Effects of multi-collisions and surface on elliptic flow

摘要

The non-central Au+Au collision at center-of-mass energy √8NN = 200 GeV is simulated using AMPT model.It is found that both the integral and differential elliptic flow behaves differently for partons freezing out at different stages.It is shown that the integral elliptic flow of freeze-out partons decreases with time at the early stage,but increases with time at the late stage.The curve of transverse momentum distribution of elliptic flow of partons is more flatter at the early stage than at the late stage.The effect of surface emitting on elliptic flow is argued to be not neglectable.