Institute of Theoretical Physics

Chinese Academy of Sciences

State Key Laboratory of Theoretical Physics

Seminar

Title

题目

Microscopic Understanding of Energy-Dependent Collective Potential and Friction Parameter in Fusion Reaction

Speaker

报告人

Professor Fumihiko Sakata

Affiliation

所在单位

Ibaraki University, Japan and Institute of Theoretical Physics, Chinese Academy of Sciences

Date

日期

2014年4月28日（周一）上午10：00

Venue

地点

Conference Hall 322, ITP/理论物理所322报告厅

Abstract

摘要

Applying a macroscopic reduction procedure on the improved quantum molecular dynamics (ImQMD), a set of macroscopic collective potential, friction parameter and random force characterizing the Langevin-type description of the heavy-ion fusion process is extracted. Systematic calculation of the ImQMD shows that an approximate fluctuation-dissipation relation in a symmetric heavy-ion fusion head-on reaction just above the Coulomb barrier fades out when the incident energy increases. It turns out that this systematics is caused by specific behavior of friction parameter which directly depends on the microscopic dynamical process how the collective energy of relative motion is transferred into the intrinsic excitation energy. It is clearly shown that the microscopic mechanism of energy dissipation is controlled by two-competitive processes; One is caused by the nucleon exchange between two fusing nuclei, and the other is due to a rearrangement process of forming a new coherent and collective state in the nucleus where many nucleons are exchanged with the other nucleus. The former mechanism increases the dissipative energy, while the latter plays a role to suppress it. The latter mechanism depends on an adiabatic parameter characterized by a velocity of relative motion between two fusing nuclei and that of the intrinsic motion, and is responsible for the energy dependence of the fusion potential as well as a fading out mechanism of the fluctuation-dissipation relation.

Contact Person

所内合作者

周善贵