2022/07/19 更新

イタガキ　ナオユキ

ITAGAKI NAOYUKI

### 担当・職階

• 大学院理学研究科 物理学専攻

教授  2022年04月 - 継続中

• 理学部 物理学科

教授  2022年04月 - 継続中

### 取得学位

• 博士(理学) （ 北海道大学 ）

• 日本物理学会

• 原子核理論論文新人賞

2001

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受賞国：日本国

### 職務経歴（学外）

• 理化学研究所基礎科学 特別研究員

1999年 - 2000年

• 日本学術振興会 特別研究員

1996年 - 1999年

• 東京大学 大学院理学系研究科 物理学専攻

### 学歴

• 北海道大学   理学研究科   物理学専攻   博士課程後期   卒業・修了

1996年04月 - 1999年03月

### 論文

• Otsuka T.

Nature Communications   13 ( 1 )   2022年12月

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Caamaño M.

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics   829   2022年06月（ ISSN:03702693

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Itagaki N.

Physical Review C   105 ( 2 )   2022年02月（ ISSN:24699985

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Ichikawa T.

Physical Review C   105 ( 2 )   2022年02月（ ISSN:24699985

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Furumoto T.

Physical Review C   104 ( 3 )   2021年09月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• First experimental determination of the radiative-decay probability of the 31− state in 12C for estimating the triple alpha reaction rate in high temperature environments 招待 査読 国際共著

M. Tsumura, T. Kawabata, Y. Takahashi, S. Adachi, H. Akimune, S. Ashikaga, T. Baba, Y. Fujikawa, H. Fujimura, H. Fujioka, T. Furuno, T. Hashimoto, T. Harada, M. Ichikawa, K. Inaba, Y. Ishii, N. Itagaki, M. Itoh, C. Iwamoto, N. Kobayashi, A. Koshikawa, S. Kubono, Y. Maeda, Y. Matsuda, S. Matsumoto, K. Miki, T. Morimoto, M. Murata, T. Nanamura, I. Ou, S. Sakaguchi, A. Sakaue, M. Sferrazza, K.N. Suzuki, T. Takeda, A. Tamii, K. Watanabe, Y.N. Watanabe, H.P. Yoshida, J. Zenihiro

Physics Letters B   817   136283 - 136283   2021年06月（ ISSN:0370-2693

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Itagaki N.

Physical Review C   103 ( 4 )   2021年04月（ ISSN:24699985

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Putri T.E.

Materials Science Forum   1016 MSF   863 - 868   2021年（ ISSN:02555476 （ ISBN:9783035736304

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Itagaki N.

Physical Review C   102 ( 2 )   2020年08月（ ISSN:2469-9985

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Itagaki N.

Physical Review C   101 ( 3 )   2020年03月（ ISSN:2469-9985

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担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Descouvemont P.

Progress of Theoretical and Experimental Physics   2020 ( 2 )   2020年02月

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担当区分：最終著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• 軽い中性子過剰核のクラスター構造に対して現実的核力を用いる試み 招待 査読 国際共著

板垣 直之, 福井 徳朗, 東崎 昭弘

日本物理学会講演概要集   75.1 ( 0 )   201 - 201   2020年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• 現実的核力を用いた微視的クラスター模型と<sup>8</sup>Beの構造 招待 査読 国際共著

福井 徳朗, 板垣 直之

日本物理学会講演概要集   75.1 ( 0 )   196 - 196   2020年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• 微視的クラスター模型とクォーク自由度 I −2核子系から4核子系とノルム積分核− 招待 査読 国際共著

東崎 昭弘, 山本 安夫, 板垣 直之

日本物理学会講演概要集   75.1 ( 0 )   200 - 200   2020年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

Springer Proceedings in Physics   238   85 - 89   2020年（ ISSN:09308989 （ ISBN:9783030323561

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Ren Z.X.

Science China: Physics, Mechanics and Astronomy   62 ( 11 )   1 - 8   2019年11月（ ISSN:1674-7348

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Afanasjev A.

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics   794   7 - 13   2019年07月（ ISSN:0370-2693

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Itagaki N.

Progress of Theoretical and Experimental Physics   2019 ( 6 )   1 - 28   2019年06月

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Tohsaki A.

Progress of Theoretical and Experimental Physics   2019 ( 6 )   1 - 11   2019年06月（ ISSN:2050-3911

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• 中性子対凝縮の微視的研究 招待 査読 国際共著

東崎（鈴木） 昭弘, 板垣 直之

日本物理学会講演概要集   74.2 ( 0 )   244 - 244   2019年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Miyahara N.

MRS Advances   4 ( 27 )   1551 - 1556   2019年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• jj-couplingシェル模型波動関数を用いたクラスター構造の研究 招待 査読 国際共著

板垣 直之, 内藤 智也, 東崎 昭弘

日本物理学会講演概要集   74.2 ( 0 )   245 - 245   2019年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Muraoka S.

MRS Advances   4 ( 27 )   1557 - 1563   2019年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• <sup>4</sup>Heおよび<sup>8</sup>Beにおけるテンソル相関と短距離相関 招待 査読 国際共著

延与 佳子, 松野 秀昭, 板垣 直之

日本物理学会講演概要集   74.1 ( 0 )   229 - 229   2019年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• <sup>14</sup>Oにおけるαクラスター状態探索 招待 査読 国際共著

岡本 慎太郎, 阪上 朱音, 稲葉 健斗, 藤川 祐輝, 土井 隆暢, 川畑 貴裕, 坂梨 公亮, 山口 英斉, 早川 勢也, 清水 英樹, 板垣 直之

日本物理学会講演概要集   74.2 ( 0 )   287 - 287   2019年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• <sup>10</sup>Be原子核の非弾性散乱断面積の計算とその励起状態の大きさについて 招待 査読 国際共著

古本 猛憲, 須原 唯広, 板垣 直之

日本物理学会講演概要集   74.1 ( 0 )   219 - 219   2019年

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担当区分：筆頭著者,　最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Tensor correlations in He 4 and Be 8 within an antisymmetrized quasicluster model 査読 国際共著

H. Matsuno, Y. Kanada-En'Yo, N. Itagaki

Physical Review C   98 ( 5 )   2018年11月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2018 American Physical Society. In this paper, we extend the framework of the improved version of a simplified method to take into account the tensor contribution (iSMT) and propose the AQCM-T, a tensor version of the antisymmetrized quasicluster model (AQCM). Although the AQCM-T is phenomenological, we can treat the S3-D3 coupling in the deuteronlike T=0NN pair induced by the tensor interaction in a very simplified way, which allows us to proceed to heavier nuclei. Using the AQCM-T and the V2m interaction, where the triplet-even channel of the Volkov no. 2 interaction is weakened to 60% so as to reproduce the binding energy of He4 after including the tensor term of a realistic interaction, the significant tensor contribution in He4 is shown, which is almost comparable to the central interaction, where the D state mixes by 8% to the major S state. The AQCM-T with the new interaction is also applied to Be8. It is found that the tensor suppression gives a significant contribution to the short-range repulsion between two α clusters.

• Tensor correlations in 4He and 8Be with antisymmetrized quasi cluster model 査読 国際共著

H. Matsuno, Y. Kanada-En'yo, N. Itagaki

Phys. Rev. C   98 ( 054306 )   1 - 15   2018年11月

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Explicit inclusion of the spin-orbit contribution in the Tohsaki-Horiuchi-Schuck-Röpke wave function 査読 国際共著

N. Itagaki, H. Matsuno, A. Tohsaki

Physical Review C   98 ( 4 )   1 - 7   2018年10月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2018 American Physical Society. The Tohsaki-Horiuchi-Schuck-Röpke (THSR) wave function has been successfully used for the studies of gaslike nature of α clusters in various nuclei, including the so-called Hoyle state of C12 and four α states of O16. In standard α cluster models, however, each α cluster wave function has spin zero because of its spatial symmetry and antisymmetrization effect. Thus the noncentral interactions do not contribute, and this situation is the same in the THSR wave function. In this work, the spin-orbit contribution, which is found to be quite important at short α-α distances, is taken into account in the THSR wave function by combing it with antisymmetrized quasicluster model (AQCM). The application to C12 is presented. The multi-integration in the original THSR wave function is carried out by using a Monte Carlo technique, which is called the Monte Carlo THSR wave function. For the nucleon-nucleon interaction, the Tohsaki interaction, which contains finite-range three-body terms and simultaneously reproduces the saturation properties of nuclear systems, the α-α scattering phase shift, and the size and binding energy of He4, is adopted.

• Coulomb energy of alpha-particle aggregates distributed on Archimedean solids 査読 国際共著

Akihiro Tohsaki, Naoyuki Itagaki

PHYSICAL REVIEW C   98 ( 1 )   1 - 6   2018年07月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We study the property of alpha aggregates distributed on Archimedean solids within a microscopic framework, which takes full account of the Pauli principle. We pay special attention to the Coulomb energy for such exotic shapes of nuclei, and we discuss the advantage of alpha clusters with geometric configurations compared with the uniform density distributions in reducing the repulsive effect. We consider four kinds of configurations of alpha clusters distributed on Archimedean solids: dual polyhedra composed of a dodecahedron and an icosahedron, an octacontahedron, and two types of truncated icosahedrons, that is, two kinds of Archimedean solids. The latter two are an icosidodecahedron and a fullerene shape. Putting an alpha cluster on each vertex of the polyhedra, four alpha-cluster aggregates correspond to the following four nuclei: Gd (64 protons), Po (84 protons), Nd (60 protons), and a nucleus with 120 protons, respectively.

• Effect of channel coupling on the elastic scattering of lithium isotopes 査読 国際共著

T. Furumoto, T. Suhara, N. Itagaki

Physical Review C   97 ( 4 )   44602   2018年04月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2018 American Physical Society. Herein, we investigated the channel coupling (CC) effect on the elastic scatterings of lithium (Li) isotopes (A=6-9) for C12 and Si28 targets at E/A=50-60 MeV. The wave functions of the Li isotopes were obtained using the stochastic multi-configuration mixing method based on the microscopic-cluster model. The proton radii of the Li7, Li8, and Li9 nuclei became smaller as the number of valence neutrons increased. The valence neutrons in the Li8 and Li9 nuclei exhibited a glue-like behavior, thereby attracting the α and t clusters. Based on the transition densities derived from these microscopic wave functions, the elastic-scattering cross section was calculated using a microscopic coupled-channel method with a complex G-matrix interaction. The existing experimental data for the elastic scatterings of the Li isotopes and Be10 nuclei were well reproduced. The Li isotope elastic cross sections were demonstrated for the C12 and Si28 targets at E/A=53 MeV. The glue-like effect of the valence neutrons on the Li isotope was clearly demonstrated by the CC effect on elastic scattering. Finally, we realize that the valence neutrons stabilized the bindings of the core parts and the CC effect related to core excitation was indeed reduced.

• Be 9 scattering with microscopic wave functions and the continuum-discretized coupled-channel method 査読 国際共著

P. Descouvemont, N. Itagaki

Physical Review C   97 ( 1 )   2018年01月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2018 American Physical Society. We use microscopic Be9 wave functions defined in a α+α+n multicluster model to compute Be9+target scattering cross sections. The parameter sets describing Be9 are generated in the spirit of the stochastic variational method, and the optimal solution is obtained by superposing Slater determinants and by diagonalizing the Hamiltonian. The Be9 three-body continuum is approximated by square-integral wave functions. The Be9 microscopic wave functions are then used in a continuum-discretized coupled-channel (CDCC) calculation of Be9+Pb208 and of Be9+Al27 elastic scattering. Without any parameter fitting, we obtain a fair agreement with experiment. For a heavy target, the influence of Be9 breakup is important, while it is weaker for light targets. This result confirms previous nonmicroscopic CDCC calculations. One of the main advantages of the microscopic CDCC is that it is based on nucleon-target interactions only; there is no adjustable parameter. The present work represents a first step towards more ambitious calculations involving heavier Be isotopes.

• Nontrivial origin for the large nuclear radii of dripline oxygen isotopes 査読 国際共著

N. Itagaki, A. Tohsaki

Physical Review C   97 ( 1 )   2018年01月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2018 American Physical Society. The anomalous large radii are exotic phenomena observed around the neutron dripline. Around the neutron dripline, the weak binding of the last bound neutron(s) causes the drastic increase of the radius, which is called the neutron halo structure. Although the nucleus O24 is located at the dripline of oxygen isotopes, the separation energies of one and two neutron(s) are 4.19 MeV and 6.92 MeV, respectively. In spite of this sufficient binding, the enhancement of the matter radius is observed. In this study, we microscopically describe the structure change of the O22 core in O24 and explain the observed large radius based on the cluster model. Two degrees of freedom for the large radius, the relative distances among four α clusters and the size of each α cluster, are examined, where the Tohsaki interaction, which has finite range three-body terms, is employed. The nucleus O22 has smaller α-α distance compared with O16 owing to the gluelike effect of six valence neutrons around four α clusters. When two neutrons are added at the center of O22, the expansion of each α cluster is energetically more favored than increasing the α-α distances for reducing the kinetic energy of the neutrons. The calculated rms matter radii of O22 and O24 are 2.75 fm and 2.92 fm, respectively. Although these are slightly smaller than the experimental values, the jump at O24 from O22 is reproduced.

• Improved version of a simplified method for including tensor effects in cluster models 査読 国際共著

N. Itagaki, A. Tohsaki

Physical Review C   97 ( 1 )   2018年01月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2018 American Physical Society. The tensor contribution can be directly incorporated in the cluster model in a simplified way. In conventional α cluster models, the contribution of the noncentral interactions exactly cancels because of the antisymmetrization effect and spatial symmetry of α clusters. The mixing of breaking components of α clusters to take into account the spin-orbit and tensor effects is needed. Previously, we proposed a simplified method to include the spin-orbit effect, and also for the tensor part, a simplified model to directly take into account the contribution of the tensor interaction (called SMT) was introduced; however, the contribution of the tensor interaction was quite limited. Here we improve SMT, which is called iSMT. Using newly proposed iSMT, the contribution of the tensor interaction in He4 is more than -40 MeV, four times larger than the previous version. The method is applied to four-α cluster structure of O16. In O16, the tensor contribution is also large, and this is coming from the finite size effect for the distances among α clusters with a tetrahedral configuration.

• alpha clustering with a hollow structure: Geometrical structure of alpha clusters from platonic solids to fullerene shape 査読 国際共著

Akihiro Tohsaki, Naoyuki Itagaki

PHYSICAL REVIEW C   97 ( 1 )   2018年01月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We study alpha-cluster structure based on the geometric configurations with a microscopic framework, which takes full account of the Pauli principle, and which also employs an effective internucleon force including finite-range three-body terms suitable for microscopic alpha-cluster models. Here, special attention is focused upon the alpha clustering with a hollow structure; all the alpha clusters are put on the surface of a sphere. All the platonic solids (five regular polyhedra) and the fullerene-shaped polyhedron coming from icosahedral structure are considered. Furthermore, two configurations with dual polyhedra, hexahedron-octahedron and dodecahedron-icosahedron, are also scrutinized. When approaching each other from large distances with these symmetries, alpha clusters create certain local energy pockets. As a consequence, we insist on the possible existence of alpha clustering with a geometric shape and hollow structure, which is favored from Coulomb energy point of view. Especially, two configurations, that is, dual polyhedra of dodecahedron-icosahedron and fullerene, have a prominent hollow structure compared with the other six configurations.

• Channel coupling effect on elastic scattering of Li isotope 査読 国際共著

T. Furumoto, T. Suhara, N. Itagaki

Phys. Rev. C   97 ( 044602 )   2018年

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• 9Be scattering with microscopic wave functions 査読 国際共著

P. Descouvemont, N. Itagaki

Phys. Rev. C   97 ( 014612 )   2018年

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Effects of cluster–shell competition and BCS-like pairing in <sup>12</sup>C 査読 国際共著

H. Matsuno, N. Itagaki

Progress of Theoretical and Experimental Physics   2017 ( 12 )   2017年12月

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© The Author(s) 2017. The antisymmetrized quasi-cluster model (AQCM) was proposed to describe α-cluster and jj-coupling shell models on the same footing. In this model, the cluster–shell transition is characterized by two parameters, R representing the distance between α clusters and Λ describing the breaking of α clusters, and the contribution of the spin–orbit interaction, very important in the jj-coupling shell model, can be taken into account starting with the α-cluster model wave function. Not only the closure configurations of the major shells but also the subclosure configurations of the jj-coupling shell model can be described starting with the α-cluster model wave functions; however, the particle–hole excitations of single particles have not been fully established yet. In this study we show that the framework of AQCM can be extended even to the states with the character of single-particle excitations. For 12C, two-particle–two-hole (2p2h) excitations from the subclosure configuration of 0p3/2 corresponding to a BCS-like pairing are described, and these shell model states are coupled with the three α-cluster model wave functions. The correlation energy from the optimal configuration can be estimated not only in the cluster part but also in the shell model part. We try to pave the way to establish a generalized description of the nuclear structure.

• Effect of <sup>12</sup>C + α clustering on the E0 transition in <sup>16</sup>O 査読 国際共著

H. Matsuno, N. Itagaki, T. Ichikawa, Y. Yoshida, Y. Kanada-En'Yo

Progress of Theoretical and Experimental Physics   2017 ( 6 )   2017年06月（ ISSN:2050-3911

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© The Author(s) 2017. We investigate cluster structures and E0 transitions of 0+ states in 16O. In particular, we discuss the mixing effect of 3α and α breaking components in the 12C cluster on the E0 transitions. To this end, we perform a microscopic calculation including α cluster and cluster-breaking model spaces. By analyzing the obtained results, we confirm that the 0+2 and 0+3 states of 16O are indeed the weak-coupling 12C(0+) + α and 12C(2+) + α cluster states, respectively. We find mainly two important mechanisms for reducing the E0 transition: (i) the difference in intrinsic spin configurations between the initial and final states caused by the cluster breaking and (ii) the mixing of planar 4α configurations in the excited states. We show that the E0 operator excites the initial (ground) state not to planar 4α configurations but predominantly to triangular pyramid 4α configurations. Thus, the mixture of the planar 4α configurations in the 0+2 state significantly reduces the E0 transition matrix elements to this state.We conclude that the E0 transitions tend to be enhanced by cluster states, but they are affected by various mechanisms originating in the detailed structures of the final states.

• Consistent description of C 12 and O 16 using a finite-range three-body interaction 査読 国際共著

N. Itagaki

Physical Review C   94 ( 6 )   2016年12月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2016 American Physical Society. Consistent description of C12 and O16 has been a long-standing problem of microscopic α cluster models, where the wave function is fully antisymmetrized and the effective interaction is applied not between α clusters but between nucleons. When the effective interaction is designed to reproduce the binding energy of O16 (four α), the binding energy of C12 (three α) becomes underbound by about 10 MeV. In the present study, by taking into account the coupling with the jj-coupling shell model components and utilizing the Tohsaki interaction, which is phenomenological but has finite-range three-body interaction terms, it is shown that consistent understanding of these nuclei can be achieved. The original Tohsaki interaction gives a small overbound value of about 3 MeV for O16, and this is improved by slightly modifying the three-body Majorana exchange parameter. Also, the coupling with the jj-coupling shell model wave function strongly contributes to the increase of the binding energy of C12. So far the application of the Tohsaki interaction has been limited to 4N nuclei; here, Bartlet and Heisenberg exchange terms are added in the two-body interaction part for the purpose of applying it to neutron-rich systems, and it is applied to He6.

