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。

Ratio of Shear Viscosity to Entropy Density of Nuclear Participant in the Intermediate Energy Heavy Ion Collisions

The ratio of shear viscosity (η) to entropy density (s) of nuclear fireball created in thecentral region of intermediate-energy heavy-ion collisions has been investigated within two transport models, namely the Boltzmann-Uehling-Uhlenbeck (BUU) model and the isospin-dependent quantum molecular dynamics (IQMD) model. Different methods are used to calculate η and s. With the collisionenergy increasing, the η/s displays a saturation value or a local minimum value at a certain beam energy.We argue that the saturation or minimum point corresponds to an occurrence of nuclear liquid gas phasetransition.