重离子碰撞两体关联输运理论Ⅲ.半经典近似下的数值计算

为了验证由相干单粒子波函数和两体关联动力学所建立的非相对论条件下的重离子碰撞两体关联输运理论的有效性,利用没有碰撞项的量子分子动力学,即时间相关的Hartree-Fock方法的经典近似,实现了两体关联输运理论在半经典近似下的数值计算.计算结果表明:这种两体关联输运理论的确能够有效地描述重离子碰撞过程中的输运和耗散过程.     

重离子碰撞中的热化、膨胀和径向流

在BUU方程框架下讨论中能重离子碰撞过程中的热华、膨胀和径向流.低能时,由四极矩和密度分布的计算知道系统的整体平衡可以达到.对于能量较高时理论计算表明,系统的整体平衡被破坏,但局域平衡可以达到.同时计算还指出重离子碰撞过程 中存在着径向膨胀.在Skyrme有效相互作用下,讨论了状态方程对径向流的影响,证明径向流对状态方程中有效质量较灵敏,对压缩系数不灵敏.     

关于重离子碰撞TBCTT和QMD两种理论计算结果的系统比较

为了检验基于两体关联动力学而建立的关于重离子碰撞的两体关联输运理论(TBCTT).对TBCTT和量子分子动力学(QMD)的理论计算结果在不同入射道条件下进行了仔细的比较.结果表明:所计算的各种物理量的时间演化过程,对两种理论而言得到了非常相似的行为,这说明TBCTT是一个具有很好发展前景的重离子碰撞动力学的输运理论.     

强相互作用自旋-轨道耦合与夸克-胶子等离子体整体极化

在非对心相对论重离子碰撞中,参与反应的原子核物质系统具有巨大的初始轨道角动量,经过强相互作用的自旋-轨道耦合,这一巨大的轨道角动量可以转化为产生的夸克-胶子等离子体的整体极化.整体极化效应在理论上提出后,首先被美国布鲁克海文国家实验室的相对论重离子对撞机上的STAR实验所证实,激发了人们对相关问题的研究,成为重离子碰撞物理研究的一个新方向——重离子碰撞自旋物理.本文简单回顾了整体极化原始基本思想、理论计算体系与主要结果以及近几年的理论进展.     

重离子碰撞两体关联输运理论──Ⅰ.理论模型:相干态表象的构造与基本运动方程

应用相干态表象和两体关联动力学,建立了非相对论重离子碰撞两体关联输运理论TBCTT(Two—Body Correlation Transport Theory).这一理论包括了时间相关的平均场.泡利阻塞和两体碰撞效应,它能够描述重离子碰撞过程中非均匀核物质的演化、涨落效应和碎裂的动力学形成.     

近玻尔速度氙离子激发钒的K壳层X射线

测量了2.4—6.0 MeV Xe~(20+)离子轰击V靶表面过程中辐射的X射线.计算了V的K壳层X射线发射截面,并将实验结果与平面波恩近似、ECPSSR、两体碰撞近似的理论计算进行了对比.讨论了近玻尔速度非对称碰撞过程中,BEA模型估算高电荷态重离子激发内壳层电离的修正因素.结果表明,综合考虑库仑偏转和有效电荷态修正后,BEA理论与实验结果符合较好.     

类氢铀离子的辐射电子俘获角分布研究

分析了在重离子冷却储存环上测量的辐射电子俘获产生的X射线能谱,得出了K REC光子的相对微分角分布,通过与非相对论理论和全相对论理论的计算结果进行比较,从实验上证明了相对论重离子 原子碰撞中自旋翻转跃迁的存在,实验结果与全相对论理论计算结果一致.同时还证实,重离子体系本身的相对论性质对碰撞过程有重要影响. Radiative electron capture process occurring in high-Z ion-atom collisions studied on the heavy ion storage ring (ERS) is reviewed. The REC differential angular distributions are deduced from the X-ray spectra recorded at various observation angles for 310 and 88 MeV/u U 92+on N 2collisions, respectively. The experimental results are compared with non-relativistic and complete relativistic calculations. Deviations from sin 2θ lab are found in both cases. The contributions to near 0°observation...     

用改进的量子分子动力学研究中能重离子碰撞中多重碎裂

本文利用改进的量子分子动力学模型(MQMD)研究中能重离子碰撞中的多重碎裂过程.在MQMD的基础上通过模拟计算发现:MQMD由于考虑了动量相关势和Pauli势,极大地改善了多重碎裂产额的计算结果与实验数据的比较.同时研究了二者对碰撞动力学的不同影响.最后,讨论了理论计算与实验结果仍有矛盾的原因,并提出了进一步改进的方案.     

中能重离子碰撞动力学研究

利用改进的量子分子动力学模型(MQMD),通过研究能够标识中能重离子碰撞动力学过程的物理量:横动量、碰撞数、核物质密度及热化的时间演化过程,了解中能重离子碰撞系统的碰撞动力学和多重碎裂机制;同时对控制和影响这种碰撞动力学的各种动力学因素:状态方程、动量相关势和介质效应进行了分析和探讨.     

