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Radial and Directed Transverse Flow in Heavy-Ion Collisions

  • R. Pak
  • D. Craig
  • E. E. Gualtieri
  • S. A. Hannuschke
  • R. A. Lacey
  • J. Lauret
  • W. J. Llope
  • A. C. Mignerey
  • D. E. Russ
  • N. T. B. Stone
  • A. M. Vander Molen
  • G. D. Westfall
  • J. Yee

Abstract

One of the fundamental problems remaining in the field of heavy-ion reaction dynamics is the description of nuclear matter in terms of an equation of state (EOS). Collective motion is ordered motion characterized by the correlation between particle positions and momenta of a dynamic origin. The study of collective flow in nucleus-nucleus collisions can provide information about the nuclear EOS.[1,2] Collective radial expansion of particle emission from central nuclear collisions, radial flow, is primarily attributed to the conversion of thermal and compressional energy into work through a pressure gradient in the hydrodynamic limit.[3] Consequently, the fragments acquire a net outward radial velocity in addition to their random thermal component, which is evident from the increased curvature in the single-particle energy spectrum. As impact parameter increases there is anisotropy in the pressure, resulting in a transverse flow of nuclear matter in the directions of lowest pressure. Collective transverse flow in the reaction plane disappears at an incident energy, termed the balance energy E bal ,[4] where the attractive scattering dominant at energies around 10 MeV/nucleon balances the repulsive interactions dominant at energies around 400 MeV/nucleon.[5,6] We present results from a systematic study for the incident energy and impact parameter dependence of collective flow from 40Ar+45Sc collisions at E = (35 – 115) MeV/nucleon. Comparison to predictions of dynamical transport models showing agreement with our measured values of flow observables are presented.

Keywords

Impact Parameter Nuclear Matter Radial Flow Reaction Plane Transverse Flow 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1996

Authors and Affiliations

  • R. Pak
    • 1
  • D. Craig
    • 1
  • E. E. Gualtieri
    • 1
  • S. A. Hannuschke
    • 1
  • R. A. Lacey
    • 2
  • J. Lauret
    • 2
  • W. J. Llope
    • 3
  • A. C. Mignerey
    • 4
  • D. E. Russ
    • 4
  • N. T. B. Stone
    • 1
  • A. M. Vander Molen
    • 1
  • G. D. Westfall
    • 1
  • J. Yee
    • 1
  1. 1.National Superconducting Cyclotron LaboratoryMichigan State UniversityUSA
  2. 2.Rice UniversityUSA
  3. 3.State University of New York at Stony BrookUSA
  4. 4.University of MarylandUSA

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