2024/07/16 更新

写真a

マツオ マサユキ
松尾 正之
MATSUO Masayuki
所属
教育研究院 自然科学系 数理物質科学系列 教授
自然科学研究科 数理物質科学専攻 教授
理学部 理学科 教授
職名
教授
外部リンク

学位

  • 理学博士 ( 1987年3月   京都大学 )

研究キーワード

  • 原子核理論

  • NUCLEAR THEORY

研究分野

  • 自然科学一般 / 素粒子、原子核、宇宙線、宇宙物理にする理論

経歴

  • 新潟大学   理学部 理学科   教授

    2017年4月 - 現在

  • 新潟大学   自然科学研究科 数理物質科学専攻   教授

    2010年4月 - 現在

  • 新潟大学   自然科学研究科 数理物質科学専攻   教授

    2010年4月 - 現在

  • 新潟大学   物理学科   教授

    2005年2月 - 2017年3月

  • 新潟大学   物理学科   助教授

    2000年3月 - 2005年1月

学歴

  • 京都大学   Graduate School, Division of Natural Science

    - 1987年

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  • 京都大学   理学研究科   物理学第二

    - 1987年

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    国名: 日本国

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  • 京都大学   理学部   物理学

    - 1982年

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    国名: 日本国

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  • 京都大学   Faculty of Science

    - 1982年

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所属学協会

 

論文

  • Continuum random-phase approximation for (n, & gamma;) reactions on neutron-rich nuclei: Collective effects and resonances

    Teruyuki Saito, Masayuki Matsuo

    PHYSICAL REVIEW C   107 ( 6 )   2023年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We formulate a microscopic theory to calculate cross section of the radiative neutron capture reaction on neutron-rich nuclei using the continuum random-phase approximation (cRPA) to the time-dependent density functional theory (TDDFT). With an intention of applying to the r process, for which the statistical reaction model may not be appropriate, we describe the transition between a initial state of incident neutron and a final state of the & gamma; decay by means of a single many-body framework of the cRPA-TDDFT. With the cRPA approach, it is possible to describe various excitation modes present in the (n, & gamma; ) reaction, including soft dipole excitation, the giant resonances, as well as noncollective excitations and the single-particle resonances. Furthermore, it enables us to describe the (n, & gamma; ) reaction where the the final states of the & gamma; transition are low-lying surface vibrational states. We demonstrate the theory by performing numerical calculation for the reaction 139Sn(n, & gamma; ) 140Sn. We discuss various new features which are beyond the single-particle model: the presence of narrow and wide resonances originating from noncollective and collective excitations and roles of low-lying quadrupole and octupole vibrational states.

    DOI: 10.1103/PhysRevC.107.064607

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  • Time-dependent extension of the self-consistent band theory for neutron star matter: Anti-entrainment effects in the slab phase

    Kazuyuki Sekizawa, Sorataka Kobayashi, Masayuki Matsuo

    PHYSICAL REVIEW C   105 ( 4 )   2022年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Background: In the solid crust of neutron stars, a variety of crystalline structures may exist. Recently the band theory of solids was applied to the inner crust of neutron stars, and the significance of the entrainment between dripped neutrons and the solid crust was advocated. Since it influences interpretations of various phenomena of neutron stars, it is desirable to develop deeper understanding of the underlying microphysics. Purpose: The purpose of the present article is to propose a fully self-consistent microscopic framework for describing time-dependent dynamics of neutron star matter, which allows us to explore diverse properties of nuclear matter, including the entrainment effect. Methods: A fully self-consistent nuclear band theory is employed with the Skyrme SLy4 energy density functional. A time-dependent extension of the microscopic band theory is developed based on the time-dependent density functional theory (TDDFT). An intuitive real-time method is proposed for extracting the collective mass of a nuclear cluster immersed in a sea of dripped neutrons, taking into account the band structure effects. Results: As the first application of the time-dependent self-consistent band theory for nuclear systems, we investigate the slab phase of nuclear matter with various proton fractions. From a dynamic response of the system to an external force, we extract the collective mass of a slab, associated with entrained neutrons (due to the Bragg scattering of dripped neutrons off the periodic potential) as well as bound nucleons. We find that the extracted collective mass is smaller than a naive estimation based on a potential profile and single-particle energies. We show that the reduction is mainly caused by "counterflow" of dripped neutrons towards the direction opposite to the motion of the slabs. We interpret it as an "anti-entrainment" effect. As a result, the number of effectively bound neutrons is reduced, indicating an enhancement of the number density of conduction neutrons. We demonstrate that those findings are consistent with a static treatment in the band theory of solids. Conclusions: The proposed approach offers a new research possibility of investigating nonlinear many-body dynamics of nuclear matter microscopically, taking full account of the periodic structure in neutron star crusts. The fully self-consistent band theory calculations, in both static and dynamic formalisms, suggest that the mobility of dripped neutrons is larger than expected without band structure effects, at least for the slab phase of nuclear matter.

    DOI: 10.1103/PhysRevC.105.045807

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  • Continuum random-phase approximation for gamma transitions between excited states in neutron-rich nuclei

    Teruyuki Saito, Masayuki Matsuo

    PHYSICAL REVIEW C   104 ( 3 )   2021年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    A characteristic feature of collective and particle-hole excitations in neutron-rich nuclei is that many of them couple to an unbound neutron in continuum single-particle orbits. The continuum random-phase approximation (cRPA) is a powerful many-body method that describes such excitations, and it provides a scheme to evaluate transition strengths from the ground state. In an attempt to apply cRPA to the radiative neutron-capture reaction, we formulate in the present study an extended scheme of cRPA that describes gamma transitions from the excited states under consideration, which decay to low-lying excited states as well as the ground state. This is achieved by introducing a nonlocal one-body operator which causes transitions to a low-lying excited state, and describing a density-matrix response against this operator. As a demonstration of this new scheme, we perform numerical calculation for dipole, quadrupole, and octupole excitations in Sn-140, and discuss E1 and E2 transitions decaying to low-lying 2(1,2)+ and 3(1)(-) states. The results point to cases where the branching ratio to the low-lying states is larger than or comparable with that to the ground state. We discuss key roles of collectivity and continuum orbits in both initial and final states.

    DOI: 10.1103/PhysRevC.104.034305

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  • Proximity effect of pair correlation in the inner crust of neutron stars

    Toshiyuki Okihashi, Masayuki Matsuo

    Progress of Theoretical and Experimental Physics   2021 ( 2 )   2020年12月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Oxford University Press (OUP)  

    Abstract

    We study the proximity effect of pair correlation in the inner crust of neutron stars by means of the Skyrme–Hartree–Fock–Bogoliubov theory formulated in coordinate space. We describe a system composed of a nuclear cluster immersed in neutron superfluid confined in a spherical box. Using a density-dependent effective pairing interaction that reproduces both the pair gap of neutron matter obtained in ab initio calculations and that of finite nuclei, we analyze how the pair condensate in a neutron superfluid is affected by the presence of the nuclear cluster. It is found that the proximity effect is characterized by the coherence length of the neutron superfluid measured from the edge position of the nuclear cluster. The calculation predicts that the proximity effect has a strong density dependence. In the middle layers of the inner crust with baryon density $5 \times 10^{-4}$ fm$^{-3} \mathop < \limits_ \sim \ \rho_b \mathop < \limits_ \sim \ 2\times 10^{-2}$ fm$^{-3}$, the proximity effect is strongly limited in the vicinity of the nuclear cluster, i.e., in a sufficiently smaller area than the Wigner–Seitz cell. In contrast, the proximity effect is predicted to extend to the whole volume of the Wigner–Seitz cell in shallow layers of the inner crust with $\rho_b \mathop < \limits_ \sim \ 2 \times 10^{-4}$ fm$^{-3}$, and in deep layers with $\rho_b \mathop > \limits_ \sim \ 5 \times 10^{-2}$ fm$^{-3}$.

    DOI: 10.1093/ptep/ptaa174

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    その他リンク: http://academic.oup.com/ptep/article-pdf/2021/2/023D03/36455177/ptaa174.pdf

  • Signature-dependent triaxiality for shape evolution from superdeformation in rapidly rotating 40Ca and 41Ca 査読

    Shinkuro Sakai, Kenichi Yoshida, Masayuki Matsuo

    Progress of Theoretical and Experimental Physics   2020 ( 6 )   2020年6月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Oxford University Press (OUP)  

    <title>Abstract</title>
    We investigate the possible occurrence of highly elongated shapes near the yrast line in $^{40}$Ca and $^{41}$Ca at high spins on the basis of the nuclear energy-density functional method. Both the superdeformed (SD) yrast configuration and the yrare configurations on top of the SD band are described by solving the cranked Skyme–Kohn–Sham equation in the three-dimensional coordinate space representation. It is suggested that some of the excited SD bands undergo band crossings and develop to hyperdeformation (HD) beyond $J \simeq 25 \hbar$ in $^{40}$Ca. We find that the change of triaxiality in response to rotation plays a decisive role in the shape evolution towards HD, and that this is governed by the signature quantum number of the last occupied orbital at low spins. This mechanism can be verified in an experimental observation of the positive-parity SD yrast signature-partner bands in $^{41}$Ca, one of which ($\alpha=+1/2$) undergoes crossings with the HD band, while the other ($\alpha=-1/2$) shows smooth evolution from collective rotation at low spins to non-collective rotation with an oblate shape at termination.

    DOI: 10.1093/ptep/ptaa071

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  • s-wave quasiparticle resonance in neutron-rich drip-line nuclei 査読

    Yoshihiko Kobayashi, Masayuki Matsuo

    Progress of Theoretical and Experimental Physics   2020 ( 1 )   2020年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/ptep/ptz136

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  • Coexistence of Anderson-Bogoliubov phonon and quadrupole cluster vibration in the inner crust of neutron stars

    Tsunenori Inakura, Masayuki Matsuo

    PHYSICAL REVIEW C   99 ( 4 )   2019年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Background: Low-lying collective excitations of the inner crust matter in neutron stars are expected to affect observables such as the quasiperiodic oscillation in giant flares or cooling of the inner crust in transient phenomena. The coupling between the Anderson-Bogoliubov (AB) superfluid phonon in superfluid neutron gas and collective excitations of nuclear clusters is crucially important.Purpose: Our aim is to describe the characteristics of the low-lying excitation modes of the superfluid inner crust matter, focusing on quadrupole excitations around a spherical nuclear cluster. We studied the effect of the inhomogeneous structure of the inner crust matter on the AB phonon of neutron superfluid and on the possible quadrupole shape vibration of clusters.Methods: The coordinate-space Hartree-Fock-Bogoliubov method and the quasiparticle random phase approximation formulated in a spherical Wigner-Seitz cell were used to describe the neutron superfluidity and low-lying collective excitations. We performed systematic numerical calculations for the quadrupole excitations by varying the neutron chemical potential and the number of protons in the cell.Results: The calculated results indicate the appearance of both AB phonon and quadrupole shape vibration of the cluster with small mixing between the two collective modes. The quadruple AB phonon is similar to that in the uniform superfluid, apart from the small admixture of the shape vibration of cluster. The excitation energy and the collectivity of the cluster vibration mode show a strong and oscillatory dependence on the neutron chemical potential (the neutron gas density), resulting in softening and instability under certain conditions. This is due to the resonance shell effect, where unbound, but resonant single-particle states of neutrons are crucially important.Conclusions: The AB phonon of the superfluid neutron gas and the quadrupole shape vibration of the nuclear cluster coexist in the inner crust. The coupling between the AB phonon and the quadrupole shape vibration is weak. The collectivity of the quadrupole shape vibration is controlled by the resonance shell effect, which suggests that the appearance of deformed nuclear clusters is possible in any layer of the inner crust.

    DOI: 10.1103/PhysRevC.99.045801

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  • Anderson-Bogoliubov phonons in the inner crust of neutron stars: Dipole excitation in a spherical Wigner-Seitz cell 査読

    Tsunenori Inakura, Masayuki Matsuo

    PHYSICAL REVIEW C   96 ( 2 )   2017年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Background: The Anderson-Bogoliubov (AB) phonon, called also the superfluid phonon, has attracted attentions since it may influence the thermal conductivity and other properties of the inner crust of neutron stars. However, there are a limited number of microscopic studies of the AB phonon where the presence of clusters is explicitly taken into account.
    Purpose: We intend to clarify how the presence of clusters affects the AB phonon in order to obtain microscopic information relevant to the coupling between the AB phonon and the lattice phonon.
    Methods: The Hartree-Fock-Bogoliubov model and the quasiparticle random-phase approximation formulated in a spherical Wigner-Seitz cell are adopted to describe neutron superfluidity and associated collective excitations. We perform systematic numerical calculations for dipole excitation by varying the neutron chemical potential and the number of protons in a cell.
    Results: The model predicts systematic emergence of the dipole AB phonon mode, which, however, exhibits strong suppression of phonon amplitude inside the cluster. We find also that the phonon amplitude around the cluster surface varies with the neutron density. At higher neutron densities (&gt;= 0.006 fm(-3)) the AB phonon mode exhibits behavior similar to the pygmy dipole resonance in neutron-rich nuclei.
    Conclusions: The dipole AB phonon mode does not penetrate into the clusters. This suggests that the coupling between the AB phonon and the lattice phonon may be weak.

    DOI: 10.1103/PhysRevC.96.025806

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  • Pairing correlation effects on width of quasi-particle resonance in neutron drip-line nuclei 査読

    Yoshihiko Kobayashi, Masayuki Matsuo

    JPS Conference Proceedings   14   2017年2月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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  • Time-dependent density-functional description of nuclear dynamics 査読

    Takashi Nakatsukasa, Kenichi Matsuyanagi, Masayuki Matsuo, Kazuhiro Yabana

    REVIEWS OF MODERN PHYSICS   88 ( 4 )   2016年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The basic concepts and recent developments in the time-dependent density-functional theory (TDDFT) for describing nuclear dynamics at low energy are presented. The symmetry breaking is inherent in nuclear energy density functionals, which provides a practical description of important correlations at the ground state. Properties of elementary modes of excitation are strongly influenced by the symmetry breaking and can be studied with TDDFT. In particular, a number of recent developments in the linear response calculation have demonstrated their usefulness in the description of collective modes of excitation in nuclei. Unrestricted real-time calculations have also become available in recent years, with new developments for quantitative description of nuclear collision phenomena. There are, however, limitations in the real-time approach; for instance, it cannot describe the many-body quantum tunneling. Thus, the quantum fluctuations associated with slow collective motions are explicitly treated assuming that time evolution of densities is determined by a few collective coordinates and momenta. The concept of collective submanifold is introduced in the phase space associated with the TDDFT and used to quantize the collective dynamics. Selected applications are presented to demonstrate the usefulness and quality of the new approaches. Finally, conceptual differences between nuclear and electronic TDDFT are discussed, with some recent applications to studies of electron dynamics in the linear response and under a strong laser field.

    DOI: 10.1103/RevModPhys.88.045004

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  • Microscopic derivation of the Bohr-Mottelson collective Hamiltonian and its application to quadrupole shape dynamics 査読

    Kenichi Matsuyanagi, Masayuki Matsuo, Takashi Nakatsukasa, Kenichi Yoshida, Nobuo Hinohara, Koichi Sato

    PHYSICA SCRIPTA   91 ( 6 )   2016年6月

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    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We discuss the nature of the low-frequency quadrupole vibrations from small-amplitude to large-amplitude regimes. We consider full five-dimensional quadrupole dynamics including three-dimensional rotations restoring the broken symmetries as well as axially symmetric and asymmetric shape fluctuations. Assuming that the time evolution of the self-consistent mean field is determined by five pairs of collective coordinates and collective momenta, we microscopically derive the collective Hamiltonian of Bohr and Mottelson, which describes low-frequency quadrupole dynamics. We show that the five-dimensional collective Schrodinger equation is capable of describing large-amplitude quadrupole shape dynamics seen as shape coexistence/mixing phenomena. We summarize the modern concepts of microscopic theory of large-amplitude collective motion, which is underlying the microscopic derivation of the Bohr-Mottelson collective Hamiltonian.

    DOI: 10.1088/0031-8949/91/6/063014

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  • Microscopic derivation of the quadrupole collective Hamiltonian for shape coexistence/mixing dynamics 査読

    Kenichi Matsuyanagi, Masayuki Matsuo, Takashi Nakatsukasa, Kenichi Yoshida, Nobuo Hinohara, Koichi Sato

    JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS   43 ( 2 )   2016年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Assuming that the time-evolution of the self-consistent mean field is determined by five pairs of collective coordinate and collective momentum, we microscopically derive the collective Hamiltonian for low-frequency quadrupole modes of excitation. We show that the five-dimensional collective Schrodinger equation is capable of describing large-amplitude quadrupole shape dynamics seen as shape coexistence/mixing phenomena. We focus on basic ideas and recent advances of the approaches based on the time-dependent mean-field theory, but relations to other time-independent approaches are also briefly discussed.

    DOI: 10.1088/0954-3899/43/2/024006

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  • Effects of pairing correlation on the low-lying quasiparticle resonance in neutron drip-line nuclei 査読

    Yoshihiko Kobayashi, Masayuki Matsuo

    PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS   ( 1 )   2016年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS INC  

    We discuss the effects of pairing correlation on quasiparticle resonance. We analyze in detail how the width of the low-lying (Ex less than or similar to 1 MeV) quasiparticle resonance is governed by the pairing correlation in the neutron drip-line nuclei. We consider the Si-46 + n system to discuss the low-lying p-wave quasiparticle resonance. Solving the Hartree-Fock-Bogoliubov equation in coordinate space with the scattering boundary condition, we calculate the phase shift, the elastic cross section, the resonance width, and the resonance energy. We find that the pairing correlation has the effect of reducing the width of the quasiparticle resonance that originates from a particle-like orbit in weakly bound nuclei.

    DOI: 10.1093/ptep/ptv175

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  • 中性子過剰核におけるs波散乱が受ける対相関効果

    小林 良彦, 松尾 正之

    日本物理学会講演概要集   71   118 - 118   2016年

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    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    <p>超流動状態にある中性子過剰核における1中性子s波散乱を考える。位相のずれや散乱断面積、S行列の極の分析を通して、s波散乱が受ける対相関効果を議論する。特に、本講演では、virtual stateの性質が対相関により、どのように支配されるのかに着目する。</p>

    DOI: 10.11316/jpsgaiyo.71.2.0_118

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  • Quasi-particle resonance near threshold in neutron drip-line nuclei 査読

    Yoshihiko Kobayashi, Masayuki Matsuo

    JPS Conference Proceedings   6   2015年6月

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    記述言語:日本語   掲載種別:研究論文(国際会議プロシーディングス)  

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  • Continuum quasiparticle random-phase approximation for astrophysical direct neutron capture reactions on neutron-rich nuclei 査読

    Masayuki Matsuo

    PHYSICAL REVIEW C   91 ( 3 )   2015年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    I formulate a many-body theory to calculate the cross section of direct radiative neutron capture reaction by means of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random-phase approximation (QRPA). A focus is put on very-neutron-rich nuclei and low-energy neutron kinetic energy in the range from 1 keV to several MeV, which is relevant to the rapid neutron capture process of nucleosynthesis. I begin with the photoabsorption cross section and the E1 strength function. Next, in order to apply the reciprocity theorem, I decompose the cross section into partial cross sections corresponding to different channels of one-and two-neutron emission decays of photo-excited states. A numerical example is shown for the photo-absorption of Sn-142 and the neutron capture of Sn-141.

