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所庆60周年系列学术报告:Symmetry energy and three body interaction at intermediate heavy ion collisions

2019/06/14 | 【 【打印】【关闭】 | 访问次数:

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,  

                 06.2015 - present  : Research Scientist 

Institute of modern Physics, Chanise Academy of Science, Lanzhou, China 

                 03.2011 – 05.2015    Visiting Professor 

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

                 1994 - 12.2010  : Research Scientist 

                1991 - 1994:    Associate Research Scientist 

                1986 - 1991:    Assistant Research Scientist 

Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany      

                April 1983 - March 1986: Postdoctral Research Fellow 

Lawrence Berkeley Laboratory, Berkeley, CA., USA 

                March 1979 - March 1983: Postdoctral Research fellow 

 

EDUCATION: 

Ph.D. Physics, March 1979; 

Kyoto University, Kyoto, Japan 

Dissertation Title: Resonant Structure in 12C + 12C system through   

                            the reaction 12C(12C,16Og.s.)Beg.s at Ec.m.=6-11   

                            MeV 

MA Physics, March 1976 

 Kyoto University, Kyoto, Japan 

Dissertation Title: Sub-Coulomb Resonances in 12C + 12C system 

        through the reaction 12C(12C,16O)Be 

BA Science,~March 1974 

Kyoto University, Kyoto, Japan 

High school, Kyoto Rakuhoku High school, graduated March 1969 

        Kyoto Takano Junior High school, graduated March 1966  

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