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

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Communications in Theoretical Physics 2022年第2期74卷 83-89页

作者： Cheng-Fu Mu Da-Li Zhang Department of physics Huzhou UniversityHuzhou 313000ZhejiangChina

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 ***,the excitation energy and E2 transition of 0_(2)^(+) state,which is intimately associated with shape coexistence,can be accurately *** 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.

关键词： shape coexistence ^(76)Se E2 and M1 transitions IBM-2

shape coexistence for ^179Hg in Relativistic Mean-Field Theory

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Communications in Theoretical Physics 2005年第4X期44卷 675-678页

作者： WANG Nan College of Science Shenzhen University Shenzhen 518060 China Institute of Theoretical Physics the Chinese Academy of Sciences Beijing 100080 China School of Physics Peking University Beijing 100871 China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion AcceleratorLanzhou 730000 China

The potential energy surface of179 Hg is traced and the multi-shape coexistence phenomenon in that nucleus is studied within the relativistic mean-field theory with quadrupole moment constraint. The calculation result... 详细信息

关键词： relativistic mean-field theory shape coexistence binding energy

shape coexistence and α-decay chains of ^293LV

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Frontiers of physics 2015年第3期10卷 29-36页

作者：李兆玺张振华赵鹏巍 School of Physics and Nuclear Energy Engineering Beihang University Beijing 100191 China State Key Laboratory of Nuclear Physics and Technology School of Physics Peking University Beijing 100871 China Mathematics and Physics Department North China Electric Power University Beijing 102206 China

Two recently observed ^293Lv （Z = 116） α-decay chains [Eur. Phys. J. A 48, 62 （2012）] are investigated in the framework of covariant density functional theory with PC-PK1, where the pairing correlations are treated by the Bardeen-Cooper-Schrieffer method with a density-independent zerorange force. From the calculated potential energy curves, it is found that two minima always occur, with one having an almost spherical shape and the other exhibiting a large deformed prolate shape. Originating from the ground state and the shape-isomeric state of ^293Lv, the two observed a-decay chains are constructed and the calculated Qα values are found to be in good agreement with the data.

关键词： shape coexistence α decay, ^293Lv covariant density functional theory

shape coexistence and evolution in neutron-def icient krypton isotopes

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Chinese Physics C 2015年第9期39卷 43-47页

作者：柏志军付熙明焦长峰许甫荣 State Key Laboratory of Nuclear Physics and Technology School of Physics Peking University National Institute for Radiological Protection Chinese Center for Disease Control and Prevention Department of Physics and Astronomy University of North Carolina Chapel Hill North Carolina

Total Routhian Surface （TRS） calculations have been performed to investigate shape coexistence and evolution in neutron-deficient krypton isotopes 72,74,76Kr. The ground-state shape is found to change from oblate in 72Kr to prolate in 74,76Kr, in agreement with experimental data. Quadrupole deformations of the ground states and coexisting 0＋ states as well as excitation energies of the latter are also well reproduced. While the general agreement between calculated moments of inertia and those deduced from observed spectra confirms the prolate nature of the low-lying yrast states of all three isotopes （except the ground state of 72Kr）, the deviation at low spins suggests significant shape mixing. The role of triaxiality in describing shape coexistence and evolution in these nuclei is finally discussed.

关键词： shape coexistence neutron-deficient krypton TRS moment of inertia triaxiality

Possible shape coexistence in Ne isotopes and the impurity effect of Λ hyperon

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Science China(Physics,Mechanics & Astronomy) 2021年第8期64卷 29-40页

作者： Chen Chen Qian-Kun Sun Yu-Xiao Li Ting-Ting Sun School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China

The possible shape coexistence in even-even Ne isotopes and the impurity effects of the sΛ and pΛ hyperons are explored employing the multidimensionally constrained relativistic-mean-field(MDC-RMF) model with the PK1 parameter set for the N N interaction and PK1-Y1 for the ΛN interaction. The quadrupole deformation potential energy surfaces(PESs), nuclear deformations, nuclear radii, binding energies, and density distributions of the hypernuclei and core nuclei are examined. The possible shape coexistence in ^(24,26,28)Ne is predicted with small energy differences of 140, 336, and 128 keV, respectively, between the two local energy minima. Different impurity effects of the sΛand pΛ hyperons are revealed. The sΛ hyperon exhibits clear shrinkage effects, which reduce the nuclear size and facilitate a spherical nuclear shape. The prolate pΛhyperon on the 1/2^(-)[110] orbital renders the nuclear shape more prolate, while the oblate pΛ hyperon on the 3/2^(-)[101] or 1/2^(-)[101] orbital renders the nuclei more oblate. Moreover, the Λ hyperon can increase the probabilities of the shape coexistence by reducing the energy differences between the two local energy minima, although the shape coexistence may disappear owing to the vanishment of one energy minimum on the flat energy surface.