    DOI: 10.1103/PhysRevC.91.034604

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  • 21aCD-8 中性子ドリップライン原子核における準粒子共鳴幅と対相関依存性のメカニズム

    小林 良彦, 松尾 正之

    日本物理学会講演概要集   70   239 - 239   2015年

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_239

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  • Quadrupole shape dynamics from the viewpoint of a theory of large-amplitude collective motion 査読

    M. Matsuo, N. Hinohara, K. Sato, K. Matsuyanagi, T. Nakatsukasa, K. Yoshida

    PHYSICA SCRIPTA   89 ( 5 )   2014年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Low-lying quadrupole shape dynamics is a typical manifestation of large-amplitude collective motion in finite nuclei. To describe the dynamics on a microscopic foundation, we have formulated a consistent scheme in which the Bohr collective Hamiltonian for the five-dimensional quadrupole shape variables is derived on the basis of the time-dependent Hartree-Fock-Bogoliubov theory. It enables us to incorporate the Thouless-Valatin effect on the shape inertial functions, which has been neglected in previous microscopic Bohr Hamiltonian approaches. Quantitative successes are illustrated for the low-lying spectra in Se-68, Mg30-34 and Cr58-64, which display shape-coexistence, shape-mixing and shape-transitional behavior.

    DOI: 10.1088/0031-8949/89/5/054020

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  • Di-neutron correlation in monopole two-neutron transfer modes in the Sn isotope chain 査読

    Hirotaka Shimoyama, Masayuki Matsuo

    PHYSICAL REVIEW C   88 ( 5 )   2013年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We study microscopic structures of monopole pair vibrational modes and associated two-neutron transfer amplitudes in neutron-rich Sn isotopes by means of the linear response formalism of the quasiparticle random phase approximation (QRPA). For this purpose we introduce a method to decompose the transfer amplitudes with respect to two-quasiparticle components of the QRPA eigenmode. It is found that pair-addition vibrational modes in neutron-rich Sn132-140 and the pair rotational modes in Sn142-150 are commonly characterized by coherent contribution of quasaiparticle states having high orbital angular momenta l greater than or similar to 5, which suggests transfer of a spatially correlated neutron pair. The calculation also predicts a high-lying pair vibration, the giant pair vibration, emerging near the one-neutron separation energy in Sn110-130, and we find that they have the same di-neutron characters as that of the low-lying pair vibration in Sn132-140.

    DOI: 10.1103/PhysRevC.88.054308

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  • Continuum dipole response near the threshold and the direct neutron capture cross section at astrophysical energies 査読

    Masayuki Matsuo

    INTERNATIONAL SYMPOSIUM ON EXOTIC NUCLEAR STRUCTURE FROM NUCLEONS (ENSFN 2012)   445   2013年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We apply the continuum quasiparticle random phase approximation to calculate the direct neutron capture cross section relevant to the r-process nucleo-synthesis. The electric dipole strength function in an even-even n-rich nucleus is decomposed with respect to the channels of direct neutron decays. Using the detailed balance relation, the partial dipole strengths are converted to obtain the direct neutron-capture cross sections. Numerical examples are given for Sn-142.

    DOI: 10.1088/1742-6596/445/1/012019

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  • Microscopic description of large-amplitude collective motions with local QRPA inertial masses 査読

    K. Sato, N. Hinohara, T. Nakatsukasa, M. Matsuo, K. Matsuyanagi

    FRENCH-JAPANESE SYMPOSIUM ON NUCLEAR STRUCTURE PROBLEMS: ORGANIZED IN THE FRAMEWORK OF FJNSP LIA AND EFES   126 - 129   2013年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    We propose a practical method for determining the collective potential and inertial functions in the five-dimensional quadrupole collective Hamiltonian. We have applied this method to large-amplitude shape mixing dynamics in the low-lying states of proton-rich Kr isotopes.

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  • Large-amplitude quadrupole collective dynamics in neutron-rich Mg and Cr isotopes 査読

    N. Hiniohara, K. Sato, K. Yoshida, T. Nakatsukasa, M. Matsuo, K. Matsuyanagi

    FRENCH-JAPANESE SYMPOSIUM ON NUCLEAR STRUCTURE PROBLEMS: ORGANIZED IN THE FRAMEWORK OF FJNSP LIA AND EFES   122 - 125   2013年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    The miroscopic method of deriving the quadrupole collective Hamiltonian is presented. Shape changes and transitions in neutron-rich magnesium and chromium isotopes are discussed using the quadrupole collective Hamiltonian.

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  • Shape transition and fluctuations in neutron-rich Cr isotopes around N=40 査読

    Koichi Sato, Nobuo Hinohara, Kenichi Yoshida, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    PHYSICAL REVIEW C   86 ( 2 )   2012年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The spherical-to-prolate shape transition in neutron-rich Cr isotopes from N = 34 to 42 is studied by solving the collective Schrodinger equation for the five-dimensional quadrupole collective Hamiltonian. The collective potential and inertial functions are microscopically derived with use of the constrained Hartree-Fock-Bogoliubov plus local quasiparticle random-phase approximation method. Nature of the quadrupole collectivity of low-lying states is discussed by evaluating excitation spectra and electric quadrupole moments and transition strengths. The result of calculation indicates that Cr isotopes around Cr-64 are prolately deformed but still possess transitional character; large-amplitude shape fluctuations dominate in their low-lying states.

    DOI: 10.1103/PhysRevC.86.024316

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  • Microscopic Analysis of Shape Coexistence/Mixing and Shape Phase Transition in Neutron-Rich Nuclei around Mg-32 査読

    Nobuo Hinohara, Koichi Sato, Kenichi Yoshida, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT   ( 196 )   328 - 333   2012年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    We have analyzed large-amplitude quadrupole collective dynamics in neutron-rich nuclei Mg30-36 using the five-dimensional quadrupole collective Hamiltonian approach. The collective Hamiltonian is microscopically derived with the constrained HFB plus local quasi-particle RPA method. Enhancement of the quadrupole collectivity from Mg-30 to Mg-34 is well described by the calculation. The shape transitional behavior in the ground band and the shape coexistence/mixing properties in the ground and excited 0(+) states are analyzed.

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  • Microscopic approach to large-amplitude deformation dynamics with local QRPA inertial masses 査読

    Koichi Sato, Nobuo Hinohara, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    RUTHERFORD CENTENNIAL CONFERENCE ON NUCLEAR PHYSICS, 2011   381   2012年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We have developed a new method for determining microscopically the five-dimensional quadrupole collective Hamiltonian, on the basis of the adiabatic self-consistent collective coordinate method. This method consists of the constrained Hartree-Fock-Bogoliubov (HFB) equation and the local QRPA (LQRPA) equations, which are an extension of the usual QRPA (quasiparticle random phase approximation) to non-HFB-equilibrium points, on top of the CHFB states. One of the advantages of our method is that the inertial functions calculated with this method contain the contributions of the time-odd components of the mean field, which are ignored in the widely-used cranking formula. We illustrate usefulness of our method by applying to oblate-prolate shape coexistence in Kr-72 and shape phase transition in neutron-rich Cr isotopes around N = 40.

    DOI: 10.1088/1742-6596/381/1/012103

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  • Shape fluctuations in the ground and excited 0(+) states of Mg-30,Mg-32,Mg-34 査読

    Nobuo Hinohara, Koichi Sato, Kenichi Yoshida, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    PHYSICAL REVIEW C   84 ( 6 )   2011年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Large-amplitude collective dynamics of shape phase transition in the low-lying states of Mg30-36 is investigated by solving the five-dimensional (5D) quadrupole collective Schrodinger equation. The collective masses and potentials of the 5D collective Hamiltonian are microscopically derived with use of the constrained Hartree-Fock-Bogoliubov plus local quasiparticle random phase approximation method. Good agreement with the recent experimental data is obtained for the excited 0(+) states as well as the ground bands. For Mg-30, the shape coexistence picture that the deformed excited 0(+) state coexists with the spherical ground state approximately holds. On the other hand, large-amplitude quadrupole-shaped fluctuations dominate in both the ground and the excited 0(+) states in Mg-32, providing a picture that is different from the interpretation of the "coexisting spherical excited 0(+) state" based on the naive inversion picture of the spherical and deformed configurations.

    DOI: 10.1103/PhysRevC.84.061302

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  • Anomalous pairing vibration in neutron-rich Sn isotopes beyond the N=82 magic number 査読

    Shimoyama Hirotaka, Matsuo Masayuki

    PHYSICAL REVIEW C   84 ( 4 )   2011年10月

  • Anomalous pairing vibration in neutron-rich Sn isotopes beyond the N=82 magic number 査読

    Hirotaka Shimoyama, Masayuki Matsuo

    PHYSICAL REVIEW C   84 ( 4 )   2011年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Two-neutron transfer associated with the pair correlation in superfluid neutron-rich nuclei is studied with focus on low-lying 0(+) states in Sn isotopes beyond the N = 82 magic number. We describe microscopically the two-neutron addition and removal transitions by means of the Skyrme-Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random phase approximation formulated in the coordinate space representation. It is found that the pair transfer strength for the transitions between the ground states becomes significantly large for the isotopes with A &gt;= 140, reflecting very small neutron separation energy and long tails of the weakly bound 3 p orbits. In (132) Sn-140, a peculiar feature of the pair transfer is seen in transitions to low-lying excited 0(+) states. They can be regarded as a kind of pair vibrational mode which is characterized by an anomalously long tail of the transition density extending to far outside of the nuclear surface, and a large strength comparable to that of the ground-state transitions. The presence of the weakly bound neutron orbits plays a central role for these anomalous behaviors.

    DOI: 10.1103/PhysRevC.84.044317

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  • Persistent contribution of unbound quasiparticles to the pair correlation in the continuum Skyrme-Hartree-Fock-Bogoliubov approach 査読

    Zhang Y, Matsuo M, Meng J

    PHYSICAL REVIEW C   83 ( 5 )   2011年5月

  • LOCAL QRPA VIBRATIONAL AND ROTATIONAL INERTIAL FUNCTIONS FOR LARGE-AMPLITUDE QUADRUPOLE COLLECTIVE DYNAMICS 査読

    N. Hinohara, K. Sato, T. Nakatsukasa, M. Matsuo

    ACTA PHYSICA POLONICA B   42 ( 3-4 )   443 - 446   2011年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:POLISH ACAD SCIENCES INST PHYSICS  

    A new microscopic approach is proposed to derive the five-dimensional quadrupole collective Hamiltonian. It is based on the time-dependent mean-field theory and the adiabatic self-consistent collective coordinate method. We apply the method to studies of oblate-prolate shape coexistence/mixing phenomena and anharmonic vibrations. Experimental data for Se isotopes are well reproduced.

    DOI: 10.5506/APhysPolB.42.443

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  • Fluctuation properties of the strength function associated with the giant quadrupole resonance in Pb-208

    Hirokazu Aiba, Masayuki Matsuo, Shigeru Nishizaki, Toru Suzuki

    PHYSICAL REVIEW C   83 ( 2 )   2011年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We performed fluctuation analysis by means of the local scaling dimension for the strength function of the isoscalar (IS) giant quadrupole resonance (GQR) in Pb-208 where the strength function is obtained by the shell model calculation including 1p1h and 2p2h configurations. It is found that at almost all energy scales, fluctuation of the strength function obeys the Gaussian orthogonal ensemble (GOE) random matrix theory limit. This is contrasted with the results for the GQR in Ca-40, where at the intermediate energy scale of about 1.7 MeV, a deviation from the GOE limit was detected. It is found that the physical origin for this different behavior of the local scaling dimension is ascribed to the difference in the properties of the damping process.

    DOI: 10.1103/PhysRevC.83.024314

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  • Microscopic description of large-amplitude shape-mixing dynamics with local QRPA inertial functions 査読

    Nobuo Hinohara, Koichi Sato, Kenichi Yoshida, Takashi Nakatsukasa, Masayuki Matsuo

    INTERNATIONAL SYMPOSIUM ON NEW FACES OF ATOMIC NUCLEI: FESTSCHRIFT IN HONOUR OF AKITO ARIMA'S 80TH BIRTHDAY   1355   2011年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    We introduce a microscopic approach to derive all the inertial functions in the five-dimensional quadrupole collective Hamiltonian. Local normal modes are evaluated on the constrained mean field in the quasiparticle random-phase approximation in order to derive the inertial functions. The collective Hamiltonians for neutron-rich Mg isotopes are determined with use of this approach, and the shape coexistence/mixing around the N = 20 region is analyzed.

    DOI: 10.1063/1.3584067

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  • ウェーブレット変換を用いた巨大共鳴強度関数のゆらぎの分析(大振幅集団運動の微視的理論,研究会報告)

    相場 浩和, 松尾 正之, 西崎 滋, 鈴野 浩大, 鈴木 徹

    素粒子論研究   119 ( 1 )   A119 - A128   2011年

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    記述言語:日本語   出版者・発行元:素粒子論グループ 素粒子論研究 編集部  

    DOI: 10.24532/soken.119.1_A119

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  • Microscopic description of large-amplitude shape-mixing dynamics with inertial functions derived in local quasiparticle random-phase approximation 査読

    Nobuo Hinohara, Koichi Sato, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    PHYSICAL REVIEW C   82 ( 6 )   2010年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    On the basis of the adiabatic self-consistent collective coordinate method, we develop an efficient microscopic method of deriving the five-dimensional quadrupole collective Hamiltonian and illustrate its usefulness by applying it to the oblate-prolate shape coexistence/mixing phenomena in proton-rich (68,70,72)Se. In this method, the vibrational and rotational collective masses (inertial functions) are determined by local normal modes built on constrained Hartree-Fock-Bogoliubov states. Numerical calculations are carried out using the pairing-plus-quadrupole Hamiltonian including the quadrupole-pairing interaction within the two major-shell active model spaces both for neutrons and protons. It is shown that the time-odd components of the moving mean-field significantly increase the vibrational and rotational collective masses in comparison with the Inglis-Belyaev cranking masses. Solving the collective Schrodinger equation, we evaluate excitation spectra, quadrupole transitions, and moments. The results of the numerical calculation are in excellent agreement with recent experimental data and indicate that the low-lying states of these nuclei are characterized as an intermediate situation between the oblate-prolate shape coexistence and the so-called gamma unstable situation where large-amplitude triaxial-shape fluctuations play a dominant role.

    DOI: 10.1103/PhysRevC.82.064313

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  • Surface-enhanced pair transfer amplitude in quadrupole states of neutron-rich Sn isotopes 査読

    Matsuo Masayuki, Serizawa Yasuyoshi

    PHYSICAL REVIEW C   82 ( 2 )   2010年8月

  • Surface-enhanced pair transfer amplitude in quadrupole states of neutron-rich Sn isotopes 査読

    Masayuki Matsuo, Yasuyoshi Serizawa

    PHYSICAL REVIEW C   82 ( 2 )   2010年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We investigate the neutron pair transfer modes associated with the low-lying quadrupole states in neutron-rich Sn isotopes by means of the quasiparticle random phase approximation based on the Skyrme-Hartree-Fock-Bogoliubov mean-field model. The transition strength of the quadrupole pair-addition mode feeding the 2(1)(+) state is enhanced in the Sn isotopes with A &gt;= 132. The transition density of the pair-addition mode has a large spatial extension in the exterior of the nucleus, reaching to r similar to 12-13 fm. The quadrupole pair-addition mode reflects sensitively a possible increase of the effective pairing interaction strength in the surface and exterior regions of neutron-rich nuclei.

    DOI: 10.1103/PhysRevC.82.024318

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  • MICROSCOPIC APPROACH TO ADIABATIC LARGE-AMPLITUDE QUADRUPOLE COLLECTIVE DYNAMICS IN Se ISOTOPES 査読

    Nobuo Hinohara, Koichi Sato, Takashi Nakatsukasa, Masayuki Matsuo

    MODERN PHYSICS LETTERS A   25 ( 21-23 )   1796 - 1799   2010年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    We develop an efficient microscopic method of deriving the five-dimensional quadrupole collective Hamiltonian on the basis of the adiabatic self-consistent collective coordinate method. We illustrate its usefulness by applying it to the oblate-prolate shape coexistence/mixing phenomena and anharmonic vibrations in Se isotopes.

    DOI: 10.1142/S0217732310000356

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  • PAIR VIBRATION 0(+) STATE IN NEUTRON-RICH Sn ISOTOPE: CONTINUUM QRPA ANALYSIS OF NEUTRON PAIR TRANSFER STRENGTH 査読

    Hirotaka Shimoyama, Masayuki Matsuo

    MODERN PHYSICS LETTERS A   25 ( 21-23 )   2024 - 2025   2010年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    We discuss the pair transfer mode populating pair vibration 0(2)(+) state in neutron-rich Sn isotopes by means of the continuum quasi particle random phase approximation (continuum QRPA). It is seen that the strength of the two-neutron addition transfer from the ground state to the 0(2)(+) state is significantly enhanced beyond the N = 82 shell gap.

    DOI: 10.1142/S0217732310000964

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  • PHENOMENOLOGICAL ANALYSIS OF THE OBLATE-PROLATE SYMMETRY BREAKING IN TRIAXIAL DEFORMATION DYNAMICS 査読

    Koichi Sato, Nobuo Hinohara, Takashi Nakatsukasa, Masayuki Matsuo

    MODERN PHYSICS LETTERS A   25 ( 21-23 )   2018 - 2019   2010年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    From a viewpoint of oblate-prolate symmetry and its breaking, we propose a simple model based on the quadrupole collective Hamiltonian to study dynamics of triaxial deformation in shape coexistence phenomena. The numerical results suggest that the oblate-prolate symmetry breaking in the rotational moments of inertia can play an important role for the oblate-prolate shape coexistence as well as that in the collective potential.

    DOI: 10.1142/S0217732310000939

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  • MICROSCOPIC ANALYSIS OF SHAPE MIXING IN LOW-LYING STATES OF PROTON-RICH Kr ISOTOPES 査読

    Koichi Sato, Nobuo Hinohara, Takashi Nakatsukasa, Masayuki Matsuo

    MODERN PHYSICS LETTERS A   25 ( 21-23 )   2020 - 2021   2010年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    We develop a method of determining microscopically the collective potential and inertial masses in the five-dimensional quadrupole collective Hamiltonian on the basis of the adiabatic self-consistent collective coordinate method. We apply this method to shape coexistence/mixing phenomena in low-lying states of the proton-rich Kr isotopes.

    DOI: 10.1142/S0217732310000940

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  • Open problems in the microscopic theory of large-amplitude collective motion 査読

    K. Matsuyanagi, M. Matsuo, T. Nakatsukasa, N. Hinohara, K. Sato

    JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS   37 ( 6 )   2010年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Construction of the microscopic theory of large-amplitude collective motion, capable of describing a wide variety of quantum collective phenomena in nuclei, is a long-standing and fundamental subject in the study of nuclear many-body systems. The present status of the challenge toward this goal is discussed taking the shape coexistence/mixing phenomena as typical manifestations of the large-amplitude collective motion at zero temperature. Some open problems in rapidly rotating cold nuclei are also briefly discussed in this connection.

