重离子碰撞中原子核阻止的同位旋效应

利用含有3种对称势形式的同位旋相关的量子分子动力学,研究了中能重离子碰撞中原子核阻止的同位旋效应和随入射道条件的系统演化过程.计算结果表明,原子核阻止灵敏地依赖束流能量、碰撞参数、碰撞系统的质量和核子–核子碰撞截面的同位旋相关性,而3种对称势和碰撞系统的中质比对它的影响不很明显,但在大约费米能量以下能区,原子核阻止同时依赖于介质中核子–核子碰撞截面和对称势.故认为在费米能量以上能区直至150MeV/u,原子核阻止是提取介质中核子–核子碰撞截面的一个新的物理观测量.     

重离子碰撞中超重核的形成机制(英文)

在双核模型框架下,用数值解主方程方法计算了超重核的熔合几率。 明确描述了包含能量、角动量和碎片形变弛豫的相对运动,并与核子扩散过程相耦合。因此,用微观方法推导出的核子跃迁几率是与时间相关的。所计算的以Pb为靶的冷熔合超重核形成截面和以48Ca为弹核的热熔合超重核形成激发函数与已知的实验值在合理的范围内符合。In the dinuclear system conception, the master equation is solved numerically to calculate the fusion probabilities of super heavy nuclei. The relative motion concerning the energy, the angular momentum and the fragment deformation relaxations is explicitly treated to couple with the diffusion process. The nucleon transition probabilities, which are derived microscopically, are related with the energy dissipation of the relative motion, thus they are time dependent. The formation cross sections of the super heavy nuclei from Pb based cold fusion and excitation functions from 48Ca induced hot fusion are reasonably consistent with known experimental data.     

Effect of three-body interaction on hot asymmetric nuclear matter

The properties of hot asymmetric nuclear matter are studied in the framework of the finite temperature Brueckner－Hartree－Fock theory that is extended to include the contribution of microscopic three-body forces. We give the variation of the critical temperature with the asymmetry parameter and show the effect brought by this three-body repulsive potential on the value of the critical asymmetry of the phase transition for asymmetric nuclear matter. Owing to the additional repulsion provided by three-body forces, this value decreases. In addition, the domain of mechanical instability for hot nuclear matter is also indicated, which gradually shrinks with increasing asymmetry and temperature.     

中能重离子碰撞中多重碎裂的同位旋效应

利用同位旋相关的量子分子动力学,研究了逆反应系统¹²⁰Xe+⁴⁰Ca,¹²⁰Cd+⁴⁰Ar和⁷⁶Kr+⁴⁰Ca,⁷⁶Zn+⁴⁰Ar中多重碎裂的同位旅效应.对于在中能区缺中子碰撞系统的中等质量碎片多重性大于丰中子碰撞系统的现象进行了分析和讨论.     

多体关联Green函数动力学——Ⅲ.截断近似

从多体关联Green函数的基本动力学方程组出发,通过对多体关联Green函数作低阶截断近似,得到了通常Green函数理论中所有主要的非微扰结果。而且二体关联Green函数动力学把梯形图对应的短程关联与环形图对应的长程关联统一在同一个动力学方程组中,这是通常的Green函数理论所没有得到的新结果。     

中子晕核结构在引起核碎裂中的特殊作用

基于同位旋相关量子分子动力学模型，研究和对比分析了中子晕核¹¹Li和相等质量稳定核¹¹B在相同入射道条件下引起核碎裂反应中的特征. 由于中子晕核松散的晕中子结构和小的分离能与相等质量稳定核相比具有容易碎裂的特征，因此在较低能区这种松散的晕结构有利于碎裂过程的发生，随入射能量升高，这种晕结构效应逐渐消失. 而且这种在碎裂中的中子晕结构作用随靶核质量和碰撞参数的增加而减弱.     

Alpha decay half-lives of heavy nuclei within a generalized liquid drop model

Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the DensityDependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.     

Alpha decay half-lives of heavy nuclei within a generalized liquid drop model

Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Q_α value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.     

Branching Ratios of α Decay for Nuclei near Deformed Shell Closures

The generalized liquid drop model （GLDM） is extended to the region around deformed shell closure ^270Hs by taking into account the excitation energy EI＋ of the residual daughter nucleus and the centrifugal potential energy Vcen（r）. The branching ratios of a decays from the ground state of a parent nucleus to the ground state 0^＋ of its deformed daughter nucleus and to the first excited state 2^＋ are calculated in the framework of the GLDM. The results support the proposal that a measurement of a spectroscopy is a feasible method to extract information on nuclear deformation of superheavy nuclei around the deformed nucleus ^270Hs.     

Theoretical Analysis and New Formulae for Half-Lives of Proton Emission

The proton radioactivity hMf-lives of spherical proton emitters are calculated by the cluster model with the con- tribution of a centrifugal potential barrier considered separately. The results are compared with the experimental data and other theoretical data, and good agreement is found for most nuclei. In addition, two formulae are pro- posed for the proton decay half-life of spherical proton emitters through the least squares fit to the experimental data available, and could reproduce the experimental half-lives successfully.