[en] Research focused on the statistical and dynamical properties of ''hot'' nuclei formed in symmetric heavy-ion reactions. Theses included ''flow'' measurements and the mechanism for multifragment disassembly. Model calculations are being performed for the reactions C+C, Ne+Al, Ar+Sc, Kr+Nb, and Xe+La. It is planned to study ⁴⁰Ar reactions from 27 to 115 MeV/nucleon. 2 figs., 41 refs

[en] A relativistic transport model is used to study Ξ^- production in 2-11 A GeV Au+Au collisions. Introducing the strangeness-exchange reactions between antikaons and hyperons as the sources for Ξ^-, we find that the cascade yield in these collisions is in reasonable agreement with the data. Although the Ξ^- abundance does not reach chemical equilibrium unless the cross section for strangeness-exchange reactions is enhanced by six times, it exhibits the strongest enhancement with increasing centrality of collision and with increasing beam energy

[en] The authors have employed multifragment correlation functions to study collective motions and time-scale for multifragment production. Recent results from the work on azimuthal correlation functions and reduced velocity correlation functions is presented

[en] The source imaging technique of Brown and Danielewicz has been used to extract two-pion emission source functions over a broad range of k_T and centralities in Au+Au collisions at √s = 200 GeV. The source functions reflect the combined contributions of a short-range Gaussian-like component and a long-range exponential-like component. A parametrization of the source function gives a RMS radius for the long-range source which is approximately three times that for the short-range source. The centrality dependence of the extracted source parameters for the short- and long-range sources indicate similar patterns. (author)

[en] Experimental results are compared for the two matched heavy ion reactions 337 MeV ⁴⁰Ar+^natAg and 640 MeV ⁸⁶Kr+⁶³Cu as a test of the extent of equilibration of the intermediate composite nucleus ¹⁴⁹Tb^*(E^*=194 MeV). Spin zones associated with the evaporation residues (ER) are found to agree well for these entrance channels. Agreement is not as close for the fission class due to the inclusion of deeply inelastic reactions (DIR) along with fusion-fission (FF) for the ⁸⁶Kr reaction. Inclusive and coincidence measurements of energy spectra and angular distributions for the light charged particles indicate that these reactions produce composite nuclei with similar temperatures, spins, and moments of inertia. The energy spectra for both reactions are identically shifted relative to statistical model calculations. This suggests that the composite nuclei are highly distended prior to their cooling by particle evaporation. Multiplicities also agree for ¹H and ⁴He production in association with the ER and FF reaction classes. It is noteworthy that prescission ¹H and ⁴He multiplicities are in such good agreement, because the magnitude of these multiplicities seems to be dictated by the dynamical time scale of the fission process. That these prescission multiplicities are large suggests that the fission time scale is slow relative to particle evaporation; that they match for these reactions indicates that this is an equilibrium property of the intermediate composite nuclei. We conclude that extensive and rapid thermalization and shape equilibration have occurred despite estimates that the nuclear relaxation time and decay lifetime are nearly the same

No abstract available

[en] Large and small angle correlation measurements are reported for a variety of light charged particle pairs from 27 and 34 A MeV ⁴⁰Ar + ^natAg reactions. Detailed comparisons of large angle and small angle coincidences are made to investigate average masses of the compound system and emission orders between different particle species. Through comparison to classical trajectory calculations, small angle correlations are used to extract characteristic time scales for emission which are compared to those extracted from parallel studies at 7 and 17 A MeV

[en] Recent PHOBOS measurements of the excitation function for the pseudo-rapidity dependence of the elliptic flow in Au+Au collisions at RHIC have posed a significant theoretical challenge. Here we show that these differential measurements, as well as the RHIC measurements on transverse momentum satisfy a universal scaling relation predicted by the Buda-Lund model, based on exact solutions of perfect fluid hydrodynamics. We also show that the recently found transverse kinetic energy scaling of the elliptic flow is a special case of this universal scaling. (orig.)

[en] Intermediate mass fragments have been studied from the reaction ⁸⁶Kr+⁶³Cu for ⁸⁶Kr beam energies of 486, 550, 640, and 730 MeV. Average center-of-mass (c.m.) energies are nearly constant with the c.m. angle and vary little with incident energy. Furthermore, the angular distributions are well approximated by 1/sinθ_c.m.. From this and other evidence we conclude that equilibration has occurred prior to fissionlike asymmetric binary breakup of the composite nucleus in the predominant mechanism for IMF production

[en] Proton elliptic flow is studied as a function of impact parameter b, for two transverse momentum cuts in 2-6 A GeV Au+Au collisions. The elliptic flow shows an essentially linear dependence on b (for 1.5< b<8 fm) with a negative slope at 2A GeV, a positive slope at 6A GeV, and near zero slope at 4A GeV. These selective flow measurements provide better understanding of the interplay of the different factors responsible for the generation of elliptic flow at AGS energies. In addition, extensive comparisons of the measured and calculated flow values indicate that such measurements offer much more stringent constraints for discriminating between various equations of state