極端状況下の原子核の構造と相互作用

1995 Fiscal Year Annual Research Report

• Project/Area Number: 05243102
• Research Institution: The University of Tokyo
• Principal Investigator: 石原 正泰 東京大学, 大学院・理学系研究科, 教授 (40013396)
• Co-Investigator(Kenkyū-buntansha): 堀内 昶 京都大学, 大学院・理学研究科, 助教授 (60027349) ; 大塚 孝治 東京大学, 大学院・理学系研究科, 助教授 (20201379) ; 郷農 靖之 九州大学, 理学部, 助教授 (50016127) ; 谷畑 勇夫 東京大学, 理化学研究所, 主任研究員 (10089873) ; 福田 共和 東京大学, 原子核研究所, 助教授 (50116092)
• Keywords: 超重元素 / 中性子過剰核 / 高スピン核異性体 / 不安定核 / 反対称化分子動力学 / 分解反応 / 核構造 / 相対論的平均場近似

Research Abstract

「超重元素探索」:^<235>U(^<40>Ar,αxn)反応で108番元素合成を示唆するデータを得た。中性子欠損新同位元素として、^<196>Rn,^<200>Fr,^<197>Rn,^<197g>Rn,^<195g>At,^<195>At,^<195m>Atを発見した。中性子過剰核のクーロン障壁付近の融合反応断面積の系統的な測定を行ない、ハロ-核^<11>Beの実験では、ハロ-中性子が融合反応に重要な寄与をしていないことがわかった。また、検出効率の高い大型のガス検出器の製作を終了した。「中性子過剰核」:中性子過剰核の弾性散乱と非弾性散乱の実験を進めた。特にビームとして^3H,^6He,^<11>Liを用いた。^<11>Liに関しては、今までに報告のあった1.2MeVの第一励起状態を確認し、その他4本の励起状態を見つけた。「高スピン原子核」:高スピンアイソマ-ビームの輸送のためのよい条件を探るために、理研のE1CビームラインとRIPSビームラインを比較した。その結果、RIPSビームラインが、総合的に有利であることがわかった。セグメント型Ge検出器を中心とした高精度のガンマ線検出器系を開発し、ドップラー効果の補正に大きな力を発揮することが実証できた。「不安定核の理論」:東京大学のグループは、連続状態RPAを用いて中性子スキンからの励起をより良い精度で研究した。3次元空間での時間依存ハートリーフォック計算による核反応の研究を開始した。量子モンテカルロ対角化法という新しい方法を提案した。京都大学のグループは反対称化分子動力学により、核構造と核反応の研究を行なった。中性子数の変化により、Li,Be,Bの同位体では、クラスター構造が大きく変化し、Cの同位体では、変形の様相が大きく変化することがわかった。新潟大学のグループは、^9Liや^9Cの構造を4クラスター模型で計算し、実験とのよい一致が得られる事を示した。時間依存するシュレ-ティンガー方程式により^<11>Beのクーロン分解反応機構を調べ、クーロン再加速の効果がチャネルに依存した複雑な様相を示すことがわかった。東北大学のグループは、相対論的平均場近似を用いて中重核から重核にかけての核構造の研究を行なった。核反応研究としては、核分裂幅の温度依存性、重イオン弾性散乱、極低エネルギーでの核融合反応についての研究を行なった。

Research Products

• [Publications] T.Motobayashi et al.: "Large Deformation of the Very Neutron-rich Nucleus ^<32>Mg from Intermediate-Energy Coulomb Excitation" Physics Letters. B346. 9-14 (1995)
• [Publications] S.Shimoura et al.: "Coulomb Dissociation Reaction and Correlations of Two Halo Neutrons in ^<11>Li" Physics Letters. B348. 29-34 (1995)
• [Publications] M.Ishihara: "Extremely Neutron-rich Nuclei and Electro-magnetic Excitations" Nuclear Physics. A583. 747C-754C (1995)
• [Publications] M.Ishihara: "Current Topics on Light Neutron-rich Nuclei" Nuclear Physics. A588. 49C-58C (1995)
• [Publications] T.Nakamura et al.: "Coulomb Dissociation of a Halo Nucleus ^<11>Be and Direct Breakup Mechanism" Nuclear Physics. A588. 81C-84C (1995)
• [Publications] K.Asahi et al.: "Electromagnetic moments of unstable nuclei studied with polarized projectile fragments" Nuclear Physics. A588. 109C-112C (1995)
• [Publications] T.Nomura et al.: "Study of α Decays in the ^<40>Ar+^<232>Th Reaction Using the RIKEN Gas-Filled Separator I-General-." Procesings of Tours Symposium on Nuclear Physics II,. (to be published). (1996)
• [Publications] M.Kurokawa et al.: "Study of α Decays in the ^<40>Ar+^<232> Th Reaction Using the RIKEN Gas-Filled Separator II-High Resolution Position-Sensitive Detector and Analysis" Proceedings of Tours Symposium on Nuclear Physics II,. (to be published). (1996)
