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Phys. Rev. C 70, 014608 (2004) [11 pages]

Effects of in-medium cross sections and optical potential on thermal-source formation in p+197Au reactions at 6.2–14.6  GeV∕c

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S. Turbide1,2, L. Beaulieu1, P. Danielewicz3, V. E. Viola4, R. Roy1, K. Kwiatkowski4 *, W.-C. Hsi4 †, G. Wang4 ‡, T. Lefort4 §, D. S. Bracken4 **, H. Breuer5, E. Cornell4 ††, F. Gimeno-Nogues6, D. S. Ginger4 ‡‡, S. Gushue7, R. Huang3, R. Korteling8, W. G. Lynch3, K. B. Morley9, E. Ramakrishnan6, L. P. Remsberg7, D. Rowland6, M. B. Tsang3, H. Xi3, and S. J. Yennello6
1Département de Physique, de Génie Physique et d’Optique, Universite Laval, Québec, Canada, G1K 7P4
2Department of Physics, McGill University, 3600 University Street, Montreal, Canada H3A 2T8
3Department of Physics and NSCL, Michigan State University, East Lansing, Michigan 48824, USA
4Department of Chemistry and IUCF, Indiana University, Bloomington, Indiana 47405, USA
5Department of Physics, University of Maryland, College Park, Maryland 20740, USA
6Department of Chemistry and Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA
7Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA
8Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A IS6
9Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

Received 25 February 2004; published 19 July 2004

Effects of in-medium cross sections and of optical potential on preequilibrium emission and on formation of a thermal source are investigated by comparing the results of transport simulations with experimental results from the p+197Au reaction at 6.2–14.6  GeV∕c . The employed transport model includes light-composite-particle production and allows for inclusion of in-medium particle-particle cross-section reduction and of momentum dependence in the particle optical potentials. Compared to the past, the model incorporates improved parametrizations of elementary high-energy processes. The simulations indicate that the majority of energy deposition occurs during the first 25  fm∕c of a reaction. This is followed by a preequilibrium emission and readjustment of system density and momentum distribution toward an equilibrated system. Within different variants of calculations, the best agreement with data, on the d∕p and t∕p yield ratios and on the residue mass and charge numbers, is obtained at the time of about 65  fm∕c from the start of a reaction, for simulations employing reduced in-medium cross sections and momentum-dependent optical potentials. By that time, the preequilibrium nucleon and cluster emission, as well as mean field readjustments, drive the system to a state of depleted average density, ρ∕ρ0∼1∕4–1∕3 for central collisions, and low-to-moderate excitation, i.e., the region of nuclear liquid-gas phase transition.


©2004 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevC.70.014608
DOI: 10.1103/PhysRevC.70.014608
PACS: 25.75.−q, 25.70.Gh

* Present address: Los Alamos National Laboratory, Los Alamos, NM 87545.
† Present address: Rush Presbyterian St. Lukes Medical Center, Chicago, IL 60612.
‡ Present address: Epsilon Inc., Dallas, TX 75240.
§ Present address: LPC Caen, 6 Boulevard Maréchal Juin, 14050 Caen Cedex, France.
** Present address: Los Alamos National Laboratory, Los Alamos, NM 87545.
†† Present address: Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
‡‡ Present address: Department of Physics, Cambridge University, United Kingdom.

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