李庆峰[2011PRC]:GSI加速器低能区的重离子碰撞中的非平衡动力学
2020-12-04
文章来源: 未知
■ Nonequilibrium dynamics in heavy-ion collisions at low energies available at the GSI Schwerionen Synchrotron
GSI加速器低能区的重离子碰撞中的非平衡动力学
作者：李庆峰，沈彩万，郭琛。跤兰，李祝霞，J. Lukasik(波兰), W. Trautmann（德国）
杂志：Physical Review C 83, 044617 (2011)
摘要：升级的极端相对论量子分子动力学模型（UrQMD)，一个微观的输运模型，被用于研究入射能量在INDRA和低能FOPI实验区域的Au+Au碰撞后的直接、椭圆集体流及核阻止效应。很明显地，这些观测量不仅敏感依赖于状态方程（EOS)中的势能项（包括同位旋标量和同位旋适量部分，以及动量依赖项），也敏感于碰撞项（包括泡利阻塞和介质修正的核子-核子弹性散射截面（NNECS））.平均场势和密度依赖的NNECS的动量修正影响重离子碰撞的集体行为。在INDRA能区（<=150 MeV/nucleon），采用一个软的EoS+动量依赖及动量修正的密度依赖型NNECS的动力学输运能够很好地描述中心快度区出射的氢同位素（Z=1）的直接流数据。
Abstract: The updated ultrarelativistic quantum molecular dynamics (UrQMD) model, a microscopic transport model, is used to study the directed and elliptic collective flows and the nuclear stopping in Au+Au collisions at incident energies covered by INDRA and lower-energy FOPI experiments. It is seen clearly that these observables are sensitive to both the potential terms (including isoscalar and isovector parts as well as the momentum dependent term) in the equation of state (EoS) and the collision term [including the Pauli blocking and the medium-modified nucleon-nucleon elastic cross section (NNECS)]. The momentum modifications of both, themean-field potentials and the density dependent NNECS, are found to affect the collectivity of heavy-ion collisions. At INDRA energies ( 150 MeV/nucleon) the dynamic transport with a soft EoS with momentum dependence and with the momentum-modified density-dependent NNECS describes the directed flow exhibited by hydrogen isotopes (Z = 1) emitted at midrapidity fairly well.
