中能重离子碰撞中集体流标度性质研究

Properties of the Scaling of Collective Flow in Intermediate Energy Heavy ion Collisions

利用同位旋相关的量子分子动力学模型模拟了40Ca+40Ca,50Ca+40Ca,64Cu+64Cu和197Au+197Au等多个碰撞系统中快度轻碎片集体流标度的性质。发现,中能区不同碰撞系统横向动量相关的椭圆流存在对碎片核子数的标度,且存在v4/v22标度,对不同碎片该比值都近似为常数0.5。同时探讨了碰撞能量、碰撞参数、核状态方程对标度律的影响,发现这些标度行为不敏感于以上物理量,可能是核碎片形成机制(组合机制)的必然结果。

The properties of light particles' collective flows from 40Ca+40Ca, 50Ca+40Ca, 64Cu+64Cu and197Au+197Au systems are simulated by Isospin-dependent Quantum Molecular Dynamics model. Transverse momentum dependent elliptic flows from different systems are found to be scaled by nucleon numbers of fragment in intermediate energy, and v4/v22scaling is also found and nearly to be a constant 0.5 for different light fragments.These scaling behaviors are investigated for different collision energies, impact parameters, nuclear equation of states and found insensitive to the above physical quantities, which may be the result of coalescence mechanism that describes the formation of fragments.