skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Effective nucleon-nucleon cross sections in symmetric and asymmetric nuclear matter

Abstract

We calculate nucleon-nucleon cross sections in the nuclear medium with unequal densities of protons and neutrons. We use the Dirac-Brueckner-Hartree-Fock approach together with realistic nucleon-nucleon potentials. We examine the effect of asymmetry in neutron and proton concentrations and find that it can be significant for scattering of identical nucleons. Numerical results are included for potential applications in transport equations.

Authors:
;  [1]
  1. Physics Department, University of Idaho, Moscow, Idaho 83844 (United States)
Publication Date:
OSTI Identifier:
20771174
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 73; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevC.73.014001; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ASYMMETRY; CROSS SECTIONS; HARTREE-FOCK METHOD; NEUTRON DENSITY; NEUTRONS; NUCLEAR FORCES; NUCLEAR MATTER; NUCLEON-NUCLEON POTENTIAL; PROTON DENSITY; PROTONS; SCATTERING; TRANSPORT THEORY

Citation Formats

Sammarruca, F., and Krastev, P. Effective nucleon-nucleon cross sections in symmetric and asymmetric nuclear matter. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.73.014001.
Sammarruca, F., & Krastev, P. Effective nucleon-nucleon cross sections in symmetric and asymmetric nuclear matter. United States. doi:10.1103/PhysRevC.73.014001.
Sammarruca, F., and Krastev, P. Sun . "Effective nucleon-nucleon cross sections in symmetric and asymmetric nuclear matter". United States. doi:10.1103/PhysRevC.73.014001.
@article{osti_20771174,
title = {Effective nucleon-nucleon cross sections in symmetric and asymmetric nuclear matter},
author = {Sammarruca, F. and Krastev, P.},
abstractNote = {We calculate nucleon-nucleon cross sections in the nuclear medium with unequal densities of protons and neutrons. We use the Dirac-Brueckner-Hartree-Fock approach together with realistic nucleon-nucleon potentials. We examine the effect of asymmetry in neutron and proton concentrations and find that it can be significant for scattering of identical nucleons. Numerical results are included for potential applications in transport equations.},
doi = {10.1103/PhysRevC.73.014001},
journal = {Physical Review. C, Nuclear Physics},
number = 1,
volume = 73,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • We provide a microscopic calculation of neutron-proton and neutron-neutron cross sections in symmetric nuclear matter at various densities, using the Brueckner-Hartree-Fock approximation scheme with the Paris potential. We investigate separately the medium effects on the effective mass and on the scattering amplitude. We determine average cross sections suitable for application in the dynamical simulation of heavy ion collisions, including a parametrization of their energy and density dependence. {copyright} {ital 1997} {ital The American Physical Society}
  • We present microscopic calculations of cross sections for scattering of identical and nonidentical nucleons in symmetric nuclear matter at various densities, using the Brueckner-Hartree-Fock approximation scheme with the Argonne v{sub 14} potential including the contribution of microscopic three-body forces. We investigate separately the effects of three-body forces on the effective mass and on the scattering amplitude. In the present calculation, the rearrangement contribution of the three-body force is considered, which reduces the neutron and proton effective mass and suppresses the magnitude of the cross section. The presence of 'Z diagrams' in the three-body force enables us to make a comparisonmore » with the medium effects on the nucleon-nucleon cross sections obtained with the Dirac-Brueckner-Hartree-Fock approximation.« less
  • The possibility of constructing such new versions of effective nucleon-nucleon forces that would make it possible to describe simultaneously the cross sections for nucleon-nucleus scattering and quantities characterizing nuclear matter and the structure of finite even-even nuclei is investigated on the basis of a microscopic nucleon-nucleus optical potential that is calculated by using effective Skyrme interaction. A procedure for optimizing the parameters of Skyrme forces by employing fits to specific angular distributions for neutron-nucleus scattering and by simultaneously testing the features of nuclear matter, the binding energy of the target nucleus, and its proton root-mean-square radius is proposed. A numbermore » of versions of modified Skyrme forces that ensure a reasonable description of both nucleon-nucleus scattering and the properties of nuclear structure are found on the basis of this procedure.« less
  • We have investigate the nucleon superfluidity in asymmetric nuclear matter and neutron star matter by using the Brueckner-Hartree-Fock approach and the BCS theory. We have predicted the isospin-asymmetry dependence of the nucleon superfluidity in asymmetric nuclear matter and discussed particularly the effect of microscopic three-body forces. It has been shown that the three-body force leads to a strong suppression of the proton {sup 1}S{sub 0} superfluidity in beta-stable neutron star matter. Whereas the microscopic three-body force is found to enhance remarkably the {sup 3}PF{sub 2} neutron superfluidity in neutron star matter and neutron stars.
  • Symmetric and asymmetric nuclear matter is studied in the framework of the relativistic Brueckner-Hartree-Fock and in the relativistic version of the so-called [Lambda][sup 00] approximation. The equations are solved self-consistently in the full Dirac space, so avoiding the ambiguities in the choice of the effective scattering amplitude in matter. The calculations were performed for some modern meson-exchange potentials constructed by Brockmann and Machleidt. In some cases we used also the Groningen potentials. First, we examine the outcome for symmetric matter with respect to other calculations, which restrict themselves to positive-energy states only. The main part is devoted to the propertiesmore » of asymmetric matter. In this case we obtain additionally to the good agreement with the parameters of symmetric matter, also a quite satisfactory agreement with the semiempirical macroscopic coefficients of asymmetric matter. Furthermore, we tested the assumption of a quadratic dependence of the asymmetry energy for a large range of asymmetries. Included is also the dependence of nucleon self-energies on density and neutron excess. For the purpose of comparison we discuss further the similarities and differences with relativistic Hartree and Hartree-Fock calculations and nonrelativistic Skyrme calculations.« less