The symmetry energy in nuclear reactions

Abstract

New results for the strength of the symmetry energy are presented which illustrate the complementary aspects encountered in reactions probing nuclear densities below and above saturation. A systematic study of isotopic effects in spectator fragmentation was performed at the ALADIN spectrometer with 124Sn primary and 107Sn and 124La secondary beams of 600 MeV/nucleon incident energy. The analysis within the Statistical Fragmentation Model shows that the symmetry-term coefficient entering the liquid-drop description of the emerging fragments decreases significantly as the multiplicity of fragments and light particles from the disintegration of the produced spectator systems increases. Higher densities were probed in the FOPI/LAND study of nucleon and light-particle flows in central and mid-peripheral collisions of 197Au+197Au nuclei at 400 MeV/nucleon incident energy. From the comparison of the measured neutron and hydrogen squeeze-out ratios with predictions of the UrQMD model a moderately soft symmetry term with a density dependence of the potential term proportional to (rho/rho_0)^{gamma} with gamma = 0.9 +- 0.3 is favored.

arXiv comment11 pages, 7 figures, Proceedings of IWND09, August 22 - 25, 2009, Shanghai (China)

References in corpus (18)

• Recent Progress and New Challenges in Isospin Physics with Heavy-Ion Reactions
• Constraints on the density dependence of the symmetry energy
• Circumstantial evidence for a soft nuclear symmetry energy at supra-saturation densities
• Systematics of pion emission in heavy ion collisions in the 1A GeV regime
• Isoscaling in Light-Ion Induced Reactions and its Statistical Interpretation
• Experimental determination of the symmetry energy of a low density nuclear gas
• Isotopic Scaling and the Symmetry Energy in Spectator Fragmentation
• Low densities in nuclear and neutron matters and in the nuclear surface
• Systematics of Stopping and Flow in Au+Au Collisions
• The Virial Equation of State of Low-Density Neutron Matter
• Statistical approach for supernova matter
• Isotopic Dependence of the Nuclear Caloric Curve
• Probing the density dependence of the symmetry potential in intermediate energy heavy ion collisions
• A systematic study of the ${\pi }^{-}/{\pi }^{+}$ ratio in heavy-ion collisions with the same neutron/proton ratio but different masses
• Symmetry Energy in Nuclear Surface
• Differential Neutron-Proton Squeeze-out
• N/Z Dependence of Projectile Fragmentation
• Discriminant Analysis and Secondary-Beam Charge Recognition

Cited by in corpus (4)

• Symmetry energy from elliptic flow in 197Au + 197Au
• Isospin-asymmetric nuclear matter
• The ASY-EOS experiment at GSI: investigating the symmetry energy at supra-saturation densities
• Symmetry energy and nucleon-nucleon cross sections