Role of neutrons to protons ratio in determining the symmetry energy at sub and supra-saturation densities, S. Kumar, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China − The symmetry energy at sub and supra-saturation densities has a great importance in understanding the exact nature of asymmetric nuclear matter as well as neutron stars.  We will implement neutrons to protons ratios from different kind of fragments to understand the symmetry energy behavior by using the IQMD model.  For the sub-saturation behavior of symmetry energy, we will compare the single and double ratio of neutrons to protons with the experimental data of NSCL collaboration.  Along with experimental data, double ratio results of IQMD will be compared with the different theoretical results of BUU97, IBUU04, BNV and ImQMD models.  For the supra-saturation behavior of symmetry energy, we will present the incident energy and isospin asymmetry dependence of single and double neutrons to protons ratio from different kind of fragments (free, light charged particles and intermediate mass fragments) by using the soft and stiff symmetry energies.  At sub-saturation densities, the soft symmetry energy is favored by our calculations, while at supra-saturation densities, the neutrons to protons ratio from free nucleons is found to be most sensitive compared to all other kind of fragments.