In-medium effects for nuclear matter in the Fermi energy domain

Abstract

We study nuclear stopping in central collisions for heavy-ion induced reactions in the Fermi energy domain, between $15$ and $100$ A\,\textrm{MeV}. Using the large dataset of exclusive measurements provided by the $4\pi$ array \emph{INDRA}, we determine the relative degree of stopping as a function of system mass and bombarding energy. We show that the stopping can be directly related to the transport properties in the nuclear medium. By looking specifically at free nucleons (here protons), we present for the first time a comprehensive body of experimental results concerning the mean free path, the nucleon-nucleon cross-section and in-medium effects in nuclear matter. It is shown that the mean free path exhibits a maximum at ${\lambda }_{NN}=9.5\pm 2$ \textrm{fm}, around $E_{inc}=35-40$ A\,\textrm{MeV} incident energy and decreases toward an asymptotic value ${\lambda }_{NN}=4.5\pm 1$ \textrm{fm} at $E_{inc}=100$ A\,\textrm{MeV}. After accounting for Pauli blocking of elastic nucleon-nucleon collisions, it is shown that the effective in-medium \emph{NN} cross section is further reduced compared to the free value in this energy range. Therefore, in-medium effects cannot be neglected in the Fermi energy range. These results bring new fundamental inputs for microscopic descriptions of nuclear reactions in the Fermi energy domain.

9 pages, 10 figures, submitted to PRC

References in corpus (4)

• Systematics of Stopping and Flow in Au+Au Collisions
• Effect of the symmetry energy on nuclear stopping and its relation to the production of light charged fragments
• In medium T-matrix for nuclear matter with three-body forces - binding energy and single particle properties
• Transverse Velocity Scaling in Au+Au Fragmentation

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• Reaction and fusion cross sections for the near-symmetric system ${}^{129}Xe{+}^{nat}Sn$ from $8$ to $35$ $AMeV$
• Effects of neutron-skin thickness on direct hard photon emission from reactions induced by the neutron-rich projectile ${}^{50}$Ca
• Isospin diffusion from ${}^{40,48}$Ca${+}^{40,48}$Ca experimental data at Fermi energies: Direct comparisons with transport model calculations
• Evolutions of in-medium baryon-baryon scattering cross sections and stiffness of dense nuclear matter from Bayesian analyses of FOPI proton flow excitation functions
• Revisiting an extended-mean-field approach in heavy-ion collisions around the Fermi energy
• Constraining neutron-proton effective mass splitting through nuclear giant dipole resonance within transport approach
• Influence of Cluster Configurations and Nucleon--Nucleon Scattering Cross-Section on Stopping Power in Heavy-Ion Collisions