Symmetry energy and the isoscaling properties of the fragments in multifragmentation of 40Ca+58Ni, 40Ar+58Ni, and 40Ar+58Fe reactions

摘要

The symmetry energy and the isoscaling properties of the fragments produced inmultifragmentation of 40Ar, 40Ca + 58Fe, 58Ni reactions at 25, 33, 45 and 53MeV/nucleon were investigated within the framework of a statistical multifragmentationmodel. The isoscaling parameter, ???? from the hot primary and cold secondary fragmentyield distributions, was studied as a function of the excitation energy, isospin (neutronto-proton asymmetry), and fragment symmetry energy.Through changing the symmetry energy in the statistical multifragmentationmodel to describe the experimental data, it is observed that the isoscaling parameter ????decreases with increasing excitation energy and decreases with decreasing symmetryenergy. The parameter ???? is also observed to increase with increasing difference in theisospin of the fragmenting system. The sequential decay of the primary fragments intosecondary fragments show very little influence on the isoscaling parameter when studiedas a function of excitation energy. However, the symmetry energy has a stronginfluence on the isospin properties of the hot fragments. The results indicate that theisospin properties of the fragments produced at high excitation energy and reduceddensity in multifragmentation reactions are sensitive to the symmetry energy, indicating that the properties of hot nuclei at excitation energies, densities, and isospin away fromnormal ground state nuclei are significantly different than those of normal (cold) nucleiat saturation density.