Density effect of the neutron halo nucleus induced reactions in intermediate energy heavy ion collisions

Using an isospin-dependent quantum molecular dynamics (IQMD) model, we study the ¹⁵C induced reactions from 30—120 MeV/nucleon systematically. Here the valence neutron of ¹⁵C is assigned at both 1d 5/2 and 2s 1/2 states respectively in order to study the density effect of reaction mechanism. It is believed that the existent neutron halo structure at the 2s 1/2 state of ¹⁵C will affect the light particle emission evidently. In our calculation, the different density distributions of ¹⁵C at two states are calculated by relativistic mean field (RMF) model and introduced in the initiation of IQMD model, respectively. It is found that some observables such as emission fragmentation multiplicity, emission neutron/proton ratio and emission neutrons' kinetic energy spectrum are sensitive to the initial density distribution.     

A Proposed Reaction Channel for the Synthesis of the Superheavy Nucleus Z=109

We apply a statistical-evaporation model (HIVAP) to calculate the cross sections of superheavy elements, mainly about actinide targets and compare with some available experimental data. A reaction channel ^30Si 4 ^243Am is proposed for the synthesis of the element Z=109 and the cross section is estimated.     

中能重离子碰撞中的各向异性流标度

用同位旋相关的量子分子动力学(IQMD)模型, 研究了25MeV/A的⁸⁶Kr+¹²⁴Sn碰撞系统在较大碰撞参数下的轻碎片的各向异性流(v₂和v₄), 发现横向动量依赖的椭圆流(v₂)存在对轻碎片核子数的标度律(number-of-nucleon scaling)现象, 以及不同轻碎片的v₄/v₂²比值都近似等于一个常数0.5. 这种标度律现象可以用核子层次碎片形成的组合(coalescence)模型来解释.     

用修正的擦碎模型研究碎裂反应的同位素分布

对统计擦碎模型(SAA)的计算方法进行修正和优化,并引入参数化的介质中核子-核子碰撞截面和核物质密度分布弥散度,可很好符合从中能到高能下碎裂反应产生同位素分布的实验截面,并能计算和拟合远离峰位、很低截面的同位素分布.     

Photons from a Chemically Equilibrating Quark-Gluon Plasma at Finite Baryon Density

We study hard photon production in a chemically equilibrating quark-gluon plasma at finite baryon density based on the Juttner distribution of partons of the system. We find that the photon yield is a strongly increasing function of the initial quark chemical potential.     

Isoscaling of projectile-like fragments

In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion--ablation model and the isoscaling behaviour of projectile-like fragments has been discussed. The isoscaling parameters α and β have been extracted respectively, for hot fragments before evaporation and cold fragments after evaporation. It looks that the evaporation has stronger effect on α than β. For cold fragments, a monotonic increase of α and β with the increase of Z and N is observed. The relation between isoscaling parameter and the change of isospin content is discussed.     

Phenomenological Scaling of Rapidity Dependence for Anisotropic Flows in 25 MeV/nucleon Ca＋Ca by Quantum Molecular Dynamics Model

Anisotropic flows （v1, v2, v3 and v4） of light fragments up to the mass number 4 as a function of rapidity are studied for 25 MeV/nucleon ^40Ca ＋ ^40Ca at large impact parameters by a quantum molecular dynamics model. A phenomenological scaling behaviour of rapidity dependent flow parameters vn （n = 1, 2, 3 and 4） is found as a function of mass number plus a constant term, which may arise from the interplay of collective and random motions. In addition, v4/v2^2 keeps to be almost independent of rapidity and remains a rough constant of 1/2 for all light fragments.     

Photon Production in a Chemically Equilibrating Quark-Gluon Plasma at Finite Baryon Density： Complete Leading Order Results

We investigate hard photon production of the near-collinear bremsstrahlung and a new process called the inelastic pair annihilation, fully including the LPM effect, in a chemically equilibrating quark-gluon plasma at finite baryon density, and find that the effect of the system evolution on the photon production and large contribution of the bremsstrahlung make the total photon yield of the two processes as a strongly increasing function of the initial quark chemical potential.     

中子分布弥散度对反应总截面的影响

在引入库仑场修正的Glauber模型基础上,区分入射弹核和靶核中的中子、质子,并考虑有限力程相互作用,发展了一个计算核反应总截面的微观修正模型.如果引入一个核内中子分布弥散度随中子分离能的变化关系,则能较好地解释奇异核(如⁸He,¹¹Li,¹¹Be)反应总截面的反常增加.同时,该修正模型还能在低能到高能的范围内较好地拟会稳定核的反应总截面.     

中能重离子碰撞中参与者区域的粘滞系数与熵密度之比(英文)

在同位旋依赖的量子分子动力学(IQMD)和Boltzmann-Uehling-Uhlenbeck(BUU)的框架下研究了重离子碰撞过程中核物质的剪切粘滞系数与熵密度的比值。用不同的方法提取了剪切粘滞系数(η)、熵密度(s)和其他相关的物理量。随着碰撞能量的增加,粘滞系数和熵密度的比值在BUU模型中逐渐趋于一个饱和值而在IQMD模型中出现了一个极小值,认为这个局域的最小值或饱和值对应于中能重离子碰撞中发生的核物质液气相变现象。