NA61/SHINE measurements of anisotropic flow relative to the spectator plane in Pb+Pb collisions at $30$A GeV/$c$

TL;DR

This paper reports measurements of anisotropic flow in lead-lead collisions at 30A GeV/c, using the NA61/SHINE experiment, and compares results with previous data at 40A GeV to understand collision dynamics.

Contribution

It provides new measurements of flow coefficients relative to the spectator plane at 30A GeV/c and compares them with earlier results at 40A GeV, enhancing understanding of collision energy dependence.

Findings

Flow coefficients vary with transverse momentum and centrality.

Comparison shows differences and similarities between 30A and 40A GeV data.

Results contribute to understanding of anisotropic flow at different energies.

Abstract

We present an analysis of the anisotropic flow harmonics in Pb+Pb collisions at beam momenta of 30$A$ GeV/$c$ collected by the NA61/SHINE experiment in the year 2016. Directed and elliptic flow coefficients are measured relative to the spectator plane estimated with the Projectile Spectators Detector (PSD). The flow coefficients are reported as a function of transverse momentum in different classes of collision centrality. The results are compared with a new analysis of the NA49 data for Pb+Pb collisions at 40$A$ GeV using forward calorimeters (VCal and RCal) for event plane estimation.