• [Publications] M.Kurokawa et al.: "Radiation Damage Factor for Ion-Implanted Silicon Detectors Irradiated with Heavy Ions" IEEE Transactions on Nuclear Science,. (to be published). (1996)
• [Publications] A.Yoshida et al.: "Measurement of Fusion Cross Section with Neutron Halo Nuclei" Nuclear Physics. A588. 109C-112C (1995)
• [Publications] C.Signorini et al.: "Fusion and Break-up around the Coulomb Barrier with Halo/Loosely Bound Unstable Nuclei" Proceedings of 2nd RIKEN/INFN Joint Symposium on Heavy Ion Reactions,. (to be published). (1996)
• [Publications] A.Yoshida et al.: "Measurement of Fusion Cross scction with Neutron Rich RI Beam" Proceedings of 2nd RIKEN/INFN Joint Symposium on Heavy Ion Reactions,. (to be published). (1996)
• [Publications] T.Nomura: "The First Result of the ^<232>TH(^<40>Ar,α3n)^<265>[106] Reaction" Proceedings of 2nd RIKEN/INFN Joint Symposium on Heavy Ion Reactions,. (to be published). (1996)
• [Publications] O.Hashiomoto et al.: "Projectile Rapidity Pions in 775 MeV/nucleon ^<139>La+^<12>C and ^<139>La+^<139>La Reactions" Physical Review. C49. 420-427 (1994)
• [Publications] A.Ozawa et al.: "Interaction Cross Sections and Radii of the Mass Number A=17 Isobar (^<17>N,^<17>F,and^<17>Ne)" Physics Letters. B334. 18-22 (1994)
• [Publications] X.Gu et al.: "The ^8Li(α,n)^<11>B Reactions and Primordial Nucleosynthesis" Physics Letters. B343. 31-35 (1995)
• [Publications] A.A.Korsheninnikov et al.: "Spectroscopy of ^<12>Be and ^<13>Be using a ^<12>Be Radioactive Beam" Physics Letters. B343. 53-58 (1995)
• [Publications] I.Tanihata et al.: "Are All Nucleus Spherical at the Drip Line?" Nuclear Physics. A583. 769-774 (1995)
• [Publications] A.Ozawa et al.: "Interaction Cross Sections and Radii of ^<11>C and ^<12>N and Effective Deformation Parameters in Light Mirror Nuclei" Nuclear Physics. A583. 807-810 (1995)
• [Publications] A.A.Korsheninnikov et al.: "Experimental Studies of Light Neutron Rich Nuclei" Nuclear Physics. A588. 23C-28C (1995)
• [Publications] K.Matsuta et al.: "Magnetic Moment of Proton Drip-Line Nucleus ^9C" Nuclear Physics. A588. 153C-156C (1995)
• [Publications] I.Tanihata: "RI Beam Factory Project" Nuclear Physics. A588. 253C-258C (1995)
• [Publications] H.Toki et al.: "Relativistic Many Body Approach for Unstable Nuclei and Supernova" Nuclear Physics. A588. 357C-364C (1995)
• [Publications] I.Tanihata: "Nuclear Structure Studies from Reaction by Induced by Radioactive Nuclear Beams" Progress of Particle and Nuclear Physics. 35. 505 (1995)
• [Publications] D.Hirata et al.: "Relativistic Mean Field Theory on the Xenon,Cesium and Barium Isotopes" Nuclear Physics. A589. 239-248 (1995)