    DOI: 10.1088/0954-3899/37/6/064018

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  • Open problems in nuclear structure near drip lines 査読

    Masayuki Matsuo, Takashi Nakatsukasa

    JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS   37 ( 6 )   2010年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Physics related to weakly bound nuclei and low-density asymmetric nuclear matter is discussed from a theoretical point of view. Especially, we focus our discussion on new correlations in nuclei near the drip lines and on open issues of the density functional theory with a proper account of the continuum.

    DOI: 10.1088/0954-3899/37/6/064017

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  • Large–amplitude quadrupole collective dynamics in Se and Kr isotopes 査読

    N. Hinohara, K. Sato, T. Nakatsukasa, M. Matsuo

    Hadron and Nuclear Physics 09: Osaka University, Japan, 16-19 November 2009   331 - 339   2010年1月

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    記述言語:英語   掲載種別:論文集(書籍)内論文   出版者・発行元:World Scientific Publishing Co.  

    Large-amplitude oblate-prolate shape coexistence dynamics in proton-rich Se and Kr isotopes is analyzed using the five-dimensional quadrupole collective Hamiltonian. The potential and inertial functions in the collective Hamiltonian are calculated using the constrained Hartree-Fock-Bogoliubov (CHFB) equation and the local quasiparticle random-phase approximation (LQRPA). The excitation spectra and the electric quadrupole transitions between the low-lying states in 68Se are calculated by solving the collective Schrodinger equation, and the shape mixing dynamics in the low-lying collective states are discussed.

    DOI: 10.1142/9789814313933_0042

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  • A Model Analysis of Triaxial Deformation Dynamics in Oblate-Prolate Shape Coexistence Phenomena 査読

    Koichi Sato, Nobuo Hinohara, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    PROGRESS OF THEORETICAL PHYSICS   123 ( 1 )   129 - 155   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    From the viewpoint of oblate-prolate symmetry and its breaking, we adopt the quadrupole collective Hamiltonian to study the dynamics of triaxial deformation in shape coexistence phenomena. It accommodates the axially symmetric rotor model, the gamma-unstable model, the rigid triaxial rotor model, and an ideal situation for the oblate-prolate shape coexistence as particular cases. Numerical solutions of this model yield a number of interesting suggestions. (1) The relative energy of the excited 0(+) state can be a signature of the potential shape along the gamma direction. (2) Specific E2 transition probabilities are sensitive to the breaking of the oblate-prolate symmetry. (3) Nuclear rotation may induce the localization of collective wave functions in the (beta, gamma) deformation space.

    DOI: 10.1143/PTP.123.129

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  • Microscopic derivation of five-dimensional collective Hamiltonian of large-amplitude quadrupole motion: application to shape coexistence in proton-rich Se isotopes 査読

    Nobuo Hinohara, Koichi Sato, Takashi Nakatsukasa, Masayuki Matsuo

    NUCLEAR PHYSICS TRENDS   1235   96 - +   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    We present a new microscopic approach which consists of the constrained Hartree-Fock-Bogoliubov (CHFB) and the local quasiparticle random-phase approximation (LQRPA) to construct the five-dimensional quadrupole collective Hamiltonian for large-amplitude collective dynamics. The excitation spectra and the electric quadrupole transitions between the low-lying states in Se-68 are calculated by solving the collective Schrodinger equation.

    DOI: 10.1063/1.3442638

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  • Pair correlations and pair transfers in neutron-rich nuclei 査読

    Masayuki Matsuo, Hirotaka Shimoyama, Hiroshi Oba

    NUCLEAR PHYSICS TRENDS   1235   9 - +   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    Features of the neutron pair correlation characteristic to neutron-rich nuclei are discussed on the basis of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random phase approximations. We discuss the monopole and quadrupole pair transfer modes in neutron-rich Sn isotopes beyond the N = 82 shell closure. We investigate also how the pair correlation behaves in deformed weakly bound nuclei, and we show that the neutron pairing enhances as the binding energy of neutrons becomes small.

    DOI: 10.1063/1.3442639

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  • Large-amplitude quadrupole collective dynamics of shape coexistence phenomena in proton-rich Se and Kr isotopes 査読

    Nobuo Hinohara, Koichi Sato, Takashi Nakatsukasa, Masayuki Matsuo

    TOURS SYMPOSIUM ON NUCLEAR PHYSICS AND ASTROPHYSICS - VII   1238   286 - +   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    The five-dimensional quadrupole collective Hamiltonian for large-amplitude collective dynamics is microscopically constructed by the constrained Hartree-Fock-Bogoliubov (CHFB) method and local quasiparticle random phase approximation (LQRPA). The excitation spectra and the electric quadrupole transitions between the low-lying states in Se-68 are calculated by solving the collective Schrodinger equation.

    DOI: 10.1063/1.3455952

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  • CONTINUUM COUPLING AND PAIR CORRELATION IN WEAKLY BOUND DEFORMED NUCLEI 査読

    Hiroshi Oba, Masayuki Matsuo

    INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS   18 ( 10 )   2015 - 2019   2009年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    We formulate a new Hartree-Fock-Bogoliubov method applicable to weakly bound deformed nuclei using the coordinate-space Green&apos;s function technique. An emphasis is put on treatment of quasiparticle states in the continuum, on which we impose the correct boundary condition of the asymptotic out-going wave. We illustrate this method with numerical examples.

    DOI: 10.1142/S0218301309014202

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  • Continuum Hartree-Fock-Bogoliubov theory for weakly bound deformed nuclei using the coordinate-space Green's function method 査読

    Oba Hiroshi, Matsuo Masayuki

    PHYSICAL REVIEW C   80 ( 2 )   2009年8月

  • Continuum Hartree-Fock-Bogoliubov theory for weakly bound deformed nuclei using the coordinate-space Green&apos;s function method 査読

    Hiroshi Oba, Masayuki Matsuo

    PHYSICAL REVIEW C   80 ( 2 )   2009年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We formulate a new scheme of the Hartree-Fock-Bogoliubov mean-field theory applicable to weakly bound and pair-correlated deformed nuclei using the coordinate-space Green&apos;s function technique. On the basis of a coupled-channel representation of the quasiparticle wave function expanded in terms of the partial waves, we impose the correct boundary condition of the asymptotically out-going waves on the continuum quasiparticle states. We perform numerical analysis for (38)Mg to illustrate properties of the continuum quasiparticle states and the pair correlation in deformed nuclei near the neutron drip line.

    DOI: 10.1103/PhysRevC.80.024301

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  • Microscopic description of oblate-prolate shape mixing in proton-rich Se isotopes 査読

    Nobuo Hinohara, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    PHYSICAL REVIEW C   80 ( 1 )   2009年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The oblate-prolate shape coexisting/mixing phenomena in proton-rich (68,70,72)Se are investigated by means of the adiabatic self-consistent collective coordinate (ASCC) method. The one-dimensional collective path and the collective Hamiltonian describing the large-amplitude shape vibration are derived in a fully microscopic way. The excitation spectra, B(E2) and spectroscopic quadrupole moments are calculated by requantizing the collective Hamiltonian and solving the collective Schroumldinger equation. The basic properties of the coexisting two rotational bands in low-lying states of these nuclei are well reproduced. It is found that the oblate-prolate shape mixing becomes weak as the rotational angular momentum increases. We point out that the rotational energy plays a crucial role in causing the localization of the collective wave function in the (beta,gamma) deformation space.

    DOI: 10.1103/PhysRevC.80.014305

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  • Rotation and shape changes in Tb-151 and Pb-196: Probes of nuclear structure and tunneling process in warm nuclei. II. Microscopic Monte Carlo simulation 査読

    S. Leoni, G. Benzoni, N. Blasi, A. Bracco, F. Camera, A. Corsi, F. C. L. Crespi, P. Mason, B. Million, D. Montanari, M. Pignanelli, E. Vigezzi, O. Wieland, M. Matsuo, Y. R. Shimizu, D. Curien, G. Duchene, J. Robin, P. Bednarczyk, M. Castoldi, B. Herskind, M. Kmiecik, A. Maj, W. Meczynski, J. Styczen, M. Zieblinski, K. Zuber, A. Zucchiatti

    PHYSICAL REVIEW C   79 ( 6 )   064307   2009年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    A Monte Carlo simulation of the gamma decay of superdeformed nuclei has been developed. It is based on microscopic calculations for the energy levels, E2 decay probabilities, collective mass parameters, and potential energy barriers. The use of microscopically calculated quantities largely reduces the parameters of the simulation, allowing one to focus on the basic ingredients of the physical processes. Calculations are performed for the warm rotating superdeformed nuclei Tb-151 and Pb-196, for which high statistics Euroball IV data are available. The dependence on the simulation parameters is investigated, together with the basic features of the microscopic calculations.&lt;/p&gt;.

    DOI: 10.1103/PhysRevC.79.064307

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  • Rotation and shape changes in Tb-151 and Pb-196: Probes of nuclear structure and tunneling process in warm nuclei. I. Experimental analysis

    S. Leoni, G. Benzoni, N. Blasi, A. Bracco, F. Camera, A. Corsi, F. C. L. Crespi, P. Mason, B. Million, D. Montanari, M. Pignanelli, E. Vigezzi, O. Wieland, M. Matsuo, Y. R. Shimizu, D. Curien, G. Duchene, J. Robin, P. Bednarczyk, M. Castoldi, B. Herskind, M. Kmiecik, A. Maj, W. Meczynski, J. Styczen, M. Zieblinski, K. Zuber, A. Zucchiatti

    PHYSICAL REVIEW C   79 ( 6 )   064306   2009年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The gamma decay associated with the warm rotation of the superdeformed nuclei Tb-151 and Pb-196 has been measured with the Euroball IV array. Several experimental quantities are presented, putting strong constraints on the decay dynamics in the superdeformed well. The data are successfully reproduced using a Monte Carlo simulation of the gamma decay based on microscopically calculated energy levels, E2 decay probabilities, collective mass parameters, and potential energy barriers between the wells associated with normal and super deformation. This allows one to test the basic ingredients of the physical process, such as the strength of the two-body residual interaction and the potential barriers as a function of spin and excitation energy. We also show that the data probe the E1 strength function, indicating an enhancement around 1-2 MeV gamma rays, which might be related to octupole vibrations.&lt;/p&gt;.

    DOI: 10.1103/PhysRevC.79.064306

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  • Continuum quasiparticle linear response theory using the Skyrme functional for multipole responses of exotic nuclei 査読

    Mizuyama Kazuhito, Matsuo Masayuki, Serizawa Yasuyoshi

    PHYSICAL REVIEW C   79 ( 2 )   2009年2月

  • Continuum quasiparticle linear response theory using the Skyrme functional for multipole responses of exotic nuclei 査読

    Kazuhito Mizuyama, Masayuki Matsuo, Yasuyoshi Serizawa

    PHYSICAL REVIEW C   79 ( 2 )   2009年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We develop a new formulation of the continuum quasiparticle random-phase approximation in which the velocity-dependent terms of the Skyrme effective interaction are explicitly treated except the spin-dependent and the Coulomb terms. Numerical analysis using the SkM(*) parameter set is performed for the isovector dipole and the isovector/isoscalar quadrupole responses in (20)O and (54)Ca. It is shown that the energy-weighted sum rule, including the enhancement factors for the isovector responses, is satisfied with good accuracy. We investigate also how the velocity-dependent terms influence the strength distribution and the transition densities of the low-lying surface modes and the giant resonances.

    DOI: 10.1103/PhysRevC.79.024313

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  • Di-Neutron Correlation in Soft Octupole Excitations of Neutron-Rich Ni Isotopes beyond N=50 査読

    Yasuyoshi Serizawa, Masayuki Matsuo

    PROGRESS OF THEORETICAL PHYSICS   121 ( 1 )   97 - 119   2009年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    We investigate the low-lying octupole response of neutron-rich Ni isotopes beyond the N = 50 shell closure using the Skyrme-Hartree-Fock-Bogoliubov mean fields and the continuum quasi-particle random phase approximation. Performing detailed numerical analyses employing the Skyrme parameter set SLy4 and a density-dependent delta interaction of the mixed type, we show that a neutron mode emerges above the neutron separation energy as a consequence of the weak binding of neutrons and that it strongly influences the di-neutron correlation.

    DOI: 10.1143/PTP.121.97

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  • Coupled-Channel Green&apos;s Function Approach to Deformed Continuum Hartree-Fock-Bogoliubov Theory 査読

    Hiroshi Oba, Masayuki Matsuo

    NUCLEAR STRUCTURE AND DYNAMICS &apos;09   1165   263 - 266   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    We formulate the coordinate-space Hartree-Fock-Bogoliubov (HFB) theory which can describe pair correlated and deformed nuclei near the drip-lines. In order to ensure the correct asymptotic form of weakly bound and continuum quasiparticle states, we adopt a coupled-channel representation based on the partial wave expansion, and then we construct the exact HFB Green&apos;s function. Numerical examples calculated for (38)Mg are discussed.

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  • Collective path and inertial mass of large-amplitude collective dynamics: Application to shape coexistence 査読

    Nobuo Hinohara, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    4TH INTERNATIONAL WORKSHOP ON NUCLEAR FISSION AND FISSION-PRODUCT SPECTROSCOPY   1175   49 - +   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    Large-amplitude collective dynamics of oblate-prolate shape coexistence in the low-lying states of proton-rich Se-68,Se-70,Se-72 are studied. The collective path (collective submanifold) is extracted from the time-dependent Hartree-Fock-Bogoliubov (HFB) manifold by use of the adiabatic self-consistent collective coordinate (ASCC) method. The inertial functions for the large-amplitude collective vibration along the collective path and for the three-dimensional rotation are microscopically calculated. Solving the collective Schrodinger equation, excitation spectra, E2 transition probabilities, and spectroscopic quadrupole moments are evaluated.

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  • Probing the order-to-chaos region in superdeformed (151)Tb and (196)Pb nuclei with continuum gamma transitions

    S. Leoni, G. Benzoni, N. Blasi, A. Bracco, S. Brambilla, F. Camera, A. Corsi, F. C. L. Crespi, P. Mason, B. Million, D. Montanari, M. Pignanelli, E. Vigezzi, O. Wieland, M. Matsuo, Y. R. Shimizu, D. Curien, G. Duchene, J. Robin, P. Bednarczyk, M. Castoldi, B. Herskind, M. Kmiecik, A. Maj, W. Meczynski, J. Styczen, M. Zieblinski, K. Zuber, A. Zucchiatti

    PHYSICAL REVIEW LETTERS   101 ( 14 )   142502   2008年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The gamma decay associated with the warm rotation of the superdeformed nuclei (151)Tb and (196)Pb has been measured with the EUROBALL IV array. Several independent quantities provide a stringent test of the population and decay dynamics in the superdeformed well. A Monte Carlo simulation of the gamma decay based on microscopic calculations gives remarkable agreement with the data only assuming a large enhancement of the B(E1) strength for 1-2 MeV gamma rays, which may be related to the evidence for octupole vibrations in both mass regions.

    DOI: 10.1103/PhysRevLett.101.142502

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  • Deformation around neutron-rich Cr isotopes in axially symmetric Skyrme-Hatree-Fock-Bogoliubov method 査読

    Hiroshi Oba, Masayuki Matsuo

    PROGRESS OF THEORETICAL PHYSICS   120 ( 1 )   143 - 157   2008年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    We analyse the deformation mechanism in neutron-rich Cr, Fe and Ti isotopes with N = 32-44 using a Skyrme-Hartree-Fock-Bogoliubov mean-field code employing a two-dimensional mesh representation in the cylindrical coordinate system. Evaluating the quadrupole deformation energy systematically; we show that the Skyrme parameter set SkM* gives a quadrupole instability around the neutron numbers N similar to 38-42 in Cr isotopes, where the deformation energy curve suggests a transitional behavior with a shallow minimum extending to a. large prolate deformation. The roles of a deformed N = 38 gap and the position of the neutron g(9/2) orbit are analysed in detail.

    DOI: 10.1143/PTP.120.143

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  • Microscopic derivation of collective Hamiltonian by means of the adiabatic self-consistent collective coordinate method 査読

    Nobuo Hinohara, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    PROGRESS OF THEORETICAL PHYSICS   119 ( 1 )   59 - 101   2008年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    The microscopic dynamics of oblate-prolate shape coexistence/mixing phenomena in (68) Se and Kr-72 are studied by means of the adiabatic self-consistent collective coordinate (ASCC) method in conjunction with the pairing-plus-quadrupole (P + Q) Hamiltonian, including the quadrupole pairing interaction. A quantum collective Hamiltonian is constructed, and excitation spectra, spectroscopic quadrupole moments and quadrupole transition properties are evaluated. The effect of the time-odd pair field on the collective mass (inertia function) of the large-amplitude vibration and the rotational moments of inertia about three principal axes is evaluated. It is found that the basic properties of the shape coexistence/mixing are qualitatively reproduced. The results of the calculation indicate that the oblate-prolate shape mixing decreases as the angular momentum increases.

    DOI: 10.1143/PTP.119.59

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  • Pairing collectivity in medium-mass neutron-rich nuclei near drip-line 査読

    M. Matsuo, Y. Serizawa, K. Mizuyama

    NUCLEAR PHYSICS A   788   307C - 315C   2007年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We look for collective excitations originating from the strong surface pairing in unstable nuclei near the neutron drip-line. The soft dipole excitation is such a pairing mode as it exhibits a character of core-vs-dineutron motion. Possibility of the hydrodynamic phonon mode (the Anderson-Bogoliubov mode) is also discussed.

    DOI: 10.1016/j.nuelphysa.2007.01.017

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  • Gauge-invariant formulation of the adiabatic self-consistent collective coordinate method 査読

    Nobuo Hinohara, Takashi Nakatsukasa, Masayuki Matsuo, Kenichi Matsuyanagi

    PROGRESS OF THEORETICAL PHYSICS   117 ( 3 )   451 - 478   2007年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    The adiabatic self-consistent collective coordinate (ASCC) method is a practical microscopic theory of large-amplitude collective motion in nuclei with superfluidity. We show that its basic equations are invariant under transformations involving the gauge angle in particle-number space. By virtue of this invariance, a clean separation of the large-amplitude collective motion and the pairing rotational motion can be made, and this allows us to restore the particle-number symmetry broken by the Hartree-Fock-Bogoliubov (HFB) approximation. We formulate the ASCC method explicitly in a gauge-invariant form. In solving the ASCC equations, it is necessary to fix the gauge. Applying this new formulation to the multi-O(4) model, we compare different gauge-fixing procedures and demonstrate that calculations using different gauges indeed yield the same results for gauge-invariant quantities, such as the collective path and quantum spectra. We propose a gauge-fixing prescription that seems most convenient in realistic calculations.