• General transformation of á cluster model wave function to jj-coupling shell model in various 4N nuclei 査読 国際共著

N. Itagaki, H. Matsuno, T. Suhara

Progress of Theoretical and Experimental Physics   2016 ( 9 )   2016年09月（ ISSN:2050-3911

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2016 The Author(s). The antisymmetrized quasi-cluster model (AQCM) is a method to describe transitions from the α cluster wave functions to jj-coupling shell model wave functions. In this model, the cluster-shell transition is characterized by only two parameters: R representing the distance between α clusters and describing the breaking of α clusters. The contribution of the spin-orbit interaction, very important in the jj-coupling shell model, can be taken into account starting with the α cluster modelwave function. In this article we showthe generality ofAQCMby extending the application to heavier regions: various 4N nuclei from 4He to 100Sn. The characteristic magic numbers of the jj-coupling shell model, 28 and 50, are described starting with the α cluster model. The competition of two different configurations is discussed in 20Ne (16O + one quasi-cluster and 12C + two quasi-clusters) and 28Si (pentagon shape of five quasi-clusters and 12C+16O). Also, we compare the energy curves for the α+40Ca cluster configuration calculated with and without the α breaking effect in 44Ti.

• Exotic structure in light neutron-rich nuclei 査読 国際共著

N. Itagaki, P. W. Zhao, J. Meng, H. Matsuno, T. Suhara

AIP Conference Proceedings   1681   2015年10月（ ISSN:0094-243X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

© 2015 AIP Publishing LLC. In this presentation I discussed two subjects. One is the persistence of threefold symmetry in the ground state of 12C. Recently D3h symmetry has been established in 12C, which reflects the geometric symmetry of the three α particles. Although the spin-orbit interaction plays a significant role and this interaction breaks the α clusters, we show that threefold symmetry of 12C is still there. We use AQCM approach and discuss that inclusion of spin-orbit interaction, which is absent in the conventional microscopic α cluster models, is possible keeping the threefold symmetry. The second subject is the appearance of rod shape in C isotopes, which has been investigated in the framework of the cranking covariant density functional theory. The relationship between the stability of such states and the spin and isospin degrees of freedom is discussed; adding valence neutrons and rotating the system. These two effects stabilize the rod shape, and in addition, their coherent effect has been found; the σ-orbits (parallel to the symmetry axis) of the valence neutrons, which enhances the rod shape, is lowered by the rotation of the system, and this σ-orbit pulls down the single particle energies of protons with linear configuration owing to the proton-neutron interaction effect.

• Examination of the stability of a rod-shaped structure in Mg 24 査読 国際共著

Yoritaka Iwata, Takatoshi Ichikawa, Naoyuki Itagaki, Joachim A. Maruhn, Takaharu Otsuka

Physical Review C - Nuclear Physics   92 ( 1 )   2015年07月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2015 American Physical Society. The stable existence of rod-shaped structures in highly excited states of Mg24 is studied based on a systematic cranked Hartree-Fock calculation with various Skyrme-type interactions. Its stability is examined by allowing the transition of the clusterlike structure to the shell-model-like structure. Especially, the rod-shaped state is exposed to two major instabilities: the bending motion, which is the main path for the transition to low-lying states, and the spin-orbit interaction, which is the driving force to break the α clusters and enhance the independent motion of the nucleons. The rod-shaped structure with large angular momentum is obtained as a metastable stationary state.

• Rod-shaped Nuclei at Extreme Spin and Isospin 査読 国際共著

P. W. Zhao, N. Itagaki, J. Meng

Physical Review Letters   115 ( 2 )   2015年07月（ ISSN:0031-9007

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2015 American Physical Society. © 2015 American Physical Society. The anomalous rod shape in carbon isotopes has been investigated in the framework of the cranking covariant density functional theory, and two mechanisms to stabilize such a novel shape with respect to the bending motion, extreme spin, and isospin are simultaneously discussed for the first time in a self-consistent and microscopic way. By adding valence neutrons and rotating the system, we have found the mechanism stabilizing the rod shape; i.e., the σ orbitals (parallel to the symmetry axis) of the valence neutrons, important for the rod shape, are lowered by the rotation due to the Coriolis term. The spin and isospin effects enhance the stability of the rod-shaped configuration. This provides a strong hint that a rod shape could be realized in nuclei towards extreme spin and isospin.

• Searching for a 4 alpha linear-chain structure in excited states of O-16 with covariant density functional theory 査読 国際共著

J. M. Yao, N. Itagaki, J. Meng

PHYSICAL REVIEW C   90 ( 5 )   054307   2014年11月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

A study of the 4 alpha linear-chain structure in high-lying collective excitation states of O-16 with covariant density functional theory is presented. The low-spin states are obtained by configuration mixing of particle-number and angular-momentum projected quadrupole deformed mean-field states with the generator coordinate method. The high-spin states are determined by cranking calculations. These two calculations are based on the same energy density functional PC-PK1. We have found a rotational band at low spin with the dominant intrinsic configuration considered to be the one whereby 4 alpha clusters stay along a common axis. The strongly deformed rod shape also appears in the high-spin region with the angular momentum 13 (h) over bar to 18 (h) over bar; however, whether the state is a pure 4 alpha linear chain is less obvious than for the low-spin states.

• T. Ichikawa, K. Matsuyanagi, J. A. Maruhn, N. Itagaki

Physical Review C - Nuclear Physics   90 ( 3 )   2014年09月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

© 2014 American Physical Society. Background: In our previous study, we found that an exotic isomer with a torus shape may exist in the high-spin, highly excited states of Ca40. The z component of the total angular momentum, Jz=60, of this torus isomer is constructed by totally aligning 12 single-particle angular momenta in the direction of the symmetry axis of the density distribution. The torus isomer executes precession motion with the rigid-body moments of inertia about an axis perpendicular to the symmetry axis. The investigation, however, has been focused only on Ca40. Purpose: We systematically investigate the existence of exotic torus isomers and their precession motions for a series of N=Z even-even nuclei from Si28 to Ni56. We analyze the microscopic shell structure of the torus isomer and discuss why the torus shape is generated beyond the limit of large oblate deformation. Method: We use the cranked three-dimensional Hartree-Fock method with various Skyrme interactions in a systematic search for high-spin torus isomers. We use the three-dimensional time-dependent Hartree-Fock method for describing the precession motion of the torus isomer. Results: We obtain high-spin torus isomers in Ar36,Ca40,Ti44,Cr48, and Fe52. The emergence of the torus isomers is associated with the alignments of single-particle angular momenta, which is the same mechanism as found in Ca40. It is found that all the obtained torus isomers execute the precession motion at least two rotational periods. The moment of inertia about a perpendicular axis, which characterizes the precession motion, is found to be close to the classical rigid-body value. Conclusions: The high-spin torus isomer of Ca40 is not an exceptional case. Similar torus isomers exist widely in nuclei from Ar36 to Fe52 and they execute the precession motion. The torus shape is generated beyond the limit of large oblate deformation by eliminating the 0s components from all the deformed single-particle wave functions to maximize their mutual overlaps.

• T. Ichikawa, K. Matsuyanagi, J. A. Maruhn, N. Itagaki

Physical Review C - Nuclear Physics   89 ( 1 )   2014年01月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate the precession motion of the exotic torus configuration in high-spin excited states of 40Ca. For this aim, we use the three-dimensional time-dependent Hartree-Fock (TDHF) method. Although the high-spin torus isomer is a unique quantum object characterized by the alignment of angular momenta of independent single-particle motions, we find that the obtained moment of inertia for rotations about an axis perpendicular to the symmetry axis is close to the rigid-body value. We also analyze the microscopic structure of the precession motion using the random-phase approximation (RPA) method for high-spin states. In the RPA calculation, the precession motion of the torus isomer is generated by coherent superposition of many one-particle-one-hole excitations across the sloping Fermi surface that strongly violates the time-reversal symmetry. By comparing results of the TDHF and the RPA calculations, we find that the precession motion obtained by the TDHF calculation is a pure collective motion well decoupled from other collective modes. © 2014 American Physical Society.

• Pure collective precession motion of a high-spin torus isomer 査読 国際共著

T. Ichikawa, K. Matsuyanagi, J. A. Maruhn, N. Itagaki

PHYSICAL REVIEW C   89 ( 1 )   2014年01月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate the precession motion of the exotic torus configuration in high-spin excited states of Ca-40. For this aim, we use the three-dimensional time-dependent Hartree-Fock (TDHF) method. Although the high-spin torus isomer is a unique quantum object characterized by the alignment of angular momenta of independent single-particle motions, we find that the obtained moment of inertia for rotations about an axis perpendicular to the symmetry axis is close to the rigid-body value. We also analyze the microscopic structure of the precession motion using the random-phase approximation (RPA) method for high-spin states. In the RPA calculation, the precession motion of the torus isomer is generated by coherent superposition of many one-particle-one-hole excitations across the sloping Fermi surface that strongly violates the time-reversal symmetry. By comparing results of the TDHF and the RPA calculations, we find that the precession motion obtained by the TDHF calculation is a pure collective motion well decoupled from other collective modes.

• Investigation of the 3/22- State of 9Li with microscopic structure and reaction models 査読 国際共著

T. Furumoto, T. Suhara, N. Itagaki

Physical Review C - Nuclear Physics   87 ( 6 )   2013年06月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The low-lying states of the 9Li nucleus are investigated with a unified framework of microscopic structure and reaction models. In the structure model, the wave function is fully antisymmetrized and the 9Li nucleus is described as an α+t+n+n four-body system, and low-lying 1/2-, 3/2 -, 5/2-, and 7/2- states are obtained by the stochastic multiconfiguration mixing method. Using these wave functions, the quasielastic cross section at E/A = 60 MeV and the elastic and inelastic cross sections at E/A = 50 MeV on the 12C target are calculated in the framework of the microscopic coupled channel (MCC) method. The characteristic inelastic angular distribution is seen in the 3/22- state, whose α+t cluster structure and valence neutron configurations are discussed in detail. We find the possibility of triaxial deformation and mixing of dineutron components in the 9Li nucleus. © 2013 American Physical Society.

• Novel and simple description for a smooth transition from α-cluster wave functions to jj-coupling shell model wave functions 査読 国際共著

T. Suhara, N. Itagaki, J. Cseh, M. Płoszajczak

Physical Review C - Nuclear Physics   87 ( 5 )   2013年05月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Synthesis of thin-long heavy nuclei in ternary collisions Yoritaka Iwata, Kei Iida, and Naoyuki Itagaki 査読 国際共著

Yoritaka Iwata, Kei Iida, Naoyuki Itagaki

Phys. Rev. C 87 014609 (2013).   2013年

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Existence of an exotic torus configuration in high-spin excited states of Ca40 査読 国際共著

T. Ichikawa, J. A. Maruhn, N. Itagaki, K. Matsuyanagi, P. G. Reinhard, S. Ohkubo

Physical Review Letters   109 ( 23 )   2012年12月（ ISSN:0031-9007

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate the possibility of the existence of the exotic torus configuration in the high-spin excited states of Ca40. We here consider the spin alignments about the symmetry axis. To this end, we use a three-dimensional cranked Skyrme Hartree-Fock method and search for stable single-particle configurations. We find one stable state with the torus configuration at the total angular momentum J=60 and an excitation energy of about 170MeV in all calculations using various Skyrme interactions. The total angular momentum J=60 consists of aligned 12 nucleons with the orbital angular momenta Λ=+4, +5, and +6 for spin-up or -down neutrons and protons. The obtained results strongly suggest that a macroscopic amount of circulating current breaking the time-reversal symmetry emerges in the high-spin excited state of Ca40. © 2012 American Physical Society.

• Search for three-α states around an 16O core in 28Si 査読 国際共著

T. Ichikawa, N. Itagaki, Y. Kanada-En'Yo, Tz. Kokalova, W. Von Oertzen

Physical Review C - Nuclear Physics   86 ( 3 )   2012年09月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Search for three-alpha states around an O-16 core in Si-28 査読 国際共著

T. Ichikawa, N. Itagaki, Y. Kanada-En'yo, Tz. Kokalova, W. von Oertzen

PHYSICAL REVIEW C   86 ( 3 )   2012年09月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate the existence of weakly coupled gaslike states comprised of three a particles around an O-16 core in Si-28. We calculate the excited states in Si-28 using the multiconfiguration mixing method based on the O-16+3 alpha cluster model. We also include the O-16+C-12 and Mg-24+alpha basis wave functions prepared by the generator coordinate method. To identify the gaslike states, we calculate the isoscalar monopole transition strengths and the overlap of the obtained states with the geometrical cluster wave function and the Tohsaki-Horiuchi-Schuck-Ropke (THSR) wave function. The results show that the obtained fourth and twelfth states significantly overlap with the THSR wave function. These two states clearly coexist with the O-16+C-12 cluster states, emerging at similar energies. The calculated isoscalar monopole strengths between those two states are significantly large, indicating that the states are members of the excitation mode. Furthermore, the calculated root-mean-square radii for these states also suggest that a layer of gaslike three alpha particles could exist around the surface of the O-16 core, which can be described as a "two-dimensional gas" in the intermediate state before the Hoyle-like three-alpha states emerge.

• Cluster correlations for low-lying intruder states of 12Be 査読 国際共著

M. Ito, N. Itagaki, K. Ikeda

Physical Review C - Nuclear Physics   85 ( 1 )   2012年01月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The formation of intruder states in the low-lying states of 12Be=α+α+4N is studied by applying the generalized two-center cluster model, which can optimize the excess neutrons' orbits depending on the α-α distance. The correlation energy for the intruder states is analyzed from the viewpoint of two different pictures based on the cluster structure: the covalent picture around two α clusters and the binary He-cluster picture. In the covalent picture, the binding energy of (π32-)2(σ12 +)2, corresponding to ν(0p)4 (1s0d)2 in a naive shell model, gains largely owing to the spin-triplet pairing of the 0d-wave neutrons, which is induced by the two-body spin-orbit interaction. The spin-triplet pairing gives rise to the reduction of the kinetic energy and the increase of the attractive spin-orbit interaction for the excess neutrons. As a result of these correlation energies, the ν(0p)4(1s0d)2 configuration becomes dominant in the ground state. In the binary cluster picture, the correlation energy is investigated from the coupled channels among α+8He, 6He+6He, and 5He+7He. The coupling to 5He+7He, which is neglected in usual binary-cluster models, plays an important role for a large reduction of kinetic energy and the formation of a pair of the low-lying 0+ states with a close energy spacing recently observed in experiment. The rotational bands are also discussed from the viewpoint of these two cluster pictures. © 2012 American Physical Society.

• Frontier Issues in Physics of Exotic Nuclei Preface 査読 国際共著

Kouichi Hagino, Naoyuki Itagaki, Yoshiko Kanada-En'yo, Masayuki Matsu, Takashi Nakatsukasa, Masayuki Yamagami

PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT   ( 196 )   I - I   2012年（ ISSN:0375-9687

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Simplified Modeling of Cluster-Shell Competition and Appearance of Various Cluster Structures in Light Nuclei 査読 国際共著

Naoyuki Itagaki, Keitaro Muta, Hiroshi Masui, Marek Ploszajczak, Jozsef Cseh

PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT   ( 196 )   192 - 197   2012年（ ISSN:0375-9687

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We apply a simple model to describe the cluster-shell competition in Ne-20 due to the spin-orbit interaction, which is called Antisymmetrized Quasi Cluster approach. By introducing one additional parameter in the trial wave function, the transformation of one a cluster into a quasi cluster, i.e. the transition from a cluster state [O-16+alpha] to a shell model state [O-16+4N], can be studied in details. Such approach can be applied to the case of 3 alpha + four neutrons in C-16, and cluster-shell competition is investigated in a neutron-rich nucleus.

• Preface 査読 国際共著

Kouichi Hagino, Naoyuki Itagaki, Yoshiko Kanada-Enyo, Masayuki Matsuo, Takashi Nakatsukasa, Masayuki Yamagami

Progress of Theoretical Physics Supplement   ( 196 )   2012年（ ISSN:0375-9687

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Nuclear Forces and Nuetron-rich Matter 査読 国際共著

Peter Ring, Takaharu Otsuka, Yasuyuki Suzuki, Naoyuki Itagaki

Mar. 1 – 31, 2012   2012年

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Static and dynamic chain structures in the mean-field theory 査読 国際共著

T. Ichikawa, N. Itagaki, N. Loebl, J. A. Maruhn, V. E. Oberacker, S. Ohkubo, B. Schuetrumpf, A. S. Umar

EPJ Web of Conferences   17   2011年10月（ ISSN:2101-6275

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

© Owned by the authors, published by EDP Sciences, 2011. We give a brief overview of recent work examining the presence of α-clusters in light nuclei within the Skyrme-force Hartree-Fock model. Of special signif cance are investigations into α-chain structures in carbon isotopes and 16O. Their stability and possible role in fusion reactions are examined in static and time-dependent Hartree-Fock calculations. We f nd a new type of shape transition in collisions and a centrifugal stabilization of the 4α chain state in a limited range of angular momenta. No stabilization is found for the 3α chain.

• Linear chain structure of four-α clusters in O16 査読 国際共著

T. Ichikawa, J.A. Maruhn, N. Itagaki, S. Ohkubo

Physical Review Letters   107 ( 11 )   2011年09月（ ISSN:0031-9007

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Three-triton states in 9Li 査読 国際共著

K. Muta, T. Furumoto, T. Ichikawa, N. Itagaki

Physical Review C - Nuclear Physics   84 ( 3 )   2011年09月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate whether three-triton states appear or not in excited states of 9Li. We also search for a signature of the gaslike three-triton state, which is partly an analogy to the the case of the three-α state in 12C (Hoyle state). For this purpose, we use both three-triton and α+t+n+n wave functions to describe the low-lying states of 9Li and take into account the coupling effect between them. We show that the states in which the three-triton components dominate indeed appear below the three-triton threshold energy, although the root-mean-square radii of those states are not so much expanded in comparison with the gaslike state of three α's. © 2011 American Physical Society.

• Gas-like state of α clusters around a O16 core in Mg24 査読 国際共著

T. Ichikawa, N. Itagaki, T. Kawabata, T. Kokalova, W. Von Oertzen

Physical Review C - Nuclear Physics   83 ( 6 )   2011年06月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Phases of cluster states 査読 国際共著

J. Cseh, N. Itagaki, M. Ploszajczak, H. Yepez-Martinez, L. Parra-Rodrigez, P. O. Hess

International Journal of Modern Physics E   20 ( 4 )   807 - 810   2011年04月（ ISSN:0218-3013

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The question of phases and phase transitions of cluster states is reviewed. First some features of the vibron model are recalled, then its extensions are investigated. Preliminary results are also presented from a study on the cluster-shell competition. © 2011 World Scientific Publishing Company.

• Three-α cluster state around <sup>40</sup>Ca core 査読 国際共著

N. Itagaki, T. Kokalova, W. Von Oertzen, J.A. Maruhn

International Journal of Modern Physics E   20 ( 4 )   1012 - 1017   2011年04月（ ISSN:0218-3013

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

• Symplectic structure and monopole strength in C12 査読 国際共著

T. Yoshida, N. Itagaki, K. Kato

Physical Review C - Nuclear Physics   83 ( 2 )   2011年02月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The relation between the monopole transition strength and existence of cluster structure in the excited states is discussed based on an algebraic cluster model. The structure of C12 is studied with a 3α model, and the wave function for the relative motions between α clusters are described by the symplectic algebra Sp(2,R)z, which corresponds to the linear combinations of SU(3) states with different multiplicities. Introducing Sp(2,R)z algebra works well for reducing the number of the basis states, and it is also shown that states connected by the strong monopole transition are classified by a quantum number Λ of the Sp(2,R) z algebra. © 2011 American Physical Society.

• Simplified modeling of cluster-shell competition in Ne-20 and Mg-24 査読 国際共著

N. Itagaki, J. Cseh, M. Ploszajczak

PHYSICAL REVIEW C   83 ( 1 )   2011年01月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate properties of the generator coordinate method (GCM) on a collective basis of antisymmetrized quasicluster states to describe the cluster-shell competition in Ne-20 and Mg-24 owing to the spin-orbit interaction. By introducing a single additional parameter in the antisymmetrized-cluster basis function, a continuous transformation of the alpha cluster(s) into independent nucleons can be described. We apply this GCM trial wave function to study in detail the transition from cluster states [O-16 + alpha] and [O-16 + alpha + alpha] to shell-model states [O-16 + 4N] and [O-16 + 8N], respectively. An optimal value of the strength of the spin-orbit interaction is deduced by reproducing level spacing in Ne-20. A possible connection to the group theoretical understanding of the cluster-shell configuration transition is also discussed.

