Pion Squeeze-Out and Flow at 1.15 GeV/Nucleon Au+Au

  • Daniel Cebra


Attaining a better understanding of the hadronic gas phase of nuclear matter has been one of the principal goals of studying heavy-ion reactions in the GeV/nucleon range. In-plane transverse flow is understood as preferential emission of particles on the projectile side or the target side of the reaction plane for velocities higher than or lower than the center of mass velocity respectively. Flow of nucleons has been seen as a signature of the compression generated during the early stage of a heavy-ion collision. The magnitude of the flow can be used to infer the compressibility of nuclear matter at high temperatures and pressures. Squeeze-out, on the other hand, is defined as a preferential emission of particles out of the reaction plane for center-of-mass rapidities. For nucleons, squeeze-out is also understood as an expression of the compression during the early stages of the reaction. It is also natural to use pion production as a probe of the hot, dense stage of a reaction, as the pions are produced during these early phases [1,2]. The pions, however, may behave differently than the nucleons, as they are mesons and not baryons and thus interact differently with the surrounding matter. The nucleons mostly experience elastic N-N collisions, while pions generally have inelastic interactions. Also, pions are produced particles and thus may respond differently to the pressure gradients within the nuclear matter. The pions are produced mostly in the dense, high pressure region which is characterized by radial expansion. The nucleons in the pressure gradient region exhibit the maximum flow.


Impact Parameter Nuclear Matter Time Projection Chamber Reaction Plane Peripheral Collision 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    R. Stock et al.,Phys. Rev. Lett. 49, 1236 (1982).Google Scholar
  2. 2.
    H. Stöcker and W. Greiner, Phys. Rev. 137, 277 (1986).Google Scholar
  3. 3.
    D. Keane et al.,Conf. Proc., ed. V. Viola (conf - 860270), 151, (1986).Google Scholar
  4. 4.
    J. Gosset et al.,Phys. Rev. Lett. 62, 1251 (1989).Google Scholar
  5. 5.
    Bao-An Li and W. Bauer, Phys. Rev. C 44, 2095 (1991).ADSCrossRefGoogle Scholar
  6. 6.
    S.A. Bass, R. Mattiello, H. Stöcker, W. Greiner, and C. Hartnack, Phys. Lett. B 302, 381 (1993).ADSCrossRefGoogle Scholar
  7. 7.
    S.A. Bass, C. Hartnack, H. Stöcker, and W. Greiner, PreprintGoogle Scholar
  8. 8.
    M. Trzaska et al.. Proceedings of the XXXII International Winter Meeting on Nuclear Physics, Editor I. Iori, 1994.Google Scholar
  9. 9.
    H.H. Gutbrod et al.,Phys. Rev. C 42, 640 (1990).Google Scholar
  10. 10.
    Y. Leifels et al.,Phys. Rev. Lett. 71, 963 (1993).Google Scholar
  11. 11.
    L.B. Venema et al.,Phys. Rev. Lett. 71, 835 (1993).Google Scholar
  12. 12.
    D. Brill et al.,Phys. Rev. Lett. 71, 336 (1993).Google Scholar
  13. 13.
    S.A. Bass, C. Hartnack, H. Stöcker, and W. Greiner, Phys. Rev. Lett. 71, 1144 (1993).ADSCrossRefGoogle Scholar
  14. 14.
    J.C. Kintner, PhD Thesis, University of California, Davis (1995).Google Scholar
  15. 15.
    M.D. Partlan ei al., Phys. Rev. Lett. 75, 2100 (1995).Google Scholar
  16. 16.
    P. Danielewicz and G. Odyniec, Phys. Lett. B 157, 146 (1985).Google Scholar

Copyright information

© Springer Science+Business Media New York 1996

Authors and Affiliations

  • Daniel Cebra
    • 1
  1. 1.Physics DepartmentUniversity of CaliforniaDavisUSA

Personalised recommendations