    DOI: 10.1143/PTP.117.451

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  • New pairing collectivity : surface di-neutron mode in neutron-rich nuclei(International Workshop on Nuclear Structure-New Pictures in the Extended Isospin Space(NS07)-)

    Matsuo Masayuki, Serizawa Yasuyoshi, Mizuyama Kazuhito

    素粒子論研究   115 ( 3 )   C88   2007年

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    記述言語:英語   出版者・発行元:素粒子論グループ 素粒子論研究 編集部  

    DOI: 10.24532/soken.115.3_C88

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  • Continuum quasiparticle linear response theory using the realistic Skyrme functional for multipole response of exotic nuclei(International Workshop on Nuclear Structure-New Pictures in the Extended Isospin Space(NS07)-)

    MIZUYAMA KAZUHITO, MATSUO MASAYUKI, SERIZAWA YASUYOSHI

    素粒子論研究   115 ( 3 )   C45   2007年

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    記述言語:英語   出版者・発行元:素粒子論グループ 素粒子論研究 編集部  

    DOI: 10.24532/soken.115.3_C45

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  • Effects of time-odd components in mean field on large amplitude collective dynamics 査読

    N Hinohara, T Nakatsukasa, M Matsuo, K Matsuyanagi

    PROGRESS OF THEORETICAL PHYSICS   115 ( 3 )   567 - 599   2006年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    We apply the adiabatic self-consistent collective coordinate (ASCC) method to the multi-O(4) model and study the collective mass (inertia function) of many-body tunneling motion. Comparing the results with those obtained from the exact diagonalization, we show that the ASCC method is capable of describing the gradual change of the excitation spectra from an anharmonic vibration about a spherical shape to a doublet pattern associated with a deformed double-well potential possessing oblate-prolate symmetry. It is found that the collective mass is significantly increased by the quadrupole-pairing contribution to time-odd components of the moving mean field. In contrast, the cranking (Inglis-Belyaev) mass based on the constrained mean field, which ignores the time-odd components, is smaller than the ASCC mass and fails to reproduce the exact spectra.

    DOI: 10.1143/PTP.115.567

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  • Collective path connecting the oblate and prolate local minima in proton-rich N = Z nuclei around 68Se 査読

    M. Kobayasi, T. Nakatsukasa, M. Matsuo, K. Matsuyanagi

    European Physical Journal A   25 ( 1 )   547 - 548   2005年9月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    By means of the adiabatic self-consistent collective coordinate method and the pairing-plus-quadrupole interaction, we have for the first time obtained a self-consistent collective path connecting the oblate and prolate local minima in 68Se and 72Kr. This self-consistent collective path is found to run approximately along the valley connecting the oblate and prolate local minima in the collective potential energy landscape. The result of this calculation clearly indicates the importance of triaxial deformation dynamics in oblate-prolate shape coexistence phenomena. © Società Italiana di Fisica / Springer-Verlag 2005.

    DOI: 10.1140/epjad/i2005-06-039-7

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  • Di-neutron correlation and soft dipole excitation in medium mass neutron-rich nuclei near drip line 査読

    M Matsuo, K Mizuyama, Y Serizawa

    PHYSICAL REVIEW C   71 ( 6 )   2005年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    The neutron pairing correlation and the soft dipole excitation in medium mass nuclei near the drip line are investigated from the viewpoint of the di-neutron correlation. Numerical analyses based on the coordinate-space Hartree-Fock-Bogoliubov method and the continuum quasiparticle random phase approximation are performed for even-even O18-24,Ca50-58, and Ni80-86. A clear signature of the di-neutron correlation is found in the ground state; two neutrons are correlated at short relative distances less than or similar to 2 fm with large probability similar to 50%. The soft dipole excitation is influenced strongly by the neutron pairing correlation, and it accompanies a large transition density for pair motion of neutrons. This behavior originates from a coherent superposition of two-quasiparticle configurations [l x (l + 1)](L=1) consisting of continuum states with high orbital angular momenta l reaching an order of l similar to 10. It suggests that the soft dipole excitation under the influence of neutron pairing is characterized by the motion of di-neutron in the nuclear exterior against the remaining A-2 subsystem. Sensitivity to the density dependence of the effective pair force is discussed.

    DOI: 10.1103/PhysRevC.71.064326

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  • Collective paths connecting the oblate and prolate shapes in Se-68 and Kr-72 suggested by the adiabatic self-consistent collective coordinate method 査読

    M Kobayashi, T Nakatsukasa, M Matsuo, K Matsuyanagi

    PROGRESS OF THEORETICAL PHYSICS   113 ( 1 )   129 - 152   2005年1月

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    記述言語:英語   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    By means of the adiabatic self-consistent collective coordinate method and the pairing-plus-quadrupole interaction, we have for the first time obtained a self-consistent collective path connecting the oblate and prolate local minima in Se-68 and Kr-72. This self-consistent collective path is found to run approximately along the valley connecting the oblate and prolate local minima in the collective potential energy landscape. The result of this calculation clearly indicates the importance of triaxial deformation dynamics in oblate-prolate shape coexistence phenomena.

    DOI: 10.1143/PTP.113.129

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  • Di-neutron correlations in medium-mass neutron-rich nuclei near the dripline 査読

    M Matsuo, K Mizuyama, Y Serizawa

    EUROPEAN PHYSICAL JOURNAL A   25   563 - 565   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    On the basis of the coordinate-space Hartree-Fock-Bogoliubov and the continuum quasiparticle random phase approximation (QRPA) theories, we demonstrate that a di-neutron correlation exists in the ground states of medium-mass neutron-rich nuclei near the dripline, and we suggest that the soft dipole excitation has the character of di-neutron motion against the remaining A - 2 subsystem.

    DOI: 10.1140/epjad/i2005-06-045-9

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  • Di-neutron dynamics in medium-mass neutron-rich nuclei 査読

    M Matsuo, Y Serizawa, K Mizuyama

    International Symposium on Correlation Dynamics in Nuclei   20   113 - 118   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    Investigating the pair correlation in medium-mass nuclei near the neutron drip-line, we find that the pairing involving several weakly bound neutrons exhibits a significant spatial correlation of the di-neutron type. We suggest that the strong spatial correlation is an inherent property of the pair correlation in nuclear matters at low densities. The di-neutron correlation influences strongly properties of the soft dipole and octupole excitations of the neutron-rich nuclei.

    DOI: 10.1088/1742-6596/20/1/019

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  • Collective path connecting the oblate and prolate local minima in Se-68 査読

    M Kobayasi, T Nakatsukasa, M Matsuo, K Matsuyanag

    PROGRESS OF THEORETICAL PHYSICS   112 ( 2 )   363 - 368   2004年8月

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    記述言語:英語   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    By means of the adiabatic self-consistent collective coordinate method and the pairing-plus-quadrupole interaction, we have obtained a self-consistent collective path connecting the oblate and prolate local minima in Se-68 for the first time. The result of the calculation indicates the importance of triaxial deformation dynamics in oblate-prolate shape coexistence phenomena.

    DOI: 10.1143/PTP.112.363

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  • Violation and persistence of the K-quantum number in warm rotating nuclei 査読

    M Matsuo, T Dossing, A Bracco, GB Hagemann, B Herskind, S Leoni, E Vigezzi

    NUCLEAR PHYSICS A   736 ( 3-4 )   223 - 240   2004年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The validity of the K-quantum number in rapidly rotating warm nuclei is investigated as a function of thermal excitation energy U and angular momentum I, for the rare-earth nucleus Er-163. The quantal eigenstates are described with a shell model which combines a cranked Nilsson mean-field and a residual two-body interaction, together with a term which takes into account the angular momentum carried by the K-quantum number in an approximate way. K-mixing is produced by the interplay of the Coriolis interaction and the residual interaction; it is weak in the region of the discrete rotational bands (U less than or similar to 1 MeV), but it gradually increases until the limit of complete violation of the K-quantum number is approached around U similar to 2-2.5 MeV The calculated matrix elements between bands having different K-quantum numbers decrease exponentially as a function of DeltaK, in qualitative agreement with recent data. (C) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.nuclphysa.2004.03.004

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  • 中性子過剰核の対相関とソフト双極子励起

    松尾 正之, 芹澤 保吉, 水山 一仁

    日本物理学会誌   59 ( 2 )   96 - 100   2004年

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    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    ドリップライン近傍の中性子過剰核は,弱く束縛した核子を含む点で安定核とは著しく異なる.このような特異な系では新しい特徴をもった核子相関が現れるのではないだろうか?中性子対相関と中性子過剰核特有の励起モードであるソフト双極子励起を例に論じる.

    DOI: 10.11316/butsuri1946.59.96

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  • Chaotic dynamics in warm rotating nuclei 査読

    M Matsuo, E Vigezzi, S Leoni, A Bracco, G Benzoni, T Dossing, B Herskind, GB Hagemann, A Lopez-Martens, TL Khoo

    LABYRINTH IN NUCLEAR STRUCTURE   701   157 - 163   2004年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    Properties of thermally excited rotating nuclei are discussed by means of the cranked shell model. Focus is put on the violation of the K-quantum number in the rare-earth deformed nucleus Er-163 and on the peculiar features of rotational motion in superdeformed Hg nuclei, which appear to be precursory of ergodic rotational bands.

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  • Di-neutron correlation and soft dipole excitation in medium mass nuclei near neutron drip-line 査読

    M Matsuo, K Mizuyama, Y Serizawa

    NEW ERA OF NUCLEAR STRUCTURE PHYSICS   246 - 250   2004年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    Pair correlation effects on the soft dipole excitation in medium mass nuclei near neutron drip-line are investigated by means of the continuum quasiparticle random phase approximation. The correlation of di-neutron type found in the ground state affects strongly the soft dipole excitation, and enhances the transition amplitude for two-neutron pair transfer.

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  • Pair correlation and collective excitations: Continuum QRPA approach to exotic nuclei near drip-line 査読

    M Matsuo

    FRONTIERS OF COLLECTIVE MOTIONS (CM2002)   312 - 317   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    By using the continuum quasiparticle random phase approximation, which we recently formulated on the basis of the coordinate-space Hartree-Fock-Bogoliubov theory, we investigate pairing effects on the low-lying dipole strength in neutron rich oxygen isotopes near the drip-line. The neutron pairing enhances the dipole strength near the threshold, especially in the case of the surface pairing. Analysis shows that spatially correlated spin-singlet neutron pairs (di-neutrons) are formed in the external region, and the low-lying dipole strength is characterized by motion of the correlated neutron pairs against the core.

    DOI: 10.1142/9789812703972_0039

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  • Experimental study of the nuclear rotational motion with statistical analysis methods 査読

    S Leoni, A Bracco, S Frattini, G Montingelli, E Vigezzi, T Dossing, B Herskind, M Matsuo

    NUCLEAR PHYSICS A   649   361C - 369C   1999年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The gamma-decay of excited rotating nuclei in the high level density region a few MeV above the yrast line has been studied through a statistical analysis of the fluctuation of counts in gamma-gamma coincident spectra. In particular, making use of the covariance technique between spectra gated by different intrinsic configurations, one can measure how the cascades feeding into different selected bands are similar. The aim is to learn about the transition between order to chaos in the nuclear many-body system, in terms of the validity of selection rules associated with the quantum numbers of the intrinsic structure. Experimental results on the nucleus Yb-164 are presented and compared to model predictions based on cranked shell model calculations including a two-body residual interaction.

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  • Nuclear structure and selection rules in the rotational quasi-continuum 査読

    S Leoni, A Bracco, S Frattini, G Montingelli, E Vigezzi, T Dossing, B Herskind, M Matsuo

    ACTA PHYSICA POLONICA B   30 ( 3 )   511 - 517   1999年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS  

    The gamma-decay of excited rotating nuclei is studied as function of heat energy through a statistical analysis of the fluctuation of counts in gamma-gamma coincident spectra. In particular, making use of the covariance technique between spectra gated by different intrinsic configurations, one can find if there are similarities among cascades feeding into different selected bands. This can be used to learn about the transition between order to chaos in the nuclear many-body system, in terms of the validity of selection rules associated with the quantum numbers of the intrinsic structure. Experimental results on the nucleus Yb-164 Seem to indicate a possible weakening of the selection rules already at the moderate excitation energy greater than or equal to 1 MeV above yrast, probed by the rotational decay-flow.

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  • Interacting excited rotational bands 査読

    T Dossing, B Herskind, GB Hagemann, A Harsmann, S Tormanen, S Odegard, M Matsuo, E Vigezzi, RA Broglia

    NUCLEAR PHYSICS A   649   370C - 378C   1999年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The role of the rotating mean field and residual interactions is discussed on the basis of recent experimental interaction matrix elements and distribution of level distances. Based on a careful identification of the rotational bands in four rare-earth nuclei, carried out earlier, most of the interactions are found to be generated by a two-body residual interaction. Some hindrance is observed with respect to changes in the K quantum number. Level distance distributions address in a more general way the question of the independence of excitations within rotational states. Both types of experimental information, band interactions and level distances, are in general accordance with mean field bands interacting with a standard surface-delta interaction.

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  • Microscopic structure of rotational damping 査読

    M Matsuo, K Yoshida, T Dossing, E Vigezzi, RA Broglia

    NUCLEAR PHYSICS A   649   379C - 386C   1999年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The damping of collective rotational motion is studied microscopically, making use of shell model calculations based on the cranked Nilsson deformed mean-field and on residual two-body interactions, and focusing on the shape of the gamma-gamma correlation spectra and on its systematic behavior. It is shown that the spectral shape is directly related to the damping width of collective rotation, Gamma(rot), and to the spreading width of many-particle many-hole configurations, Gamma(mu). The rotational damping width is affected by the shell structure, and is very sensitive to the position of the Fermi surface, besides mass number, spill and deformation. This produces a rich variety of features in the rotational damping phenomena.

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  • Non-axial octupole deformations of N = Z nuclei in A similar to 60-80 mass region 査読

    M Matsuo, S Takami, K Yabana

    NUCLEAR STRUCTURE 98   481   345 - 352   1999年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    By performing a fully three dimensional Hartree-Fock calculation with use of the Skyrm forces, we demonstrate possibility of exotic deformations violating both the reflection and the axial symmetries of N = Z nuclei in A similar to 60 - 80 mass region. The Y-32 tetrahedral shape predicted in excited Zr-80 arises from a shell gap at N, Z = 40 which is enhanced for the tetrahedron deformation. Softness toward the Y-33 triangular deformation of the oblate state in Se-68 is also predicted.

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  • Rotation of highly excited nuclei: Mass dependence of rotational damping 査読

    B Million, S Frattini, A Bracco, S Leoni, F Camera, N Blasi, G Lo Bianco, M Pignanelli, E Vigezzi, B Herskind, T Dossing, M Bergstrom, P Varmette, S Tormanen, A Maj, M Kmiecik, DR Napoli, M Matsuo

    EXPERIMENTAL NUCLEAR PHYSICS IN EUROPE   495   225 - 228   1999年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    The gamma-decay of the continuum has been measured in two mass regions. The excitation function of the continuum decay as well as spectral shape and fractional Doppler shifts are discussed for both Te-114 and Yb-164 compound nuclei, and show the typical features of rotational collective motion. Moreover, in both cases an upper limit of Gamma(rot) is given and the number of decay-paths is determined from the fluctuation analysis method. Simulations based on microscopic calculations of the rotational damping model reproduce quite well the experimental findings for both N-path and the scaling of Gamma(rot) as a function of the mass number.

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  • Tetrahedron and triangular prism shapes of Z=N nuclei in mass region A similar to 60-80 査読

    S Takami, K Yabana, M Matsuo

    PROCEEDINGS OF THE XVII RCNP INTERNATIONAL SYMPOSIUM ON INNOVATIVE COMPUTATIONAL METHODS IN NUCLEAR MANY-BODY PROBLEMS   372 - 374   1998年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    We study static non-axial octupole deformations in proton-rich Z = N nuclei, Ge-64, Se-68, Kr-72, Sr-76 and Zr-80, by using the Skyrme Hartree-Fock plus BCS method with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in Se-68 is extremely soft for the Y-33 triangular deformation, and that in Zr-80 the low-lying local minimum state coexisting with the prolate ground state has the Y-32 tetrahedral deformation.

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  • Chaos, order and damping of collective rotation in warm nuclei 査読

    M Matsuo, K Yoshida, T Dossing, E Vigezzi

    PROCEEDINGS OF THE XVII RCNP INTERNATIONAL SYMPOSIUM ON INNOVATIVE COMPUTATIONAL METHODS IN NUCLEAR MANY-BODY PROBLEMS   375 - 379   1998年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    A shell model diagonalization method utilizing the cranked deformed mean-field has been developed to investigate the rotational damping phenomena and the coexistence of order and chaos in rapidly rotating warm nuclei.

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  • Effect of shell structure in single particle alignment on rotational damping 査読

    K Yoshida, M Matsuo

    PROCEEDINGS OF THE XVII RCNP INTERNATIONAL SYMPOSIUM ON INNOVATIVE COMPUTATIONAL METHODS IN NUCLEAR MANY-BODY PROBLEMS   380 - 382   1998年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD  

    Shell effect on rotational damping associated with single particle alignment is discussed. Dispersion of rotational frequency is shown to be sensitive to single particle alignment structure at the Fermi surface. It is illustrated that shell oscillation of s.p. alignment influences significantly the dispersion of rotational frequency. In superdeformed Hg-192 th, shell effect causes considerably small rotational damping width Gamma(rot) similar to 30 keV, and large number of rotational bands N-band similar to 150, which are quite different from those in A similar to 150 superdeformed nuclei and normal deformed nuclei.

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  • Two-phonon gamma-vibrational state in Er-168 査読

    M Oshima, T Morikawa, Y Hatsukawa, S Ichikawa, N Shinohara, M Matsuo, H Kusakari, N Kobayashi, M Sugawara, T Inamura

    PHYSICAL REVIEW C   52 ( 6 )   3492 - 3495   1995年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    In order to identify double-gamma vibrational states in well-deformed regions, we have made a Coulomb excitation experiment for Er-168. We could observe 1235-keV and 962-keV gamma transitions decaying from the 2056-keV 4(+) state. The measured E2 transition probabilities support the assignment of the 4(+) state as a two-phonon gamma-vibrational state.

    DOI: 10.1103/PhysRevC.52.3492

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  • 2 AND 3-DIMENSIONAL GAMMA-RAY CORRELATIONS IN ROTATIONAL NUCLEI 査読

    B HERSKIND, T DOSSING, S LEONI, M MATSUO, N NICA, DC RADFORD, P RASMUSSEN

    NUCLEAR PHYSICS A   557   C191 - C210   1993年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Several new methods for the study of nuclear structure at low temperature are reviewed. The methods analyze the fluctuations of the intensity of E(gamma)1 - E(gamma)2 spectra, and the shape and width GAMMA(rot) of the correlated patterns with different characteristics of the rotational motion in cold and warm nuclei. New results are given for the rotational damping width, and the number of 2-step-paths below and above U0 almost-equal-to 800 keV, considered to be the energy of the borderline between undamped and damped rotational motion. The rotational damping width GAMMA(rot) is studied as function of rotational frequency for selected regions of entry states in Tm-163, and found to be rather constant almost-equal-to 80 keV, significantly smaller than current theoretical predictions. The fluctuation analysis supports the damping picture in general, and confirms that a strong branching of the transition strength for each step in the E2 cascades exists at high spin. This can be taken as evidence for damping of the rotational motion in warm nuclei.