• T. Ichikawa, N. Itagaki, N. Loebl, J. A. Maruhn, V. E. Oberacker, S. Ohkubo, B. Schuetrumpf, A. S. Umar

5TH INTERNATIONAL CONFERENCE FUSION11   17   07002   2011年（ ISSN:2100-014X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

We give a brief overview of recent work examining the presence of alpha-clusters in light nuclei within the Skyrme-force Hartree-Fock model. Of special signif cance are investigations into alpha-chain structures in carbon isotopes and O-16. Their stability and possible role in fusion reactions are examined in static and time-dependent Hartree-Fock calculations. We f nd a new type of shape transition in collisions and a centrifugal stabilization of the 4 alpha chain state in a limited range of angular momenta. No stabilization is found for the 3 alpha chain.

• Di-neutron correlations in the super neutron-rich nucleus; <sup>7</sup>H 査読 国際共著

S. Aoyama, N. Itagaki

Modern Physics Letters A   25 ( 21-23 )   1828 - 1832   2010年07月（ ISSN:0217-7323

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

We study the di-neutron correlations in the super neutron-rich nucleus 7H with the AMD triple-S (AMD superposition of selected snapshots). 7H is the most neutron-rich nucleus in the neutron ratio to the proton (N/Z = 6). And the strong di-neutron correlations are expected due to the weak binding properties. In this paper, the mixing of di-neutron cluster components is estimated by calculating the squared overlap with the di-neutron condensate type wave function. The calculated results show significant mixing of di-neutron (t + 2n + 2n) components (70 ∼ 80%). © 2010 World Scientific Publishing Company.

• Three α state around <sup>40</sup>Ca 査読 国際共著

N. Itagaki, T.Z. Kokalova, W. Von Oertzen

Modern Physics Letters A   25 ( 21-23 )   1947 - 1950   2010年07月（ ISSN:0217-7323

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

• Three-α state around Ca<inf>40</inf> 査読 国際共著

N. Itagaki, Tz Kokalova, W. Von Oertzen

Physical Review C - Nuclear Physics   82 ( 1 )   2010年07月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We have studied three-α states around Ca40 based on a microscopic α-cluster model. Quite recently experimental evidence for such states has been obtained. This study was performed by introducing a Monte Carlo technique for the description of the Tohsaki-Horiuchi-Schuck-Röpke (THSR) wave function, which is called the "virtual THSR" wave function. The three-α-cluster state around Ca40 has an energy below the Coulomb-barrier top energy with a spatial extension comparable to the second 0+ state of C12. © 2010 The American Physical Society.

• Linear-chain structure of three-α-clusters in <sup>12</sup>C, <sup>16</sup>C, and <sup>20</sup>C 査読 国際共著

J.A. Maruhn, N. Loebl, A.S. Umar, N. Itagaki, M. Kimura, H. Horiuchi, A. Tohsaki

Modern Physics Letters A   25 ( 21-23 )   1866 - 1869   2010年07月（ ISSN:0217-7323

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Three-α state around Ca<sub>40</sub> 査読 国際共著

N. Itagaki, T. Kokalova, W. Von Oertzen

Physical Review C - Nuclear Physics   25 ( 21-23 )   1947 - 1950   2010年07月（ ISSN:0217-7323

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• THREE alpha STATE AROUND Ca-40 査読 国際共著

N. Itagaki, T. Z. Kokalova, W. Von Oertzen

MODERN PHYSICS LETTERS A   25 ( 21-23 )   1947 - 1950   2010年07月（ ISSN:0217-7323

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We have studied three alpha states around Ca-40 based on a microscopic alpha-cluster model, which has been succeeded experimentally quite recently. This was performed by introducing a Monte Carlo technique for the description of the THSR (Tohsaki Horiuchi Schuck Ropke) wave function, which is called the "virtual THSR" wave function. The three alpha cluster state around Ca-40 has an energy below the Coulomb barrier top energy with a spatial extension comparable to the second 0(+) state of C-12.

• Suppression of charge equilibration leading to the synthesis of exotic nuclei.

Iwata Y, Otsuka T, Maruhn JA, Itagaki N

Physical review letters   104 ( 25 )   252501   2010年06月（ ISSN:0031-9007

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• Microscopic study of the triple-α reaction 査読 国際共著

A.S. Umar, J.A. Maruhn, N. Itagaki, V.E. Oberacker

Physical Review Letters   104 ( 21 )   2010年05月（ ISSN:0031-9007

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Geometric classification of nucleon transfer at moderate low-energies 査読 国際共著

Y. Iwata, T. Otsuka, J. A. Maruhn, N. Itagaki

Nuclear Physics A   836 ( 1-2 )   108 - 118   2010年05月（ ISSN:0375-9474

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

Nucleon transfer is studied with a focus on charge equilibration. It is completely classified into six types. The preferred nucleon transfer (i.e. neutron transfer, proton transfer, dual-way transfer, etc.) is predictable based on this classification, which is verified within the framework of microscopic time-dependent density functional calculations. This classification gives a simple explanation for the reason why the proton-richness does not necessarily result in the enhancement of proton transfer contrary to the neutron-richness in neutron transfer. © 2010 Elsevier B.V. All rights reserved.

• Linear-chain structure of three α-clusters in <sup>16</sup>C and <sup>20</sup>C 査読 国際共著

J.A. Maruhn, N. Loebl, N. Itagaki, M. Kimura

Nuclear Physics A   833 ( 1-4 )   1 - 17   2010年02月（ ISSN:0375-9474

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Algebraic net model: Application to <sup>12</sup>c 査読 国際共著

T. Yoshida, K. Kato, N. Itagaki

Hadron and Nuclear Physics 2009, HNP 2009   279 - 284   2010年

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Two different modes associated with the composite nucleus - the charge and mass distributions for exotic nuclear synthesis 査読 国際共著

Yoritaka Iwata, Takaharu Otsuka, Joachim A. Maruhn, Naoyuki Itagaki

CNR '09: SECOND INTERNATIONAL WORKSHOP ON COMPOUND NUCLEAR REACTIONS AND RELATED TOPICS   2   13002   2010年（ ISSN:2100-014X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The mass-dependent structure of the composite nucleus is shown based on three-dimensional time-dependent Hartree-Fock calculations with Skyrme interactions (SLy4d and SkM*). One remarkable result is that the isovector monopole excitation dominantly appears for collisions of heavy nuclei, and the isovector dipole excitation for those of light ones. Such a difference found in the dynamical structure of composite nucleus plays a role in the equilibration of charge.

• Y. Iwata, T. Otsuka, J. A. Maruhn, N. Itagaki

Società Italiana di Fisica Atti Di Conferenze   Vol. 101   291   2010年

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Erratum to: Synthesis of exotic nuclei in heavy-ion collisions at higher energies (Eur. Phys. J. A, (2009), 42, (613), 10.1140/epja/i2009-10851-1) 査読 国際共著

Y. Iwata, T. Otsuka, J. A. Maruhn, N. Itagaki

European Physical Journal A   42 ( 3 )   625 - 625   2009年12月（ ISSN:1434-6001

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Synthesis of exotic nuclei in heavy-ion collisions at higher energies 査読 国際共著

Y. Iwata, T. Otsuka, J. A. Maruhn, N. Itagaki

European Physical Journal A   42 ( 3 )   613 - 621   2009年12月（ ISSN:1434-6001

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The charge equilibration upper energy-limit formula is proposed. It shows not only the basic mechanism of charge equilibration but also does imply the possibility of controlling the exotic nuclear synthesis. To understand the mechanism of charge equilibration, charge and mass distributions of final fragments of the heavy-ion collisions are studied based on three-dimensional time-dependent Hartree-Fock calculations with a Skyrme interaction. © Società Italiana di Fisica / Springer-Verlag 2009.

• Di-neutron correlations in H7 査読 国際共著

S. Aoyama, N. Itagaki

Physical Review C - Nuclear Physics   80 ( 2 )   2009年08月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate the dineutron correlations in H7. The ground state of H7 is solved by superposing many AMD (antisymmetrized molecular dynamics) Slater determinants with various t+n+n+n+n configurations based on AMD triple-S (AMD superposition of selected snapshots). The mixing of dineutron cluster components is estimated by calculating the squared overlap with the wave function of the dineutron condensate, which is an extension of the studies on the α condensate in 4N nuclei. The calculated results show significant mixing of components of dineutron clusters (t+2n+2n) with a spatially extended distribution (~70%) much larger than that of He8, where the core nucleus is changed from t to He4. © 2009 The American Physical Society.

• Di-neutron correlations in H-7 査読 国際共著

S. Aoyama, N. Itagaki

PHYSICAL REVIEW C   80 ( 2 )   2009年08月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate the dineutron correlations in H-7. The ground state of H-7 is solved by superposing many AMD (antisymmetrized molecular dynamics) Slater determinants with various t+n+n+n+n configurations based on AMD triple-S (AMD superposition of selected snapshots). The mixing of dineutron cluster components is estimated by calculating the squared overlap with the wave function of the dineutron condensate, which is an extension of the studies on the alpha condensate in 4N nuclei. The calculated results show significant mixing of components of dineutron clusters (t+(2)n+(2)n) with a spatially extended distribution (similar to 70%) much larger than that of He-8, where the core nucleus is changed from t to He-4.

• COVALENT, IONIC, AND ATOMIC STRUCTURES IN Be-12 査読 国際共著

Makoto Ito, Naoyuki Itagaki

MODERN PHYSICS LETTERS A   24 ( 11-13 )   1005 - 1008   2009年04月（ ISSN:0217-7323

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The generalized two-center cluster model (GTCM), which can treat various single particle configurations in general two center systems, is applied to the light neutron-rich system, Be-12 =alpha+alpha+4N. We discuss the change of the neutrons' configuration around two alpha-cores as a variation of an excitation energy. We show that the covalent, ionic and atomic configurations appear in the unbound region above the alpha+He-8(g.s.) particle-decay threshold, and they coexist within a quite small energy interval.

• THE APPLICATION OF THSR WAVE FUNCTION USING MONTE CARLO TECHNIQUE 査読 国際共著

Naoyuki Itagaki, Masaaki Kimura, Makoto Ito, Shigeyoshi Aoyama, Yuichi Hirata

INTERNATIONAL JOURNAL OF MODERN PHYSICS A   24 ( 11 )   2019 - 2026   2009年04月（ ISSN:0217-751X

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The condensed states of alpha-clusters or di-neutrons are studied by introducing a Monte Carlo technique for the description of the THSR (Tohsaki Horiuchi Schuck Ropke) wave function. The condensed state of five alpha particles is shown to be stable around the threshold energy even after taking into account the coupling effect between normal cluster states with O-16+alpha configurations. Next, the mixing of di-neutron components in He-8 is studied. The ground state of 8He corresponds to the sub-closed-shell configuration of the spin-orbit favored orbits (p(3/2)) for the neutrons, and the shell-model-like configuration is considered to be dominant. However, He-8 is a drip-line nucleus with a two-neutron separation energy of 2.1 MeV, and the di-neutron configuration, which is a characteristic feature of the weakly bound systems, mixes in the ground state. Finally, characteristic mechanism for the binding of clusters in neutron-rich nuclei (s(2) bond) is discussed.

• Appearance of cluster states in C13 査読 国際共著

T. Yoshida, N. Itagaki, T. Otsuka

Physical Review C - Nuclear Physics   79 ( 3 )   2009年03月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We study the structure of low-lying states of C13 with a microscopic cluster model. In addition to the 3α-n model space, the breaking effect of one of the α clusters due to the spin-orbit interaction is also taken into account. The isoscalar E0 transition probabilities from the ground 1/2- state to the excited ones are discussed associated with the cluster structure of these states. © 2009 The American Physical Society.

• Cluster structure stabilized by s2 neutrons in light neutron-rich nuclei 査読 国際共著

N. Itagaki, M. Kimura

Physical Review C - Nuclear Physics   79 ( 3 )   2009年03月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We systematically investigate the possibility that the s2 configuration of the two neutrons in the middle of the nucleus is a characteristic bond of α-clusters in light neutron-rich nuclei. The series of cluster states seen in Be10(2α+2n) and C14(3α+2n) is extended to the cases of heavier nuclei, O18(4α+2n) and Ne22(5α+2n), and we show the appearance of cluster structure with the s2 bond in the excited states by using a microscopic Nα+2n model, in which the coupling with low-lying states is included. © 2009 The American Physical Society.

• UNIFIED STUDIES OF NUCLEAR REACTIONS AND EXOTIC STRUCTURES IN Be-12 査読 国際共著

Makoto Ito, Naoyuki Itagaki

INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS   17 ( 10 )   2061 - 2066   2008年11月（ ISSN:0218-3013

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The alpha+He-8 low-energy reactions and the exotic structures of Be-12 are studied using the generalized two-center cluster (alpha+alpha+N) model. In the two-neutron transfer reactions, alpha+He-8(g.s.) -> He-6(g.s.)+He-6(g.s.), a resonant peak with J(pi) = 0(+) appears around E similar to 1.3 MeV above the He-6(g.s.) + He-6(g.s.) threshold as the result of the formation of the covalent superdeformation, which has a hybrid structure of covalent and ionic configurations for the valence neutrons. The covalent superdeformation gives rise to an isomeric state with a sharp width of Gamma similar to 400keV.

• THE COMPETITIVE REACTION MECHANISM IN EXOTIC NUCLEAR REACTIONS 査読 国際共著

Yoritaka Iwata, Naoyuki Itagaki, Joachim A. Maruhn, Takaharu Otsuka

INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS   17 ( 9 )   1660 - 1668   2008年10月（ ISSN:0218-3013

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

Two principal reaction dynamics are introduced. One is the spin displacement, which is caused from the spin-dependence of the interaction, and the other is the isovector displacement, which is caused from the isospin-dependence of it. The competition of these two dynamics is a rather important factor as the target or projectile has more excess neutrons or protons. In this paper the competitive reaction mechanism is theoretically formulated, where the time-dependent mean field calculations are performed for justification.

• Covalent isomeric state in Be12 induced by two-neutron transfers 査読 国際共著

M. Ito, N. Itagaki

Physical Review C - Nuclear Physics   78 ( 1 )   2008年07月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The α+He8 low-energy reactions and the exotic structures of Be12 are studied using the generalized two-center cluster (α+α+4N) model. In the two-neutron transfer reactions, α+He8g.s.→He6g.s.+He6g.s., a resonant peak with Jπ=0+ appears around E~ 1.3 MeV above the He6g.s.+He6g.s. threshold as the result of the formation of the covalent superdeformation, which has a hybrid structure of covalent and ionic configurations for the valence neutrons. The covalent superdeformation gives rise to an isomeric state with a sharp width of Γ~400 keV, which is smaller by about one order of magnitude than the typical width observed in molecular resonances above the Coulomb barrier. The energy-spin systematics for the two-neutron transfer reactions is investigated, and our calculation predicts a sequence of resonant structures in the range of 3-14 MeV in the center-of-mass energy with spins 0-8. © 2008 The American Physical Society.

• Mixing of di-neutron components in He-8 査読 国際共著

N. Itagaki, M. Ito, K. Arai, S. Aoyama, Tz. Kokalova

PHYSICAL REVIEW C   78 ( 1 )   2008年07月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The mixing of di-neutron components in He-8 is studied. The ground state of He-8 corresponds to the sub-closed-shell configuration of the spin-orbit favored orbits (p(3/2)) for the neutrons, and the shell-model-like configuration is considered to be dominant. However, He-8 is a drip-line nucleus with a two-neutron separation energy of 2.1 MeV, and the di-neutron configuration, which is a characteristic feature of the weakly bound systems, mixes in the ground state. The motion of four neutrons around the He-4 core is solved by superposing the wave functions of antisymmetrized molecular dynamics. The mixing of di-neutron configurations is estimated by coupling the THSR (Tohsaki-Horiuchi-Schuck-Ropke) wave function, which successfully describes the alpha-condensed state of light nuclei.

• Coexistence of α+α+n+n and α+t+t cluster structures in Be10 査読 国際共著

N. Itagaki, M. Ito, M. Milin, T. Hashimoto, H. Ishiyama, H. Miyatake

Physical Review C - Nuclear Physics   77 ( 6 )   2008年06月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The coexistence of the α+α+n+n and α+t+t cluster structures in the excited states of Be10 has been discussed. In the previous analysis, all the low-lying states of Be10 were found to be well described by the motion of the two valence neutrons around two α clusters. However, the α+t+t cluster structure was found to coexist with the α+α+n+n structure around Ex=15 MeV, close to the corresponding threshold. We have introduced a microscopic model to solve the coupling effect between these two configurations. The K=0 and K=1 states are generated from the α+t+t configurations due to the spin coupling of two triton clusters. The present case of Be10 is one of the few examples in which completely different configurations of triton-type (α+t+t three-center) and α-type (α+α+n+n two-center) clusters coexist in a single nucleus in the same energy region. © 2008 The American Physical Society.

• Coexistence of alpha+alpha+n+n and alpha+t+t cluster structures in Be-10 査読 国際共著

N. Itagaki, M. Ito, M. Milin, T. Hashimoto, H. Ishiyama, H. Miyatake

PHYSICAL REVIEW C   77 ( 6 )   2008年06月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The coexistence of the alpha + alpha + n + n and alpha + t + t cluster structures in the excited states of Be-10 has been discussed. In the previous analysis, all the low-lying states of Be-10 were found to be well described by the motion of the two valence neutrons around two alpha clusters. However, the alpha + t + t cluster structure was found to coexist with the alpha + alpha + n + n structure around E-x=15 MeV, close to the corresponding threshold. We have introduced a microscopic model to solve the coupling effect between these two configurations. The K=0 and K=1 states are generated from the alpha + t + t configurations due to the spin coupling of two triton clusters. The present case of Be-10 is one of the few examples in which completely different configurations of triton-type (alpha + t + t three-center) and alpha-type (alpha + alpha + n + n two-center) clusters coexist in a single nucleus in the same energy region.

• Coexistence of α+α+n+n and α+t+t cluster structures in Be10 査読 国際共著

N. Itagaki, M. Ito, M. Milin, T. Hashimoto, H. Ishiyama, H. Miyatake

Physical Review C - Nuclear Physics   77 ( 6 )   2008年06月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Coexistence of covalent superdeformation and molecular resonances in an unbound region of Be12 査読 国際共著

M. Ito, N. Itagaki, H. Sakurai, K. Ikeda

Physical Review Letters   100 ( 18 )   2008年05月（ ISSN:0031-9007

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The generalized two-center cluster model, which can treat static structures and dynamical reactions in excited states, is applied to the light neutron-rich system, Be12=α+α+4N. We discuss the change of the neutrons' configuration around two α cores from the covalent structure to the ionic one. We show that, in the unbound region above particle-decay thresholds, the ionic configurations appear as the molecular resonances of α+He8, He6+He6, and He5+He7. A new type of superdeformation is possible, and we find here a covalent superdeformation with a hybrid configuration of both the covalent and ionic structures. The excitation of these exotic structures through the two-neutron transfer reaction is also discussed. © 2008 The American Physical Society.

• Coupling between α-condensed states and normal cluster states 査読 国際共著

N. Itagaki, Tz. Kokalova, M. Ito, M. Kimura, W. Von Oertzen

Physical Review C - Nuclear Physics   77 ( 3 )   2008年03月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Coupling between alpha-condensed states and normal cluster states 査読 国際共著

N. Itagaki, Tz. Kokalova, M. Ito, M. Kimura, W. von Oertzen

PHYSICAL REVIEW C   77 ( 3 )   2008年03月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We have studied the alpha-condensed states of O-16 and Ne-20 based on a microscopic alpha-cluster model. This was performed by introducing a Monte Carlo technique for the description of the THSR (Tohsaki Horiuchi Schuck Ropke) wave function, which is called the "virtual THSR" wave function. Earlier microscopic calculations pointed out the possibility of the existence of four-alpha-cluster condensed states. Here, in addition to studying the four-alpha case, we also studied the case of five-alpha particles, for which the states are shown to be stable around the threshold energy even after taking into account the coupling effect between normal cluster states with O-16+alpha configurations.

