Low-lying states of heavy nuclei within the nucleon pair approximation

et al. 2010

In this paper we study the structure coefficients of collective pairs with spin zero and spin two (SD) in a number of configurations by a few realistic nuclei. We investigate the robustness of these structure coefficients with respect to different configurations and the evolution of SD-pair structure coefficients with valence nucleon number.nuclear structure: collective levels, nuclear structure models and methods, shell model PACS: 21.10.Re, 21.60.Cs Nucleon pair approximation (NPA) [1] provides us with an efficient scheme to truncate the huge shell-model (SM) [2] space for medium and heavy nuclei. Among numerous work along this line the interacting boson model [3,4], in which spin-zero and spin-two pairs (SD) are further simplified to sd bosons, has been widely applied to study low-lying states of atomic nuclei. Other well-known work such as the fermion dynamical symmetry model [5], the generalized seniority scheme [6,7], broken-pair approximation [8], and the favored pair model [9], also attracted much attention. The validity of the pair approximations was reviewed in ref. [4] and was further studied in recent years in ref. [10].Recently, the NPA was applied to mass number around 130 and 200 region by a number of groups [11][12][13][14][15][16]. In these calculations, one of the most important flexibilities is to determine the structure coefficients of collective pairs. These pairs are building blocks of the wave functions of states to be studied. If the pair structure coefficients are not properly determined, the calculated results are in principle not good approximations of the exact SM results.In this paper we study the structure coefficients of spinzero and spin-two pairs by a few single closed-shell nuclei. We also discuss the robustness of these structure coefficients *Corresponding author (email: ymzhao@sjtu.edu.cn) with respect to various configurations and the evolution of pair structure coefficients with valence pair number. Hamiltonian and model spaceThe collective pairs are defined as follows:whereis called non-collective pair in this paper, and y(abr)'s are pair structure coefficients of collective pair with spin r. The model space is constructed by stepwise coupling of collective pairs. The Hamiltonian for a single closed-shell nuclei iswhich represents single-particle energy, monopole and quadrupole pairing interactions, and quadrupole-quadrupole interaction, respectively.n j = C † j ×C j,where r is the radius with respect to

Section: Hamiltonian and Model Spacesupporting

confidence: 83%

“…Calculations based on D pairs such obtained were done in refs. [11,12,14,16]. This approach can be easily generalized to obtain collective pairs with other spins.…”

Section: Hamiltonian and Model Spacementioning

confidence: 99%

“…(2) and ref. [16]). We first obtain structure coefficients of spin-zero (i.e., S ) pairs by using the lowest state φ 0 in the subspace S j S j S j and maximizing the overlap S 3 |φ 0 .…”

Section: Robustness Of Sd Pairsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

SD-pair structure in the pair approximation of the nuclear shell model

Lei

et al. 2010

“…We have calculated low-lying states of nuclei with A ∼ 130-150 in ref. [8] and the A ∼ 210 region [9]. We take the Hamiltonian as shown in eq.…”

Section: Application Of the Npamentioning

confidence: 99%

The nucleon pair approximation (NPA) of the shell model

Lei

et al. 2011

Low-lying states of Hg isotopes within the nucleon pair approximation

Jiang

2011

The low-lying states of 200−205 Hg nuclei have been studied by using the nucleon pair approximation (NPA) of the shell model. We calculate low-excited energy levels, electric quadrupole moments, and magnetic dipole moments, and investigate dominant configurations of low-lying states in the nucleon pair basis. Our calculations reasonably reproduce the available experimental data. We also tabulate our predicted results of low-lying states, including excitation energies, electric quadrupole moments and magnetic moments.collective levels, shell model, γ transitions and level energies