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  • RECENT STUDIES OF THE HIGH-SPIN QUASI-CONTINUUM 査読

    B HERSKIND, T DOSSING, S LEONI, M MATSUO, E VIGEZZI

    PROGRESS IN PARTICLE AND NUCLEAR PHYSICS, VOL 28   235 - 267   1992年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:PERGAMON PRESS LTD  

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  • Treatment of Nucleon-Number Conservation in the Selfconsistent Collective-Coordinate Method : Coupling between Large-Amplitude Collective Motion and Pairing Rotation : Nuclear Physics

    Matsuo Masayuki, Department of Physics Kyoto University

    Progress of theoretical physics = Progress of theoretical physics   76 ( 2 )   372 - 386   1986年8月

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    記述言語:英語   出版者・発行元:Published for the Research Institute for Fundamental Physics by Physical Society of Japan  

    The selfconsistent collective-coordinate (SCC) method is extended in order to microscopically describe large-amplitude collective motions in superconducting nuclei. To restore the nucleon-number conservation violated by the use of the quasiparticle representation, the collective variables representing the pairing rotation are explicitly introduced. The coupling between the large-amplitude collective motion and the pairing rotation is treated in such a way that unphysical deviation of the average nucleon number from the ground-state value is eliminated automatically. It is shown that the basic equations of the extended version of the SCC method can be solved by an iterative method similar to the well-known (η-*,η) expansion. Applicability of the proposed method is investigated for an O(4) model.

    DOI: 10.1143/PTP.76.372

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    その他リンク: https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=348626

  • MICROSCOPIC DESCRIPTION OF ANHARMONIC GAMMA-VIBRATIONS BY MEANS OF THE SELFCONSISTENT-COLLECTIVE-COORDINATE METHOD .1. 査読

    M MATSUO, K MATSUYANAGI

    PROGRESS OF THEORETICAL PHYSICS   74 ( 6 )   1227 - 1244   1985年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KYOTO UNIV  

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  • APPLICABILITY OF THE CANONICAL QUANTIZATION PROCEDURE FOR THE COLLECTIVE HAMILTONIAN DERIVED BY THE SELFCONSISTENT-COLLECTIVE-COORDINATE METHOD 査読

    M MATSUO, K MATSUYANAGI

    PROGRESS OF THEORETICAL PHYSICS   74 ( 2 )   288 - 300   1985年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

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  • Anharmonicities of the Double Gamma-Vibrational States in ^<168>Er

    Matsuo Masayuki, Department of Physics Kyoto University

    Progress of theoretical physics = Progress of theoretical physics   72 ( 3 )   666 - 669   1984年9月

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    記述言語:英語   出版者・発行元:Published for the Research Institute for Fundamental Physics by Physical Society of Japan  

    The selfconsistent collective・coordinate method proposed by Marumori, Maskawa, Sakata and Kuriyama is applied to the analysis of the double gamma-vibrational states in ^<168>Er. It is found that the potential energy surface calculated microscopically has the minimum at γ&bne;O. The calculation predicts the double γ-vibrational states to appear in the region of excitation energy 2.0-2.5MeV.

    DOI: 10.1143/PTP.72.666

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    その他リンク: https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=347894

▶ 全件表示

MISC

  • 中性子過剰核におけるs波散乱が受ける対相関効果

    小林 良彦, 松尾 正之

    原子核研究 2016年夏の学校特集号   61 ( Suppl.1 )   46 - 47   2017年3月

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  • 中性子ドリップライン周辺原子核における1中性子s波散乱と対相関効果

    小林 良彦, 松尾 正之

    原子核研究 2014年夏の学校特集号   59 ( Suppl.1 )   61 - 63   2015年3月

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  • 27aTA-2 弱束縛原子核における中性子クーパーペアの遠方漸近性(27aTA 不安定核,理論核物理領域)

    Zhang Ying, 松尾 正之, Meng Jie

    日本物理学会講演概要集   69 ( 1 )   42 - 42   2014年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 27aTA-3 中性子ドリップライン周辺核における1中性子s波散乱状態が受ける対相関効果(27aTA 不安定核,理論核物理領域)

    小林 良彦, 松尾 正之

    日本物理学会講演概要集   69 ( 1 )   43 - 43   2014年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • ドリップライン原子核における低エネルギー中性子共鳴と対相関効果

    小林 良彦, 松尾 正之, 中島 和人

    原子核研究 2013年夏の学校特集号   58 ( Suppl.2 )   42 - 44   2014年1月

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  • 21pSB-6 中性子過剰核における中性子弾性散乱と対相関II : 波動関数を用いた分析(核反応,理論核物理領域)

    小林 良彦, 松尾 正之, 中島 和人

    日本物理学会講演概要集   68 ( 2 )   38 - 38   2013年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 26pHA-6 中性子過剰核における中性子弾性散乱と対相関(26pHA 軽い核・不安定核の構造,理論核物理領域)

    小林 良彦, 松尾 正之, 中島 和人

    日本物理学会講演概要集   68 ( 1 )   47 - 47   2013年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • ドリップライン近傍核にける中性子の共鳴現象と対相関

    小林 良彦, 松尾 正之, 中島 和人

    原子核研究 2012年夏の学校特集号   57 ( Suppl.1 )   79 - 82   2013年1月

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  • 12pSB-10 3次元座標空間表示による空間対称性を課さないHartree-Fock-Bogoliubov方程式の並列計算解法(12pSB 中重核,理論核物理領域)

    広川 一也, 松尾 正之, 吉田 賢市

    日本物理学会講演概要集   67 ( 2 )   41 - 41   2012年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 11pSA-5 R過程における中性子直接捕獲反応断面積と連続状態QRPA(11pSA 中性子過剰核・天体核,理論核物理領域)

    松尾 正之, 下山 裕考

    日本物理学会講演概要集   67 ( 2 )   31 - 31   2012年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 19aSF-4 N=40付近の中性子過剰Cr核における変形転移の研究(19aSF 中性子過剰核(II),理論核物理領域)

    佐藤 弘一, 日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   66 ( 2 )   58 - 58   2011年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 26pGJ-3 中性子過剰Cr同位体における変形ダイナミクスの微視的解析(26pGJ 実験核物理領域,理論核物理領域合同 不安定核II(合同),実験核物理領域)

    佐藤 弘一, 日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   66 ( 1 )   88 - 88   2011年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 12aSB-8 中性子過剰Mg核の大振幅変形ダイナミクスの微視的記述(12aSB 理論核物理領域,実験核物理領域合同 不安定核I(合同),理論核物理領域)

    日野原 伸生, 佐藤 弘一, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   65 ( 2 )   33 - 33   2010年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 22pBD-9 中性子過剰Sn同位体における0^+対振動状態 : 2中性子移行強度のQRPA理論による研究(22pBD 実験核物理領域,理論核物理領域合同 不安定核I(合同),実験核物理領域)

    下山 裕考, 松尾 正之

    日本物理学会講演概要集   65 ( 1 )   90 - 90   2010年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 20aBC-4 四重極集団HamiltonianによるSe同位体の低励起状態の系統的記述(20aBC 実験核物理領域,理論核物理領域合同 核構造(合同)(核分光・核モーメント・理論),実験核物理領域)

    日野原 伸生, 佐藤 弘一, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   65 ( 1 )   66 - 66   2010年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 30aXF-3 変形した中性子ドリップライン核における対相関と連続状態結合(30aXF 平均場模型,理論核物理領域)

    大庭 広士, 松尾 正之

    日本物理学会講演概要集   64 ( 1 )   55 - 55   2009年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 30aXF-4 簡単なモデルによる非軸対称変形ダイナミクスの統一的記述(30aXF 平均場模型,理論核物理領域)

    佐藤 弘一, 日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   64 ( 1 )   56 - 56   2009年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 22aSA-2 Hartree-Fock-Bogoliubov理論に基づく連続状態Green関数の変形核への拡張(22aSA 平均場理論,理論核物理領域)

    大庭 広士, 松尾 正之

    日本物理学会講演概要集   63 ( 2 )   39 - 39   2008年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 21aSB-9 Se・Kr同位体の低励起状態におけるオブレート・プロレート変形共存ダイナミクス(21aSB 理論核物理領域,実験核物理領域合同 不安定核,理論核物理領域)

    日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   63 ( 2 )   34 - 34   2008年8月

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  • 26aZH-7 A=80・100領域における低励起状態のAdiabatic SCC法による微視的記述(平均場理論,理論核物理領域)

    日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   63 ( 1 )   59 - 59   2008年2月

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  • 26aZH-8 変形不安定核を対象とした結合チャネルHFB理論と自己無撞着解(平均場理論,理論核物理領域)

    大庭 広士, 松尾 正之

    日本物理学会講演概要集   63 ( 1 )   59 - 59   2008年2月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 22pZD-10 Adiabatic SCC法による変形共存核の低励起状態の記述(不安定核,22pZD 実験核物理領域,理論核物理領域合同,実験核物理領域)

    日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   62 ( 2 )   86 - 86   2007年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 26aSB-11 Skyrme有効相互作用を用いた現実的な連続状態QRPA : ^<20>O,^<54>Caの双極子、四重極子励起と和則(26aSB 中性子過剰核,理論核物理領域)

    水山 一仁, 松尾 正之, 芹澤 保吉

    日本物理学会講演概要集   62 ( 1 )   37 - 37   2007年2月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 27pSB-5 ^<68>Se付近の変形共存核における大振幅集団運動(27pSB 核構造(平均場・多体基礎論),理論核物理領域)

    日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   62 ( 1 )   44 - 44   2007年2月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 22pSC-7 Quadrupole pairing contribution to collective mass in shape coexisting nuclei around ^<68>Se

    日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   61 ( 2 )   21 - 21   2006年8月

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  • 28aWF-12 ^<68>Se領域の原子核の変形共存解明に向けて(28aWF 核構造(平均場・集団運動),理論核物理領域)

    日野原 伸生, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   61 ( 1 )   39 - 39   2006年3月

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  • 24aWD-5 Adiabatic SCC 法における質量パラメターの効果(核構造・多体基礎論,理論核物理)

    日野原 伸生, 小林 将人, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   60 ( 1 )   34 - 34   2005年3月

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  • 24aWD-4 Oblate-prolate-spherical shape coexistence in ^<80>Zr studied by means of Adiabatic Self-consistent Collective Coordinate Method(核構造・多体基礎論,理論核物理)

    小林 将人, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   60 ( 1 )   33 - 33   2005年3月

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  • 30aZH-9 A microscopic study of prolate-oblate shape coexistence in ^<68>Se on the basis of the Adiabatic SCC method (II)(核構造・多体基礎論)(理論核物理)

    小林 将人, 中務 孝, 松尾 正之, 松柳 研一

    日本物理学会講演概要集   59 ( 1 )   47 - 47   2004年3月

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  • Application of the adiabatic self-consistent collective coordinate method to a solvable model of prolate-oblate shape coexistence

    M Kobayashi, T Nakatsukasa, M Matsuo, K Matsuyanagi

    PROGRESS OF THEORETICAL PHYSICS   110 ( 1 )   65 - 91   2003年7月

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    記述言語:英語   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    The adiabatic self-consistent collective coordinate method is applied to an exactly solvable multi-O(4) model that is designed to describe nuclear shape coexistence phenomena. The collective mass and dynamics of large amplitude collective motion in this model system are analyzed, and it is shown that the method yields a faithful description of tunneling motion through a barrier between the prolate and oblate local minima in the collective potential. The emergence of the doublet pattern is clearly described.

    DOI: 10.1143/PTP.110.65

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  • Rotational damping and compound formation in warm rotating nuclei

    M Matsuo, S Leoni, C Grassi, E Vigezzi, A Bracco, T Dossing, B Herskind

    FRONTIERS OF NUCLEAR STRUCTURE   656   32 - 39   2003年

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    記述言語:ウェールズ語   出版者・発行元:AMER INST PHYSICS  

    The rotational damping width Gammarot and the compound damping width Gammacomp are two fundamental quantities that characterize rapidly rotating compound nuclei having finite thermal excitation energy. A two-component structure in the strength function of consecutive E2 transitions reflects the two widths, and it causes characteristic features in the double and triple gamma-ray spectra. We discuss a new method to extract experimentally values of Gammarot and Gammacomp. The first preliminary result of this method is presented.

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  • Collective excitations and pairing effects in drip-line nuclei - Continuum RPA in coordinate-space HFB

    M Matsuo

    PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT   146, 110 ( 146 )   110 - 119   2002年

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    記述言語:英語   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    We discuss novel features of a new continuum RPA formulated in the coordinate-space Hartree-Fock-Bogoliubov framework. This continuum quasiparticle RPA takes into account both the one- and two-particle escaping channels. The theory is tested with numerical calculations for monopole, dipole and quadrupole excitations in neutron-rich oxygen isotopes near the drip-line. Effects of the particle-particle RPA correlation caused by the pairing interaction are discussed in detail, and importance of the selfconsistent treatment is emphasized.

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  • Continuum linear response in coordinate space Hartree-Fock-Bogoliubov formalism for collective excitations in drip-line nuclei

    M Matsuo

    NUCLEAR PHYSICS A   696 ( 3-4 )   371 - 395   2001年12月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    We formulate a continuum linear response theory on the basis of the Hartree-Fock-Bogoliubov formalism in the coordinate space representation in order to describe low-lying and high-lying collective excitations which couple to one-particle and two-particle continuum states. Numerical analysis is done for the neutron drip-line nucleus O-24. A low-lying collective mode that emerges above the continuum threshold with large neutron strength is analyzed. The collective state is sensitive to the density-dependence of the pairing. The present theory satisfies accurately the energy weighted sum rule. This is guaranteed by treating the pairing self-consistently both in the static HFB and in the dynamical linear response equation. (C) 2001 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0375-9474(01)01133-2

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  • Barrier penetration and rotational damping of thermally excited superdeformed nuclei

    K Yoshida, M Matsuo, YR Shimizu

    NUCLEAR PHYSICS A   696 ( 1-2 )   85 - 122   2001年12月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    We construct a microscopic model of thermally excited superdeformed states that describes both the barrier penetration mechanism, leading to the decay-out transitions to normal deformed states, and the rotational damping causing fragmentation of rotational E2 transitions. We describe the barrier penetration by means of a tunneling path in the two-dimensional deformation energy surface, which is calculated with the cranked Nilsson-Strutinsky model. The individual excited superdeformed states and associated E2 transition strengths are calculated by the shell-model diagonalization of the many-particle-many-hole excitations interacting with the delta-type residual two-body force. The effects of the decay-out on the excited superdeformed states are discussed in detail for Dy-152, Eu-143 and Hg-192. The model predicts that the decay-out brings about a characteristic decrease in the effective number of excited superdeformed rotational bands. (C) 2001 Elsevier Science B.V. All fights reserved.

    DOI: 10.1016/S0375-9474(01)01123-X

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  • Symmetry-unrestricted Skyrme-Hartree-Fock-Bogoliubov calculations for exotic shapes in N = Z nuclei from Ge-64 to Mo-84

    M Yamagami, K Matsuyanagi, M Matsuo

    NUCLEAR PHYSICS A   693 ( 3-4 )   579 - 602   2001年10月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    By performing fully 3D symmetry-unrestricted Skyrme-Hartree-Fock-Bogoliubov calculations, we discuss shape coexistence and possibility of exotic deformations simultaneously breaking the reflection and axial symmetries in proton-rich N = Z nuclei: Ge-64, Se-68, Kr-72,Sr-76, Zr-80 and Mo-84. Results of calculation indicate that the oblate ground state of Se-68 is extremely soft against the Y-33 triangular deformation, and that the low-lying spherical minimum coexisting with the prolate ground state in Zr-80 is extremely soft against the Y-32 tetrahedral deformation. (C) 2001 Elsevier Science B.V. All rights reserved.

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  • Gamma-ray strength functions in thermally excited rotating nuclei

    T Dossing, B Herskind, A Maj, M Matsuo, E Vigezzi, A Bracco, S Leoni, RA Broglia

    ACTA PHYSICA POLONICA B   32 ( 9 )   2565 - 2576   2001年9月

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    記述言語:英語   出版者・発行元:ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS  

    A general discussion and illustration is given of strength functions for rotational transitions in two-dimensional E-gamma1 x E-gamma2 spectra. Especially, a narrow component should be proportional to the compound damping width, related to the mixing of basis rotational bands into compound bands with fragmented transition strength. Three E-gamma1 x E-gamma2 spectra are made by setting gates on triple coincidences, selecting cascades which feed into specific low-lying bands in the nucleus Hf-168. In each of the gated spectra, we find a ridge, carrying about 100 decay paths. This ridge is ascribed to rotational transitions in the excitation energy range of 1.0 to 1.5 MeV above the yrast line. The FWHM of the ridges axe around 40 keV, about a factor of two smaller than calculated on the basis of mixed cranked mean field bands.

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  • Coupling between thermal and rotational motion in nuclei

    T Dossing, B Herskind, M Matsuo, S Leoni, A Bracco, E Vigezzi, RA Broglia

    NUCLEAR PHYSICS A   682   439C - 448C   2001年2月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    Two aspects of rotational motion of thermally excited nuclei are discussed. First, the schematic cases of ordered or chaotic motion of intrinsic and rotational motion are presented: discrete rotational bands, ergodic bands, damping of the rotational motion. Secondly, the strength functions of mixing of basis bands and of E2-transitions over one or two decay steps are discussed. The two-step E2-strength displays both a narrow and wide component, yielding different types of information about the basis bands and their interaction. Indications of the presence of a narrow component is found in energy correlations of consecutive transitions on displaced rotational bands of a three dimensional spectrum for the nucleus Yb-168.

    DOI: 10.1016/S0375-9474(00)00671-0

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  • Theoretical study of the decay-out spin of superdeformed bands in the Dy and Hg regions

    YR Shimizu, M Matsuo, K Yoshida

    NUCLEAR PHYSICS A   682   464C - 469C   2001年2月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    The decay of the superdeformed bands has been studied mainly concentrating upon the decay-out spin, which is sensitive to the tunneling probability between the super- and normal-deformed wells. Although the basic features are well understood by the calculations, it is difficult to precisely reproduce the decay-out spins in some cases. Comparison of the systematic calculations with experimental data reveals that values of the calculated decay-out spins scatter more broadly around the average value in both the A approximate to 150 and 190 regions, which reflects the variety of calculated tunneling probability in each band.

    DOI: 10.1016/S0375-9474(00)00674-6

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  • Correlation and fluctuation measures for damped collective motion

    M Matsuo

    NONEQUILIBRIUM AND NONLINEAR DYNAMICS IN NUCLEAR AND OTHER FINITE SYSTEMS   597   269 - 276   2001年

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    記述言語:英語   出版者・発行元:AMER INST PHYSICS  

    Strength functions for damped collective motion sometimes exhibit fluctuation that is called tine structure. Using two examples, i.e. the damped collective rotation of deformed compound nuclei and the giant resonances, we discuss statistical measures that characterize the fine structures, and demonstrate how such measures tell us important information on the microscopic mechanism of the damping phenomena.

