报告题目：Nuclear Symmetry Energy – from nucleus to neutron star

报 告 人：Betty Tsang，National Superconducting Cyclotron Laboratory, Michigan State University

报告时间：9月26日16:00

报告地点：理科楼郑裕彤大讲堂

报告摘要：When a system moves away from equal number of neutron and protons, the energy increases. This “penalty” is termed the symmetry energy, similar to the term in the liquid drop model mass formula. Effects of the symmetry energy are especially important in systems with very different composition of neutron and proton such as neutron stars and heavy nuclei. Substantial progress has been achieved in recent years in constraining the density dependence of nuclear symmetry energy at and around the saturation density with a wide range of experiments and nuclear masses. Recent discovery of a two solar-mass neutron star suggests that the symmetry energy at high density is large. However, recent extraction of neutron star radius of around 9 km provides the apparently contradictory evidence that the density dependence of symmetry energy is weak above the saturation density. In this talk, I will review these results and discuss new experimental programs in Asia and in the US to probe the symmetry energy using heavy ion reactions.