Nuclear Symmetry Energy Extracted from Laboratory Experiments
The Equation of State (EOS) of uniform neutron-rich nucleonic matter of isospin asymmetry δ = (ρn — ρp)/ρ and density ρ can be expressed in terms of the energy per nucleon E (ρ, δ) within the parabolic approximation as (1) where Esym (ρ) = 1/2(∂2E(ρ, δ)/∂δ2)δ=0 ≈ E(ρ, 1) — E(ρ, 0) is the symmetry energy of asymmetric nuclear matter (ANM). It is approximately the energy cost of converting symmetric nuclear matter (SNM, with equal numbers of protons and neutrons) into pure neutron matter (PNM). Many interesting questions including the dynamics of supernova explosions, heavy-ion collisions, structures of neutron stars and rare isotopes, frequencies, and strain amplitudes of gravitational waves from both isolated pulsars and collisions involving neutron stars all depend critically on the EOS of neutron-rich nucleonic matter.