• alpha+He-6,He-8 resonant scattering and exotic structures in Be-10,Be-12 査読 国際共著

Makoto Ito, Naoyuki Itagaki

ORIGIN OF MATTER AND EVOLUTION OF GALAXIES   1016   199 - +   2008年（ ISSN:0094-243X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The alpha+He-6,He-8 low-energy reactions and the structural changes of Be-10 in the microscopic alpha+alpha+2N model are studied by the generalized two-center cluster model with the Kohn-Hulthen-Kato variation method. It is found that in the inelastic scattering to the alpha+He-6(2(1)(+)) channel, characteristic enhancements are expected as the results of the parity-dependent non-adiabatic dynamics. The similar method is applied to the resonant scattering of a+He-8, and the coupling with the compound configurations of alpha+alpha+4N are discussed.

• E0 transition strength and cluster structure in 13 C 査読 国際共著

T. Yoshida, N. Itagaki, T. Otsuka

AIP Conference Proceedings   1016   451 - 453   2008年（ ISSN:0094-243X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

© 2008 American Institute of Physics. We study the structure of low-lying states of 13C with a microscopic cluster model. The second 0+ state of 12C, which is known as the Hoyle state and is important for astrophysical reactions, has been clarified to have dilute α-cluster structure. On the basis of the α-cluster model, we discuss the effect of one valence neutron in 13C on the α-cluster configuration of the Hoyle state. For these purpose, we investigate the iso-scalar E0 transition probability from the ground 1/2- state to this excited states.

• A systematic analysis of cluster components in He-isotopes by using a new AMD approach 査読 国際共著

S. Aoyama, N. Itagaki, M. Oi

Nuclear Physics A   790 ( 1-4 )   307c - 310c   2007年06月（ ISSN:0375-9474

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The t + t cluster components in the ground-state structure of He-isotopes are analysed through a new AMD approach. The method is called AMD triple-S which has been developed on the basis of the anti-symmetrized molecular dynamics (AMD), the generator coordinate method (GCM) and the stochastic variational method (SVM). In the AMD triple-S, variational calculations are carried out by means of the GCM with the AMD wave functions produced by the SVM procedure. © 2007 Elsevier B.V. All rights reserved.

• Simplified modeling of cluster-shell competition in carbon isotopes 査読 国際共著

H. Masui, N. Itagaki

Physical Review C - Nuclear Physics   75 ( 5 )   2007年05月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We study the cluster-shell competition in carbon isotopes. Two parameters are introduced for the C12 core to characterize the transition from a cluster state to a shell-model state as a measure of the cluster-shell competition: one expresses the relative distance between α clusters and the other does the dissolution of one of the α clusters. We show the energy curves as functions of these parameters. The calculation is performed by combining the simplified modeling of cluster-shell competition for the C12 core and AMD triple-S. As the neutron number increases, the α-α distance becomes smaller; on the contrary, the dissolution of α clusters is enhanced. The origins of the anomalously small B(E2) value of C16 are discussed from cluster-shell competition point of view, and the appearance of pure cluster state around the 10 MeV region is suggested. © 2007 The American Physical Society.

• α-condensed state with a core nucleus 査読 国際共著

N. Itagaki, M. Kimura, C. Kurokawa, M. Ito, W. Von Oertzen

Physical Review C - Nuclear Physics   75 ( 3 )   2007年03月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Linear-chain structure of three alpha clusters in C-13 査読 国際共著

N. Itagaki, W. von Oertzen, S. Okabe

PHYSICAL REVIEW C   74 ( 6 )   2006年12月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We investigate a linear-chain configuration of three alpha clusters with a neutron in C-13. To characterize this configuration, an operator P is introduced, which is the sum of parity inversion operators for each proton. The states with positive expectation values for this operator are found to form a rotational band structure, and the moment of inertia agrees well with the experimentally suggested value. Allowing a small bending angle stabilizes the linear-chain configuration of three alpha clusters with a valence neutron, which is a hyper-deformed state.

• t+t clustering in He-isotopes 査読 国際共著

S. Aoyama, N. Itagaki, K. Arai, K. Kato, M. Oi

Modern Physics Letters A   21 ( 31-33 )   2499 - 2502   2006年10月（ ISSN:0217-7323

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

t+t clustering in He isotopes is investigated by using two theoretical approaches. A role of the t+t cluster component in the ground state is examined with AMD triple-S, allowing the wider configuration space containing simultaneously the "t+t+valence neutrons" structure and "4He+valence neutrons" structure. We understand the importance of the t+t component even for the ground state. Further, t+t resonances are investigated with RGM type approach. We obtained many t+t states as resonances near to t+t threshold. © World Scientific Publishing Company.

• Systematic analyses of the t+t clustering effect in He isotopes 査読 国際共著

S. Aoyama, N. Itagaki, M. Oi

PHYSICAL REVIEW C   74 ( 1 )   2006年07月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

A systematic study on the ground-state structure of He isotopes (including He-10) is presented through a new method developed on the basis of antisymmetrized molecular dynamics (AMD), the generator coordinate method (GCM), and the stochastic variational method (SVM). In this approach, variational calculations are carried out by means of the GCM with the AMD wave functions produced by means of the SVM. A role of the t+t cluster component is examined with the present method, allowing the wider configuration space containing simultaneously the "t+t+valence neutrons" structure and "He-4+valence neutrons" structure.

• Signatures for multi-α-condensed states 査読 国際共著

Tz. Kokalova, N. Itagaki, W. Von Oertzen, C. Wheldon

Physical Review Letters   96 ( 19 )   2006年05月（ ISSN:0031-9007

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Simplified method to include the tensor contribution in α-cluster model 査読 国際共著

N. Itagaki, H. Masui, M. Ito, S. Aoyama, K. Ikeda

Physical Review C - Nuclear Physics   73 ( 3 )   2006年03月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Linear-chain structure of three α clusters in C13 査読 国際共著

N. Itagaki, W. Von Oertzen, S. Okabe

Physical Review C - Nuclear Physics   74 ( 6 )   2006年（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Systematic analyses of the t+t clustering effect in He isotopes 査読 国際共著

S. Aoyama, N. Itagaki, M. Oi

Physical Review C - Nuclear Physics   74 ( 1 )   2006年（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

A systematic study on the ground-state structure of He isotopes (including He10) is presented through a new method developed on the basis of antisymmetrized molecular dynamics (AMD), the generator coordinate method (GCM), and the stochastic variational method (SVM). In this approach, variational calculations are carried out by means of the GCM with the AMD wave functions produced by means of the SVM. A role of the t+t cluster component is examined with the present method, allowing the wider configuration space containing simultaneously the "t+t+valence neutrons" structure and "He4+valence neutrons" structure. © 2006 The American Physical Society.

• Simplified modeling of cluster-shell competition 査読 国際共著

N. Itagaki, H. Masui, M. Ito, S. Aoyama

Physical Review C - Nuclear Physics   71 ( 6 )   2005年06月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We propose a simple model to describe cluster-shell competition. Introducing only one parameter (Λ) to the wave function makes it possible to describe the asymptotic transition of two valence neutrons in Be10 (α+α+n+n) from a di-neutron to independent particles when the contribution of the spin-orbit interaction is taken into account. Similarly in C12, a transition from a 3α configuration to a 2α+4N configuration is represented, and we show a strong contribution of the spin-orbit interaction in the ground state. We investigate further this transition from the cluster state (α+O16) to the shell-model state (O16 + four nucleons) in Ne20. In these examples, the wave functions for cluster-breaking states are prepared in the same general way. © 2005 The American Physical Society.

• AMD plus GCM study of structure of carbon isotopes 査読 国際共著

G Thiamova, N Itagaki, T Otsuka, K Ikeda

ORIGIN OF MATTER & EVOLUTION OF GALAXIES 2003   545 - 548   2005年

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The ground state properties of the carbon isotopes are investigated using the extended version of the Antisymmetrized Molecular Dynamics (AMD) Multi Slater Determinant method. We can reproduce reasonably well many experimental data for C-12-C-22. In this contribution we present a systematic calculation of binding energies, energies of the 2(+)(1) states and B(E2) transition strengths.

• Wandering in color-space - Why is the life of pentaquark so long? 査読 国際共著

Y Maezawa, T Maruyama, N Itagaki, T Hatsuda

ACTA PHYSICA HUNGARICA A-HEAVY ION PHYSICS   22 ( 1-2 )   61 - 68   2005年（ ISSN:1219-7580

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The problem of the long life time of the pentaquark Theta(+) is investigated on the basis of the color molecular dynamics simulation. We find that it takes a long time (typically of 50-100 fm/c) for the initial pentaquark state to rearrange its color and spatial positions to decay into the nucleon+kaon final state. Structure of the potential surface in the color and position spaces also supports this picture. Pentaquark wanders on the potential surface to find a narrow channel to decay.

• Dynamics of pentaquark in color molecular dynamics simulation 査読 国際共著

Y Maezawa, T Maruyama, N Itagaki, T Hatsuda

Pentaquark 04, Proceedings   386 - 389   2005年

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

Life time of the pentaquark Theta(+) is investigated on the basis of the color molecular dynamics simulation. We find that it takes a long time (typically of 50 - 100 fm/c) for the initial pentaquark-state to rearrange its color and spatial configurations to decay into the nucleon+kaon final state. The potential surface in the color and position spaces also supports this picture: Pentaquark wanders on the potential surface to find a narrow channel to decay.

• Systematic study of structure of carbon isotopes with the antisymmetrized molecular dynamics plus generator coordinate method 査読 国際共著

G. Thiamova, N. Itagaki, T. Otsuka, K. Ikeda

European Physical Journal A   22 ( 3 )   449 - 454   2004年12月（ ISSN:1434-6001

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structure of low-lying states of the carbon isotopes is investigated using the improved version of the Antisymmetrized Molecular Dynamics (AMD) Multi-Slater Determinant model. The theoretical method is found to be very useful to study ground-state properties of various nuclei covering light unstable nuclei. The calculations succeed to reproduce reasonably well many experimental data for the carbon isotopes 12C-22C such as binding energies, the energies of the 21+ states in the even-even isotopes, radii and electromagnetic transition strengths. We investigate the structure change with the increasing neutron number and observe the existence of various exotic phenomena, like the development of a neutron skin and large deformations which appear in unstable nuclei. Our calculations clearly support the existence of the N = 8 and N = 16 neutron magic numbers. The role of the spin-orbit interaction in the description of the studied isotopes and in the development of cluster structures is discussed. A special approach, important for weakly bound systems, is adopted for 15C. It enables us to better describe the tail of the wave function. © Società Italiana di Fisica/Springer-Verlag 2004.

• Cluster-shell competition in light nuclei 査読 国際共著

N. Itagaki, S. Aoyama, S. Okabe, K. Ikeda

Physical Review C - Nuclear Physics   70 ( 5 )   054307 - 1   2004年11月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We demonstrate whether the cluster structure dissolves or remains when the shell-model-like model space is introduced in addition to the cluster model space in light nuclei. Although the binding energies of 8Be, 10Be, and 10B become larger by about 1-2 MeV by adding shell-model-like basis states to the α+α+N+N+⋯ basis states, the α-α structure is a dominant configuration of the ground states. However, α-breaking wave functions strongly mix in 12C, and the decrease of the energy from the 3α configuration by about 6 MeV is a clue to resolving a long-standing problem of the binding energies of 12C and 12O. The improved version of antisymmetrized molecular dynamics (AMD), AMD superposition of selected snapshots (AMD triple-S), is used to show the cluster-shell competition of these nuclei.

• Structure of even-even beryllium isotopes studied by AMD+GCM method 査読 国際共著

G. Thiamova, N. Itagaki, T. Otsuka

Czechoslovak Journal of Physics   54 ( 7 )   739 - 747   2004年07月（ ISSN:0011-4626

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The ground state properties and the properties of low-lying states of the even-even 6Be- 12Be beryllium isotopes are investigated using the extended version of the Antisymmetrized Molecular Dynamics Multi-Slater Determinant model. The theoretical method is found to be very useful to study ground state properties of various nuclei covering light unstable nuclei. Many experimental data can be successfully reproduced by the adopted approach. Binding energies, the energies of the 2 +1 states, electromagnetic transition strengths and quadrupole moments of proton and neutron distribution are calculated.

• Exotic cluster structure in light neutron-rich nuclei 査読 国際共著

N. Itagaki, S. Aoyama, T. Otsuka, T. Yoshida, S. Okabe, K. Ikeda

Nuclear Physics A   738 ( 1-4 SUPPL. )   17 - 23   2004年06月（ ISSN:0375-9474

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

A new method to calculate the low-lying states of light nuclei is proposed: Antisymmetrized Molecular Dynamics (AMD) - Superposition of Selected Snapshots (AMD triple S). In addition to the cluster features of the core nucleus, the properties of the wave of the valence nucleons are well expressed in terms of a superposition of selected AMD wave functions. Our previous results based on Molecular-orbits are justified using this new framework. For example, the three O+ states of 10Be are found to be well described. Here, the importance of solving the cooling equation for the imaginary part of the Gaussian centers for the nucleons is examined. For 12Be, the newly observed J = 0 state at 2.24 MeV is analyzed to be the second O+ state. The method is further applied to Ne isotopes with 5α-core, and parity mixing of the single-particle orbit around parity-asymmetric core is discussed. © 2004 Published by Elsevier B.V.

• Systematic analyses on H- and He-isotopes by using an extended AMD approach 査読 国際共著

S. Aoyama, N. Itagaki

Nuclear Physics A   738 ( 1-4 SUPPL. )   362 - 366   2004年06月（ ISSN:0375-9474

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We study systematically H- and He-isotopes using an extended AMD (Antisymmetrized Molecular Dynamics) approach. In this approach, AMD combined with the generator coordinate method is extended with the idea of the stochastic variational method. By using this new method, we study many body-cluster states of extremely neutron-rich nuclei such as 7H (t+n+n+n+n) or 10He (4He+n+n+n+n+n+n . © 2004 Elsevier B.V. All rights reserved.

• Equilateral-triangular shape in <sup>14</sup>C 査読 国際共著

N. Itagaki, T. Otsuka, K. Ikeda, S. Okabe

Physical Review Letters   92 ( 14 )   142501 - 1   2004年04月（ ISSN:0031-9007

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The molecular-orbit (MO) model of an equilateral-triangular shape of three α clusters surrounded by excess neutrons was investigated. An equilateral-triangular symmetry was determined by an attractive interaction between an excess neutron and α particle was found to stabilize K πx = 0+ and 3- rotational bands. The rotational band with 3- value at 3 MeV below the 10Be + α threshold energy corresponded to the band built on top of second 3 - state. The molecular 3-α structure stabilization was suggested by excess neutrons which were observed as realization of α crystallization in dilute nuclear medium.

• Study of the structure of light nuclei by AMD + GCM method 査読 国際共著

G. Thiamova, N. Itagaki, T. Otsuka

Czechoslovak Journal of Physics   54 ( 3 )   329 - 338   2004年03月（ ISSN:0011-4626

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structure of stable and unstable light nuclei in the carbon region is investigated using the extended version of the Antisymmetrized Molecular Dynamics Multi-Slater Determinant model. This method has proved to be very flexible when describing structure of light nuclei where both shell model and cluster structure can appear. In this paper we address specifically the development of cluster structure in the 02+ state in the 10Be isotope. The possibility of description of halo structure within the adopted method is discussed in the case of 15C. Systematic calculations for even-even oxygen isotopes support the development of new magic number N=16.

• Exotic cluster structure in light neutron-rich nuclei 査読 国際共著

N Itagaki, S Aoyama

LABYRINTH IN NUCLEAR STRUCTURE   701   49 - 53   2004年（ ISSN:0094-243X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

A new method for calculating the low-lying states of light nuclei is proposed: Antisymmetrized Molecular Dynamics (AMD) - Superposition of Selected Snapshots (AMD triple-S). In addition to the cluster features of the core nucleus, the properties of the wave of valence nucleons are well expressed in terms of a superposition of selected AMD wave functions. For He-6, the binding energy and the halo nature are reproduced using effective interactions determined from a phase-shift analysis. For the deformed core cases, in Be-12, the newly observed J = 0 state at 2.24 MeV is analyzed to be the second 0(+) state.

• Systematic AMD plus GCM study of structure of carbon isotopes 査読 国際共著

G Thiamova, N Itagaki, T Otsuka, K Ikeda

LABYRINTH IN NUCLEAR STRUCTURE   701   44 - 48   2004年（ ISSN:0094-243X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The structure of low-lying states of the carbon isotopes is investigated using the extended version of the Antisymmetrized Molecular Dynamics (AMD) Multi-Slater Determinant model. We can reproduce reasonably well many experimental data for carbon isotopes C-12-C-22. A special approach is adopted for C-15 to better describe the tail of the wave function.

• New description of light nuclei by extending the AMD approach 査読 国際共著

N. Itagaki, A. Kobayakawa, S. Aoyama

Physical Review C - Nuclear Physics   68 ( 5 )   543021 - 543027   2003年11月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

A new method for calculating the low-lying states of light nuclei is proposed: antisymmetrized molecular dynamics (AMD)-superposition of selected snapshots. In addition to the cluster features of the core nucleus, the properties of the wave of valence nucleons are well expressed in terms of a superposition of selected AMD wave functions. For 6He, the binding energy and the halo nature are reproduced using effective interactions determined from a phase-shift analysis. For the deformed core cases, the three 0+ states of 10Be are well described. Here, the importance of solving the cooling equation for the imaginary part of the Gaussian centers for the nucleons is examined. For 12Be, the newly observed J=0 state at 2.24 MeV is analyzed to be the second 0+ state.

• Importance of clustering in light neutron-rich nuclei 査読 国際共著

N. Itagaki, K. Hagino, T. Otsuka, S. Okabe, K. Ikeda

Nuclear Physics A   719 ( 1-4 )   C205 - C208   2003年05月（ ISSN:0375-9474

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We discuss two topics about the cluster structure in light neutron-rich nuclei with the astrophysical interests. One is 9Be: using a microscopic α + α + n model, the photodisintegration cross section is analyzed. It is shown that good agreement is achieved with the recently measured B(E1) transition probability from the ground 3/2- state to the first excited state (1/2+), which is 2 times larger than the previous measurement. The other topic is the cluster-shell mixing in 12C, which is crucial to explain the B(E2) value from the second O+ state to the first 2+ state in triple-α reaction.

• Systematic analysis of neutron-rich carbon isotopes 査読 国際共著

G. Thiamova, N. Itagaki, T. Otsuka, K. Ikeda

Nuclear Physics A   719 ( 1-4 )   C312 - C315   2003年05月（ ISSN:0375-9474

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The low-lying structure of the C isotopes is investigated using the Antisymmetrized Molecular Dynamics (AMD) Multi-Slater Determinant model. The calculated 2± energies of the even-even isotopes indicate the change from spherical to deformed structure at N = 8. This is consistent with the isotope change of the single particle energy deduced from recent experiments. Binding energies and r.m.s. radii are also calculated and compared with the experimental data.

