Determination of centrality in nucleus-nucleus collisions on the MPD/NICA installation

TL;DR

This paper discusses the challenges in accurately determining collision centrality in nucleus-nucleus collisions at NICA due to detector limitations, and proposes a new method using a multiplicity scintillator detector for improved accuracy.

Contribution

A new method is proposed for determining collision centrality at NICA, accounting for the actual detector geometry to improve accuracy over existing calorimeter-based methods.

Findings

Current calorimeter methods have 30-40% error in centrality determination.

The proposed scintillator detector method improves accuracy of centrality measurement.

Accounting for detector geometry enhances the reliability of collision analysis.

Abstract

Measurement of the number of spectators in nucleus-nucleus collisions could be used to determine the number of participant nucleons involved in the interaction, i.e. get information about collision centrality. However, at energies of the NICA collider, energy resolution of the forward hadron calorimeter is insufficient for separation amplitude corresponding to different number of spectators. Uncertainty in the number of spectators leads to a large error in determining centrality. For central events inaccuracy in determining the collision parameter is about 40%, for peripheral ones, no better than 30% at a beam energy of 2.5 AGeV. The multiplicity scintillator detector will allow to obtain more accurate data. A method is proposed for determining the centrality, taking into account the real MPD installation geometry.