An issue of determination of the centrality in nucleus-nucleus collisions

TL;DR

This paper investigates the accuracy of measuring spectator energy in nucleus-nucleus collisions using the FHCal calorimeter, analyzing fluctuations and the statistical process of photoelectron registration in photomultipliers.

Contribution

It introduces a statistical approach to relate photoelectron registration in PMs to spectator nucleon detection in calorimeters, enhancing measurement precision understanding.

Findings

Photoelectron registration process is statistically similar to spectator nucleon detection.

Measured single photoelectron data agrees with the theoretical variance formula.

The study improves understanding of energy measurement accuracy in nuclear collision experiments.

Abstract

The accuracy of measuring the total energy of the spectators in the FHCal calorimeter, depending on the fluctuations in the number of nucleons and the hadron shower is obtained. It is shown that, from the point of view of statistics, the process of registering photoelectrons in a photomultiplier (PM) is similar to the process of registering spectator nucleons in a calorimeter. The measurements of single photoelectrons in the PM are in good agreement with the obtained formula for the relative variance of the charge detected by the PM.