• [Publications] A.Ozawa et al.: "Study of the β-delayed Neutron Emission of ^<19>C" Nuclear Physics. A592. 244-256 (1995)
• [Publications] T.Suzuki et al.: "Neutron Skin of Na Isotopes Studied via Their Interaction Cross Sections" Physical Review Letters. 75. 3241-3244 (1995)
• [Publications] I.Tanihata: "Study of Light Exotic Nuclei using Radioactive Nuclear Beams" Proceedings of International School-Seminar on Heavy Ion Physics. 1. 3 (1994)
• [Publications] W.Benenson et al.: "Isomer Production in Fragmentation Reactions" Proceedings of the 10th Winter Workshop on Nuclear Dynamics"Advance in Nuclear Dynamics". 175 (1994)
• [Publications] I.Tanihata: "Physics with Radioactive Nuclear Beams" Proceedings of International School of Heavy Ion Physics 3rd Course:Probing the Nuclear Paradigm with Heavy Ion Reactions. 116 (1994)
• [Publications] I.Tanihata: "RI Beam Factory Project" Proceedings of Third IN2P3-RIKEN Symposium on Heavy Ion Collisions. 441-451 (1995)
• [Publications] I.Tanihata: "RI Beam Factory Project" Proceedings of XV Nuclear Physics Divisional Conference. 19 (1995)
• [Publications] A.A.Korsheninnikov et al.: "Experimental Studies of Light Exotic Nuclei" Proceedings of XV Nuclear Physics Divisional Conference. 62 (1995)
• [Publications] K.Sugimoto et al.: "Nuclear Structures Studied with Exotic Nuclear Beams" Variations on Nuclear Themes. 329 (1994)
• [Publications] 谷畑 勇夫: "注目される不安定核ビームの利用" 日本物理学会誌. 49. 433-439 (1994)
• [Publications] 谷畑 勇夫: "中性子スキンと中性子ハロ-" パリティ. 09. 42-45 (1994)
• [Publications] 谷畑 勇夫: "不安定原子核と宇宙での元素合成" 科学. 65. 163-170 (1995)
• [Publications] 谷畑 勇夫: "超重ヘリウム^<10>Heの発見" 科学と工業. 48. 521-523 (1995)
• [Publications] 谷畑 勇夫: "RIビームファクトリー計画" 原子力工業. 41. 54-60 (1995)
• [Publications] 谷畑 勇夫: "重イオンの物理" パリティ. 08. 36-46 (1995)
• [Publications] 谷畑 勇夫: "RIビームファクトリー計画" Isotope News. 10月号. 2-7 (1995)
• [Publications] T.Morikawa et al.: "Coulomb Excitation of ^<174>Hf K-Isomer-γ-Ray Spectroscopy with High-Spin Isomer Beam" Physics Letters. B350. 169-172 (1995)
• [Publications] Y.Gono et al.: "Gamma-Ray Spectroscopy with High-Spin Isomer Beams" Nuclear Physics. A588. 241C-246C (1995)
• [Publications] E.Ideguchi et al.: "High-Spin States in ^<148>Tb" Zeitschrift fur Physik. A352. 363-364 (1995)
• [Publications] Y.Gono: "Spectroscopy with Unstable Nuclear Beams" 原子核研究所. 39. 5-23 (1995)
• [Publications] T.Akagi et al.: "Experimental study of the Rare Decays K^0_L→μe,K^0_L→ee,K^0_L→μμ and K^0_L→eeee" Rhysical Review. D51. 2061-2089 (1995)
• [Publications] V.Guimaraes et al.: "Structure of Light Proton-Rich Nuclei on the Drip-Line" Nuclear Physics. A588. 161C-164C (1995)
• [Publications] N.Pietralla et al.: "Odd-Spin Yrast States as Multiple Quadrupole-Phonon Excitations" Physics Letters. B349. 1-6 (1995)
• [Publications] T.Otsuka et al.: "Structure of Nuclei Far from Stability" Nuclear Physics. A588. 113C-120C (1995)
