THE ANGULAR-MOMENTUM CORRELATION COEFFICIENT IN DISSIPATIVE HEAVY-ION COLLISIONS

Based on a transport equation of the Fokker-Planck type the correlations in theangular-momentum distributions of binary fragments in deeply inelastic heavy-ion col-lisions are investigated. A strong anticorrelation is found due to the centrifugal part ofthe driving potential. The correlation angle increases towards mass symmetry andreaches 45° for symmetric fragmentation.     

THE ROLE OF NUCLEAR STRUCTURE EFFECTS ON THE NUCLEON EXCHANGE PROCESS IN DISSIPATIVE HEAVY-ION COLLISIONS

Based on the model of nucleon exchange,including the nucleon exchange between two nuclei and the particle-hole excitation in a nucleus,this paper discuss the role of the dynamical evolution in nuclear deformation and the shell effects on the nucleon exchange process in dissipative heavy-ion collision.A nice agreement between theoretical results and experimental data has been gotten.     

PARTICLE DENSITIES AT THE CENTER REGION IN HIGH ENERGY HEAVY-ION COLLISIONS

Based on the two-chain model by A.Capella et al. the rapidity distributions of the multiplicity in high energy heavy-ion collisions, especially in head-on collisions, are discussed. The energy density at the center region in head-on collisions is estimated for different incident energies and different heavy ions. It is shown that the condition of the phase transition to the quark-gluon plasma can be realized in heavy-ion collisions at several tens of GeV.     

p-p碰撞中π介子多重产生电荷关联的集团效应

高能多重产生现象表现出很强的统计性,并且已显示出π介子产生时很可能是通过中间集团产生的。我们首先讨论电荷分布的集团效应。 π介子的同位旋为1,为了合理解释π介子多重产生中的许多统计特征,一个合理的假定是认为多重产生时,产生的π介子绝大多数是组成一些同位旋为零的集团,这些集团也可能是一些已知的或未知的介子。显然,首先要考察的最重要的是相当于e介子和ω介子的集团,前者表现为2π,后者表现为3π。     

同位旋相关的输运理论和中能重离子碰撞中同位旋效应研究进展

本对现有的描述中能重离子碰撞中同位旋相关的输运理论进行了评述，并给出了采用这些理论研究中能重离子碰撞中同位旋效应的最新成果，最后指出了进一步研究的方向。     

金属银表面-分子体系中电荷转移效应的形成过程

本文报道从吸收光谱观察到分子吸附在银表面上所出现的电荷转移效应,着重研究分子与表面之间电荷转移随时间的变化过程,并且对其机理进行初步分析。 关键词：     

红宝石中自旋—晶格弛豫直接过程的计算

本文计算了在低温、低浓度下红宝石基态自旋-晶格弛豫的直接过程。应用强场耦合表象中基态的二级微扰波函数,在θ=90°,脉冲饱和法测量条件下,计算了基态四能级之间的无辐射跃迁几率。然后,用求解粒子数方程的方法,计算1.4°K的自旋-晶格弛豫时间。计算结果与Pace等人的实验结果较好地符合。     

耗散两态系统的动力学特性

利用Born-Oppenheimer近似研究了零温时耗散两态系统的动力学特性.在不同环境谱分布下,给出了两态之间的跃迁几率随时间的变化.数值结果表明:当环境的谱分布为Ohmic形式时,跃迁几率是一个衰减的函数;而当谱分布为随机取值时,跃迁几率具有“量子跳跃”的特性.与之相对比,我们还给出了当把环境等价成无穷多个谱振子的集合时,跃迁几率随时间的变化.     

THE INFLUENCE OF THE ZERO POINT OSCILLATION ON THE CHARGE TRANSFER IN THE HEAVYION DEEP INELASTIC COLLISIONS

We discuss the variance of the charge distribution in the heavy ion deep inelasticcollision on the basis of the Langevin equation. In order to explain the difference ofthe initial slope (early stage) of the charge distribution for the different reactionsystems and different bombarding energy, an initial condition of the charge drift inthe early stage of Dic is introduced. It is given by the harmonic or inhamonic motionaround the zero point and closely depends on the nuclear structure and incident energy.The difference of the inertial mass and stiffness parameter may be the one of thereason for the difference of charge transfer. In addition we also analyse the charac-terstic of the inertial mass parameter.     

