Probing the symmetry energy with isospin ratio from nucleons to   fragments
  Within the framework of ImQMD05, we study several isospin sensitive observables, such as DR(n/p) ratios, isospin transport ratio (isospin diffusion), yield ratios for LCPs between the projectile region and mid-rapidity region for the reaction systems Ni+Ni, Zn+Zn, Sn+Sn at low-intermediate energies. Our results show that those observables are sensitive to the density dependence of symmetry energy, and also depend on the cluster formation mechanism. By comparing these calculations to the data, the information of the symmetry energy and reaction mechanism is obtained. 
Yingxun Zhang, Zhuxia Li, Chengshuang Zhou, Jixian Chen, M. Colonna,   P. Danielewicz and M. B. Tsang
nucl-th