The influence of cluster emission and the symmetry energy on neutron–protonspectral double ratios

摘要

The emissions of neutrons, protons and bound clusters from central 124Sn + 124Sn and 112Sn + 112Sn collisionsare simulated using the Improved Quantum Molecular Dynamics model for two different densitydependentsymmetry-energy functions. The calculated neutron–proton spectral double ratios for thesetwo systems are sensitive to the density dependence of the symmetry energy, consistent with previouswork. Cluster emission increases the double ratios in the low energy region relative to values calculatedin a coalescence-invariant approach. To circumvent uncertainties in cluster production and secondary decays,it is important to have more accurate measurements of the neutron–proton ratios at higher energiesin the center of mass system, where the influence of such effects is reduced.