Azimuthal correlations of transverse energy for Pb on Pb at 158 GeV/nucleon

Azimuthal correlations have been studied in heavy ion reactions over a wide range of beam energies. At low incident energies up to 100 MeV/nucleon where collective effects like the directed sidewards flow are generally small, azimuthal correlations provide a useful tool to determine the reaction plane event by event. In the energy regime of the BEVALAC (up to 1 GeV/nucleon for heavy ions) particular emission patterns, i.e. azimuthal correlations of nucleons and light nuclei with respect to the reaction plane, have been associated with the so called squeeze out and sidesplash effects. These effects are of particular interest because of their sensitivity to the equation of state at the high baryon density which is build up during the collision process. Angular distributions similar to the squeeze out have been observed for pions at the SIS in Darmstadt as well as from the EOS - collaboration. Recently also the sideward flow was measured for pions and kaons. However, the origin of the signal in the case of produced mesons is thought to be of a different nature than that for the nucleon flow. At the AGS, azimuthally anisotropic event shapes have been reported from the E877 collaboration for the highest available heavy ion beam energy (11.4 GeV/nucleon). Using a Fourier analysis of the transverse energy distribution measured in calorimeters, it was concluded that sideward flow is still of significant magnitude. Here we will report a first analysis of azimuthal correlations found in the transverse energy distribution from Pb on Pb collisions at the CERN SPS (158 GeV/nucleon)