报告题目：Symmetry energy and three body interaction at intermediate heavy ion collisions

报告人：Roy Wada （Texas A&M University, USA)

报告时间：2019年6月19日 下午 2：30-4：00  

报告地点：学术活动中心302室

报告人： Roy Wada （Texas A&M University, USA) 

摘要： 

Nuclear symmetry energy is defined as the difference of the energy between symmetric nuclear matter and neutral nuclear matter of same sizes besides known Coulomb energy. The density dependence of the symmetry energy is important for the cluster formation in intermediate heavy ion collisions as well as neutron star radius in astrophysics and etc. We established a method to evaluate the symmetry energy, density and temperature using IMF yields from our experiments for 64Zn+112Sn @40 A MeV, combined with AMD simulations, and successfully extracted these characteristic values. Then we apply the same method to higher incident energies 40Ca+40Ca in the incident range of 100-300 AMeV to study the density dependence of the symmetry energy. However we found that at this energy range IMF are produced at an expanded density stage (at a freezeout volume) and does not carry the symmetry energy information at a supra-normal density. 

In order to probe the symmetry energy at a supra-normal nuclear density, we move on to study high energy proton emission. These high energy protons (and neutrons) are emitted at an early stage of collisions before the hot nuclear matter is expanded and therefore they may carry the symmetry energy information at a supra-normal density of hot nuclear matter. In order to use AMD as a probe, we had to incorporate a Fermi boost and three body collision terms to reproduce the experimental high energy proton spectra. With these extra process, AMD indeed shows that these high energy protons are emitted at very early stages and can be used as a probe for the hot nuclear matter study. We are currently working on this subject experimentally and theoretical modeling study. I will give a summary of our symmetry energy study and the present  status of our study, and discuss our future prospects. 

简历： 

WORK EXPERIENCE: 

 Cyclotron Institute, Texas A\&M University, College Station,