps, single-particle properties, islands-of-inversion, collectivity, neutron decay, neutron halos, two-proton decay, effective charge, and quenching in knockout reactions.
The theoretical uncertainty in the nuclear Schiff moment is an obstacle to set constraints on $ CP $ violation beyond the standard model from experimental upper bounds on atomic electric dipole moments. We perform large-scale shell-model calculations of the $^{129}$Xe and $^{199}$Hg nuclei with realistic effective interactions. To estimate the Schiff moments caused by the $ P $, $ T $-odd $ πNN $ interaction perturbatively, we employ the one-particle one-hole approximation to the intermediate states. The Schiff moments of $^{129}$Xe and $^{199}$Hg are reduced due to the configuration mixing by…
Manifestation of three-body forces in f7/2-shell nuclei
传统的核壳模型方法被扩展到包括多体力。本文构造了0 f ~（7/2）壳层上全同核子在三体作用下的经验哈密顿量。研究了三体力在光谱、结合能、资历混合、粒子-空穴对称性、电磁和粒子跃迁率等方面的表现。结果表明，除了通常的扩展的价空间内的transmittance两体壳模型，在哈密顿量的三体组件可以是一个重要的组成部分，提高质量的理论方法。
The density-dependent finite-range Gogny force has been used to derive the effective Hamiltonian for the shell-model calculations of nuclei. The density dependence simulates an equivalent three-body force, while the finite range gives a Gaussian distribution of the interaction in the momentum space and hence leads to an automatic smooth decoupling between low-momentum and high-momentum components of the interaction, which is important for finite-space shell-model calculations. Two-body interaction matrix elements, single-particle energies and the core energy of the shell model can be determine…
The nuclear shell model has been perhaps the most important conceptual and computational paradigm for the understanding of the structure of atomic nuclei. While the shell model has been predominantly used in a phenomenological context, there have been efforts stretching back over a half century to derive shell model parameters based on a realistic interaction between nucleons. More recently, several ab initio many-body methods---in particular many-body perturbation theory, the no-core shell model, the in-medium similarity renormalization group, and coupled cluster theory---have developed the c…
The origin of the asymmetry in the fragment mass distribution of low-energy nuclear fission is considered from the semiclassical point of view. Using the semiclassical periodic-orbit theory, one can define and quantify the shell effect associated with spatially localized nascent-fragment (prefragment) part of the potential. We investigate the roles of prefragments in the deformed shell effect using a simple cavity potential model but with realistic shape degrees of freedom for describing the fission processes. The results suggest that the prefragment magic numbers play essential roles in deter…
Quasi-nuclear systems, representing nuclei with variable size, are studied to investigate the occurrence of the spin-orbit term in the nuclear mean field in the transition from infinite nuclear matter to finite nuclei. Relativistic as well as non-relativistic mean field calculations based on models for the nucleon-nucleon ($NN$) interaction, which fit the $NN$ scattering data, are considered. A very strong correlation between the strength of the spin-orbit term and radius of the nuclear system is observed. The origin of the spin-orbit term is analyzed by inspecting the contributions of the dif…
