Quantum Fluctuation Effects on Fragment Formation Processes

量子涨落对碎片形成过程的影响

• 批准号: 09640329
• 负责人: OHNISHI Akira
• 金额: $ 1.92万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640329/
• 关键词: Quantum Langevin; AMD; Multifragmentation; Liquid-gas transition; Atomic Cluster; Stopped Ξ^-; GeV Proton; Percolation; 核間カスケード; 静止Ξ-反応; 2粒子運動量相関; ΛΛ相互作用; 量子揺らぎ; AA相互作用; 相転移; 分子動力学; 波束の統計力学; カロリー曲線; ツイン・ハイパー核

One of the main goals of nuclear reaction study is to explore various phases of nuclear matter and achieve an understanding of the associated phase transitions. Since the the experimental exploration of nuclear phases must rely on nuclear collisions, it is necessary to have deep knowledges of nuclear collision dynamics, including the non-equilibrium character as well as the quantal statistical nature of the nuclear system.In this research project, first we have developed a tractable method to describe the quantum statistical mechanics of wave-packets. Then we have constructed a dynamical model, the Quantum Langevin model, in which we implement a stochastic term having a quantum mechanical origin into wave-packet molecular dynamics. With this stochastic term, it is ensured that the system relaxes to proper quantum statistical equilibrium automatically, by the form of the equations of motion itself. We have successfully applied this model to various fragmentation processes : multifragmen … More tation in heavy-ion collisions, atomic cluster formation, and double, twin, and single-hyperfragment formation from Ξ^- absorption at rest. From these studies, we have clarified the following important roles of quantum fluctuations in fragment formation processes. (1) Inclusion of quantum fluctuation drastically improves the statistical properties of nuclear systems. (2) With quantum fluctuations, it becomes possible to describe dynamical formation of cold fragments, which are stable enough to survive later statistical decays. (3) This dynamical fragment formation is much faster than that in usual molecular dynamics without fluctuations. This fast fragmentation would be the origin of anomalous IMF angular distribution (side peaked) observed in high-energy proton induced reactions. We have verified this idea by using a combined framework of a intranuclear cascade model with a non-equilibrium percolation model.Based on these achievements and other works on strangeness nuclear physics and relativistic heavy-ion collisions, we have published twelve original papers (incl.one submitted paper), and fifteeen conference proceedings during these four years. Less

核反应研究的主要目标之一是探索核物质的各个相，并了解相关的相变。由于核相的实验研究必须依赖于核碰撞，因此必须对核碰撞动力学有深入的了解，包括核系统的非平衡性质和量子统计性质。然后，我们建立了一个动力学模型，量子朗之万模型，其中我们实现了一个随机项具有量子力学的起源到波包分子动力学。有了这个随机项，就可以确保系统通过运动方程本身的形式自动弛豫到适当的量子统计平衡。我们已经成功地将此模型应用于各种碎片化过程： ...更多信息 重离子碰撞中的基态、原子团簇的形成，以及由静止时的π ^-吸收形成的双超碎片、孪超碎片和单超碎片。从这些研究中，我们已经澄清了以下重要作用的量子涨落在碎片形成过程中。(1)量子涨落的引入极大地改善了核系统的统计性质。(2)有了量子涨落，就有可能描述冷碎片的动力学形成，这些碎片足够稳定，可以在以后的统计衰变中幸存下来。(3)这种动力学碎片的形成比通常的分子动力学中没有涨落的碎片形成快得多。这种快速的碎裂可能是在高能质子诱导反应中观察到的反常IMF角分布（侧峰）的起源。我们使用核内级联模型和非平衡逾渗模型的组合框架验证了这一想法。基于这些成果以及奇异核物理和相对论重离子碰撞方面的其他工作，我们在这四年中发表了十二篇原创论文（包括一篇提交论文）和五十篇会议记录。少

项目成果

Akira Ohnishi et al.: "Quantum fluctuation effects on nuclear multifragmentation"Proc.of 3rd Japan-Italy Joint Symp. '97, Perspectives in Heavy Ion Physics (World Scientific). 162-171 (1999)

Akira Ohnishi 等：“量子涨落对核多碎裂的影响”Proc.of 3rd Japan-Italy Joint Symp.

Takayuki Myo et al.: "Resonance and Continuum Components of the Strength Function"Prog.Theor.Phys.. 99. 801-817 (1998)

Takayuki Myo 等人：“强度函数的共振和连续体成分”Prog.Theor.Phys.. 99. 801-817 (1998)

Yuichi Hirata et al.: "Quantum fluctuation effects on hyperfragment formation from Ξ^- absorption at rest on ^<12>C"Prog.Theor.Phys.. 102. 89-119 (1999)

Yuichi Hirata等人：“量子涨落对^ 12 C上静止的Ξ^-吸收的超碎片形成的影响”Prog.Theor.Phys.. 102. 89-119 (1999)

Y.Nara et al.: "Study of (K^-, K^+) Reactions within the Quantum Molecular Dynamics Approach"Proc.of the 25th INS Int.Symp.on Nuclear and Particle Physics with High-Intensity Proton Accelerators (World Scientific). 324-329 (1998)

Y.Nara 等人：“量子分子动力学方法中的 (K^-, K^) 反应研究”Proc.of the 25th INS Int.Symp.on Nuclear and Particle Chemistry with High-Intensity Proton Accelerators (World Scientific)

Akira Ohnishi et al.: "Quantum Fluctuation Effects on Nuclear and Atomic Cluster Formation"Nucl.Phys.. A630. 223c-230c (1998)

Akira Ohnishi 等人：“量子涨落对核和原子团簇形成的影响”Nucl.Phys.. A630。