a Two Dimensional Analysis of Density Fluctuations in the Azimuthal Angle and Pseudorapidity of Particles Produced in Ultra-Relativistic Heavy Ion Collisions

As members of the EMU01 collaboration, we performed experiments using ultra-relativistic heavy ion beams at Brookhaven National Laboratory and CERN. These beams range in energy from 10 to 200 A GeV, and in composition from ^{16}O to ^ {207}Pb. Our detectors precisely measure the production angles of charged particles created when these energetic nuclei collide with fixed targets. The purpose of this experiment was to study the behavior of nuclear matter under the conditions of high energy density, and with large numbers of nucleons. Large fluctuations in particle density are one possible signature of QGP formation or other collective phenomena in high density nuclear matter at finite temperature. I examined the scale dependent fluctuations of particle densities in pseudorapidity, -log tan(theta/2), and azimuthal angle, through the use of factorial cumulant moments. I have analyzed moments in pseudorapidity for 11 A GeV Au+Au data and found that the signal strength is consistent with the inverse scaling dependence on particle density found in previous studies (1). Two dimensional analysis in both pseudorapidity and azimuthal angle reveals information not contained in pseudorapidity alone. Restricting the analysis to large scales minimizes effects of pair contamination on second order moments and effects of empty bins on third order moments. Significant signals were seen in first and second order moments. The signal strength of the second order moments scales inversely with the particle density, indicating a superposition of independent sources. The 11 A GeV Au+Au data shows that this behavior is independent of projectile energy.