• [Publications] Ka-Hae Kim et al.: "Transfer and Fusion Reactions of Unstable Nuclei" Nuclear Physics. A588. 105C-108C (1995)
• [Publications] T.Otsuka and N.Fukunishi: "Nuclear Mean Field on and near the Drip Lines" Physics. 264. 297-310 (1996)
• [Publications] T.Otsuka et al.: "Structure and Excitation of Nuclei Far from Stability" Proceedings of the Tours Symposium on Nuclear Physics II. 210-223 (1995)
• [Publications] T.Otsuka et al.: "Nuclear Structure Studies and Unstable Nuclei" Proceedings of the 3rd IN2P3-RIKEN Symposium on Heavy-Ion Collisions. 13-22 (1995)
• [Publications] T.Otsuka and T.Mizusaki: "Interacting Boson Model for O(6)Nuclei" Proceedings of the International Symposium on Frontiers of Nuclear Structure Physics. 69-81 (1996)
• [Publications] T.Otsuka et al.: "A Relation between E2 Matrix Elements Connecting Collective States of Deformed Nuclei" Physics Letters. B351. 6-10 (1995)
• [Publications] M.Yokoyama et al.: "Giant Quadrupole Excitation in Nuclei with Neutron Skin" Physical Review. C52. 1122-1125 (1995)
• [Publications] M.Honma et al.: "Diagonalization of Hamiltonians for Many-body Systems by Auxiliary Field Quantum Monte Carlo Technique" Physical Review Letters. 75. 1284-1287 (1995)
• [Publications] K.H.Kim and T.Otsuka: "Multiphonon Structure in a γ-unstable Fermionic Model" Physical Review. C52. 2792-2795 (1995)
• [Publications] T.Suzuki et al.: "Magnetic Moment of ^<11>Be" Physics Letters. B364. 69-74 (1995)
• [Publications] A.Mengoni et al.: "Direct Radiative Capture of p-wave Neutrons" Physical Review. C52. R2334-R2338 (1995)
• [Publications] E.I.Tanaka et al.: "Proton Inelastic Scattering to Continuum Studied with Antisymmetrized Molecular Dynamics" Physical Review. C52. 316-325 (1995)
• [Publications] Y.Kanada-En′yo et al.: "Structure of Li and Be Isotopes Studied with Antisymmetrized Molecular Dynamics" Physical Review. C52. 628-646 (1995)
• [Publications] Y.Kanada-En′yo and H.Horiuchi: "Neutron-Rich B Isotopes Studied with Antisymmetrized Molecular Dynamics" Physical Review. C52. 647-662 (1995)
• [Publications] A.Engel et al.: "Δ Degrees of Freedom in Antisymmetrized Molecular Dynamics and (p,p′)Reactions in the Δ Region" Physical Review. C52. 3231-3248 (1995)
• [Publications] H.Horiuchi and Y.Kanada-En′yo: "Light Neutron-Rich Nuclei Studied with Antisymmetrized Molecular Dynamics" Nuclear Physics. A588. 121C-127C (1995)
• [Publications] 堀内 昶、他: "反対称化分子動力学による核反応と核構造の研究" 日本物理学会誌. 50. 473-476 (1995)
• [Publications] Y.Ohbayasi and Y.Suzuki: "An Exploratory Study of ^<11>Li β Decay in to ^9 Li and Deuteron" Physics Letters. B346. 223-226 (1995)
• [Publications] K.Arai et al.: "Neutron-Proton Halo Structure of the 3.563-MeV O^+ State in ^6Li" Physical Review. C51. 2488-2493 (1995)