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  • The rotational gamma-continuum in the mass region A approximate to 110

    A Bracco, S Frattini, S Leoni, F Camera, B Million, N Blasi, G Falconi, G Lo Bianco, M Pignanelli, E Vigezzi, B Herskind, M Bergstrom, P Varmette, S Tormanen, A Maj, M Kmiecik, DR Napoli, M Matsuo

    NUCLEAR PHYSICS A   673 ( 1-4 )   64 - 84   2000年6月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    Unresolved gamma transitions of Te-114 and of Sn-112 sorted into one-dimensional and two-dimensional spectra have been studied. The reaction Ni-64 + Cr-54 at bombarding energies 230, 240, 250, 260, 270 MeV was used and the gamma-rays were detected with the EUROBALL array. In the case of the nucleus 114Te the values of the multiplicity as a function of bombarding energy and of the moment of inertia were obtained. The effective moment of inertia was found to be almost constant in the interval I = 20-40 h, in contrast to the decreasing behaviour of the dynamic moment of inertia for the terminating yrast band. The ridge valley structures in E-gamma 1 x E-gamma 2 spectra of Te-114 and of Sn-112 were analysed with the fluctuation analysis technique. The analysis of the two nuclei are compared to simulations based on microscopic cranking calculations with residual interactions included. A rather good agreement is found between data and predictions. (C) 2000 Elsevier Science B.V. All rights reserved.

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  • Covariance analysis of selection rules governing the gamma-decay cascades of the rotational nucleus Yb-164

    S Leoni, T Dossing, A Bracco, S Frattini, G Montingelli, E Vigezzi, M Bergstrom, GB Hagemann, B Herskind, M Matsuo

    NUCLEAR PHYSICS A   671 ( 1-4 )   71 - 95   2000年5月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    The gamma-cascades feeding specific intrinsic configurations of Yb-164 are studied making use of a statistical analysis of counts fluctuations in gamma-gamma coincident spectra. In particular, variance and covariance spectra are obtained starting from the measured (0, +), (0, -) and (1, -) gate-selected matrices. The analysis of the first ridge of the spectra yields about 25 excited bands carrying rotational energy correlations for the total spectrum, and about 10 in coincidence with each of the (alpha, pi) configurations. The covariance of count fluctuations between the different (alpha, pi) gates is expressed by an experimental correlation coefficient, r, which measures the degree of sharing of decay paths through the excited bands, and thereby the extent to which selection rules are obeyed by the decay. The correlation coefficient is around r approximate to 0.3 for the ridge, and also in general rather small for valley fluctuations, Only at the highest valley energies, a tendency to larger correlation coefficients is seen, indicating some weakening of the selection rules over longer decay cascades. The results of the experimental analysis are compared to rotational damping model predictions based on cranked shell model plus residual interactions, and rather good agreement is found. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

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  • Adiabatic selfconsistent collective coordinate method for large amplitude collective motion in nuclei with pairing correlations

    M Matsuo, T Nakatsukasa, K Matsuyanagi

    PROGRESS OF THEORETICAL PHYSICS   103 ( 5 )   959 - 979   2000年5月

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    記述言語:英語   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

    An adiabatic approximation to the selfconsistent collective coordinate method is formulated in order to describe large amplitude collective motions in nuclei with pairing correlations on the basis of the time-dependent Hartree-Fock-Bogoliubov equations of motion. The basic equations are presented in a local harmonic form which can be solved in a manner similar to that of the quasiparticle RPA equations. The formalism guarantees the conservation of nucleon number expectation values. An extension to the multi-dimensional case is also discussed.

    DOI: 10.1143/PTP.103.959

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  • Spreading width of compound states through coincidence spectra of rotational gamma-rays

    M Matsuo, T Dossing, B Herskind, S Leoni, E Vigezzi, RA Broglia

    PHYSICS LETTERS B   465 ( 1-4 )   1 - 7   1999年10月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    The intrinsic width of (multiparticle-multihole) compound states is an elusive quantity, of difficult direct access, as it is masked by damping mechanisms which control the collective response of nuclei. Through microscopic cranked shell model calculations, it is found that the strength function associated with two-dimensional gamma-coincidence spectra arising from rotational transitions between states lying at energies &gt; 1 MeV above the yrast line, exhibits a two-component structure controlled by the rotational (wide component) and compound (narrow component) damping width. This last component is found to be directly related to the width of the multiparticle-multihole autocorrelation function. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0370-2693(99)01058-8

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  • Scaling analysis of the fluctuating strength function

    H Aiba, M Matsuo

    PHYSICAL REVIEW C   60 ( 3 )   034307   1999年9月

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    記述言語:英語   出版者・発行元:AMERICAN PHYSICAL SOC  

    We propose a new method to analyze fluctuations in the strength function phenomena in highly excited nuclei. Extending the method of multifractal analysis to the cases where the strength fluctuations do not obey power scaling laws, we introduce a new measure of fluctuation, called the local scaling dimension, which characterizes scaling behavior of the strength fluctuation as a function of energy bin width subdividing the strength function. We discuss properties of the new measure by applying it to a model system which simulates the doorway damping mechanism of giant resonances. It is found that the local scaling dimension well characterizes fluctuations and their energy scales of fine structures in the strength function associated with the damped collective motions. [80556-2813(99)01609-X].

    DOI: 10.1103/PhysRevC.60.034307

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  • Multistep rotational energy correlations probed by high fold gamma coincidence data

    S Leoni, A Bracco, T Dossing, B Herskind, JC Lisle, M Matsuo, E Vigezzi, J Wrzesinski

    EUROPEAN PHYSICAL JOURNAL A   4 ( 3 )   229 - 231   1999年3月

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    記述言語:英語   出版者・発行元:SPRINGER VERLAG  

    The number of discrete rotational bands in the nucleus Yb-168 is Obtained by a fluctuation analysis of the rotational ridge structure in double and triple gamma coincidence matrices. The data are compared with cranked shell model calculations including a surface delta interaction. It is found that the number of calculated bands strongly depends on the interaction strength V-0, and agreement between data and calculations supports the standard value V-0=27.5/A MeV.

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  • Unresolved γ rays in 114Te: Mass dependence of rotational damping

    S. Frattini, A. Bracco, S. Leoni, F. Camera, B. Million, N. Blasi, G. lo Bianco, M. Pignanelli, E. Vigezzi, B. Herskind, T. Døssing, M. Bergström, P. Varmette, S. Törmänen, A. Maj, M. Kmiecik, D. R. Napoli, M. Matsuo

    Physical Review Letters   83 ( 25 )   5234 - 5237   1999年1月

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    記述言語:英語  

    Unresolved γ rays of 114Te sorted into one- and two-dimensional spectra were studied. The reaction 64Ni(Ebeam = 230-270MeV)+54 Cr was used and the γ rays were detected with the EUROBALL array. The effective moment of inertia for the quasicontinuum was found to be almost constant for I=(20-40)ħ, in contrast with the decreasing behavior of the terminating yrast band. A comparative analysis with the nucleus 164Yb is presented and the results from a fluctuation analysis were compared with cranked shell model calculations. The comparison shows consistency in the scaling of the rotational damping width with mass number. © 1999 The American Physical Society.

    DOI: 10.1103/PhysRevLett.83.5234

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  • Tetrahedral and triangular deformations of Z=N nuclei in mass region A similar to 60-80

    S Takami, K Yabana, M Matsuo

    PHYSICS LETTERS B   431 ( 3-4 )   242 - 248   1998年7月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    We study static non-axial octupole deformations in proton-rich Z=N nuclei, Ge-64, Se-68, Kr-72, Sr-76, Zr-80 and Mo-84, by using the Skyrme Hartree-Fock plus BCS calculation with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in Se-68 is extremely soft for the Y-33 triangular deformation, and that in Zr-80 the low-lying local minimum state coexisting with the prolate ground state has the Y-32 tetrahedral deformation. (C) 1998 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0370-2693(98)00545-0

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  • Shell effects on rotational damping in superdeformed nuclei

    K Yoshida, M Matsuo

    NUCLEAR PHYSICS A   636 ( 2 )   169 - 188   1998年6月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    Damping of collective rotational motion in A similar to 190 and A similar to 150 superdeformed nuclei is studied by means of the cranked shell model with two-body residual force. Numerical calculations predict that in a typical A similar to 190 superdeformed nucleus, Hg-192, the rotational damping width is significantly small, Gamma(rot) similar to 30 keV, and that the number of superdeformed bands in the off-yrast region amounts up to 150 at a given rotational frequency. These features are quite different from the prediction for A similar to 150 superdeformed nuclei and rare-earth normally deformed nuclei. It is shown that the single-particle alignments of the cranked Nilsson orbits have strong shell oscillation. It affects significantly the properties of rotational damping in superdeformed Hg-192. (C) 1998 Elsevier Science B.V.

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  • Level statistics of near-yrast states rapidly rotating nuclei

    M Matsuo, T Dossing, E Vigezzi, S Aberg

    NUCLEAR PHYSICS A   620 ( 3 )   296 - 316   1997年7月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    The nearest neighbour level spacing distribution and the Delta(3) statistic of level fluctuations associated with very high spin states (I greater than or similar to 30) in rare-earth deformed nuclei are analysed by means of a cranked shell model, The many particle-many hole configurations created in the rotating Nilsson potential are mixed by the surface-delta two-body residual interaction, The levels in the near-yrast region show a Poisson-like level spacing distribution. As the intrinsic excitation energy U increases, the level statistics shows a gradual transition from order to chaos, reaching at U greater than or similar to 2 MeV the Wigner distribution typical of the Gaussian orthogonal ensemble of random matrices, This transition is caused by the residual two-body interaction, On the other hand, the level spacings between the yrast and the first excited state show a peculiar behaviour, displaying a Wigner-like distribution instead of the Poisson-like distribution seen for the other near-yrast rotational states, The lowest spacings reflect the properties of the single-particle orbits in the mean-field, and are only weakly affected by the residual two-body interaction. (C) 1997 Elsevier Science B.V.

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  • Shell model for warm rotating nuclei

    M Matsuo, T Dossing, E Vigezzi, RA Broglia, K Yoshida

    NUCLEAR PHYSICS A   617 ( 1 )   1 - 33   1997年4月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    In order to provide a microscopic description of levels and E2 transitions in rapidly rotating nuclei with internal excitation energy up to a few MeV, use is made of a shell model which combines the cranked Nilsson mean-field and the residual surface delta two-body force. The damping of collective rotational motion is investigated in the case of a typical rare-earth nucleus, namely Yb-168. It is found that rotational damping sets in at around 0.8 MeV above the yrast line, and the number of levels which form rotational band structures is thus limited. We predict at a given rotational frequency the existence of about 30 rotational bands of various lengths, in overall agreement with the experimental findings. The onset of the rotational damping proceeds quite gradually as a function of the internal excitation energy. The transition region extends up to around 2 MeV above yrast and it is characterized by the presence of scars of discrete rotational bands which extend over few spin values and stand out among the damped transitions, and by a two-component profile in the E-gamma-E-gamma correlation. The important role played by the high-multipole components of the two-body residual interaction is emphasized. (C) 1997 Elsevier Science B.V.

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  • Two-phonon gamma-vibrational state in Er-168 (vol 52, pg 3492, 1995)

    M Oshima, T Morikawa, Y Hatsukawa, S Ichikawa, N Shinohara, M Matsuo, H Kusakari, N Kobayashi, M Sugawara, T Inamura

    PHYSICAL REVIEW C   55 ( 3 )   1604 - 1604   1997年3月

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    記述言語:英語   出版者・発行元:AMERICAN PHYSICAL SOC  

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  • Onset of rotational damping in superdeformed nuclei

    K Yoshida, M Matsuo

    NUCLEAR PHYSICS A   612 ( 1 )   26 - 52   1997年1月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    We discuss damping of the collective rotational motion in A similar to 150 superdeformed nuclei by means of a shell-model combining the cranked Nilsson mean field and the surface and volume delta two-body residual forces. It is shown that, because of the shell structure associated with the superdeformed mean field, onset energy of the rotational damping becomes E(x) similar to 1.5-3 MeV above the yrast line, with significant variation for different neutron and proton numbers. The mechanism of the shell structure effect is investigated through detailed analysis of level densities in superdeformed nuclei. The variation in onset of damping is associated with variation in the single-particle structure at the Fermi surface.

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  • Study of band mixing in the rotational quasi-continuum

    A Bracco, P Bosetti, S Leoni, S Frattini, E Vigezzi, T Dossing, B Herskind, M Matsuo

    PROGRESS IN PARTICLE AND NUCLEAR PHYSICS, VOL 38   38   185 - 194   1997年

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    記述言語:英語   出版者・発行元:PERGAMON PRESS LTD  

    The rotational continuum for normally deformed nuclei of the rare earth region is investigated making use of statistical analysis methods, With these techniques it is possible to extract information on the rotational motion from the region of high level density, in this connection, two points will be discussed: i) the important role of the residual interaction in the description of the experimental data and ii) the dependence of the mixing among rotational bands on the symmetry quantum numbers of the nuclear states, This last point was investigated for the nucleus Er-163 for which it has been found that the gamma-cascades feeding into low-K bands are different from those feeding high-K bands, This result indicates that the K-selection rules are effective for excited rotational bands within the angular momentum 30h less than or equal to I less than or equal to 40h.

    DOI: 10.1016/S0146-6410(97)00026-4

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  • From discrete rotational bands to damped rotational motion

    E Vigezzi, T Dossing, M Matsuo, K Yoshida, P Bosetti, A Bracco, S Frattini, B Herskind, S Leoni

    ZEITSCHRIFT FUR PHYSIK A-HADRONS AND NUCLEI   358 ( 2 )   207 - 211   1997年

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    記述言語:英語   出版者・発行元:SPRINGER VERLAG  

    We present shell model calculations for warm rotating nuclei, combining the cranked Nilsson mean field and a residual surface-delta two-body interaction, The model is used to describe the transition from the region of well-defined rotational bands into the region dominated by rotational damping, and the results are in overall agreement with the experimental findings.

    DOI: 10.1007/s002180050310

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  • Scars of discrete rotational bands in hot nuclei

    RA Broglia, T Dossing, M Matsuo, E Vigezzi, P Bosetti, A Bracco, S Frattini, B Herskind, S Leoni, P Rasmussen

    ZEITSCHRIFT FUR PHYSIK A-HADRONS AND NUCLEI   356 ( 3 )   259 - 262   1996年12月

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    記述言語:英語   出版者・発行元:SPRINGER VERLAG  

    Rotational motion loses its coherence as a function of the nuclear internal excitation energy. The damping process does not proceed in a continuous fashion and scars of discrete rotational bands are found, inbedded in a background of damped rotational states, regardless whether the calculations are carried out using effective or ''random'' forces. The complexity of the damping mechanism is revealed in the lineshape of the ridges in the gamma-gamma correlation spectrum.

    DOI: 10.1007/s002180050178

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  • Microscopic simulations of gamma cascades in warm rotating nuclei

    A Bracco, P Bosetti, S Frattini, E Vigezzi, S Leoni, T Dossing, B Herskind, M Matsuo

    PHYSICAL REVIEW LETTERS   76 ( 24 )   4484 - 4487   1996年6月

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    記述言語:英語   出版者・発行元:AMERICAN PHYSICAL SOC  

    The gamma decay of the excited rotating Yb-168 nucleus has been simulated considering the competition between El and E2 transitions, using microscopically calculated rotational bands. The simulations were made for two different cases: (i) pure rotating mean field bands and (ii) rotational bands mixed by a residual interaction. Simulated gamma-gamma spectra were analyzed in the typical rotational ridge-valley region. The fluctuation analysis method, sensitive to the effective number of gamma-decay paths, was also applied. An overall agreement between experimental and simulated data is found for the case of mixed rotational bands.

    DOI: 10.1103/PhysRevLett.76.4484

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  • Fluctuation analysis of rotational spectra

    T Dossing, B Herskind, S Leoni, A Bracco, RA Broglia, M Matsuo, E Vigezzi

    PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS   268 ( 1 )   1 - 84   1996年4月

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    記述言語:英語   掲載種別:書評論文,書評,文献紹介等   出版者・発行元:ELSEVIER SCIENCE BV  

    It is well established that nucleons in the atomic nucleus can organize their motion, leading to quadrupole deformed shapes of the average field and to rotations of the nucleus as a whole. At an excitation energy of few MeV above the yrast line, rotational bands become very closely spaced in energy. Any single band can be viewed as a collective sequence of related states embedded in a dense background of other (more or less complicated) states, to which ii will couple by residual interactions. This coupling leads to stationary states of the system (the compound nucleus) which are complicated mixtures of unperturbed configurations. The rotational degree of freedom is &apos;&apos;damped&apos;&apos; in these compound states in the sense that the electric quadrupole decay of a single quantum state with angular momentum I will not go to a unique final state with spin I - 2 (as for the unperturbed bands) but will exhibit a spectrum of final states all having spin I - 2. In other words, for each compound nucleus formed in an experiment, the cascade of similar to 20 gamma-rays, which eventually will cool the system, will find many transitions through which to proceed in the regions where bands mix strongly (damped region) and only few in the region of discrete bands. In actual experiments, the cascade of gamma-rays associated with each of the members of the ensemble of compound nuclei will use each of the &apos;&apos;discrete&apos;&apos; transitions many more times than the &apos;&apos;continuum&apos;&apos; transitions. Relatively large and small fluctuations in the recorded coincidence spectrum will ensue, respectively. The analysis of the fluctuations will be shown to be instrumental to gain insight into the phenomenon of rotational damping. For this purpose, two- and higher-fold coincidence spectra emitted from rotating nuclei are analyzed with respect to the count fluctuations. The coincidences from consecutive gamma-rays emitted from discrete rotational bands generate ridges in the E(gamma 1) . E(gamma 2) spectrum, and the fluctuation analysis of the ridges is based upon the ansatz of a random selection of transition energies from band to band. This ansatz is supported by a cranked mean-field calculation for the nucleus Yb-168, as well as by analyzing resolved bands in Yb-168 and its neighbors. Consecutive gamma-rays emitted from the region of rotational damping spread out more in the E(gamma 1) . E(gamma 2) plane than those associated with transitions between members of discrete rotational bands, and are studied most clearly in the central valley (E(gamma 1) = E(gamma 2)) The fluctuation analysis of the valley is based upon the ansatz of fluctuations in the intensity of the transitions of Porter-Thomas type superposed on a smooth spectrum of transition energies. This ansatz is again supported by a mixed-band calculation. The mathematical treatment of count fluctuations is formulated in general terms, and the connection to earlier treatments of one-fold spectra of high level density is established. The statistical assumptions underlying the fluctuation analysis imply the existence of a principal uncertainty, which is examined in detail. In the experimental section, the fluctuation analysis is applied to two-dimensional gamma-spectra, the only available data at present with sufficient intensity to warrant a meaningful analysis. Large fluctuations are observed in the ridge structures from the four cases analyzed, showing that only a rather low number( approximate to 30) of discrete rotational bands exist.
    In contrast, only weak fluctuations are found along the central valley, revealing that the spectrum in the valley effectively contains different (of the order of 10(5)) coincidence combinations. This number is considerably larger than what is found assuming that the rotational decay leads to a unique final stare, showing that the transition strength through each decay step is spread over many states within a given energy interval, the damping width, and thus providing fairly direct evidence of the rotational damping picture.

