Collective Flow In Au Au Collisions With Incident Energies From 025 To 115 A Gev

Based on a preliminary sample of Au + Au collisions in the EOS time projection chamber at the Bevalac, we study sideward flow as a function of bombarding energy between 0.25A GeV and 1.2A GeV. We focus on the increase in in-plane transverse momentum per nucleon with fragment mass. We also find event shapes to be close to spherical in the most central collisions, independent of bombarding energy and fragment mass up to 4He.

The 12th Winter Workshop on Nuclear Dynamics carried on the tradition, started in 1978, of bringing together scientists working in all regimes of nuclear dynamics. This broad range of related topics allows the researcher attending the Workshop to be exposed to work that normally would be considered outside his/her field, but could po tentially add a new dimension to the understanding of his/her work. At Snowbird, we brought together experimentalists working with heavy ion beams from 10 MeV/nucleon up to 200 GeV /nucleon and theoretical physicists working in diverse areas ranging from antisymmetrized fermionic dynamics to perturbative quantum chromo dynamics. Fu ture work at RHIC was discussed also, with presentations from several of the experimen tal groups. In addition, several talks addressed issues of cross-disciplinary relevance, from the study of water-drop-collisions, to the multi-fragmentation of buckyballs. Clearly the field of nuclear dynamics has a bright future. The understanding of the nuclear equation of state in all of its manifestations is being expanded on all fronts both theoretically and experimentally. Future Workshops on Nuclear Dynamics will certainly have much progress to report. Gary D. Westfall Wolfgang Bauer Michigan State Universzty v PREVIOUS WORKSHOPS The following table contains a list of the dates and locations of the previous Winter Workshops on Nuclear Dynamics as well as the members of the organizing committees. The chairpersons of the conferences are underlined.

Presents a powerful new framework for out-of-equilibrium hydrodynamics, with connections to kinetic theory, AdS/CFT and applications to high-energy particle collisions.

The EOS experiment at the Bevalac has recently carried out exclusive event-by-event measurements of relativistic heavy ion collisions with a variety of projectile, target and beam energy combinations. The data was obtained using the EOS Time Projection Chamber. We present preliminary results on inclusive spectra, collective flow and azimuthal correlations obtained from a study of Au + Au reactions with beam energies covering 0.6 - 1.2 A GeV.

Measurements of collective flow and two-particle correlations have proven to be effective tools for understanding the properties of the system produced in ultrarelativistic nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC). Accurate modeling of the initial conditions of a heavy ion collision is crucial in the interpretation of these results. The anisotropic shape of the initial geometry of heavy ion collisions with finite impact parameter leads to an anisotropic particle production in the azimuthal direction through collective flow of the produced medium. In "head-on" collisions of Copper nuclei at ultrarelativistic energies, the magnitude of this "elliptic flow" has been observed to be significantly large. This is understood to be due to fluctuations in the initial geometry which leads to a significant anisotropy even for most central Cu+Cu collisions. This thesis presents a phenomenological study of the effect of initial geometry fluctuations on two-particle correlations and an experimental measurement of the magnitude of elliptic flow fluctuations which is predicted to be large if initial geometry fluctuations are present. Two-particle correlation measurements in Au+Au collisions at the top RHIC energies have shown that after correction for contributions from elliptic flow, strong azimuthal correlation signals are present at A0 = 0 and A0 ~ 120. These correlation structures may be understood in terms of event-by-event fluctuations which result in a triangular anisotropy in the initial collision geometry of heavy ion collisions, which in turn leads to a triangular anisotropy in particle production. It is observed that similar correlation structures are observed in A Multi-Phase Transport (AMPT) model and are, indeed, found to be driven by the triangular anisotropy in the initial collision geometry. Therefore "triangular flow" may be the appropriate description of these correlation structures in data. The measurement of elliptic flow fluctuations is complicated by the contributions of statistical fluctuations and other two-particle correlations (non-flow correlations) to the observed fluctuations in azimuthal particle anisotropy. New experimental techniques, which crucially rely on the uniquely large coverage of the PHOBOS detector at RHIC, are developed to quantify and correct for these contributions. Relative elliptic flow fluctuations of approximately 30-40% are observed in 6-45% most central Au+Au collisions at s NN= 200 GeV. These results are consistent with the predicted initial geometry fluctuations.