Nucleon-nucleon cross sections in neutron-rich matter and isospin transport in heavy-ion reactions at intermediate energies
- Department of Chemistry and Physics, P.O. Box 419, Arkansas State University, State University, Arkansas 72467-0419 (United States)
- Institute of Theoretical Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)
Nucleon-nucleon (NN) cross sections are evaluated in neutron-rich matter using a scaling model according to density, momentum, and isospin dependent nucleon effective masses. It is found that the in-medium NN cross sections are not only reduced but also have a different isospin dependence compared with the free-space ones. Because of the neutron-proton effective mass splitting the difference between nn and pp scattering cross sections increases with the increasing isospin asymmetry of the medium. Within the transport model IBUU04, the in-medium NN cross sections are found to influence significantly the isospin transport in heavy-ion reactions. With the in-medium NN cross sections, a symmetry energy of E{sub sym}({rho}){approx_equal}31.6({rho}/{rho}{sub 0}){sup 0.69} was found most acceptable compared with both the MSU isospin diffusion data and the presently acceptable neutron-skin thickness in {sup 208}Pb. The isospin dependent part K{sub asy}({rho}{sub 0}) of isobaric nuclear incompressibility was further narrowed down to -500{+-}50 MeV. The possibility of determining simultaneously the in-medium NN cross sections and the symmetry energy was also studied. The proton transverse flow, or even better the combined transverse flow of neutrons and protons, can be used as a probe of the in-medium NN cross sections without much hindrance from the uncertainties of the symmetry energy.
- OSTI ID:
- 20771120
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 72, Issue 6; Other Information: DOI: 10.1103/PhysRevC.72.064611; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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