The influence of cluster emission and the symmetry energy on neutron-proton spectral double ratios

TL;DR

This study uses simulations to analyze how cluster emission and symmetry energy influence neutron-proton spectral double ratios in nuclear collisions, highlighting their sensitivity to the symmetry energy and the importance of high-energy data for accurate insights.

Contribution

It demonstrates the sensitivity of neutron-proton spectral double ratios to the symmetry energy and examines the impact of cluster formation, providing guidance for experimental data collection.

Findings

Double ratios are sensitive to the symmetry energy in the nuclear equation of state.

Cluster formation affects double ratios mainly at low energies.

High-energy data are crucial for accurate symmetry energy analysis.

Abstract

Emissions of free neutrons and protons from the central collisions of 124Sn+124Sn and 112Sn+112Sn reactions are simulated using the Improved Quantum Molecular Dynamics model with two different density dependence of the symmetry energy in the nuclear equation of state. The constructed double ratios of the neutron to proton ratios of the two reaction systems are found to be sensitive to the symmetry terms in the EOS. The effect of cluster formation is examined and found to affect the double ratios mainly in the low energy region. In order to extract better information on symmetry energy with transport models, it is therefore important to have accurate data in the high energy region which also is affected minimally by sequential decays.