Residue temperatures in intermediate energy nucleus-nucleus collisions

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Physical Review, C (Nuclear Physics); (United States)

DOI:https://doi.org/10.1103/PhysRevC.50.1659· OSTI ID:7203891

Xu, H M; Lynch, W G; Danielewicz, P ^[1]

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1. National Superconducting Cyclotron Laboratory and Department of Physics, Michigan State University, East Lansing, Michigan 48824 (United States) Cyclotron Institute, Texas A M University, College Station, Texas 77843 (United States)

With an improved Boltzmann-Uehling-Uhlenbeck (BUU) model, we have investigated the reaction dynamics leading to the thermal freeezout for [sup 40]Ar+[sup 124]Sn collisions. Several criteria are assessed for defining the proper thermal freezout time which separates preequilibrium processes from equilbrium processes. One of these criteria, the time dependence of the thermal excitation energy, provides consistent results for defining the thermal freezeout. The other two criteria, the emission rate of nucleons and the quadrupole moment of the momentum distributions, do not consistently provide accurate freezeout times due to the existence of long time scale collective vibrations. The predicted values for the excitation energies and temperatures, obtained assuming Fermi gas level densities, are quite sensitive to the equation of state and the impact parameter. Surprisingly, both the thermal excitation energies and the residue temperatures, in the limit of a large ensemble of parallel collisions, show little sensitivity to the in-medium nucleon-nucleon cross section.

• DOE Contract Number: FG05-86ER40256
• OSTI ID: 7203891
• Journal Information: Physical Review, C (Nuclear Physics); (United States), Journal Name: Physical Review, C (Nuclear Physics); (United States) Vol. 50:3; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

663300 -- Nuclear Reactions & Scattering
General-- (1992-)
663450* -- Heavy-Ion-Induced Reactions & Scattering-- (1992-)
663560 -- Nuclear Mass Ranges-- A=90-149-- (1992-)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ARGON 40 REACTIONS
CHARGED-PARTICLE REACTIONS
COLLECTIVE EXCITATIONS
CROSS SECTIONS
EMISSION
ENERGY-LEVEL DENSITY
ENERGY-LEVEL TRANSITIONS
EQUATIONS
EQUATIONS OF STATE
EXCITATION
FERMI GAS
FLUIDS
FRAGMENTATION
GASES
HEAVY ION REACTIONS
MATTER
NUCLEAR MATTER
NUCLEAR REACTIONS
NUCLEAR TEMPERATURE
QUADRUPOLE MOMENTS
TARGETS
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
TIN 124 TARGET