Hadron Calorimeter (Projectile Spectator Detector—PSD) of NA61/SHINE experiment at CERN

The fixed target experiment NA61/SHINE at the CERN SPS aims to study the onset of deconfinement and search for the critical point of strongly interacting matter. A segmented hadron calorimeter, the Projectile Spectator Detector (PSD), is used in the NA61 experiment to determine the collision centrality and to reconstruct the event plane orientation in collisions of nuclei. The PSD precisely characterizes the event class for the analysis and provides the centrality selection at the trigger level. The wide ranges of beam energies and sizes of the collision system require high dynamic range of the electronic readout. At the same time sensitivity to small signals is needed for the PSD calibration based on minimum ionizing particles. The PSD was also used for particle identification to distinguish electrons and positrons from pions in the 2017 data taking of reference measurements for Fermilab neutrino beam lines. The performance of the PSD for hadrons is discussed as well as a proposal to upgrade the PSD for the NA61 experimental program beyond 2020.