Forward hadron calorimeter (PSD) of NA61/SHINE for heavy ion studies and its upgrade for experiments beyond 2020

The Projectile Spectator Detector (PSD) is a segmented modular hadron calorimeter currently used in the NA61/SHINE experiment at the CERN SPS. The PSD is used for collision centrality determination as well as for estimation of the event plane orientation in nucleus-nucleus collisions. The main goal of the NA61/SHINE experiment includes studying the onset of deconfinement and searching for the critical point of strongly interacting matter. It is of crucial importance to have a precise event class characterization for the analysis of event-by-event observables. The PSD has been already used for centrality selection at the trigger level in measurements of Be+Be, Ar+Sc, Xe+La and Pb+Pb reactions at a wide range of beam energies (13 - 158 AGeV). The performance of the PSD in different collision systems will be shown and the proposed upgrade of the forward hadron calorimeter system for future experiments planned at NA61/SHINE beyound 2020 will be presented.