• Isomeric 0<sup>+</sup> state in <sup>12</sup>Be 査読 国際共著

S. Shimoura, A. Saito, T. Minemura, Y. U. Matsuyama, H. Baba, H. Akiyoshi, N. Aoi, T. Gomi, Y. Higurashi, K. Ieki, N. Imai, N. Iwasa, H. Iwasaki, S. Kanno, S. Kubono, M. Kunibu, S. Michimasa, T. Motobayashi, T. Nakamura, H. Sakurai, M. Serata, E. Takeshita, S. Takeuchi, T. Teranishi, K. Ue, K. Yamada, Y. Yanagisawa, M. Ishihara, N. Itagaki

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics   560 ( 1-2 )   31 - 36   2003年05月（ ISSN:0370-2693

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

An isomeric 0+ state in 12Be was found at Ex = 2.24 MeV. The isomer was identified by measuring coincident two γ-rays from in-flight 12Be nuclei, 12mBe → 12Be* (21+) → 12Beg.s., produced by the projectile fragmentation of 18O at 100 A MeV on a beryllium target. Its spin was determined to be 0+ by the angular correlation of the two γ-rays. The low excitation energy of the 0+ state is a strong evidence of the break of the N = 8 shell closure in the 12Be nucleus. © 2003 Published by Elsevier Science B.V.

• Exotic cluster structure in light neutron-rich nuclei 査読 国際共著

N Itagaki, S Hirose, T Otsuka, S Okabe, K Ikeda

PROCEEDINGS OF THE THIRD INTERNATIONAL CONFERENCE FISSION AND PROPERTIES OF NEUTRON-RICH NUCLEI   159 - 166   2003年

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The triaxial deformation in Be-10 is investigated using a microscopic alpha+alpha+n+n model. The states of two valence neutrons are classified based on the molecular-orbit (MO) model, and the pi-orbit is introduced about the axis connecting the two alpha-clusters for the description of the rotational bands. There appear two rotational bands comprised mainly of K-pi = 0(+) and K-pi = 2(+), respectively, at low excitation energy, where the two valence neutrons occupy K-pi = 3/2(-) or K-pi = 1/2(-) orbits. The triaxiality and the K-mixing are discussed in connection to the molecular structure, particularly, to the spin-orbit splitting. The extent of the triaxial deformation is evaluated in terms of the electro-magnetic transition matrix elements (Davydov-Filippov model). The obtained values turned out to be gamma = 15 degrees similar to 20 degrees. Furthermore, the mirror symmetry breaking of the triaxial deformation of C-10 is investigated. The triaxiality of protons in C-10 is much larger than that of neutrons in Be-10 due to the weak binding nature of the valence particles. This agrees with the recent experiment which suggests the mirror symmetry breaking of these nuclei through the beta-decay transition strength.

• Systematic analysis of neutron-rich even-even carbon isotopes 査読 国際共著

G Thiamova, N Itagaki, T Otsuka, K Ikeda

CAPTURE GAMMA-RAY SPECTROSCOPY AND RELATED TOPICS   837 - 841   2003年

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The low-lying structure of the even-even C isotopes is investigated using the Multi-Slater Determinant AMD model. The calculated 2(+) energies show the change from spherical to deformed structure at N = 8 and it is consistent with the isotope change of the single particle energy deduced from recent experiments. Binding energies and r.m.s. radii are also calculated and compared with the experimental data.

• Exotic cluster structure in light neutron-rich nuclei 査読 国際共著

N. Itagaki, T. Otsuka, S. Okabe, K. Ikeda

Acta Physica Hungarica New Series Heavy Ion Physics   18 ( 2-4 )   173 - 178   2003年（ ISSN:1219-7580

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The cluster structure of C isotopes is investigated using a microscopic α+α+α+n+n... model based on the molecular orbit (MO) model. The stability of the linear chain of 3α with respect to the breathing mode and the bending mode for various neutron configurations is investigated. The combination of the valence neutrons in the π- and σ-orbits is promising to stabilize for these modes, and the excited states of 16C with the (3/2π-)2(1/2σ-)2 configuration for the four valence neutrons are one of the most promising candidates for such structure. Furthermore, the equilateral-triangular shape of 3α surrounded by valence neutrons is suggested for 14C. The 3-, 4-, and 5 - members of this rotational band appear around the 10Be+α threshold, and these calculated states correspond to the experimentally observed 3- state (9.80 MeV) and 4- state (11.67 MeV). A positive-parity rotational band (0+, 2+, 4+) also arises around this threshold energy, and these results suggest that the picture of inversion doublet structure works also in neutron-rich nuclei.

• Triaxial deformation in Be-10 査読 国際共著

N Itagaki, S Hirose, T Otsuka, S Okabe, K Ikeda

PHYSICAL REVIEW C   65 ( 4 )   443021 - 443026   2002年04月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The triaxial deformation in Be-10 is investigated using a microscopic alpha+alpha+n+n model. The states of two valence neutrons are classified based on the molecular-orbit (MO) model, and the pi orbit is introduced about the axis connecting the two alpha clusters for the description of the rotational bands. There appear two rotational bands comprised mainly of K-pi=0(+) and K-pi=2(+), respectively, at low excitation energy, where the two valence neutrons occupy K-pi=3/2(-) or K-pi=1/2(-) orbits. The triaxiality and the K mixing are discussed in connection to the molecular structure, particularly to the spin-orbit splitting. The extent of the triaxial deformation is evaluated in terms of the electromagnetic transition matrix elements (Davydov-Filippov model, Q-invariant model) and density distribution in the intrinsic frame. The obtained values turned out to be gamma=15degrees-20degrees.

• Exotic cluster shapes in neutron-rich Be and C isotopes 査読 国際共著

N Itagaki, K Ikeda, S Okabe, T Otsuka

PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT   ( 146 )   207 - 211   2002年（ ISSN:0375-9687

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structure of C isotopes are investigated using a microscopic alpha+alpha+alpha+n+n... model based on the molecular orbit (MO) model. The stability of the linear-chain of 3alpha with respect to the breathing mode and the bending mode for various neutron configurations is investigated. The combination of the valence neutrons in the pi- and the sigma-orbit is promising to stabilize for these modes, and the excited state of C-16 with the (3/2(pi)(-))(2) (1/2(sigma)(-))(2) configuration for the four valence neutrons is one of the most promising candidates for such structure. Furthermore, the equilateral-triangular shape of 3alpha surrounded by valence neutrons is suggested for C-14 based on a microscopic cluster model. The 3(-), 4(-) and 5(-) members of this rotational band appear around the Be-10+alpha threshold, and these calculated states correspond to the experimentally observed 3(-) state (9.80 MeV) and 4(-) state (11.67 MeV). A positive-parity rotational band (0(+), 2(+), 4(+)) also arises around this threshold energy, and these results suggest that the picture of inversion doublet structure works also in neutron-rich nuclei.

• The exotic clustering and nucleon-nucleon correlations in light neutron-rich nuclei 査読 国際共著

Shunsuke Hirose, Naoyuki Itagaki, Takaharu Otsuka, Shigeto Okabe, Kiyomi Ikeda

Progress of Theoretical Physics   ( 146 SUPPL. )   565 - 566   2002年（ ISSN:0033-068X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

• The exotic clustering and nucleon-nucleon correlations in light neutron-rich nuclei 査読 国際共著

S Hirose, N Itagaki, T Otsuka, S Okabe, K Ikeda

PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT   ( 146 )   565 - 566   2002年（ ISSN:0375-9687

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

• Molecular-orbital structure in neutron-rich Be and C isotopes 査読 国際共著

N. Itagaki, S. Okabe, K. Ikeda, I. Tanihata

European Physical Journal A   13 ( 1-2 )   43 - 47   2002年（ ISSN:1434-6001

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structure of Be and C isotopes are investigated based on the molecular-orbit (MO) model. The low-lying states are characterized by several configurations of valence neutrons, which are constructed as combinations of basic orbits. In 10Be, all of the observed positive-parity bands and the negative-parity bands are described within the model. The second 0 + state of 10Be has a large α-α cluster structure, and this is characterized by a (1/2+σ) 2 configuration. An enlargement of the α-α distance due to two-valence neutrons along the α-α axis makes their wave function smooth and reduces the kinetic energy drastically. Furthermore, the contribution of the spin-orbit interaction due to coupling between the S z = 0 and the S z = 1 configurations, is important. In the ground state of 12Be, the calculated energy exhibits similar characteristics, that the remarkable α clustering and the contribution of the spin-orbit interaction make the binding of the state with (3/2-π)2(1/2+σ)2 configuration properly stronger in comparison with the closed p-shell (3/2 -π)2(1/2-π) 2 configuration. This is related to the breaking of the N = 8 (closed p-shell) neutron magic number. Also, the molecule-like structure of the C isotopes is investigated using a microscopic α+α+α+n+n+ . . . model. The combination of the valence neutrons in the π- and the σ-orbit is promising to stabilize the linear-chain state against the breathing and bending modes, and it is found that the excited states of 16C are the most promising candidates for such structure. © Società Italiana di Fisica and Springer-Verlag 2002.

• Low-energy photodisintegration of [Formula Presented] with the molecular orbit model 査読 国際共著

N. Itagaki, K. Hagino

Physical Review C - Nuclear Physics   66 ( 5 )   4   2002年（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We use a microscopic three-cluster model with the [Formula Presented] configuration to analyze with astrophysical interests the photodisintegration cross section of [Formula Presented] The valence neutron in [Formula Presented] is treated in the molecular orbit model, including continuum states by the box discretization method. It is shown that good agreement is achieved with the recently measured [Formula Presented] transition probability from the ground state to the first [Formula Presented] state when the box size is enlarged, resulting in reasonable reproduction of the experimental data for the photodisintegration cross section. The Coulomb dissociation of [Formula Presented] is also discussed. © 2002 The American Physical Society.

• Exotic cluster structure of light neutron-rich nuclei 査読 国際共著

N Itagaki, T Otsuka, S Okabe, K Ikeda

EXOTIC CLUSTERING   644   62 - 67   2002年（ ISSN:0094-243X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The molecule-Re structure of the C isotopes is investigated using a microscopic alpha+alpha+alphaln+n+(.) (.) (.) model. The valence neutrons are classified based on the molecular-orbit (MO) model, and both pi-orbit and sigma-orbit are introduced around three alpha-clusters. The excited states of C-16 is one of the most promising candidates for the linear-chain structure. The equilateral-triangular shape of 3alpha surrounded by valence neutrons is also suggested for C-14. The cluster around the Be-10+alpha threshold energy corresponds to the experimentally observed band built on top of the second 3(-) state.

• Exotic cluster shapes in neutron-rich Be and C isotopes 査読 国際共著

Naoyuki Itagaki, Kiyomi Ikeda, Shigeto Okabe, Takaharu Otsuka

Progress of Theoretical Physics   ( 146 SUPPL. )   207 - 211   2002年（ ISSN:0033-068X

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

The structure of C isotopes are investigated using a microscopic α+α+α+n+n. . . model based on the molecular orbit (MO) model. The stability of the linear-chain of 3α with respect to the breathing mode and the bending mode for various neutron configurations is investigated. The combination of the valence neutrons in the π- and the σ-orbit is promising to stabilize for these modes, and the excited state of 16C with the (3/2π-)2 (1/2σ-)2 configuration for the four valence neutrons is one of the most promising candidates for such structure. Furthermore, the equilateral-triangular shape of 3α surrounded by valence neutrons is suggested for 14C based on a microscopic cluster model. The 3-, 4- and 5- members of this rotational band appear around the 10Be+α threshold, and these calculated states correspond to the experimentally observed 3- state (9.80 MeV) and 4- state (11.67 MeV). A positive-parity rotational band (0+, 2+, 4+) also arises around this threshold energy, and these results suggest that the picture of inversion doublet structure works also in neutron-rich nuclei.

• Molecular-orbital structure in neutron-rich C isotopes 査読 国際共著

N. Itagaki, S. Okabe, K. Ikeda, I. Tanihata

Physical Review C - Nuclear Physics   64 ( 1 )   143011 - 143015   2001年07月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The moleculelike structure of the C isotopes (A = 12, 14, 16) is investigated using a microscopic α + α + α + n + n + ⋯ model. The valence neutrons are classified based on the molecular-orbit model, and both π orbit and σ orbit are introduced around three α clusters. The valence neutrons which occupy the π orbit increase the binding energy and stabilize the linear chain of 3 α against the breathinglike breakup. However, 14C with the π orbit does not show a clear energy minimum against the bendinglike path. The combination of the valence neutrons in the π and σ orbits is promising to stabilize the linear-chain state against the breathing and bending modes, and it is found that the excited states of 16C with the (3/2-π)2(1/2-σ)2 configuration for the four valence neutrons is one of the most promising candidates for such a structure.

• Molecular-orbital structure in Be isotopes 査読 国際共著

N Itagaki, S Okabe, K Ikeda

ACTA PHYSICA HUNGARICA NEW SERIES-HEAVY ION PHYSICS   13 ( 1-3 )   153 - 156   2001年（ ISSN:1219-7580

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structure of Be-12 is investigated using a microscopic alpha+alpha +4n model based on the molecular-orbit (MO) model. It is shown that the remarkable alpha -clustering and the contribution of the spin-orbit interaction make the binding of the state with the (3/2(-))(2)(1/2(+))(2) configuration for the valence neutrons properly stronger in comparison with the closed p-shell (3/2(-))(2)(1/2(-))(2) configuration. The molecular-like structure of the C isotopes is also investigated using a microscopic alpha+alpha+alpha +n+n+(...) model.

• Molecular-orbital structure in light neutron-rich nuclei 査読 国際共著

Naoyuki Itagaki, Shigeto Okabe, Kiyomi Ikeda

Progress of Theoretical Physics Supplement   ( 142 )   297 - 323   2001年（ ISSN:0375-9687

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structures of Be isotopes and C isotopes are investigated using a microscopic α+α+n+n· · · model and α+α+α+n+n· · · model, respectively, based on the molecular orbit (MO) model. The low-lying states of the Be isotopes are characterized by several configurations of valence neutrons, which are constructed as combinations of three basic orbits. The model space employed is extended from that of conventional MO models, and the orbits are expressed as linear combinations of local Gaussians. Their positions are determined variationally. In 10Be, all of the observed positive-parity bands and negative-parity bands are described within the model. It is found that the second 0+ state of 10Be has a large α-α structure with a (1/2+)2 configuration. Increase of the α-α distance due to the existence of two valence neutrons along the α-α axis makes their wave function smooth and reduces the kinetic energy drastically. Here, the contribution of the spin-orbit interaction due to coupling between the Sz = 0 and the Sz = 1 configurations is important. The energy surface of 12Be is found to exhibit similar characteristics, with a significant α clustering and the contribution of the spin-orbit interaction causing the binding of the ground state with the (1/2+)2 configuration to become much stronger. As a result, the (3/2-)2(1/2+)2 configuration for the four valence neutrons almost degenerate with the (3/2-)2(1/2-)2 configuration. This is related to the breaking of the N = 8 magic number. For the C isotopes, the stability of the linear chain of 3α with respect to the breathing-like mode and the bending-like mode are investigated for various neutron configurations. It appears likely that a combination of the valence neutrons in the π-and the σ-orbit is to stabilize the system with respect to such modes, and it is found that the excited states of 16C with the (3/2-π)2(1/2-σ)2 configuration for four valence neutrons is one of the most probable of such structures.

• Important role of the spin-orbit interaction in forming the 1/2(+) orbital structure in Be isotopes 査読 国際共著

N Itagaki, S Okabe, K Ikeda

PHYSICAL REVIEW C   62 ( 3 )   343011 - 343018   2000年09月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structure of the second 0(+) state of Be-10 is investigated using a microscopic alpha+alpha+n+n model based on the molecular-orbit (MO) model. The second 0(+) state, which has dominantly the(1/2(+))(2) configuration, is shown to have a particularly enlarged alpha-alpha structure. The kinetic energy of the two valence neutrons occupying along the alpha-alpha axis is reduced remarkably due to the strong alpha clustering and, simultaneously, the spin-orbit interaction unexpectedly plays an important role in making the energy of this state much lower. The mixing of states with different spin structure is shown to be important in negative-parity states. The experimentally observed small-level spacing between 1(-) and 2(-) (similar to 300 keV) is found to be evidence of this spin-mixing effect. Be-12 is also investigated using the alpha+alpha+4n model, in which four valence neutrons are considered to occupy the (3/2(-))(2)(1/2(+))(2) configuration. The energy surface of Be-12 is shown to exhibit similar characteristics, that the remarkable alpha clustering and the contribution of the spin-orbit interaction make the binding of the state with the (3/2(-))(2)(1/2(+))(2) configuration properly stronger in comparison with the closed p-shell (3/2(-))(2)(1/2(-))(2) configuration.

• Systematic study on he isotopes with the antisymmetrized molecular dynamics plus generator coordinate method 査読 国際共著

N. Itagaki, S. Aoyama

Physical Review C - Nuclear Physics   61 ( 2 )   243031 - 243035   2000年02月（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

We study the structure of He isotopes systematically using a model in which the frameworks of the anti-symmetrized molecular dynamics (AMD) and the generator coordinate method (GCM) are combined. The present AMD+GCM can reproduce basic features of the isotopes, for example halo structures in 6He and tendency of the binding energies of the isotopes within relatively small number of basis functions. In 7He, the importance of two configurations, 6He-n and (4He-n)-2n, is shown for the ground state. In 8He, the calculated rms radius is smaller than the experimental one.

• Be-12 is not a magic number nucleus 査読 国際共著

N Itagaki, S Okabe

PROCEEDINGS OF THE 7TH INTERNATIONAL CONFERENCE ON CLUSTERING ASPECTS OF NUCLEAR STRUCTURE AND DYNAMICS   268 - 270   2000年

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

Be-10 and Be-12 are investigated by a microscopic alpha+alpha +n+n ... model based on the Molecular Orbit (MO) model. The low-lying states are characterized by several configurations of valence neutrons which are constructed as combinations of three basic orbits: K-pi=3/2(-), 1/2(-) and 1/2(+). In Be-10, all the observed positive parity bands and negative parity bands are described within the model, and the second 0(+) state has large alpha - alpha structure. The configuration is (1/2(+))(2) corresponding to the sd-shell, and two valence neutrons along the alpha - alpha axis enhance the alpha - alpha distance. In Be-12, this configuration strongly mixes in the ground state, and due to this, the observed slow beta -decay to B-12 is explained. This is the breaking of N = 8 magic number in Be-12.

• Structures of Be nuclei by a new molecular orbital approach 査読 国際共著

N Itagaki, S Okabe

FEW-BODY PROBLEMS IN PHYSICS '99   12   145 - 148   2000年（ ISSN:0177-8811

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

We discuss the importance of clustering in light neutron-rich nuclei. As examples, we analyse Be-10 and Be-12 based on a microscopic alpha+alpha +valence n model and show that the alpha-alpha clustering is enlarged due to valence neutrons.
In Be-10, all the observed positive parity bands and negative parity bands are described within the model (alpha+alpha +n+n), and the second 0(+) state is shown to have a large alpha-alpha distance. Here, the two valence neutrons occupy along the alpha-alpha axis and they enlarge the alpha-alpha distance. The configuration of the valence neutrons corresponds to (1/2(+))(2) (sigma -orbit in terms of MO), and these neutrons reduce their kinetic energy caused by the Pauli principle as the increase of the alpha-alpha distance.
This mechanism is related to the breaking of N = 8 magic number in Be-12. In Be-12, this (1/2(+))(2) component plays an important role in the ground state. The calculated energy of this configuration is lower than the closed p-shell configuration for neutrons. Due to this effect, the observed slow beta -decay probability from Be-12 to B-12 can be explained.