关键词： single-Λhypernuclei shape coexistence impurity effects Ne isotope

Two-neutron transfer reactions as a tool to study the interplay between shape coexistence and quantum phase transitions

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Chinese Physics C 2020年第12期44卷 103-113页

作者： J.E.García-Ramos J.M.Arias A.Vitturi Departamento de Ciencias Integradas y Centro de Estudios Avanzados en Física Matemática y ComputaciónUniversidad de Huelva21071 HuelvaSpain Instituto Carlos I de Física Teórica y Computacional Universidad de GranadaFuentenueva s/n18071 GranadaSpain Departamento de Física Atómica Molecular y NuclearUniversidad de SevillaApdo.106541080 SevillaSpain Dipartimento di Fisica e Astronomia“Galileo Galilei” Universitádegli Studi di PadovaPadovaItaly

The atomic mass table presents zones where the structure of the states changes rapidly as a function of the neutron or proton *** them,notable examples are the A≈100 Zr region,the Pb region around the neutron midshell(N=104),and the N≈90 rare-earth *** observed phenomena can be understood in terms of either shape coexistence or quantum phase *** objective of this study is to find an observable that can distinguish between both shape coexistence and quantum phase *** an observable to be analyzed,we selected the two-neutron transfer intensity between the 0+states in the parent and daughter *** framework used for this study is the Interacting Boson Model(IBM),including its version with configuration mixing(IBM-CM).To generate wave functions of isotope chains of interest needed for calculating transfer intensities,previous systematic studies using IBM and IBM-CM were used without changing the *** results of two-neutron transfer intensities are presented for Zr,Hg,and Pt isotopic chains using ***,for Zr,Pt,and Sm isotopic chains,the results are presented using IBM with only a single configuration,i.e.,without using configuration *** Zr,the two-neutron transfer intensities between the ground states provide a clear observable,indicating that normal and intruder configurations coexist in the low-lying spectrum and cross at A=98→*** can help clarify whether shape coexistence induces a given quantum phase *** Pt,in which shape coexistence is present and the regular and intruder configurations cross for the ground state,there is almost no impact on the value of the two-neutron transfer *** is the situation with Hg,where the ground state always has a regular *** the Sm isotope chain,which is one of the quantum phase transition paradigms,the value of the two-neutron transfer intensity is affected strongly.

关键词： two nucleon transfer reactions shape coexistence quantum phase transition interacting boson model

Possible shape coexistence in odd-A Ne isotopes and the impurity effects ofΛhyperons

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Chinese Physics C 2022年第7期46卷 138-148页

作者： Qian-Kun Sun Ting-Ting Sun Wei Zhang Shi-Sheng Zhang Chen Chen School of Physics and Microelectronies Zhengzhou UniversityZhengzhou 450001China School of Physics and Nuclear Energy Engineering Beihang UniversityBeijing 100191China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China

In this study, shape evolution and possible shape coexistence are explored in odd-A Ne isotopes in the framework of the multidimensionally constrained relativistic-mean-field(MDC-RMF)model. By introducing ~sΛ and phyperons, the impurity effects on the nuclear shape, energy, size, and density distribution are *** the NN interaction, the PK1 parameter set is adopted, and for the ΛN interaction, the PK1-Y1 parameter set is used. The nuclear ground state and low-lying excited states are determined by blocking the unpaired odd neutron in different orbitals around the Fermi surface. Moreover, the potential energy curves(PECs), quadrupole deformations,nuclear r.m.s. radii, binding energies, and density distributions for the core nuclei as well as the corresponding hy pernuclei are analyzed. By examining the PECs, possibilities for shape coexistence inNe and a triple shape coexistence inNe are found. In terms of the impurity effects ofΛhyperons, as noted for even-even Ne hypernuclear isotopes, the shyperon exhibits a clear shrinkage effect, which reduces the nuclear size and results in a more spherical nuclear shape. The phyperon occupying the 1/2~-[110]orbital is prolate, which causes the nuclear shape to be more prolate, and the phyperon occupying the 3/2~-[101] orbital displays an oblate shape, which drives the nuclei to be more oblate.

关键词： hypernuclei shape coexistence impurity effects Ne isotope

Triaxiality and shape coexistence in the A ～ 30 “island of inversion”nuclei

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Science China(Physics,Mechanics & Astronomy) 2015年第11期58卷 99-106页

作者： DONG GuoXiang WANG XiaoBao YU ShaoYing School of Science Huzhou University

Understanding the properties of nuclei inside "island of inversion" is still an interesting issue. Based on a simple Nilsson model with a new set of isospin-dependent parameters, and with non-axial deformations considered, we have performed three-dimensional potential-energy-surface calculations for Ne, Na, Mg and Al isotopes that are claimed to be in or nearby the A～30 island of inversion". It is found that shape coexistence and triaxial deformation(or softness) exist in these nuclei. Large deformations are obtained by the improved Nilsson parameters, which explains the observed large electric quadrupole transition probabilities. The large deformations happening in30 Ne,31Na,32 Mg and33Al indicate the quenching of the spherical N = 20 neutron shell gap. The calculations of nuclear binding and two-neutron separation energies have been also improved with the isospin-dependent parameters and the inclusion of the non-axial deformation degree of freedom.

关键词： island of inversion shell evolution triaxial deformation shape coexistence

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

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Communications in Theoretical Physics 2020年第5期72卷 65-69页

作者： Cheng-Fu Mu Da-Li Zhang Department of physics Huzhou UniversityHuzhou 313000ZhejiangChina

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 *** 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)*** have calculated the electric monopole strengthρ^2(E0,02^+→01^+),and our result agrees with the experimental *** calculation indicates that shape coexistence and MS states are simultaneously well described using IBM-2.

关键词： shape coexistence mixed-symmetry state IBM-2 E2 and M1 transitions