重离子碰撞中K介子和π介子产生的统一动力学模拟

用RVUU模型统一地研究了重离子碰撞中产生的K介子和π介子的动力学过程.考虑了K产生和输运过程的介质效应,同时,计入了π在核物质中的传播.用它模拟了每核子1GeV入射能量的重离子碰撞中π产生和阈下K产生过程.讨论了核介质效应对π末态性质的影响,以及对K末态性质的联带影响.计算结果表明,吸引的π光学势,影响了末态π动量分布,使横动量分布中具有小动量的π产额增大,同时明显增大了K的产额,改变了K的动量分布.这说明要合理地评价重离子碰撞的探测信息,需要统一地研究K和π的这些末态动力学作用.     

Two -Body Correlation Transport Theory for Heavy Ion Collisions Ⅰ. Theory Model: Construction of Coherent State Representation and Basic Equations of Motion

A two-body correlation transport theory(TBCTT) for describing the dynamical process in heavy ion collisions(HIC)is established by means of time-dependent coherent single particle state representations and the two-body correlation dynamics.Containing time-dependent mean field effect, Pauli block, and two-body collisions,this model is capable of describing the time-evolution of nonuniform nuclear matter,fluctuation effects and dynamical formation of fragments in HIC.     

重离子碰撞两体关联输运理论──Ⅰ．理论模型：相干态表象的构造与基本运动方程

应用相干态表象和两体关联动力学，建立了非相对论重离子碰撞两体关联输运理论ＴＢＣＴＴ（Ｔｗｏ—ＢｏｄｙＣｏｒｒｅｌａｔｉｏｎＴｒａｎｓｐｏｒｔＴｈｅｏｒｙ）．这一理论包括了时间相关的平均场．泡利阻塞和两体碰撞效应，它能够描述重离子碰撞过程中非均匀核物质的演化、涨落效应和碎裂的动力学形成．     

Two-Body Correlation Transport Theory for Heavy Ion Collisions Ⅱ.The Time-Evolution Equations of Single Particle States Given by Means of the Time Dependent Variational Principle and Antisymmetrized Molecular Dynamics

Using the two-body correlation dynamics and the time dependent variational principle the equations of nonrelativistic two-body correlation transport theory(TBCTT) for heavy ion collisions are established.This theory is used to discuss Fermionic Molecular Dynamics (FMD) and Antisymmetrized Molecular Dynamics (AMD).The collision effects can naturely appear in the time-evolution equations of its single particle states.     

重离子碰撞的两体关联输运理论

对中能重离子碰撞的两体关联输运理论、它的Ｈｉｅｒａｒｃｈｙ截断和守恒定律进行了研究．该理论包括了时间相关的平均场、两体关联和Ｐａｕｌｉ原理，并且时间相关的平均场和两体关联动力学之间在自洽耦合和非耦合两种情况下进行了数值计算和讨论．初步计算结果表明，两体关联输运理论能对重离子碰撞动力学过程进行合理的描述，总粒子数、总动量和总能量基本上守恒，从而表明该理论是一个很有发展前景的输运理论． The Two body Correlation Transport Theory (TBCTT), its several hierarchy truncations and conservation laws for intermediate energy heavy ion collision have been investigated. This approach contains time dependent mean field, two body correlation effects and Pauli principle, the self consistent coupling between time dependent mean field and two body correlation dynamics is emphasized and preserved in realistic numerical calculation by a set of coupled dynamical equations...     

Two-Body Correlation Transport Theory for Heavy Ion Collision Ⅲ.Numerical Study for Semiclassical Approximation

In order to demonstrate the usefulness of Two Body Correlation Transport Theory (TBCTT),by using the Quantum Molecular Dynamics (QMD) without collision term,the numerical study for the semiclassical approximation of TBCTT is carried out.The calculation results show that the TBCTT can well describe the transport and dissipative process in heavy ion collisions.     

热核的稳定性和动力学效应

本文对中能重离子碰撞中热核的形成过程和稳定性作了评述,特别讨论了动力学效应和中间质量碎片的平衡和非平衡特征. The formation process and stability of hot nucleus produced in heavy ion collision(HIC)at intermediate energy range have been reviewed.The dynamical effect and equilibrium and non-equilibrium charactristies of intermediate mass fragments(IMF) are especially discussed.     

An extended time-dependent mean-field theory for strongly correlated nuclear systems

We perform an extension of the time-dependent mean-field theory by an explicit inclusion of strong two-body correlations of short range on a level of microscopic reversibility relating them to realistic nucleon-nucleon forces. Invoking a least action principle for correlated basis functions, equations of motion for the correlation functions and the single-particle model wave function are derived to the lowest order of the FAHT cluster expansion. Higher order effects as well as longrange correlations we consider only to the extent to which they contribute to the mean field via a readjusted phenomenological effective two-body interaction. The corresponding correlated stationary problem is investigated and appropriate initial conditions to describe a heavy ion reaction are proposed. The single-particle density matrix is evaluated. Norm, energy and particle number conservation are proved. Possible simplifications are discussed. Standard TDHF appears as a limiting case if the range of the explicitly considered part of the bare nucleon-nucleon interaction goes to zero.