The Microscopic Approach of sdgIBM-1 and Its Application to Nucleus^(154) Gd

Based on the Dyson expansion theory, a microscopic approach of sdgIBM\|1 is presented and applied to nucleus 154 Gd in this paper. The energy spectra and E 2 transition have been calculated. Good agreement is obtained in comparison with experimental results.

Description of spectrum and electromagnetic transitions in ^(94)Mo through the proton-neutron interacting boson model

We investigated the properties of low-lying states in ^(94)Mo within the framework of the proton-neutron interacting boson model(IBM-2), with special focus on the characteristics of mixed-symmetry states. We calculated level energies and M1 and E2 transition strengths. The IBM-2 results agree with the available quantitative and qualitative experimental data on ^(94)Mo. The properties of mixed-symmetry states can be well described by IBM-2 given that the energy of the d proton boson is different from that of the neutron boson, especially for the transition of B(M1, 4_2^+→ 4_1^+).

Systematic dependence of SFE＊B(E2)↑ and ROTE＊B(E2)↑on N_pN_n in the framework of shape fluctuation model

A systematic dependence of shape fluctuation energy product SFE ＊ B（E2）↑ and rotational energy product ROTE ＊ B（E2）↑ on the valence nucleon product Np Nn is carried out in the Z = 50-82,N = 82-126 major shell space.For the shape transitional nuclei,the product SFE＊B（E2）↑ drops to zero and becomes negative,indicating direct dependence on N_pN_n.A relative rise,on the other hand,is observed in the product ROTE＊B（E2） ↑plotted against N_pN_n for all the nuclei in Z = 50-82 and N = 82-126.In the N 〉 104 region,large positive values of the product SFE ＊ B（E2） ↑ are observed for the Pt nucleus,which indicates sphericity.A systematic study of the product SFE ＊ B（E2）↑ and ROTE ＊ B（E2） ↑ with atomic number Z is also discussed.The products SFE ＊ B（E2） ↑and ROTE ＊ B（E2） ↑ vary sharply with Z for the N = 88 isotones.We discuss here for the first time the correlation between SFE ＊ B（E2） ↑ and ROTE ＊ B（E2） ↑ with valence nucleon product N_pN_n.

Structure of the even-even ^(78-84)Kr isotopes within SD-pair shell model

The collective properties in the even-even ^78-84Kr isotopes have been studied within the framework of the SD-pair shell model. It is found that the collectivity of low-lying states in the even-even Kr isotopes can be described very well.

A unified description of shape coexistence and mixed-symmetry states in^98Mo using IBM-2

Level structure and electromagnetic transitions in^98Mo have been investigated on the basis of the proton-neutron interacting boson model(IBM-2)by considering the energy difference between neutron bosonενand proton bosonεπ.The results are compared with the recent experimental data and it is observed that they are in good agreement.In particular,the strongest M1 transition from 25^+state to 22^+can be well reproduced,from which one can determine the 25^+as an mixed-symmetry(MS)state.We have calculated the electric monopole strengthρ^2(E0,02^+→01^+),and our result agrees with the experimental one.The calculation indicates that shape coexistence and MS states are simultaneously well described using IBM-2.

Nuclear structure of ^(76)Ge from proton-neutron interacting boson model calculations

The properties of low-lying states in 76Ge, especially the characteristics of the mixed-symmetry states, have been investigated within the neutron-proton interacting boson model （IBM-2）. By considering the relative energy of d proton boson to be different from that of neutron boson, the low-lying positive parity levels and M1, E2 transition strengths have been calculated. The IBM-2 calculated results are in good agreement with the experimental data. Particularly, the mixed-symmetry states have been reproduced quite well. The calculation and systematic analysis demonstrated that the collective character of 76Ge lies closest to the SUπv^＊（3）, with some possible Oπv（6） dynamic symmetry in IBM-2 viewpoint.

Shape coexistence in 76Se within the neutron–proton interacting boson model

We have investigated the low-lying energy spectrum and electromagnetic transition strengths in even-even ^(76)Se using the proton-neutron interacting boson model(IBM-2).The theoretical calculation for the energy levels and E2 and M1 transition strengths is in good agreement with the experimental data.Specifically,the excitation energy and E2 transition of 0_(2)^(+) state,which is intimately associated with shape coexistence,can be accurately reproduced.The analysis on lowlying states and the key structure indicators R_(1),R_(2),R_(3) and R_(4) and M1 transitions indicates that there is a coexistence between spherical shape and γ-soft shape in ^(76)Se.