• Molecular orbital structures in [Formula Presented] 査読 国際共著

N. Itagaki, S. Okabe

Physical Review C - Nuclear Physics   61 ( 4 )   13   2000年（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structure of [Formula Presented] is investigated using a microscopic [Formula Presented] model based on the molecular orbit (MO) model. The low-lying states are characterized by several configurations of valence neutrons, which are constructed as combinations of three basic orbits. The model space employed is extended from the traditional MO models, and the orbits are expressed as linear combinations of local Gaussians. Their positions are determined variationally. Using this model, we reanalyze the structure of [Formula Presented] and show that this extension enables us to use the original two-body spin-orbit interaction determined from a scattering phase-shift analysis of [Formula Presented] In [Formula Presented] all of the observed positive-parity bands and the negative-parity bands are described within the model. The [Formula Presented] ground state of [Formula Presented] is described by a dominant [Formula Presented] configuration. The state has a rather large binding energy (8.38 MeV from the [Formula Presented] threshold experimentally), and the mechanism leading to binding, such as a pairing effect and reduction of the kinetic energy between two clusters, is discussed in detail. In spite of this large binding, the [Formula Presented] clustering in the ground state persists due to a coupling effect between the [Formula Presented] configuration and the [Formula Presented] configuration, which provides a smooth potential for the valence neutrons. The second [Formula Presented] state of [Formula Presented] has a large [Formula Presented] structure with a [Formula Presented] configuration. An enlargement of the [Formula Presented] distance due to two-valence neutrons along the [Formula Presented] axis makes their wave function smooth and reduces the kinetic energy drastically. Furthermore, the contribution of the spin-orbit interaction due to coupling between the [Formula Presented] and the [Formula Presented] configurations is important. We also show the mediation effect of two valence neutrons between two [Formula Presented] clusters. © 2000 The American Physical Society.

• Important role of the spin-orbit interaction in forming the [Formula Presented] orbital structure in Be isotopes 査読 国際共著

N. Itagaki, S. Okabe, K. Ikeda

Physical Review C - Nuclear Physics   62 ( 3 )   8   2000年（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

The structure of the second [Formula Presented] state of [Formula Presented] is investigated using a microscopic [Formula Presented] model based on the molecular-orbit (MO) model. The second [Formula Presented] state, which has dominantly the [Formula Presented] configuration, is shown to have a particularly enlarged [Formula Presented]-[Formula Presented] structure. The kinetic energy of the two valence neutrons occupying along the [Formula Presented]-[Formula Presented] axis is reduced remarkably due to the strong [Formula Presented] clustering and, simultaneously, the spin-orbit interaction unexpectedly plays an important role in making the energy of this state much lower. The mixing of states with different spin structure is shown to be important in negative-parity states. The experimentally observed small-level spacing between [Formula Presented] and [Formula Presented] keV) is found to be evidence of this spin-mixing effect. [Formula Presented] is also investigated using the [Formula Presented] model, in which four valence neutrons are considered to occupy the [Formula Presented] configuration. The energy surface of [Formula Presented] is shown to exhibit similar characteristics, that the remarkable [Formula Presented] clustering and the contribution of the spin-orbit interaction make the binding of the state with the [Formula Presented] configuration properly stronger in comparison with the closed p-shell [Formula Presented] configuration. © 2000 The American Physical Society.

• Thomas-Ehrman effect on s(1/2) and p(1/2) resonance states in C-10+p 査読 国際共著

S Aoyama, N Itagaki, K Kato, K Ikeda

PHYSICAL REVIEW C   57 ( 2 )   975 - 977   1998年02月（ ISSN:2469-9985

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

By using the complex scaling method, the C-10+p resonance parameters are determined in order to investigate the spectroscopic property of the proton-rich nucleus N-11 in comparison with the mirror nucleus Be-11 which has a typical neutron halo structure. The obtained resonance energy (E-r) and width (Gamma) of N-11 are (E-r, Gamma)=(1.29 MeV, 1.39 MeV) and (2.12 MeV, 0.95 MeV) for s(1/2) and p(1/2) states, respectively. These results are in good agreement with the recent experimental data reported by Axelsson et nl. Thomas-Ehrman effect on the 1/2(-) and 1/2(+) resonance states in N-11 is discussed in association with the weakly bound states in Be-11.

• AMD+GCM for many-body cluster system 査読 国際共著

N Itagaki, S Aoyama, S Okabe

PROCEEDINGS OF THE XVII RCNP INTERNATIONAL SYMPOSIUM ON INNOVATIVE COMPUTATIONAL METHODS IN NUCLEAR MANY-BODY PROBLEMS   109 - 111   1998年

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

We investigate the structure of Be-10 within the microscopic cluster model based on the Molecular Orbit and show the presence of a rotational band consisting of states with large cu-cu clustering. The configuration of valence neutrons corresponding to 1/2(+) orbit enhances alpha-alpha clustering. The existence of these clusterized states is proven by the large E2 transition probability from 2(3)(+) to 0(2)(+).

• Thomas-Ehrman effect on [Formula Presented] and [Formula Presented] resonance states in [Formula Presented] 査読 国際共著

S. Aoyama, N. Itagaki, K. Katō, K. Ikeda

Physical Review C - Nuclear Physics   57 ( 2 )   975 - 977   1998年（ ISSN:0556-2813

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

By using the complex scaling method, the [Formula Presented] resonance parameters are determined in order to investigate the spectroscopic property of the proton-rich nucleus [Formula Presented] N in comparison with the mirror nucleus [Formula Presented] Be which has a typical neutron halo structure. The obtained resonance energy [Formula Presented] and width [Formula Presented] of [Formula Presented] N are [Formula Presented] Γ)=(1.29 MeV, 1.39 MeV) and (2.12 MeV, 0.95 MeV) for [Formula Presented] and [Formula Presented] states, respectively. These results are in good agreement with the recent experimental data reported by Axelsson et al. Thomas-Ehrman effect on the [Formula Presented] and [Formula Presented] resonance states in [Formula Presented] N is discussed in association with the weakly bound states in [Formula Presented] Be. © 1998 The American Physical Society.

• Molecular structure of Be and C nuclei by a multi-configuration cluster model 査読 国際共著

S Okabe, N Itagaki

PROCEEDINGS OF THE XVII RCNP INTERNATIONAL SYMPOSIUM ON INNOVATIVE COMPUTATIONAL METHODS IN NUCLEAR MANY-BODY PROBLEMS   120 - 124   1998年

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掲載種別：研究論文（国際会議プロシーディングス）   国際・国内誌：国際誌

We discuss molecular structures of Be and C nuclei by a multi-configuration cluster model. Especially, both an E2-transition and an alpha-decay width from 0(2)(+) state of C-12 nuclei are well reproduced, which determines nucleosynthesis of C-12.

• Microscopic a-Cluster Model for l2C and 16O Based on Antisymmetrized Molecular Dynamics. Consistent Understanding of the Binding Energies of l2C and 16O 査読 国際共著

Naoyuki Itagaki, Akira Ohnishi, Kiyoshi Kato

Progress of Theoretical Physics   94 ( 6 )   1019 - 1038   1995年（ ISSN:0033-068X

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掲載種別：研究論文（学術雑誌）   国際・国内誌：国際誌

In many previous calculations within microscopic models, the binding energy difference between C-12 and O-16 nuclei has been too large compared with the experimental data, and it has not been possible to describe these nuclei reasonably by the same effective interaction simultaneously. In this paper, we apply the N alpha-cluster model so as to clarify what is the most essential problem in the description of C-12 and O-16 by using a very large functional space and various effective interactions. This procedure is carried out by combining frameworks of the constraint cooling method introduced in Antisymmetrized Molecular Dynamics (AMD) and generator coordinate method (GCM). The resultant energy levels of O-16 show that various effective interactions give the second O+ slate of O-16 just around the C-12 + alpha threshold energy. This result agrees with the picture of the Ikeda diagram. However, even if we use some density dependent interactions, the binding energy difference between C-12 and O-16 cannot be remarkably improved.

### 書籍等出版物

• International Symposium on Origin of Matter and Evolution of Galaxies, Kawabata T., Itagaki N., Kanada-En'yo Y., Maeda K., Nishimura N., Ogata K., 嶋 達志, Tamii A., Terada K., Uchida H., Yamaguchi H., Yoshida K.

Physical Society of Japan  2020年  （ ISBN:9784890271443

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• 大塚 孝治, 板垣 直之, 下浦 亨, 梶野 敏貴, 水崎 高浩, 本間 道雄

大塚孝治  2007年

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### MISC（その他記事）

• Reduction of channel coupling effect on Li isotope elastic scatterings by glue-like behaviour of excess neutron 査読

Takenori Furumoto, Tadahiro Suhara, Naoyuki Itagaki

PROCEEDINGS OF THE 4TH INTERNATIONAL WORKSHOP ON STATE OF THE ART IN NUCLEAR CLUSTER PHYSICS (SOTANCP4)   2038   020039   2018年（ ISSN:0094-243X （ eISSN:1551-7616

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The glue-like behavior of valence neutrons has been investigated in the Li isotopes. The Li-7 nucleus is well known to be weakly bound system with the alpha + t cluster structure. By adding the valence neutrons, the reduction of the root-mean-square (RMS) radius of the proton density for the Li-7, Li-8 and, Li-9 nuclei is also well known from the viewpoint of the experimental data and theoretical approach. Elastic scattering cross sections of the Li isotopes on the C-12 and Si-28 targets at E/A similar to 50 MeV are calculated. We find the change of the channel coupling (CC) effect on elastic scatterings of such Li isotopes by the glue-like role of the valence neutrons. Finally, we realize that the valence neutrons stabilize the binding of core parts, and the CC effect related the core excitation is indeed reduced.

• 球面上に一様分布するアルファクラスターとクーロンエネルギー

板垣 直之, 東崎(鈴木) 昭弘

日本物理学会講演概要集   73 ( 0 )   194 - 194   2018年

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• Study of similarity and dissimilarity between<sup>10</sup>Be and<sup>9</sup>Li nuclei with microscopic structure and reaction models 査読

T. Furumoto, T. Suhara, N. Itagaki

Journal of Physics: Conference Series   863 ( 1 )   012014   2017年07月（ ISSN:1742-6588 （ eISSN:1742-6596

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© Published under licence by IOP Publishing Ltd. We apply the microscopic nuclear structure and reaction models to the elastic scattering of the10Be and9Li nuclei. The states of the10Be and9Li nuclei are described as an α + α(t) + n + n four-body system based on the cluster wave function, respectively. The elastic scattering cross section is obtained by the microscopic coupled channel (MCC) calculation with the MPa interaction, which is the latest version of the complex G-matrix interaction derived from the ESC NN interaction model. We compare the channel coupling (CC) effect of the10Be nucleus with that of the9Li nucleus in the elastic scattering cross sections calculated with the same incident energy per nucleon. At the backward angles, the CC effect on the elastic scattering cross section for the incident10Be nucleus is clearly larger than that for the incident9Li nucleus. We investigate the dissimilarity for the CC effect through the dynamical polarization potential.

• 松野秀昭, 板垣直之, 延與佳子

原子核研究   61 ( Supplement 1 )   70‐71   2017年03月（ ISSN:0367-4169

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• 板垣 直之, 東崎 昭弘

日本物理学会講演概要集   72 ( 0 )   176 - 176   2017年（ ISSN:2189-079X

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<p>前回の講演において、２中性子クラスター物質の無限系の取り扱いに言及した。今回は、２中性子クラスター物質内での２中性子クラスターの崩れ、２中性子クラスター物質の表面の安定性に焦点を当てる。パウリ原理の完全な取り扱い、中性子間相互作用の導入によるクラスター物質の性質を探るのが究極の目標である。</p>

• 板垣 直之, 東崎 昭弘

日本物理学会講演概要集   72 ( 0 )   132 - 132   2017年（ ISSN:2189-079X

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<p>軽い核のクラスター構造とシェル構造を同時に扱える枠組みを用い、両者の競合を議論する。特にスピン軌道力のみならず、有効有限レンジ３体力の効果や、テンソル力に着目する。テンソル力に関しては、two-particle two-hole励起の効果を簡単に取り組める枠組みを提案する。</p>

• 直鎖α粒子構造と環状α粒子構造の安定性

板垣 直之, 東崎 昭弘

日本物理学会講演概要集   72 ( 0 )   163 - 163   2017年

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• クラスター模型を拡張して一粒子励起を記述する方法と<sup>12</sup>Cへの適用

松野 秀昭, 板垣 直之

日本物理学会講演概要集   72 ( 0 )   156 - 156   2017年

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• 古本猛憲, 須原唯広, 板垣直之

日本物理学会講演概要集(CD-ROM)   71 ( 1 )   ROMBUNNO.19PAC‐11   2016年03月（ ISSN:2189-079X

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• 松野秀昭, 板垣直之, 市川隆敏

日本物理学会講演概要集(CD-ROM)   71 ( 1 )   ROMBUNNO.19AAC‐11   2016年03月（ ISSN:2189-079X

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• 板垣 直之, 松野 秀昭, 須原 唯広

日本物理学会講演概要集   71 ( 0 )   180 - 180   2016年（ ISSN:2189-079X

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• 19pAC-11 微視的核構造反応模型を用いた^<10>Be原子核の研究

古本 猛憲, 須原 唯広, 板垣 直之

日本物理学会講演概要集   71 ( 0 )   205 - 205   2016年

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• Comparison Between <sup>9</sup>Li And <sup>10</sup>Be Nuclei from Viewpoint Of Nuclear Structure And Reaction 査読

Takenori Furumoto, Tadahiro Suhara, Naoyuki Itagaki

Proceedings of Science   2016-September   224   2016年（ eISSN:1824-8039

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© Copyright owned by the author(s). Recently, we proposed the microscopic structure and reaction models. The model firstly constructs the nuclear structure by the stochastic multi-configuration mixing (SMCM) method based on the cluster model. Next, the cross section is obtained by the microscopic coupled-channel (MCC) calculation based on the folding model with the complex G-matrix interaction. In this work, we compare the 9Li nucleus with the 10Be nucleus from the viewpoint of the nuclear structure and reaction. The 9Li (10Be) nucleus is described as an α + t (α) + n + n four-body system based on the cluster model. The elastic and inelastic scattering cross sections for the 9Li + 12C and 10Be + 12C systems are obtained by the MCC calculation with the MPa interaction which is the latest version of the complex G-matrix interaction derived from the ESC nucleon-nucleon interaction model. The excitation energies of the low-lying states for the 9Li and 10Be nuclei well reproduce the data. The MCC model including the excitation effect of the projectile and target shows the visible channel coupling effect on the elastic cross section. The contribution of the 10Be excitation effect is clearly larger than that of the 9Li excitation effect.

• 板垣 直之

日本物理学会誌   71 ( 6 )   350 - 351   2016年（ ISSN:0029-0181

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• 松野 秀昭, 板垣 直之, 延與 佳子

日本物理学会講演概要集   71 ( 0 )   144 - 144   2016年（ ISSN:2189-079X

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<p>^16^Oや^13^C等の軽くN=Zライン近傍に位置する原子核のモノポールとクラスター構造について議論する。</p>

• 板垣 直之, 東崎 昭弘

日本物理学会講演概要集   71 ( 0 )   143 - 143   2016年（ ISSN:2189-079X

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<p>Tohsaki等によって提案された有限レンジ3体力項を含む有効相互作用を拡張し、軽い原子核へと適用する。中性子過剰核への適用を可能にするとともに、3体力部分の改善を行い、実際の原子核構造計算を行う。</p>

• Examination of the stability of a rod-shaped structure in Mg-24 査読

Yoritaka Iwata, Takatoshi Ichikawa, Naoyuki Itagaki, Joachim A. Maruhn, Takaharu Otsuka

PHYSICAL REVIEW C   92 ( 1 )   2015年07月（ ISSN:0556-2813 （ eISSN:1089-490X

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The stable existence of rod-shaped structures in highly excited states of Mg-24 is studied based on a systematic cranked Hartree-Fock calculation with various Skyrme-type interactions. Its stability is examined by allowing the transition of the clusterlike structure to the shell-model-like structure. Especially, the rod-shaped state is exposed to two major instabilities: the bending motion, which is the main path for the transition to low-lying states, and the spin-orbit interaction, which is the driving force to break the alpha clusters and enhance the independent motion of the nucleons. The rod-shaped structure with large angular momentum is obtained as a metastable stationary state.

• 22aCD-8 Rod-shaped nuclei at extreme spin and isospin in C isotopes

板垣 直之, Zhao Pengwei, Meng Jie

日本物理学会講演概要集   70 ( 0 )   313 - 313   2015年（ ISSN:2189-079X

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• 松野 秀昭, 板垣 直之, 市川 隆敏

日本物理学会講演概要集   70 ( 0 )   214 - 214   2015年（ ISSN:2189-079X

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• 24aCC-7 高スピントーラスアイソマー状態の系統的探索

市川 隆敏, 松柳 研一, Mathun J. A., 板垣 直之

日本物理学会講演概要集   70 ( 0 )   209 - 209   2015年（ ISSN:2189-079X

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• Erratum: Investigation of the 3/ 22- state of Li 9 with microscopic structure and reaction models (Physical Review C - Nuclear Physics (2013) 87 (064320)) 査読

T. Furumoto, T. Suhara, N. Itagaki

Physical Review C - Nuclear Physics   90 ( 3 )   2014年09月（ ISSN:0556-2813 （ eISSN:1089-490X

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• Experimental plan for search of 10N resonances with resonant scattering of 9C off polarized proton

MILMAN Evgeniy, UESAKA Tomohiro, KAWAHARA Tomomi, TATEISHI Kenichiro, SAKAGUCHI Satoshi, TERANISHI Takashi, ITAGAKI Naoyuki, IMAI Nobuaki

日本物理学会講演概要集   69 ( 1 )   89   2014年03月（ ISSN:1342-8349

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• <sup>13</sup>Cにおけるクラスター・シェル構造

板垣直之

日本物理学会講演概要集   68 ( 2 )   61   2013年08月（ ISSN:1342-8349

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• <sup>16</sup>Cのクラスター構造とMono‐pole遷移強度

升井洋志, 板垣直之

日本物理学会講演概要集   68 ( 2 )   61   2013年08月（ ISSN:1342-8349

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• 系統的なCranking‐Hartree‐Fock計算に基づくα直鎖状態の存在性

岩田順敬, 市川隆敏, 板垣直之, MARUHN J.A, 大塚孝治

日本物理学会講演概要集   68 ( 2 )   32   2013年08月（ ISSN:1342-8349

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• 計算核物理

根村英克, 清水則孝, 阿部喬, 江尻信司, 古本猛憲, 堀内渉, 板垣直之, 藏増嘉伸, 中務孝, 佐々木勝一, 住吉光介, 大西明

原子核研究   57 ( Supplement 2 )   275 - 312   2013年02月（ ISSN:0367-4169

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• Yoritaka Iwata, Kei Iida, Naoyuki Itagaki

PHYSICAL REVIEW C   87 ( 1 )   2013年01月（ ISSN:0556-2813 （ eISSN:1089-490X

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We illustrate the formation of a thin, long structure of heavy nuclei by three-nucleus simultaneous collisions within time-dependent density functional theory. The impact parameter dependence for such a formation is systematically demonstrated through clarifications of the difference between binary and ternary collision events. A new method for producing thin, long heavy nuclei in the laboratory is suggested, as well as the possible formation of the thin, long structure in hot dense matter such as that encountered in core collapse supernovae. DOI: 10.1103/PhysRevC.87.014609

• 20pSA-2 ^<13>Cにおけるクラスター・シェル構造(不安定核(II)(合同),実験核物理領域,理論核物理領域合同,実験核物理領域)

板垣 直之

日本物理学会講演概要集   68 ( 0 )   61 - 61   2013年（ ISSN:1342-8349

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• 20pSA-3 ^<16>Cのクラスター構造とMono-pole遷移強度(不安定核(II)(合同),実験核物理領域,理論核物理領域合同,実験核物理領域)

升井 洋志, 板垣 直之

日本物理学会講演概要集   68 ( 0 )   61 - 61   2013年（ ISSN:1342-8349

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• 21aSB-5 Existence of 6 alpha linear chain state based on systematic Cranking-Hartree-Fock calculations

岩田 順敬, 市川 隆敏, 板垣 直之, Maruhn J.A., 大塚 孝治

日本物理学会講演概要集   68 ( 0 )   32 - 32   2013年（ ISSN:1342-8349

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• Nuclear equation of state and hypernuclear physics 査読

Hans-Josef Schulze, Emiko Hiyama, Akira Onishi, Naoyuki Itagaki

International molecule-type workshops Jan. 4 – Jan. 31, 2013   2013年

• M. A. Klatt, T. Ichikawa, K. Iida, N. Itagaki, J. A. Maruhn, K. Matsuyanagi, K. Mecke, S. Ohkubo, P. G. Reinhard, B. Schuetrumpf

Journal of Physics: Conference Series   445 ( 1 )   2013年（ ISSN:1742-6588 （ eISSN:1742-6596

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Investigations of exotic cluster-like phenomena in the framework of the Skyrme-Hartree-Fock approach are reported. The occurrence of highly excited isomeric states is discussed in connection with the question of their stability in static and time-dependent Hartree Fock (TDHF) calculations. We find rotational stabilization of a 4α chain structure in 16O occurring for a limited range of angular momenta. A toroidal configuration of 40Ca was also stabilized by rotation and provides a very interesting example of rotation about a symmetry axis with a strictly quantized total angular momentum. Finally we look at the formation of nuclear pasta phases in a time-dependent approach and their classification.