正负离子碰撞过程中电荷转移的理论研究

文中用渐近方法，采用未微扰的原子波函数，导出了正负离子碰撞过程中，当离子间的距离很大时，入射离子道与出射共价道之间的交换相互作用的解析表达式。利用该相互作用的解析表达式，并考虑在入射通道里Ｈ－离子核外有两个同科电子的情况，由多通道Ｌａｎｄａｕ－Ｚｅｎｅｒ模型分别计算了低能Ｈ＋＋Ｈ－和Ｄ＋＋Ｈ－碰撞过程中的电荷转移总截面。计算结果与已有的实验数据进行了比较。     

热库中振子弛豫过程的精确解

本文从VonNeumanm方程出发,求出了热库中振子跃迁几率的精确解。在不作弱耦合近似情况下得到了平衡态分布的形式。 关键词：     

低能重离子耗散反应产物的激发函数研究

述评低能重离子耗散碰撞激发函数中截面涨落现象的主要实验结果：截面及其涨落的不可平滑性、不可重复性以及大角度之间的长程能量关联；述评与实验结果相应的理论研究进展：用双核系统的衰变、相干转动以及相位无规化过程这样三种不同运动形态的相互复杂作用定量描述耗散反应随时间的演化。     

高分子光激发的超快过程与弛豫

利用多声子跃迁理论,解释了聚合物中光激发动力学中的快成分(100fs)和慢成分(ns)的起源。并分别计算了它们的演化时间。结果表明,快成分对应于从自由电子-空穴对形成中性双极化子,慢成分对应于中性双极化子的无辐射衰变。还用解动力学方程的方法模拟了双极化子的形成。 关键词：     

非平衡耗散系统定常态的Goldstone模

在有时空结构的非平衡定常态上,由于对称性的自发破缺,形成非零能、带耗散的Goldstone模。本文以么模激光的饱和状态为例,从普遍的相位对称性出发,应用闭路格林函数中的Ward-Takahashi恒等式,具体地导出了这种带耗散的推广的Goldstone定理的一个形式,讨论了相应的Goldstone模式的物理意义。求得了饱和状态光量子态的分裂。具体给出了状态从相位有序→相位无序的转化规律,从而给自发破缺的对称性的恢复一个具体的描述。 关键词：     

耗散量子隧道系统中的形变效应与耦合指数的关系

采用变分方法，比较了超欧姆耗散两能态系统中位移变分态和位移－压缩变分态的特性。通过研究发现，在强耦合区域，位移－压缩态较稳定，其基态性质不仅取决于谱密度，而且还依赖于耦合强度ｇ₁～ω₁^λ的指数λ；位移－压缩态稳定的区域将随λ减小而增加。对于欧姆耗散两能态系统，在位移－压缩态退局域相区域亦有同样的特性，且该区域亦随λ减小而增加。 关键词：     

CHARGE ASYMMETRY AND THE Z0 BOSON MASS IN UNPOLARIZED e+e-→μ+μ- REACTION

Department of Physics, Zhongshan University, Guangzhou, China     

MASS DRIFT FLUCTUATION AND THE SHELL EFFECT IN HEAVY ION COLLISIONS

Master equation is solved numerically for mass drift and fluctuation of three reactions.The driven potential is calculated by means of D.Myers' mass formula plus shell correction.The results indicated that the lack of mass drift in the range of zero to a considerable energy loss in heavy ion collisions could be explained by transport theory.Due to small mass mobility coefficient the mass does not drift considerably during a short time interval.The effect of shell structure in the driven potential is obvious for mass relaxation in low energy loss region.     

离子碰撞过程中电荷转移的理论研究

用经典轨道蒙托卡罗(CTMC)方法计算离子与氢原子碰撞过程电荷转移截面,并计算俘获电子的n(n为主量子数)壳层分布。对于多电荷离子的碰撞过程,利用约化变量得到了截面的q标度规律。计算结果与实验测量符合得很好。     

电荷在一类点电荷系统中的非线性振动

本文用数值计算的方法讨论了电荷在一类点电荷系统中的非线性振动及其特点。     

DESCRIPTIONS OF THE EQUILIBRATION PROCESS OF THE INTRINSIC DEGREES OF FREEDOM AND DISSIPATIVE PROCESS OF THE NUCLEAR COLLECTIVE MOTION

In this paper the Hamiltonian model is used for studying the nuclear dynamics by taking both the one-body and two-body interaction mechanisms into account. On the basis of the Von Neuman equation the coupling between the collective motion and the single particle degrees of freedom is discussed. Thus, the equations obtained are physically transparent and easy for numerical computations. They may be useful for describing the dissipative process of the nuclear collective motion as well as the equilibration process of the intrinsic degrees of freedom.