Home Contact Sitemap 中文CAS
 
About Us Research People International Cooperation News Education & Training Societies & Publications Join Us Papers Resources Links
Events
Events
Int’l Cooperation News
Upcoming Events
Location: Home>News>Events
Normal or Abnormal Isospin-fractionation as a Qualitative Probe of Nuclear Symmetry Energy at Supradensities
Author:
ArticleSource:
Update time: 2014-11-28
Close
Text Size: A A A
Print

The researchers of Nuclear Theory Group at the Institute of Modern Physics, Chinese Academy of Sciences (IMP) have investigated the effect of nuclear symmetry energy at supradensities on the isospin-fractionation (IsoF). It is pointed out that the normal or abnormal isospin-fractionation of energetic nucleons can be a qualitative probe of nuclear symmetry energy at supradensities. 

Although nuclear symmetry energy and its slope at normal density of nuclear matter from recent 28 analyses of terrestrial nu-clear laboratory experiments and astrophysical observations have been roughly pinned down, recent interpretations of FOPI and FOPI-LAND data by different transport models give divergent density-dependent symmetry energy at supradensities. The divergence is shown in Fig.1. 

The studies show that with positive/negative symmetry potential at supradensities (i.e., values of symmetry energy increase/decrease with density above saturation density), for energetic nucleons, the value of neutron to proton ratio of free nucleons is larger/smaller than that of bound nucleon fragments (shown in Fig.2). On account of the same qualitative results produced by both UrQMD and IBUU, the present study is less model dependent. Compared with extensively studied quantitative observables of nuclear symmetry energy, the normal or abnormal isospin-fractionation of energetic nucleons can be a qualitative probe of nuclear symmetry energy at supradensities.  

The results have been published in Physics Letters B738 (2014)397–400.  http://www.sciencedirect.com/science/article/pii/S0370269314007345 

Fig.1 Density dependent nuclear symmetry energy extracted from FOPI and FOPI-LAND data

by different groups (Image by IMP). 

 

Fig.2 Neutron to proton ratio n/p of free and bound nucleons as a function of nucleon kinetic energy

 in the central 197Au+197Aureaction at a beam energy of 400MeV/A with positive (left) and negative

 (right) symmetry potentials at supra-saturation densities. Simulated with the IBUU and the UrQMD transport models (Image by IMP). 

Download:
Copyright © 2004-2013 All Rights Reserved Institute of Modern Physics, Chinese Academy of Sciences
Email: webmaster@impcas.ac.cn ADD: 509 Nanchang Rd., Lanzhou 730000, China