• N. Itagaki, T. Ichikawa, J. A. Maruhn, S. Ohkubo, Tz Kokalova, W. Von Oertzen

Journal of Physics: Conference Series   420 ( 1 )   2013年（ ISSN:1742-6588 （ eISSN:1742-6596

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We discuss the appearance of various cluster structures in light nuclei. One of the examples is the appearance of geometric cluster configurations; gas-like α cluster states found in 12C and 16O could be stabilized with geometric shapes by adding neutrons or giving large angular momentum. We show in 16O that four α particles can have linear configurations with large angular momentum, which is very stable with respect to the bending motion using Skyrme cranked Hartree-Fock method. There exists a region of angular momentum (13-18 strok h sign) where the linear chain configuration is stabilized. The calculated moment of inertia (strok h sign 2/2(- ∼ 0.06-0.08 MeV) agrees well with conventional cluster model calculations. Another example of exotic cluster structure is the gas-like state of α clusters. The most famous example is the second 0+ state in 12C, the so called Hoyle state, which plays a dominant role in the synthesis of 12C and the heavier elements in the stars. We go one step further that such a dilute state of α particles exists around a strongly bound core in heavier systems. This study is performed by introducing a Monte Carlo technique for the description of the THSR (Tohsaki Horiuchi Schuck Röpke) wave function, and first we apply such method to three α state around a 40Ca core. Furthermore, coupling effect to other low-lying cluster states is taken into account; a large isoscalar monopole (E0) transition strength from the ground to the gas-like state is discussed in 24Mg. The gas-like state of two α clusters in 24Mg around the 16O core appears slightly below the 2α-thresliold energy.

• Coexistence of weak and strong binding in unstable nuclei and its dynamics 査読

Antonio M.Moro Munoz, Kazuyuki Ogata, Yoshiko Kanada-En'yo, Naoyuki Itagaki

International molecule-type workshops Mar. 4 – Mar. 22, 2013   2013年

• H. Masui, N. Itagaki

Journal of Physics: Conference Series   436 ( 1 )   2013年（ ISSN:1742-6588 （ eISSN:1742-6596

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We construct nuclear wave functions from alpha clusters and some additional valence nucleons, and allow the inter-cluster distance to change and one alpha to dissolve from the (0s)4 structure as a result of the nuclear interaction. The change of the inter-cluster distance and the dissolution of the alpha particle can be interpreted as resulting from the competition of the 'shell model' and 'cluster model'. We demonstrate this competition through a few parameters.

• T. Yoshida, N. Itagaki, K. Kato

Journal of Physics: Conference Series   436 ( 1 )   2013年（ ISSN:1742-6588 （ eISSN:1742-6596

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We investigate the properties of the states observed around the α-cluster breakup threshold region in 12C and 16O. We apply the orthogonality condition model (OCM), where the model space is given by the SU3 algebra. From bases of this SU3 configuration, two algebraic approaches of the symplectic (sp) method and μ-truncation method are introduced. In 12C, we show that the sp-quanta are important to understand the mechanism of the appearance of the large E0 transition strength. With these methods, both strong- and weak-coupling configurations are taken into account at the same time. Therefore, the properties of gas-like and linear-chain states are investigated easily. In 16O, a simpler truncation utilizing the μ quanta is applied. Here, the energy levels and the linear-chain (L. C.) configurations are investigated.

• <sup>9</sup>Liにおける非軸対称変形の効果(II)

古本猛憲, 須原唯広, 板垣直之

日本物理学会講演概要集   67 ( 2 )   58   2012年08月（ ISSN:1342-8349

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• アルファクラスター模型による酸素(16O)原子核の直鎖構造の研究

吉田亨, 板垣直之, 加藤幾芳

日本物理学会講演概要集   67 ( 2 )   47   2012年08月（ ISSN:1342-8349

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• クラスター・シェル競合を記述する模型の発展

須原唯広, 板垣直之

日本物理学会講演概要集   67 ( 2 )   46   2012年08月（ ISSN:1342-8349

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• 24aXB-10 sp代数模型に基づく12C,16O原子核の励起状態の研究(24aXB 核力・ハイパー核・クラスター,理論核物理領域)

吉田 亨, 板垣 直之, 加藤 幾芳

日本物理学会講演概要集   67 ( 1 )   2012年03月（ ISSN:1342-8349

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• <sup>9</sup>Liにおける非軸対称変形の効果(I)

古本猛憲, 須原唯広, 板垣直之

日本物理学会講演概要集   67 ( 1 )   78   2012年03月（ ISSN:1342-8349

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• <sub>sp</sub>代数模型に基づく12C,16O原子核の励起状態の研究

吉田亨, 板垣直之, 加藤幾芳

日本物理学会講演概要集   67 ( 1 )   43   2012年03月（ ISSN:1342-8349

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• 11aSC-2 ^9Liにおける非軸対称変形の効果(II)(11aSC 実験核物理領域,理論核物理領域合同,不安定核(合同),実験核物理領域)

古本 猛憲, 須原 唯広, 板垣 直之

日本物理学会講演概要集   67 ( 0 )   58 - 58   2012年（ ISSN:1342-8349

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• 13aSA-13 アルファクラスター模型による酸素(16O)原子核の直鎖構造の研究(13aSA 核力・少数体系・クラスター,理論核物理領域)

吉田 亨, 板垣 直之, 加藤 幾芳

日本物理学会講演概要集   67 ( 0 )   47 - 47   2012年（ ISSN:1342-8349

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• 13aSA-11 クラスター・シェル競合を記述する模型の発展(13aSA 核力・少数体系・クラスター,理論核物理領域)

須原 唯広, 板垣 直之

日本物理学会講演概要集   67 ( 0 )   46 - 46   2012年（ ISSN:1342-8349

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• 24aXC-2 ^9Liにおける非軸対称変形の効果(I)(24aXC 実験核物理領域,理論核物理領域合同 不安定核(合同),実験核物理領域)

古本 猛憲, 須原 唯広, 板垣 直之

日本物理学会講演概要集   67 ( 0 )   78 - 78   2012年（ ISSN:1342-8349

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• T. Yoshida, N. Itagaki, K. Kato

AIP Conference Proceedings   1484   424 - 426   2012年（ ISSN:0094-243X （ eISSN:1551-7616

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Both from theoretical and experimental sides, the existence of cluster structure in light nuclei has been studied for a few decades and the appearance has been confirmed. To confirm the properties of these states is important also from the astrophysical view point. We investigate the properties of the structure of 12C above the α cluster threshold. Here, we apply orthogonality condition model (OCM), where the model space is given by SU(3) and its symplectic (sp) configuration. This enables us to treat both strong and weak coupling configuration. We show that sp-quanta is important to understand the mechanism of the appearance of large E0 strength. We also show that the other transition properties have good correspondence with experiments. © 2012 American Institute of Physics.

• Exotic Cluster Structure of light nuclei 査読

Naoyuki Itagaki

11th International Conference on Nucleus-Nucleus Collisions, San Antonio (USA), plenary invited talk, May 27- June 1 2012.   2012年

• 17pSF-3 Nアルファクラスターモデルにおけるsymplectie構造とモノポール遷移強度(17pSF 少数多体系,理論核物理領域)

吉田 亨, 板垣 直之, 加藤 幾芳

日本物理学会講演概要集   66 ( 2 )   2011年08月（ ISSN:1342-8349

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• Nアルファクラスターモデルにおけるsymplectic構造とモノポール遷移強度

吉田享, 板垣直之, 加藤幾芳

日本物理学会講演概要集   66 ( 2 )   41   2011年08月（ ISSN:1342-8349

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• .ALPHA.-Chain Structures in Light Nuclei and Nuclear Matter

MARUHN Joachim A, ITAGAKI Naoyuki, UMAR Sait A, OBERACKER Volker E

日本物理学会講演概要集   66 ( 1 )   88   2011年03月（ ISSN:1342-8349

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• 12Cにおけるsp代数とモノポール遷移強度の関係の研究

吉田亨, 板垣直之, 加藤幾芳

日本物理学会講演概要集   66 ( 1 )   60   2011年03月（ ISSN:1342-8349

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• 25aGJ-4 炭素同位体におけるクラスター・シェル競合と励起状態におけるクラスター構造の出現(25aGJ 理論核物理領域,実験核物理領域合同 不安定核I,理論核物理領域)

牟田 啓太郎, 升井 洋志, 板垣 直之

日本物理学会講演概要集   66 ( 1 )   2011年03月（ ISSN:1342-8349

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• 28aGH-11 酸素原子核をコアとしたαガス状態(28aGH 核構造(軽い核),理論核物理領域)

板垣 直之, 市川 隆敏

日本物理学会講演概要集   66 ( 1 )   2011年03月（ ISSN:1342-8349

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• 炭素同位体におけるクラスター・シェル競合と励起状態におけるクラスター構造の出現

牟田啓太郎, 升井洋志, 板垣直之

日本物理学会講演概要集   66 ( 1 )   42   2011年03月（ ISSN:1342-8349

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• 酸素原子核をコアとしたαガス状態

板垣直之, 市川隆敏

日本物理学会講演概要集   66 ( 1 )   61   2011年03月（ ISSN:1342-8349

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• Exotic clustering in light nuclear systems 査読

Naoyuki Itagaki

Plenary, at “GCOE Symposium Links among Hierarchies” , Kyoto Univ., Kyoto, Japan, February 2011.   2011年

• Yoritaka Iwata, Takaharu Otsuka, Joachim A. Maruhn, Naoyuki Itagaki

EPJ Web of Conferences   2   2010年03月（ ISSN:2101-6275 （ eISSN:2100-014X

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© 2010 Owned by the authors, published by EDP Sciences. The mass-dependent structure of the composite nucleus is shown based on three-dimensional timedependent Hartree-Fock calculations with Skyrme interactions (SLy4d and SkM∗). One remarkable result is that the isovector monopole excitation dominantly appears for collisions of heavy nuclei, and the isovector dipole excitation for those of light ones. Such a difference found in the dynamical structure of composite nucleus plays a role in the equilibration of charge.

• 20aBH-7 重イオン衝突におけるスピン偏極ダイナミクスの理論的研究(20aBH 核反応・重イオン反応,理論核物理領域)

岩田 順敬, 大塚 孝治, Maruhn Joachim A, 板垣 直之

日本物理学会講演概要集   65 ( 1 )   2010年03月（ ISSN:1342-8349

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• 重イオン衝突におけるスピン偏極ダイナミクスの理論的研究

岩田順敬, 大塚孝治, MARUHN Joachim A, 板垣直之

日本物理学会講演概要集   65 ( 1 )   36   2010年03月（ ISSN:1342-8349

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• T. Yoshida, K. Kato, N. Itagaki

Hadron and Nuclear Physics 09: Osaka University, Japan, 16-19 November 2009   279 - 284   2010年01月

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© 2010 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. Algebraic nuclear models have successfully applied for various mass regions. In 12C, we couple this model space with treatment of the so-called complex scaling method for resonance states. We use the Sp(2, R), algebra to create ladder states on SU(3) bases which have large harmonic oscillation quanta. One advantage of this method is that it is possible naturally to extend to Nα: systems. The wave function is semi-microscopic and satisfies the Pauli principle (orthogonal to the Pauli forbidden states). We study basic properties of this wave function.

• 岩田順敬, 大塚孝治, J. A. Maruhn, 板垣直之

東京大学大学院理学系研究科プレスリリース; 日経プレスリリース   2010年

• 3α cluster state around 40Ca 査読

Naoyuki Itagaki

Invited, in 2nd Workshop on “State of the Art in Nuclear Cluster Physics,” Free University, Brussels, Belgium, May 2010.   2010年

• Specific structure of light neutronrich nuclei 査読

Naoyuki Itagaki

(YITP) : YITP Colloquium   2010年

• Geometric and gas-like cluster structure in light nuclei 査読

Naoyuki Itagaki

Invited, in a mini Workshop on “Nuclear Symmetry Energy and KoRIA”, Yonsei University, Seoul, Korea, October 2010.   2010年

• “Appearance of geometric cluster states in light neutron-rich nuclei,” 査読

Naoyuki Itagaki

YITP colloquium, July 2010.   2010年

• “Specific structure of light neutron-rich nuclei,” 査読

Naoyuki Itagaki

Dept. of Phys., Osaka City Univ., July 2010.   2010年

• 中性子の果たす"糊"の効果とαクラスターの結合形態(最近の研究から)

板垣 直之, Maruhn Joachim A, 木村 真明

日本物理學會誌   64 ( 11 )   840 - 844   2009年11月（ ISSN:0029-0181

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原子核は励起エネルギーの関数として様々な構造へと変異する.基底状態近傍では陽子や中性子の独立粒子運動が支配的であるが,α粒子などの放出の敷居エネルギー付近ではαクラスター構造が出現する.これまで,陽子数と中性子数の等しい軽い安定核を対象に,敷居エネルギー付近のαクラスターの気体的な状態が研究されてきたが,そこに中性子が加わった軽い中性子過剰核においては,中性子の&quot;糊&quot;の効果により,幾何学的なクラスター構造が安定化し,原子核はさらに多様な構造を持ち得ることが明らかになりつつある.

• 中性子の果たす“糊”の効果とαクラスターの結合形態

板垣直之, MARUHN Joachim A, 木村真明

日本物理学会誌   64 ( 11 )   840 - 844   2009年11月（ ISSN:0029-0181

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• Makoto Ito, Naoyuki Itagaki

Modern Physics Letters A   24 ( 11-13 )   1005 - 1008   2009年04月（ ISSN:0217-7323

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The generalized two-center cluster model (GTCM), which can treat various single particle configurations in general two center systems, is applied to the light neutron-rich system, 12Be= α+α+4N. We discuss the change of the neutrons' configuration around two α-cores as a variation of an excitation energy. We show that the covalent, ionic and atomic configurations appear in the unbound region above the α+ 8Heg.s. particle-decay threshold, and they coexist within a quite small energy interval. © 2009 World Scientific Publishing Company.

• 27aXF-7 中性子過剰核の高励起状態における新奇な構造(27aXF 実験核物理領域,理論核物理領域合同シンポジウム:SAMURAIスペクトロメータで拓く核物理,実験核物理領域)

板垣 直之, 木村 真明, Maruhn J. A

日本物理学会講演概要集   64 ( 1 )   2009年03月（ ISSN:1342-8349

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• 28aXF-11 低エネルギー重イオン衝突における衝突方向依存性(28aXF 核反応・クラスター模型,理論核物理領域)

岩田 順敬, 大塚 孝治, 板垣 直之, 西尾 勝久

日本物理学会講演概要集   64 ( 1 )   2009年03月（ ISSN:1342-8349

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• 中性子過剰核の高励起状態における新奇な構造

板垣直之, 木村真明, MARUHN J.A

日本物理学会講演概要集   64 ( 1 )   66   2009年03月（ ISSN:1342-8349

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• 低エネルギー重イオン衝突における衝突方向依存性

岩田順敬, 大塚孝治, 板垣直之, 西尾勝久

日本物理学会講演概要集   64 ( 1 )   47   2009年03月（ ISSN:1342-8349

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• Y. Iwata, T. Otsuka, J. A. Maruhn, N. Itagaki

AIP Conference Proceedings   1175   363 - 366   2009年（ ISSN:0094-243X （ eISSN:1551-7616

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Nucleon transfer is studied with focusing on the charge equilibration. The proposed classification of nucleon transfer in deep inelastic collisions at intermediate energies is verified by three-dimensional TDHF calculations. © 2009 American Institute of Physics.

• Y. Iwata, T. Otsuka, J. A. Maruhn, N. Itagaki

AIP Conference Proceedings   1098   308 - 313   2009年（ ISSN:0094-243X （ eISSN:1551-7616

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A condition for the upper energy-limit of charge equilibration is proposed based on a Fermi gas-like treatment. The validity of this condition is confirmed by three-dimensional time-dependent Hartree-Fock calculations with a full Skyrme interaction. © 2009 American Institute of Physics.

• M. Ito, N. Itagaki

AIP Conference Proceedings   1098   231 - +   2009年（ ISSN:0094-243X （ eISSN:1551-7616

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The α+8 He low-energy reactions and the exotic structures of Be are studied using the generalized two-center cluster (α+α+4N) model. The energy-spin systematics for the two-neutron transfer reactions is investigated, and our calculation predicts a sequence of resonant structures in the range of 3 - 14 MeV in the center-of-mass energy with spins 0ℏ- 8ℏ © 2009 American Institute of Physics.

• 20aSA-10 クラスター模型による13Cの構造計算とEO遷移強度(20aSA クラスター構造,理論核物理領域)

吉田 亨, 板垣 直之, 大塚 孝治

日本物理学会講演概要集   63 ( 2 )   2008年08月（ ISSN:1342-8349

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• 21aSB-3 ^<10>Beにおけるα+t+t状態(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)

板垣 直之, 伊藤 誠, Milin Makto, 橋本 尚志, 石山 博恒, 宮武 宇也

日本物理学会講演概要集   63 ( 2 )   2008年08月（ ISSN:1342-8349

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• 20aSA-12 Simplified modeling for spin-orbit interactionによる^<15>Cの構造研究(20aSA クラスター構造,理論核物理領域)

升井 洋志, 板垣 直之

日本物理学会講演概要集   63 ( 2 )   2008年08月（ ISSN:1342-8349

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• Simplified modeling for spin‐orbit interactionによる<sup>15</sup>Cの構造研究

升井洋志, 板垣直之

日本物理学会講演概要集   63 ( 2 )   25   2008年08月（ ISSN:1342-8349

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• クラスター模型による13Cの構造計算とE0遷移強度

吉田亨, 板垣直之, 大塚孝治

日本物理学会講演概要集   63 ( 2 )   25   2008年08月（ ISSN:1342-8349

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• M. Ito, N. Itagaki, H. Sakurai, K. Ikeda

Journal of Physics: Conference Series   111 ( 1 )   2008年05月（ ISSN:1742-6588 （ eISSN:1742-6596

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The generalized two-center cluster model (GTCM), which can treat static structures and dynamical reactions in excited states, is applied to the light neutron-rich system, 12Beα+α+4N. We discuss the change of the neutrons' configuration around two α-cores from the covalent structure to the ionic one. It is shown that, in the unbound region above particle-decay thresholds, the ionic configurations appear as the molecular resonances of α+8He, 6He+6He and 5He+7He. A new type of superdeformation is possible, and we find here the covalent superdeformation which has a hybrid configuration of the covalent and ionic ones. The excitation of these exotic structures through the two neutron transfer reaction is also discussed. © 2008 IOP Publishing Ltd.

• N. Itagaki, H. Masui, J. Cseh

Journal of Physics: Conference Series   111 ( 1 )   2008年05月（ ISSN:1742-6588 （ eISSN:1742-6596

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Nuclear systems are usually considered to be in the liquid phase, however, here we discuss the competition between the shell (liquid phase) and cluster structure in light neutron-rich nuclei. The appearance of molecular structure of α clusters with a geometric (equilateral triangular) shape is stabilized by the valence neutrons, and the nuclear systems with specific shapes are considered to be in the solid state. Also, α-condensed states originally suggested in 12C and 16O are extended to heavier nuclei with core nucleus, which are in the gas phase. © 2008 IOP Publishing Ltd.

