Observation of Anisotropic Event Shapes and Transverse Flow in Au+Au Collisions at AGS Energy

TL;DR

This paper reports the observation of anisotropic event shapes and transverse flow in gold-gold collisions at AGS energy, revealing significant flow signals in semicentral collisions through Fourier analysis of azimuthal energy distributions.

Contribution

It introduces a Fourier expansion method to analyze event anisotropy and transverse flow in heavy-ion collisions at AGS energies, providing new insights into collision dynamics.

Findings

Pronounced event anisotropy in semicentral collisions

Flow signal amplitude up to 7% of mean transverse energy

Decreased anisotropy in peripheral and very central collisions

Abstract

Event shapes for Au + Au collisions at 11.4 GeV/c per nucleon were studied over nearly the full solid angle with the E877 apparatus. The analysis was performed by Fourier expansion of azimuthal distributions of the transverse energy (E_T) measured in different pseudorapidity intervals. For semicentral collisions a pronounced event anisotropy is identified beyond that expected due to fluctuations in particle multiplicity. The signal decreases for peripheral and very central collisions. The amplitude of the flow signal reaches up to 7% of the mean E_T.