Analysis of anisotropic transverse flow in Pb-Pb collisions at 40A GeV in the NA49 experiment

TL;DR

This paper presents an analysis of anisotropic transverse flow in Pb-Pb collisions at 40A GeV, addressing detector acceptance biases and applying correction techniques, with results compared across experiments and future applications discussed.

Contribution

The study introduces a correction method for detector acceptance anisotropy in flow analysis, extending the Qn-Corrections Framework for use in fixed target experiments at CERN.

Findings

Flow measurements obtained after acceptance corrections

Comparison with STAR and previous NA49 results

Validation of correction procedure for future analyses

Abstract

Anisotropic transverse flow is one of the most important observables in the study of ultra-relativistic nucleus-nucleus collisions. Detector acceptance non-uniformity in the transverse plane introduces substantial bias in the flow analysis dictating the need for specific corrections. The results of flow analysis in Pb-Pb collisions at the beam energy of 40$A$~GeV recorded with the fixed target experiment NA49 at the CERN SPS are presented. The three-subevent technique is used for the differential measurements of the directed and elliptic flow. Corrections for the detector acceptance anisotropy in the transverse plane are applied using an extension of the Qn-Corrections Framework developed originally for the ALICE experiment at the LHC. The results are compared with those previously published by the STAR at RHIC and the NA49 at CERN SPS collaborations. In the future, the developed procedure will be used for the analysis of the new Pb-Pb data collected by the NA61/SHINE experiment at the CERN SPS.