• 軽い核構造研究の概観と最近の進展

板垣直之

原子核研究   52 ( Supplement 4 )   19 - 28   2008年03月（ ISSN:0367-4169

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• 23pZV-3 ^<13>CにおけるE0遷移強度とアルファクラスター構造(軽い核の構造と反応,理論核物理領域)

吉田 亨, 板垣 直之, 大塚 孝治

日本物理学会講演概要集   63 ( 1 )   2008年02月（ ISSN:1342-8349

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• TDHFによる重い原子核反応機構に関する研究

岩田順敬, 板垣直之, MARUHN Joachim. A, 大津秀暁, 大塚孝治

日本物理学会講演概要集   63 ( 1 )   64   2008年02月（ ISSN:1342-8349

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• Coupling effect between the .ALPHA. condensed states and normal cluster states

ITAGAKI Naoyuki, ITO Makoto

日本物理学会講演概要集   63 ( 1 )   42   2008年02月（ ISSN:1342-8349

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• <sup>13</sup>CにおけるE0遷移強度とアルファクラスター構造

吉田亨, 板垣直之, 大塚孝治

日本物理学会講演概要集   63 ( 1 )   42   2008年02月（ ISSN:1342-8349

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• 26pZH-4 TDHFによる重い原子核反応機構に関する研究(多体構造・反応論,理論核物理領域)

岩田 順敬, 板垣 直之, Maruhn Joachim. A, 大津 秀暁, 大塚 孝治

日本物理学会講演概要集   63 ( 1 )   2008年02月（ ISSN:1342-8349

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• 24pZF-7 α+^8He低エネルギー散乱における共鳴現象(実験核物理領域,理論核物理領域合同,不安定核(合同)II,実験核物理領域)

伊藤 誠, 板垣 直之

日本物理学会講演概要集   63 ( 1 )   2008年02月（ ISSN:1342-8349

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• 23pZV-5 アルファ凝縮状態と通常のクラスター状態の結合(軽い核の構造と反応,理論核物理領域)

板垣 直之, 伊藤 誠

日本物理学会講演概要集   63 ( 1 )   2008年02月（ ISSN:1342-8349

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• 「α+<sup>8</sup>He低エネルギー散乱における共鳴現象」

伊藤誠, 板垣直之

日本物理学会講演概要集   63 ( 1 )   79   2008年02月（ ISSN:1342-8349

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• 中性子過剰核におけるクラスター構造 : 課題と展望(不安定核でのクラスターと共鳴状態,原子核クラスター物理の現状と展望,研究会報告)

板垣 直之

素粒子論研究   115 ( 4 )   D4 - D8   2007年10月（ ISSN:0371-1838

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• 中性子過剰核におけるクラスター構造...課題と展望

板垣直之

素粒子論研究   115 ( 4 )   D4-D8   2007年10月（ ISSN:0371-1838

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• 21aYE-1 炭素同位体におけるアルファクラスター構造(21aYE 核構造,理論核物理領域)

吉田 亨, 板垣 直之, 大塚 孝治

日本物理学会講演概要集   62 ( 2 )   2007年08月（ ISSN:1342-8349

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• Molecular states of carbon isotopes

YOSHIDA Tooru, ITAGAKI Naoyuki, ITAGAKI Naoyuki, OTSUKA Takaharu

素粒子論研究   115 ( 3 )   C115   2007年08月（ ISSN:0371-1838

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• 26aSB-6 Cluster-shell competition in C-isotopes

升井 洋志, 板垣 直之

日本物理学会講演概要集   62 ( 1 )   2007年02月（ ISSN:1342-8349

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• T. Yoshida, N. Itagaki, T. Otsuka

Journal of Physics: Conference Series   49 ( 1 )   124 - 125   2006年10月（ ISSN:1742-6588 （ eISSN:1742-6596

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Structure of Ne isotopes are investigated by a microscopic model, where thousands of Slater determinants are stochastically generated, and important ones are selected out of them. The importance of the α-cluster correlation is systematically shown, and also, the singleparticle parity of each nucleon is studied, and deviation from the pure shell-model-like picture is discussed. © 2006 IOP Publishing Ltd.

• N. Itagaki

Journal of Physics: Conference Series   49 ( 1 )   116 - 121   2006年10月（ ISSN:1742-6588 （ eISSN:1742-6596

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The competition between the cluster and shell structure of light nuclei is discussed. First, we demonstrate in 12C by superimposing many Slater determinants that the cluster structure dissolute when the shell-model-like model space is introduced. The decrease of the energy from the 3α configuration by about 6 MeV is a clue to resolve a long-standing problem of the binding energies of 12C and 16O. As a next step, we propose a simple model to include the spin-orbit interaction (SMSO). By introducing only one parameter (Γ) to the wave function, describing an asymptotic transition of 12C from a 3α configuration to a 2α+4N configuration is represented, and we show a strong contribution of the spin-orbit interaction in the ground state. Furthermore, we propose a simplified model to directly take into account the contribution of the tensor interaction (SMT) for light nuclei by extending α-cluster model. The coupling effect of SMSO and SMT is shown to be important in 12C, contrary to 8Be. © 2006 IOP Publishing Ltd.

• T. Yoshida, N. Itagaki, T. Otsuka

Journal of Physics: Conference Series   20 ( 1 )   197 - 198   2005年01月（ ISSN:1742-6588 （ eISSN:1742-6596

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To investigate structure of 21Ne, where the core has a parity asymmetric property, we superpose thousands of Slater determinants. Applying the method we can see importance of α-correlation for several low-lying states and also property of a valence neutron. The 13C nucleus is studied as parity asymmetric core with 3α. We confirm the change of spin quantization. © 2005 IOP Publishing Ltd.

• Wandering in color-space - Why is the life of pentaquark so long? 査読

Yuu Maezawa, Toshiki Maruyama, Naoyuki Itagaki, Tetsuo Hatsuda

Acta Physica Hungarica, Series A: Heavy Ion Physics   22 ( 1-2 )   61 - 68   2005年（ ISSN:1219-7580

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The problem of the long life time of the pentaquark θ+ is investigated on the basis of the color molecular dynamics simulation. We find that it takes a long time (typically of 50-100 fm/c) for the initial pentaquark state to rearrange its color and spatial positions to decay into the nucleon+kaon final state. Structure of the potential surface in the color and position spaces also supports this picture. Pentaquark wanders on the potential surface to find a narrow channel to decay. © 2005 Akadémiai Kiadó, Budapest.

• 28pSG-8 クラスターの結晶化構造の検証と意義(核構造・多体基礎論/核反応/超重核, 理論核物理)

板垣 直之, 大塚 孝治

日本物理学会講演概要集   59 ( 2 )   2004年08月（ ISSN:1342-8349

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• 29aSG-1 新しい AMD 法による軽い核のシェル的状態とクラスター的状態の競合の分析(不安定核, 理論核物理)

板垣 直之, 青山 茂義

日本物理学会講演概要集   59 ( 2 )   2004年08月（ ISSN:1342-8349

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• 11pSE-5 エキゾチック核のクラスター構造とγ線

板垣 直之

日本物理学会講演概要集   58 ( 2 )   2003年08月（ ISSN:1342-8349

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• 29aSA-6 C 同位体におけるアルファチェイン状態の励起構造

板垣 直之, 池田 清美, 岡部 成玄

日本物理学会講演概要集   58 ( 1 )   2003年03月（ ISSN:1342-8349

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• N. Itagaki, K. Hagino

Physical Review C - Nuclear Physics   66 ( 5 )   573011 - 573014   2002年11月（ ISSN:0556-2813

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We use a microscopic three-cluster model with the α + α + n configuration to analyze with astrophysical interests the photodisintegration cross section of 9Be. the valence neutron in 9Be is treated in the molecular orbit model, including continuum states by the box discretization method. It is shown that good agreement is achieved with the recently measured B(E1) transition probability from the ground state the the first 1/2+ state when the box size is enlarged, resulting in reasonable reproduction of the experimental data for the photodisintegration cross section. The Coulomb dissocitaion of 9Be is also discussed.

• N. Itagaki, S. Hirose, T. Otsuka, S. Okabe, K. Ikeda

Physical Review C - Nuclear Physics   65 ( 4 )   6 - 443026   2002年（ ISSN:0556-2813 （ eISSN:1089-490X

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The triaxial deformation in [Formula Presented] is investigated using a microscopic [Formula Presented] model. The states of two valence neutrons are classified based on the molecular-orbit (MO) model, and the π orbit is introduced about the axis connecting the two α clusters for the description of the rotational bands. There appear two rotational bands comprised mainly of [Formula Presented] and [Formula Presented] respectively, at low excitation energy, where the two valence neutrons occupy [Formula Presented] or [Formula Presented] orbits. The triaxiality and the K mixing are discussed in connection to the molecular structure, particularly to the spin-orbit splitting. The extent of the triaxial deformation is evaluated in terms of the electromagnetic transition matrix elements (Davydov-Filippov model, Q-invariant model) and density distribution in the intrinsic frame. The obtained values turned out to be γ=15°–20°. © 2002 The American Physical Society.

• N. Itagaki, S. Okabe, K. Ikeda

Physical Review C - Nuclear Physics   62 ( 3 )   343011 - 343018   2000年09月（ ISSN:0556-2813 （ eISSN:1089-490X

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The structure of the second 0+ state of 10Be is investigated using a microscopic α + α + n + n model based on the molecular-orbit (MO) model. The second 0+ state, which has dominantly the (1/2+)2 configuration, is shown to have a particularly enlarged α-α structure. The kinetic energy of the two valence neutrons occupying along the α-α axis is reduced remarkably due to the strong α clustering and, simultaneously, the spin-orbit interaction unexpectedly plays an important role in making the energy of this state much lower. The mixing of states with different spin structure is shown to be important in negative-parity states. The experimentally observed small-level spacing between 1- and 2- (∼300 keV) is found to be evidence of this spin-mixing effect. 12Be is also investigated using the α + α + 4n model, in which four valence neutrons are considered to occupy the (3/2-)2(1/2+)2 configuration. The energy surface of 12Be is shown to exhibit similar characteristics, that the remarkable α clustering and the contribution of the spin-orbit interaction make the binding of the state with the (3/2-)2(1/2+)2 configuration properly stronger in comparison with the closed p-shell (3/2-)2(1/2-)2 configuration.

• N. Itagaki, S. Okabe

Physical Review C - Nuclear Physics   61 ( 4 )   443061 - 4430613   2000年04月（ ISSN:0556-2813 （ eISSN:1089-490X

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The structure of 10Be is investigated using a microscopic α+α+n+n model based on the molecular orbit (MO) model. The low-lying states are characterized by several configurations of valence neutrons, which are constructed as combinations of three basic orbits. The model space employed is extended from the traditional MO models, and the orbits are expressed as linear combinations of local Gaussians. Their positions are determined variationally. Using this model, we reanalyze the structure of 9Be and show that this extension enables us to use the original two-body spin-orbit interaction determined from a scattering phase-shift analysis of α-n. In 10Be, all of the observed positive-parity bands and the negative-parity bands are described within the model. The 0+ ground state of 10Be is described by a dominant (3/2-)2 configuration. The state has a rather large binding energy (8.38 MeV from the α+α+n+n threshold experimentally), and the mechanism leading to binding, such as a pairing effect and reduction of the kinetic energy between two clusters, is discussed in detail. In spite of this large binding, the α-α clustering in the ground state persists due to a coupling effect between the 6He+α configuration and the 5He+5He configuration, which provides a smooth potential for the valence neutrons. The second 0+ state of 10Be has a large α-α structure with a (1/2+)2 configuration. An enlargement of the α-α distance due to two-valence neutrons along the α-α axis makes their wave function smooth and reduces the kinetic energy drastically. Furthermore, the contribution of the spin-orbit interaction due to coupling between the Sz=0 and the Sz=1 configurations is important. We also show the mediation effect of two valence neutrons between two α clusters.

• 軽い核の特徴的な「形」 中性子過剰核を中心に

板垣直之

原子核研究   44 ( 4 )   91 - 95   2000年01月（ ISSN:0367-4169

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• 23aSH-5 Be同位体の1/2^+軌道におけるスピン・軌道相互作用の寄与

板垣 直之, 岡部 成玄

日本物理学会講演概要集   54 ( 2 )   1999年09月（ ISSN:1342-8349

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• Be同位体の1/2<sup>+</sup>軌道におけるスピン・軌道相互作用の寄与

板垣直之, 岡部成玄

日本物理学会講演概要集   54 ( 2 )   25   1999年09月（ ISSN:1342-8349

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• 31a-YG-6 中性子過剰核におけるクラスター構造の発達

板垣 直之, 岡部 成玄

日本物理学会講演概要集   54 ( 1 )   1999年03月（ ISSN:1342-8349

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• 中性子過剰核におけるクラスター構造の発達

板垣直之, 岡部成玄

日本物理学会講演概要集   54 ( 1 )   40   1999年03月（ ISSN:1342-8349

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• Be、C同位体のクラスター励起状態(3 クラスター模型の新しい適用,不安定核の構造と反応,研究会報告)

板垣 直之

素粒子論研究   97 ( 6 )   F25 - F29   1998年09月（ ISSN:0371-1838

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• 5a-C-4 ^<12>Beのクラスター構造

板垣 直之, 岡部 成玄

日本物理学会講演概要集   53 ( 2 )   1998年09月（ ISSN:1342-8349

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• <sup>12</sup>Beのクラスター構造

板垣直之, 岡部成玄

日本物理学会講演概要集   53 ( 2 )   38   1998年09月（ ISSN:1342-8349

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• <sup>12</sup>Cの構造 荷電形状因子と密度分布

板垣直之, 岡部成玄

日本物理学会講演概要集(年会)   53 ( 1 )   35   1998年03月（ ISSN:1342-8349

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• S. Aoyama, N. Itagaki, K. Kato, K. Ikeda

Physical Review C - Nuclear Physics   57   975 - 977   1998年02月（ ISSN:0556-2813

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By using the complex scaling method, the 10C+p resonance parameters are determined in order to investigate the spectroscopic property of the proton-rich nucleus 11N in comparison with the mirror nucleus 11Be which has a typical neutron halo structure. The obtained resonance energy (Er) and width (Γ) of 11N are (Er, Γ)=(1.29 MeV, 1.39 MeV) and (2.12 MeV, 0.95 MeV) for s1/2 and p1/2 states, respectively. These results are in good agreement with the recent experimental data reported by Axelsson et al. Thomas-Ehrman effect on the 1/2- and 1/2+ resonance states in 11N is discussed in association with the weakly bound states in 11Be.

• 21p-A-2 ^<12>C"α相関とスピン軌道力"

板垣 直之, 岡部 成玄

日本物理学会講演概要集   52 ( 2 )   1997年09月（ ISSN:1342-8349

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• <sup>12</sup>C”α相関とスピン軌道力”

板垣直之, 岡部成玄

日本物理学会講演概要集(分科会)   1997   36   1997年09月

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• AMD+GCMによる軽い核構造研究(原子核とマイクロクラスターの類似性と異質性)

板垣 直之

物性研究   68 ( 2 )   171 - 172   1997年05月（ ISSN:0525-2997

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この論文は国立情報学研究所の電子図書館事業により電子化されました。

• 29a-YM-1 Beアイソトープの励起構造

板垣 直之, 岡部 成玄

日本物理学会講演概要集   52 ( 1 )   1997年03月（ ISSN:1342-8349

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• 29P-YM-5 中性子過剰Liアイソトープの励起状態

青山 茂義, 板垣 直之, 加藤 幾芳, 池田 清美

日本物理学会講演概要集   52 ( 1 )   1997年03月（ ISSN:1342-8349

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• Beアイソトープの励起構造

板垣直之, 岡部成玄

日本物理学会講演概要集(年会)   52 ( 1 Pt 1 )   43   1997年03月（ ISSN:1342-8349

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• 中性子過剰Liアイソトープの励起状態

青山茂義, 板垣直之, 加藤幾芳, 池田清美

日本物理学会講演概要集(年会)   52 ( 1 Pt 1 )   48   1997年03月（ ISSN:1342-8349

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• 9a-G-3 "^4He+t+過剰中性子模型"を用いた中性子過剰Liアイソトープの束縛と励起機構 : ^<11>Liの励起状態における^9Liコアの励起自由度

青山 茂義, 板垣 直之, 加藤 幾芳

日本物理学会講演概要集. 秋の分科会   1996 ( 1 )   1996年09月

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• 9p-G-3 多重配位クラスター模型による軽い核の構造

板垣 直之, 岡部 成玄

日本物理学会講演概要集. 秋の分科会   1996 ( 1 )   1996年09月

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• “<sup>4</sup>He+t+過剰中性子模型”を用いた中性子過剰Liアイソトープの束縛と励起機構 <sup>11</sup>Liの励起状態における<sup>9</sup>Liコアの励起自由度

青山茂義, 板垣直之, 加藤幾芳

日本物理学会講演概要集(分科会)   1996 ( Autumn Pt 1 )   141   1996年09月

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• 多重配位クラスター模型による軽い核の構造

板垣直之, 岡部成玄

日本物理学会講演概要集(分科会)   1996 ( Autumn Pt 1 )   151   1996年09月

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• Four-Alpha Linear-Chain States in 16O

Naoyuki Itagaki, Akira Ohnishi, Kiyoshi Kato

1996年06月

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掲載種別：機関テクニカルレポート，技術報告書，プレプリント等

We study 4$\alpha$ linear-chain states in 16O in comparison with 3$\alpha$
states in 12C by using the Generator Coordinate Method within a microscopic
$N\alpha$-cluster model. It is shown to be very important to solve relative
motion of $\alpha$-clusters by taking into account the orthogonality between
the linear-chain states and other low-lying states including the ground state.
For 12C, the 3$\alpha$ chain state disappears because of this orthogonality.
The $4\alpha$ chain state in 16O, on the other hand, is hardly affected by
low-lying states and persists to remain above the 4$\alpha$ threshold. The
calculated moment of inertia of the $4\alpha$ linear-chain rotational band (88
keV) reproduces the experimentally suggested value qualitatively.

• <sup>12</sup>Cにおけるαクラスターの崩れ

板垣直之, 大西明, 加藤幾芳

日本物理学会講演概要集(年会)   51st ( 1 )   104   1996年03月（ ISSN:1342-8349

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• Microscopic α-Cluster Model Based on Antisymmetrized Molecular Dynamics〔邦文〕 (中重核・重い領域の原子核における分子的構造)

板垣 直之

素粒子論研究   92 ( 2 )   B68 - B70   1995年11月（ ISSN:0371-1838

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• 28a-SE-2 αの崩れの効果を含めた軽い4N核の構造分析

板垣 直之, 大西 明, 加藤 幾芳

日本物理学会講演概要集. 秋の分科会   1995 ( 1 )   1995年09月

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• αの崩れの効果を含めた軽い4N核の構造分析

板垣直之, 大西明, 加藤幾芳

日本物理学会講演概要集(分科会)   1995 ( Autumn Pt 1 )   68   1995年09月

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• 28a-YA-2 拘束冷却された基底によるGCMとそのα粒子模型への応用II

板垣 直之, 大西 明, 加藤 幾芳

日本物理学会講演概要集. 年会   50 ( 1 )   1995年03月

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• 拘束冷却された基底によるGCMとそのα粒子模型への応用 II

板垣直之, 大西明, 加藤幾芳

日本物理学会講演概要集(年会)   50th ( 1 )   42   1995年03月（ ISSN:1342-8349

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### 講演・口頭発表等

• Exotic cluster structure in light nuclei

11th International Conference on Nucleus-Nucleus Collisions, at San Antonio (USA)  2012年05月

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会議種別：口頭発表（招待・特別）