• [Publications] Y.Suzuki et al.: "Study of Halo Structure in Light Nuclei with a Multicluster Model" Nuclear Physics. A588. 15C-21C (1995)
• [Publications] Y.Ogawa et al.: "Transverse Momentum Distributions of a ^9Li Fragment in the(^<11>Li,^9Li) Reaction and Neutron Correlations" Nuclear Physics. A588. 77C-80C (1995)
• [Publications] K.Yabana and Y.Suzuki: "One Dimensional Three-body Model for Low Energy Reactions of Halo Nuclei" Nuclear Physics. A588. 99C-103C (1995)
• [Publications] K.Varga et al.: "Microscopic Multicluster Description of the ^7Li-^7Be,^8Li-^8B and ^9Li-^9C Mirror Nuclei" Nuclear Physics. A588. 157C-160C (1995)
• [Publications] K.Varga and Y.Suzuki: "Precise Solution of Few-Body Problems with the Stochastic Variational Method on a Correlated Gaussian Basis" Physical Review. C52. 2885-2905 (1995)
• [Publications] K.Varga et al.: "Microscopic Four-Cluster Description of the Mirror Nuclei ^9Li and ^9C" Physical Review. C52. 3013-3025 (1995)
• [Publications] K.Varga and Y.Suzuki: "Stochastic Variational Method with Correlated Gaussian Basis" Physical Review A. (to be published). (1996)
• [Publications] T.Kido et al.: "Coulomb Breakup Mechanism of Neutron-Halo Nuclei in a Time-Dependent Method" Physical Review C. (to be published). (1996)
• [Publications] N.Takigawa et al.: "Dynamical Norm Method for Non-Adiabatic Macroscopic Quantum Tunneling" Physical Review. C51. 187-197 (1995)
• [Publications] T.Tazawa et al.: "Resonance Enhanced Landau Zener Transition" Nuclear Physics. A583. 291-294 (1995)
• [Publications] S.K.Patra et al.: "Hexadecapole Shape Change in Ytterbium Isotopes" Physical Review. C51. 2248-2251 (1995)
• [Publications] N.Takigawa et al.: "Multi-Nucleon Transfer Reactions and Fusion with Unstable Nuclei" Nuclear Physics. A588. 91C-98C (1995)
• [Publications] H.Sagawa et al.: "Life Time of Soft Multipole Excitations" Zeitschrift fur Physik. A351. 385-389 (1995)
• [Publications] K.Hagino et al.: "Effects of Finite Excitation Energy of Environment on Sudden Quantum Tunneling" Physical Review. C51. 3190-3200 (1995)
• [Publications] S.Yoshida et al.: "Surface Properties of Cs Isotopes" Physical Review. C52. 157-163 (1995)
• [Publications] K.Hagino et al.: "Path Integral Approach to No-Coriolis Approximation in Heavy-Ion Collisions" Physical Review. C52. 286-290 (1995)
• [Publications] N.Takigawa et al.: "Reply to "Comment on 'Shape and Superdeformed Structure in Hg Isotopes in Relativistic Mean Field Model' and 'Struture of Neutron-Deficient Pt,Hg and Pb isotopes"'" Physical Review C. (to be published). (1996)
• [Publications] K.Hagino et al.: "Thermal Fission Rate around Superfluid-Normal Phase Transition" Physical Review C. (to be published). (1996)
• [Publications] K.Morita et al.: "New α-decaying Neutron Isoropes ^<197>Rn and ^<200>Fr" Zeitschrift fur Physik. A352. 7-8 (1995)