    DOI: 10.1016/0370-1573(95)00060-7

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  • Two-phonon gamma-vibrational state in Er-168

    M Oshima, T Morikawa, Y Hatsukawa, S Ichikawa, N Shinohara, M Matsuo, H Kusakari, N Kobayashi, M Sugawara, T Inamura

    PHYSICAL REVIEW C   52 ( 6 )   3492 - 3495   1995年12月

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    記述言語:英語   出版者・発行元:AMERICAN PHYSICAL SOC  

    In order to identify double-gamma vibrational states in well-deformed regions, we have made a Coulomb excitation experiment for Er-168. We could observe 1235-keV and 962-keV gamma transitions decaying from the 2056-keV 4(+) state. The measured E2 transition probabilities support the assignment of the 4(+) state as a two-phonon gamma-vibrational state.

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  • A FINITE NUMBER OF REGULAR ROTATIONAL BANDS IN THE SUPERDEFORMED WELL OF EU-143

    S LEONI, B HERSKIND, T DOSSING, K YOSHIDA, M MATSUO, A ATAC, GB HAGEMANN, F INGEBRETSEN, HJ JENSEN, RM LIEDER, GV MARTI, N NICA, J NYBERG, M PIIPARINEN, H SCHNARE, G SLETTEN, K STRAHLE, M SUGAWARA, PO TJOM, A VIRTANEN

    PHYSICS LETTERS B   353 ( 2-3 )   179 - 183   1995年6月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    The number of excited superdeformed bands in Eu-143 is measured by use of the Fluctuation Analysis Method. Between 10 and 40 rotational bands, displaying typical rotational energy correlations over two consecutive transitions, are populated within a rather narrow range in transition energy, E(gamma) approximate to 1300-1500 keV. These numbers are close to the values found for normally deformed nuclei and agree with microscopic cranking + band mixing calculations for the specific superdeformed nucleus, which predict the onset of rotational damping to occur at the excitation energy U-0 = 1.3-1.6 MeV above the yrast line.

    DOI: 10.1016/0370-2693(95)00549-Z

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  • THE DISTRIBUTION OF THE ROTATIONAL TRANSITION STRENGTH IN WARM NUCLEI STUDIED THROUGH GAMMA-RAY CORRELATIONS

    S LEONI, B HERSKIND, T DOSSING, P RASMUSSEN, P BOSETTI, A BRACCO, S FRATTINI, M MATSUO, N NICA, E VIGEZZI, A ATAC, M BERGSTROM, A BROCKSTEDT, H CARLSSON, P EKSTROM, F INGEBRETSEN, HJ JENSEN, J JONGMAN, GB HAGEMANN, RM LIEDER, T LONNROTH, A MAJ, B MILLION, A NORDLUND, J NYBERG, M PIIPARINEN, H RYDE, DC RADFORD, M SUGAWARA, PO TJOM, A VIRTANEN

    NUCLEAR PHYSICS A   587 ( 3 )   513 - 540   1995年5月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    The study of damping of rotational motion applying the rotational plane mapping (RPM) method is presented and discussed. The aim of this technique is to extract the distribution of the rotational transition strength from an analysis of the shape of the ''central valley'' of two- and three-dimensional gamma-ray spectra. The method is applied to a triple gamma-coincidence data set of Tm-162,Tm-163 nuclei formed in Cl-37+Te-130 reactions. The rotational transition strength is obtained as a function of rotational frequency for selected regions of entry states, and the width is found to be rather constant and approximately equal to 80 keV. This value is significantly smaller than the value predicted theoretically for the rotational damping width Gamma(rct). Also the ratio between the observed depth and width of both the 2D and 3D valleys does not agree with the simple model adopted in the RPM method, These discrepancies point to the presence of both a wide and a narrow component in the distribution of rotational strength as extracted by the RPM method. The analysis of simulated spectra obtained on the basis of realistic band-mixing calculations, including residual interactions, confirms this behaviour.

    DOI: 10.1016/0375-9474(95)00024-U

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  • TOWARDS COMPLETE SPECTROSCOPY IN RAPIDLY ROTATING NUCLEI

    B HERSKIND, S LEONI, T DOSSING, GB HAGEMANN, P BOSETTI, A BRACCO, S FRATTINI, E VIGEZZI, M MATSUO

    ACTA PHYSICA POLONICA B   26 ( 2-3 )   153 - 173   1995年2月

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    記述言語:英語   出版者・発行元:POLISH ACAD SCIENCES INST PHYSICS  

    The progress in gamma-spectroscopy is discussed with special emphasis on the transition region in excitation energy, from the rather well known cold nuclei characterized by regular rotational motion built on specific single particle configurations with well defined quantum numbers, to the region above 800 keV in heat energy, where the rotational motion is damped, as a result of a spreading of the rotational transition strength, due to residual interactions acting between the close lying bands. A general analysis scheme is advocated, aiming at a more direct comparison between the experimental results and theoretical models to give a more complete picture of nuclear structure going from cold to warm nuclei. A simulation model for describing the rotational and statistical decay of high spin states has been developed based on microscopically calculated energies and the spreading of rotational transition strength due to residual interactions. The calculations predict that scars of regular rotational motion may be found at excitation energies as high as 2 MeV above yrast, far into the region characterized by damped rotational motion. Traces of this new phenomenon are identified and studied in the experimental spectra from high spin states in rare earth nuclei. A prominent example of isolated structures in the quasi-continuum region are bands built on high-K quantum numbers. Recent results from a fluctuation analysis of counts in low-K and high-X configurations in Er-163 are discussed, and indicate that states in the quasi-continuum feeding high-K bands are different from states feeding the low-K bands.

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  • POISSON AND PORTER-THOMAS FLUCTUATIONS IN OFF-YRAST ROTATIONAL TRANSITIONS

    M MATSUO, T DOSSING, B HERSKIND, S FRAUENDORF

    NUCLEAR PHYSICS A   564 ( 3 )   345 - 365   1993年11月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    Fluctuations associated with stretched E2 transitions from high-spin levels in nuclei around Yb-168 are investigated by a cranked shell model extended to include residual two-body interactions. In the cranked mean-field model without residual interactions, it is found that gamma-ray energies behave like random variables and the energy spectra show Poisson fluctuation. With two-body residual interactions included, the discrete transition pattern with unmixed rotational bands is still valid up to around 600 keV above yrast, in good agreement with experiments. At higher excitation energy, a gradual onset of rotational damping emerges. At 1.8 MeV above yrast, complete damping is observed with GOE-type fluctuations for both energy levels and transition strengths (Porter-Thomas fluctuations).

    DOI: 10.1016/0375-9474(93)90509-V

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  • Two and three dimensional gamma ray correlations in rotational nuclei

    B. Herskind, T. Døssing, S. Leoni, M. Matsuo, N. Nica, D. C. Radford, P. Rasmussen

    Nuclear Physics, Section A   557 ( C )   191 - 210   1993年5月

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    記述言語:英語  

    Several new methods for the study of nuclear structure at low temperature are reviewed. The methods analyze the fluctuations of the intensity of Eγ1 · Eγ2 spectra, and the shape and width Γrot of the correlated patterns with different characteristics of the rotational motion in cold and warm nuclei. New results are given for the rotational damping width, and the number of 2-step-paths below and above U0 ≈ 800 keV, considered to be the energy of the borderline between undamped and damped rotational motion. The rotational damping width Γrot is studied as function of rotational frequency for selected regions of entry states in 163Tm, and found to be rather constant ≈ 80 keV, significantly smaller than current theoretical predictions. The fluctuation analysis supports the damping picture in general, and confirms that a strong branching of the transition strength for each step in the E2 cascades exists at high spin. This can be taken as evidence for damping of the rotational motion in warm nuclei. © 1993.

    DOI: 10.1016/0375-9474(93)90541-5

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  • FLUCTUATIONS AND MEAN-FIELD EFFECTS IN ROTATIONAL DAMPING

    RA BROGLIA, PF BORTIGNON, A BRACCO, B HERSKIND, S LEONI, M MATSUO, E VIGEZZI

    NUCLEAR PHYSICS A   557   C181 - C189   1993年5月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    The experimental data emerging from the fluctuation analysis of the rotational gamma-decay are used to provide evidence for three regimes in the rotational spectrum. Namely discrete bands, fragmented transitions and rotational damping.
    The mechanisms which are expected to be at work in the damping of rotational motion are briefly reviewed and a parallel is made with the relaxation of giant resonances, focusing on the interplay of mean field (average) effects and of chaotic (fluctuation) behaviour. A simple, yet accurate model of rotational damping where chaotic behaviour emerges from effective, though realistic, two-body interactions acting among unperturbed rotational bands indicates the possibility of obtaining novel insight on the nuclear structure, through the study of rotational motion. In particular, the onset of chaos can be related to the high-multipole components of the nuclear force which are not able to generate mean field effects.

    DOI: 10.1016/0375-9474(93)90540-E

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  • MICROSCOPIC ORIGIN OF QUANTUM CHAOS IN ROTATIONAL DAMPING

    M MATSUO, T DOSSING, E VIGEZZI, RA BROGLIA

    PHYSICAL REVIEW LETTERS   70 ( 18 )   2694 - 2697   1993年5月

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    記述言語:英語   出版者・発行元:AMERICAN PHYSICAL SOC  

    The rotational spectrum of Yb-168 is calculated by diagonalizing different effective interactions within the basis of unperturbed rotational bands provided by the cranked shell model. A transition between order and chaos taking place in the energy region between 1 and 2 MeV above the yrast line is observed, associated with the onset of rotational damping. It can be related to the higher multipole components of the force acting among the unperturbed rotational bands.

    DOI: 10.1103/PhysRevLett.70.2694

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  • CHAOTIC BEHAVIOR IN WARM DEFORMED-NUCLEI INDUCED BY RESIDUAL 2-BODY INTERACTIONS

    M MATSUO, T DOSSING, B HERSKIND, S FRAUENDORF, E VIGEZZI, RA BROGLIA

    NUCLEAR PHYSICS A   557   C211 - C217   1993年5月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    Band mixing calculations in rapidly rotating well-deformed nuclei are presented, investigating the properties of energy levels and rotational transitions as a function of excitation energy. Substantial fragmentation of E2 transitions is found for E(x) greater than or similar to 800 keV above yrast, which represents the onset of rotational damping. Above E(x) almost-equal-to 2 MeV, energy levels and E2 strengths display fluctuations typical of quantum chaotic systems, which are determined by the high multipole components of the two-body residual interaction.

    DOI: 10.1016/0375-9474(93)90542-6

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  • FLUCTUATION ANALYSIS OF THE ROTATIONAL MOTION OF EXCITED NUCLEI

    T DOSSING, B HERSKIND, M MATSUO, S LEONI, E VIGEZZI

    NUCLEAR PHYSICS A   553   C505 - C508   1993年3月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    The structure of excited rotational bands in well deformed nuclei is discussed. It is shown how fluctuations of 2-dimensional energy-energy gamma-ray spectra can give quite detailed information about both the region of discrete bands and the region of rotational damping.

    DOI: 10.1016/0375-9474(93)90648-H

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  • Count fluctuations in Multi-fold γ-spectra and the onset of Damping in Deformed and Superdeformed Nuclei (jointly worked)

    Proceedings of International Seminar on the Frontiers of Nuclear Spectroscopy   1993年

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  • FLUCTUATION ANALYSIS OF ROTATIONAL DECAY FROM EXCITED NUCLEI

    B HERSKIND, A BRACCO, RA BROGLIA, T DOSSING, A IKEDA, S LEONI, J LISLE, M MATSUO, E VIGEZZI

    PHYSICAL REVIEW LETTERS   68 ( 20 )   3008 - 3011   1992年5月

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    記述言語:英語   出版者・発行元:AMERICAN PHYSICAL SOC  

    A statistical method to analyze the gamma decay of excited, rapidly rotating nuclei is presented. It is based on the fact that the cooling path of these systems goes through regions of both suppressed and enhanced fluctuations typical of large and low level density, respectively. The method is applied to the study of the high-spin quasicontinuum of Yb-167, Yb-168.

    DOI: 10.1103/PhysRevLett.68.3008

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  • RECENT STUDIES OF THE HIGH-SPIN QUASI-CONTINUUM

    B HERSKIND, T DOSSING, S LEONI, M MATSUO, E VIGEZZI

    PROGRESS IN PARTICLE AND NUCLEAR PHYSICS   28   235 - 267   1992年

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    記述言語:英語   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Two new methods, the Rotational Plane Mapping, and the Fluctuation Analysis Method are reviewed, and applied to the study of high spin quasi-continuum states in 167,168Yb and Tm-163 nuclei. New results are given for the rotational damping width GAMMA(rot) and the number of different 2-step-paths below and above U0, defined to be the energy of the borderline between undamped regular rotational motion for bands along the yrast line and the region of heated nuclei with damped rotational motion. The results indicate that at least 30 bands with regular rotational structure exist in the I = 40 h region before damping becomes dominating. The fundamental concept of rotational damping may be questioned, and has never been verified experimentally. The analysis support the damping picture, giving evidence for a strong branching of the E2 decay, showing 10 times as many 2-step-paths through the continuum than expected if only regular rotational E2 decay, and E1 statistical branching were the decay modes.

    DOI: 10.1016/0146-6410(92)90023-U

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  • Diabatic Approach to Shape Coexistence Phenomena in Semi-Magic Nuclei. I : Illustration of Basic Ideas : Nuclear Physics

    Fukui Takahiro, Matsuo Masayuki, Matsuyanagi Kenichi, Department of Physics Kyoto University, Yukawa Institute for Theoretical Physics Kyoto University, Department of Physics Kyoto University

    Progress of theoretical physics = Progress of theoretical physics   85 ( 2 )   281 - 303   1991年

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    記述言語:英語   出版者・発行元:Published for the Research Institute for Fundamental Physics by Physical Society of Japan  

    A new microscopic method based on the diabatic picture is proposed to describe the low-lying deformed excited 0^+ states in semi-magic nuclei. In this method, the couplings between anharmonic shape vibrations associated with different Hartree-Fock-Bogoliubov minima are diagonalized after constructing the diabatic basis. Basic ideas are illustrated for three kinds of exactly solvable models. Several examples are given which exhibit well localized deformed wave functions around the second minimum of the collective potential. It is possible that such deformed excited states well retain their identities against the mixing with the spherical configurations, even when their existence can hardly be expected from the properties of the adiabatic potential-energy functions.

    DOI: 10.1143/PTP.85.281

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    その他リンク: https://projects.repo.nii.ac.jp/?action=repository_uri&item_id=350141

  • Mean Field Dynamics and Low-Lying Collective Excitations

    Proceedings of Nishinomiya Yukawa Memorial Symposium   1991年

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  • DAMPED COLLECTIVE VIBRATION IN SCHEMATIC SHELL-MODEL OF HIGHLY EXCITED NUCLEI

    M MATSUO

    PROGRESS OF THEORETICAL PHYSICS   84 ( 6 )   1126 - 1144   1990年12月

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    記述言語:英語   出版者・発行元:KYOTO UNIV  

    Damping property of the collective vibration is numerically analyzed for a schematic shell model which simulates a giant collective vibration built on compound states. Microscopic mechanism of the motional narrowing of the damping width is investigated in reference to the residual interaction which causes configuration mixing. Statistical aspects of the damping mechanism are also discussed. It is shown that the response function method which we formulated in a preceding paper provides a consistent and microscopic description of the damped collective vibration embedded in the highly excited region.

    DOI: 10.1143/PTP.84.1126

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  • QUANTUM STATISTICAL-THEORY OF DAMPED COLLECTIVE TRANSITION IN HIGHLY EXCITED NUCLEI

    M MATSUO

    PROGRESS OF THEORETICAL PHYSICS   84 ( 2 )   269 - 290   1990年8月

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    記述言語:英語   出版者・発行元:KYOTO UNIV  

    DOI: 10.1143/PTP.84.269

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  • DISSIPATION MECHANISM OF THE LARGE-AMPLITUDE COLLECTIVE MOTION - DYNAMICAL EVOLUTION OF A COLLECTIVE BUNDLE OF TRAJECTORIES IN THE TDHF PHASE-SPACE FOR A SIMPLE SOLUBLE MODEL

    M MATSUO, F SAKATA, T MARUMORI

    PROGRESS OF THEORETICAL PHYSICS   82 ( 6 )   1084 - 1105   1989年12月

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    記述言語:英語   出版者・発行元:PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

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  • MASTER-EQUATIONS IN THE MICROSCOPIC THEORY OF NUCLEAR COLLECTIVE DYNAMICS

    F SAKATA, M MATSUO, T MARUMORI, YZ ZHUO

    ANNALS OF PHYSICS   194 ( 1 )   30 - 64   1989年8月

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    記述言語:英語   出版者・発行元:ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS  

    DOI: 10.1016/0003-4916(89)90031-6

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  • MICROSCOPIC DESCRIPTION OF ANHARMONIC GAMMA-VIBRATIONS BY MEANS OF THE SELFCONSISTENT-COLLECTIVE-COORDINATE METHOD .3.

    M MATSUO, K MATSUYANAGI

    PROGRESS OF THEORETICAL PHYSICS   78 ( 3 )   591 - 608   1987年9月

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    記述言語:英語   出版者・発行元:KYOTO UNIV  

    DOI: 10.1143/PTP.78.591

    Web of Science

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  • MICROSCOPIC ANALYSIS OF THE HEXADECAPOLE STRENGTHS TO THE GAMMA-VIBRATIONAL BANDS

    M MATSUO

    PROGRESS OF THEORETICAL PHYSICS   78 ( 3 )   609 - 615   1987年9月

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    記述言語:英語   出版者・発行元:KYOTO UNIV  

    DOI: 10.1143/PTP.78.609

    Web of Science

    CiNii Article

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  • MICROSCOPIC DESCRIPTION OF ANHARMONIC GAMMA-VIBRATIONS BY MEANS OF THE SELFCONSISTENT-COLLECTIVE-COORDINATE METHOD .2.

    M MATSUO, K MATSUYANAGI

    PROGRESS OF THEORETICAL PHYSICS   76 ( 1 )   93 - 114   1986年7月

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    記述言語:英語   出版者・発行元:KYOTO UNIV  

    DOI: 10.1143/PTP.76.93

    Web of Science

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  • 30p-CL-8 Spuriousな核子数励起を伴わない大振幅集団運動の記述法(原子核理論)

    松尾 正之

    年会講演予稿集   41 ( 1 )   62 - 62   1986年3月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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▶ 全件表示

共同研究・競争的資金等の研究

  • 原子核密度汎関数理論で記述するr過程元素合成と中性子星物性

    研究課題/領域番号:20K03945

    2020年4月 - 2024年3月

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:4290000円 ( 直接経費:3300000円 、 間接経費:990000円 )

    1. 中性子星内殻における中性子超流体の理論研究:対相関を記述できるよう拡張した原子核密度汎関数理論を用いて関連する課題に取り組むものであるが、本年度は、a. 中性子対相関の対凝縮エネルギーの定量化手法の開発、b. 中性子超流体の集団励起と中性子過剰原子核の相互作用の焦点を当てて研究を遂行した。
    a. 対凝縮はゲージ対称性の自発的破れを引き起こし、アンダーソン・ボゴリューボフ・モードとヒッグス・モードの2つの集団モードが生じる。本研究ではヒッグス・モードの自由度を表現する演算子と、この演算子に関する線形応答の強度関数が、対凝縮エネルギーを定量化するとの着想を得ている。そこで、この着想を確認するために、有限核を対象とした密度汎関数+線形応答計算を実行し、その数値計算結果の分析から、少なくともスズ同位体鎖ではこの予想が成立することを確認した。予備的結果は物理学会で発表し、現在論文を準備中である。
    b. 準1次元格子構造を持つスラブ様の内殻物質に対して、原子核=スラブの並進運動に対する中性子流体のエントレインメント効果を時間依存密度汎関数理論に基づく数値解析を行った。3次元格子を対象とした先行研究とは異なり、中性子超流体がスラブと逆方向に流れる反エントレインメント効果を見出したことから、その詳細を分析し、論文を投稿した。
    2.本研究の主要課題の他の1つは、 rプロセス元素合成の基礎過程の一つである中性子捕獲反応を原子核密度汎関数理論理論に基づいて記述する新しい理論枠組みの構築である。中性子捕獲断面積は光吸収演算子に対する強度関数から構成可能であるが、本研究の第1段階として、低励起状態を初期状態とする光吸収強度関数を計算する理論的手法を開発した。その成果を学術論文として出版した。

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  • 中性子星内殻と中性子過剰原子核の対相関ダイナミックス

    研究課題/領域番号:17K05436

    2017年4月 - 2020年3月

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    松尾 正之, 関澤 一之

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    配分額:4290000円 ( 直接経費:3300000円 、 間接経費:990000円 )

    中性子過剰原子核と希薄な中性子超流体とが共存する中性子星の内殻物質を対象に、原子核密度汎関数を主たる手法として、超流動性の微視的起源である対相関が引き起こす低エネルギー集団モードを解明する理論研究を行なった。中性子超流体の素励起モードである超流体音波と中性子過剰原子核の集団励起(並進運動・表面振動)との結合が弱いという新たな知見を得た。また、中性子過剰原子核と非束縛中性子の相互作用が対相関によって影響を受け、通常のポテンシャル共鳴とは異なる特異な性質を持つ準粒子共鳴が現れることを明らかにした。

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  • 核子多体論に基づくr過程中性子捕獲反応理論の構築

    研究課題/領域番号:26400268

    2014年4月 - 2017年3月

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:4550000円 ( 直接経費:3500000円 、 間接経費:1050000円 )

    本研究において、座標表示ハートレー・フォック・ボゴリューボフ理論(HFB理論)と連続状態準粒子乱雑位相近似(連続状態QRPA理論)に基づいて、r過程元素合成の基礎プロセスである中性子直接捕獲反応の理論を構築した。この理論の特徴は、中性子の超流動性(対相関)と低エネルギー集団励起モードがこの反応過程に及ぼす影響を記述することが出来る点にある。この研究ではまた、直接捕獲反応の始状態である中性子の低エネルギー散乱状態に対する対相関効果を詳細に分析し、対相関が準粒子共鳴の幅を減少させたり、S波に共鳴的な振る舞いを引き起こすなど特徴的な振る舞いをもたらすことを明らかにした。

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  • 原子核の低エネルギー集団励起と核融合・核分裂機構の解明

    研究課題/領域番号:25287065

    2013年4月 - 2017年3月

    制度名:科学研究費助成事業

    研究種目:基盤研究(B)

    提供機関:日本学術振興会

    中務 孝, 市川 隆敏, 吉田 賢市, 松尾 正之, 矢花 一浩, 江幡 修一郎

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    配分額:18850000円 ( 直接経費:14500000円 、 間接経費:4350000円 )

    原子核反応は星のエネルギー源であり、星や爆発的天体現象の中で進行する重元素合成のミクロな過程である。特に重要な低エネルギーでの核融合・核分裂といった反応機構は、多核子が関与する集団的な運動であり、量子的かつ非調和的な性格を持った問題で、理論物理として挑戦的課題である。また、これらの反応は原子核における低エネルギー集団励起モードと深く関連しており、核構造の問題としても大変興味がもたれる。通常の研究では反応経路は仮定され、ポテンシャル等を調整することで記述しているが、本研究では、この反応経路を、様々な仮定を排除して核子の自由度から決定し、核反応を記述する集団ハミルトニアンを導出することに成功した。

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  • 中性子星と核物質の理論研究

    研究課題/領域番号:24105008

    2012年6月 - 2017年3月

    制度名:科学研究費助成事業

    研究種目:新学術領域研究(研究領域提案型)

    提供機関:日本学術振興会

    大西 明, 原田 融, 中田 仁, 飯田 圭, 松尾 正之, 木村 真明, 土手 昭伸, 巽 敏隆, 小野 章, 中里 健一郎, 国広 悌二, 西崎 滋, 親松 和浩, 丸山 敏毅, 阿武木 啓朗, 大橋 洋士, 柴崎 徳明, 山本 康夫, 高塚 龍之, 河野 通郎, 宮川 貴彦, 武藤 巧, 住吉 光介, 佐川 弘幸, 祖谷 元, 森田 健司, 山縣 淳子, 椿原 康介, 大西 祥太, 稲倉 恒法, 池野 なつ美, 石塚 知香子, 李 東奎

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    配分額:122980000円 ( 直接経費:94600000円 、 間接経費:28380000円 )

    高密度多成分物質、中性子過剰物質、コンパクト天体現象の3つの方向から中性子星と核物質の理論研究を進め、約370編の出版論文でその成果を発表した。実験・観測と連携した代表的な成果として、反K中間子核束縛エネルギーの予言と検証、ハイペロン・原子核ポテンシャルの強さの決定、運動量相関によるΛΛ相互作用パラメータの制限、低エネルギーE1強度と中性子スキンの相関の予言、中性子過剰核衝突におけるπー/π+比の予言、冷却原子状態方程式を用いた対称エネルギーパラメータの制限、天体現象に適用できる新たな微視的状態方程式の作成、星震データによる対称エネルギーの制限などが挙げられる。

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  • 原子核密度汎関数理論で解明する弱束縛中性子の集団ダイナミックス

    研究課題/領域番号:23540294

    2011年 - 2013年

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:4810000円 ( 直接経費:3700000円 、 間接経費:1110000円 )

    原子核密度汎関数理論を用い、構成中性子の束縛エネルギーが小さい中性子過剰原子核に出現すると考えられる特徴的な集団ダイナミックスについて以下の3つの課題から研究を実施した。対振動モードの異常性とそれに付随する中性子対移行振幅の特徴を解明した。r過程元素合成にかかわる中性子直接捕獲反応断面積を記述できる連続状態乱雑位相近似を開発した。中性子ドリップライン近傍核のダイニュートロン相関の発現機構を解明した。

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  • 密度汎関数アプローチによる全核種精密計算

    研究課題/領域番号:21340073

    2009年 - 2012年

    制度名:科学研究費助成事業

    研究種目:基盤研究(B)

    提供機関:日本学術振興会

    中務 孝, 矢花 一浩, 松尾 正之, 稲倉 恒法, 吉田 賢市

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    配分額:18070000円 ( 直接経費:13900000円 、 間接経費:4170000円 )

    自然界に存在しない不安定な原子核を含め、その励起・核反応ダイナミクスの解明を目的として、そのための理論手法の開発、特に(時間)依存密度汎関数理論に基づく線形応答計算、実時間発展計算、大振幅集団運動理論の開発を実施した。より精密な予言を可能にするため、対相関エネルギー汎関数の精度向上も行った。さらに、手法の開発と並行して、安定核および不安定核に対する系統的な数値解析を実行し、陽子・中性子数がアンバランスな不安定核の素励起モードの予言およびその性質・発現機構を解明した。

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  • 連続領域での光・ニュートリノ核応答 : 元素合成素過程への核子多体論アプローチ

    研究課題/領域番号:21105507

    2009年 - 2010年

    制度名:科学研究費助成事業

    研究種目:新学術領域研究(研究領域提案型)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:3380000円 ( 直接経費:2600000円 、 間接経費:780000円 )

    r過程に関与する中性子過剰核の(γ,n)/(n,γ)反応と、超新星爆発で重要な役割を果たすとされる^4Heおよび^3He,^3Hのニュートリノによる励起過程のうち特に連続領域の原子核応答を研究した。
    1.中性子過剰核での(γ,n)/(n,γ)反応断面積の連続状態QRPA理論に基づく記述
    Skyrme密度汎関数と連続状態QRPAに基づき、Sn同位体におけるE1応答を10keVのエネルギー分解能で計算した。マックスウェル平均(n,γ)反応断面積を求め、離散化連続状態を仮定するQRPA計算との違いを定量的に明らかにした。マックスウェル平均(n,γ)反応断面積の温度範囲と必要とされるエネルギー分解能の関連を明らかにした。
    2.ニュートリノによる^4He,^3He,^3Hの連続エネルギー領域応答の第一原理計算(連携研究者鈴木宜之)
    ^3H,^3He,^4Heの基底状態がニュートリノによって励起される強度関数の計算を行った。始状態と終状態は相関ガウス関数と回転運動を記述するグローバルベクトル表示を組み合わせて表現した。また独立に、3体クラスターと1核子の模型により直接連続状態を求めて強度関数を計算し、前者と比較して閾値近傍での強度関数の立ち上がりについて確定した結果を得ることができた。

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  • 中質量領域中性子過剰原子核に現れるダイニュートロン相関とエキゾチック集団励起

    研究課題/領域番号:20540259

    2008年 - 2010年

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:4160000円 ( 直接経費:3200000円 、 間接経費:960000円 )

    中重質量領域の中性子過剰原子核において予想される原子核構造の特徴、特にダイニュートロン相関とエキゾチックな集団励起について、座標表示ハートレー・フォック・ボゴリューボフ理論と連続状態準粒子乱雑位相近似を用いて研究を行った。ダイニュートロン相関に対する間接的なプローブとして、四重極および単極型の2中性子移行応答が有効であること、N=82魔法数を超えるスズ同位体において異常な対振動が現れることを明らかにした。また、軸対称変形をもつ場合の座標表示ハートレー・フォック・ボゴリューボフ理論をグリーン関数法で扱うことに成功し、ドリップライン近傍変形核における対相関と準粒子スペクトルの特徴を明らかにした。

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  • 弱束縛核子多体問題への平均場アプローチ-ダイニュートロン相関と集団相関-

    研究課題/領域番号:17540244

    2005年 - 2007年

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:2910000円 ( 直接経費:2700000円 、 間接経費:210000円 )

    1.低密度核物質におけるダイニュートロン相関の研究
    低密度の一様核物質における対相関を分析することで、ダイニュートロン相関が低密度核物質で顕在化する強結合対相関の表れであることを解明したこと。これに関連して、弱結合BCS極限と複合ボーズ系のボーズアインシュタイン凝縮(BEC)との境界に位置するBCS-BECクロスオーバー領域での強結合対相関であることを指摘した
    2.表面ダイニュートロン励起モードの研究
    中性子過剰核に特有のソフト励起が、スキン表面領域における表面ダイニュートロン運動というエキゾチック集団励起モードと見なしえることを明らかにした。1Sチャネルの対相互作用が密度非依存のデルタ型相互作用であると仮定し、その強度を散乱長さを再現するように設定した強結合対相関の状況において、表面型ダイニュートロン相関を示す低エネルギー集団振動モードが双極子、四重極、八重極のいずれにも現れることを示した。
    3.Skyrme型HFB汎関数を組み込んだ連続状態QRPA理論の定式化
    Skyme有効相互作用の速度依存項まで取り入れた連続状態QRPA理論を初めて完成させた。エネルギー加重強度和則を満たすことなど、従来の連続状態QRPA理論の問題点を克服していることを確認した。
    4.軸対称座標表示HFBコードの開発と中性子過剰Cr領域の変形機構の研究
    変形した中性子過剰核の記述にむけて円筒座標を用いた軸対称座標表示Skyrme-HFBコードを開発し、中性子過剰Cr,Fe,Te同位体の変形機構を分析した。

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  • ドリップライン近傍核の集団相関と励起構造-cHFB線形応答理論の展開-

    研究課題/領域番号:14540250

    2002年 - 2004年

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:2500000円 ( 直接経費:2500000円 )

    1.質量ドリップライン近傍核である0,Ca, Niを対象にしたcHFB(座標表示Hartree-Fock-Bogoliubov)平均場計算から、ダイニュートロン相関の特徴の定量的詳細を明らかにした。相関中性子対は、2-3fm程度以内の相対近接領域で強く相関し、この近接領域に存在する確率が30-50%に達すること。核表面付近から核表面から2-3fm程度外部領域にある中性子過剰核のスキン領域でもっとも顕著となる、などである。核の内部や安定核においてもダイニュートロン相関がみられることも明らかにし、ダイニュートロン相関が原子核における対相関の一般的性質であることも示した。
    2.ダイニュートロン相関の量子多体論的な微視的構造に関して、Hartree-Fock1粒子状態を基底とした配位混合の観点から分析した。ダイニュートロン相関の形成には高い軌道角運動量をもつ1粒子軌道および10-50MeV程度の高い準粒子エネルギーをもつ1粒子軌道の配位混合の寄与が重要であることを解明した。
    3.一様核物質中のダイニュートロン相関を分析し、通常密度の1/5から1/100程度のスキン領域に対応する低密度状態において最も顕著なダイニュートロン相関が生じることを明らかにした。ゼロレンジ有効力との比較から、ダイニュートロン相関が有限レンジであるかどうかに依らない普遍性を持つことを明らかにした。
    4.質量領域ドリップライン近傍球形核におけるソフト双極子励起の研究については、cHFB線形応答理論(連続状態QRPA理論)により、中性子間の対相間の結果ソフト双極子励起が、粒子空孔型励起ではなく粒子対型励起となる原因の分析を行なった。1粒子軌道の分析から、高い軌道角運動量軌道の寄与がこの増大の主要な原因であること、また、この理由から、このモードがダイニュートロンの相対運動としての性格を持つ励起モードであることを明らかにした。
    5.Skyrme有効相互作用をcHFB平均場計算での組み込んだことに加え、cHFB線形応答理論においては速度依存(スピン非依存)項から付随する密度場と応答関数の定式化を球対称の場合の定式化を完成した。

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  • 高励起原子核における減衰性集団励起とカオス

    研究課題/領域番号:10640267

    1998年 - 1999年

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    松尾 正之, 相場 浩和

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    配分額:500000円 ( 直接経費:500000円 )

    高角運動量を有する有限温度の原子核には減衰性回転運動という特徴ある現象が見いだされるが、我々は、その原因が励起エネルギーの増大とともに進展する励起準位波動関数の複雑化にあることに着目し、本研究において両者の間の関係を理論的に解明しようとした。
    高励起原子核の量子カオス性を特徴づける動的な指標として、複合核状態を形成するのに必要な時間スケールと、複合核状態のエネルギー分散幅に着目した。減衰性回転運動に伴う準連続ガンマ線のエネルギー相関スペクトルには二重構造が存在することが我々の理論模型で予言される。二重構造は、ガンマ線強度分布に顕著な微細構造が存在することを反映したものであり、また、その微細構造は、複合核状態のエネルギー分散幅によって特徴づけられることを解明した。これは、準連続ガンマ線のエネルギー相関スペクトルを通して複合核状態分散幅を測定する可能性を初めて開くものである。本研究ではまた,減衰性回転運動の総合的理解を目指し、質量数依存性などに関する理論的予想や、最近の実験結果の分析なども行なった。さらに、微細構造や大きな揺らぎを有する強度関数を分析する一般的方法を開発した。そのために局所スケーリング次元という新しい概念を導入し、その有効性を幾つかの例で確認した。

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  • 高速回転する原子核のカスケード電磁遷移とカオス的性質

    研究課題/領域番号:05740176

    1993年

    制度名:科学研究費助成事業

    研究種目:奨励研究(A)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:1000000円 ( 直接経費:1000000円 )

    この研究では、高スピン・高励起領域の変形原子核の性質を「回転する殻模型」という微視的モデルを用いて理論的に分析することを主たる目的としていた。特に、「回転する殻模型」から得られるカスケードガンマ線の多重相関を分析することによって系の性質、特にカオス性についての知見を得ることを目指した。一年間の研究によって得られた成果は以下のように要約される。
    1.イラスト線近傍の準位統計の分析を行った。この結果、イラスト線近傍では、原子核状態は「カオス(=乱雑行列理論から帰結されるWigner分布)」と「規則(=ポアソン分布)」の中間的様相を示すことを理論モデルは予言する。従前の解析結果とあわせると、カオス性のエネルギー依存性は、(1)回転バンド構造が存在するイラスト近傍では、カオス性と規則性の中間にある、(2)励起エネルギーが約1MeV程度以上では、回転減衰が発現するのに併せて、カオス性が増大する。(3)約2MeV以上で励起状態はカオス的になる。
    2.E2遷移ガンマ線の二重相関関数を求め、そのプロファイルと励起エネルギー依存性を分析した。(1)励起工ネルギー1MeV以下では、回転バンド構造が存続していることに対応して相関はデルタ関数的である。(2)1MeVから2MeVの間では、相関関数がニつの成分(約100keV程度の幅をもつ成分と30keV程度の狭い幅をもつ成分)をもつという新しい現象を示す。大きい幅の成分は回転減衰の幅と解釈できるが、狭い幅の成分は従来予想されなかった。(3)2MeV以上では、狭い幅の成分は消滅する。
    3.以上のことから、(1)E2遷移ガンマ線の二重相関関数には狭い幅をもつ新しい成分が実験でも現れることが予想される、(2)狭い幅の成分は、カオス性が不完全な状況で発現する現象であるので、狭い幅の成分は「規則-カオス転移」に対する重要な指標になる、のニ点が結論される。

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  • 高励起原子核の集団運動に対するランジュバンの方法

    研究課題/領域番号:03640269

    1991年 - 1993年

    制度名:科学研究費助成事業

    研究種目:一般研究(C)

    提供機関:日本学術振興会

    阿部 恭久, 岡部 成玄, 松尾 正之

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    配分額:1600000円 ( 直接経費:1600000円 )

    高励起原子核の分裂について、二自由度散逸系としてランジュバン方程式を解き、分裂片運動エネルギーに関する実験データを再現した。さらに粒子放出による冷却過程も考慮し、異常中性子多重度と分裂片運動エネルギーを同時に説明することに成功した。この分析から、高励起核物質の摩擦係数が大きく、エネルギー散逸の強い系であることが示唆された。この結果はPhysical Review Lettersに発表された(11.研究発表参照)。現在、詳しい報告を準備中である。

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  • 原子核の大振幅集団運動における非線形動力学

    研究課題/領域番号:01790187

    1989年

    制度名:科学研究費助成事業

    研究種目:奨励研究(A)

    提供機関:日本学術振興会

    松尾 正之

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    配分額:1000000円 ( 直接経費:1000000円 )

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  • 高スピン原子核構造の研究, 不安定原子核構造の研究

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    資金種別:競争的資金

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  • Study of Nuclear Structure at High Spin

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    資金種別:競争的資金

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