Measurements of Spectators with Forward Hadron Calorimeter in MPD/NICA Experiment

The main goal of the MPD/NICA experiment is the investigation of the QCD phase diagram in the region of high net baryon chemical potential and moderate temperatures. The basic detectors of MPD are intended for the study of the produced particles, using their track reconstruction and identification capabilities. The forward hadron calorimeter (FHCal) is a dedicated detector of the spectators, i.e. the non-interacting fragments of the colliding nuclei. The fine transverse segmentation of FHCal allows the reconstruction of both the energy and space distributions of the spectators. In spite of indirect participation in the ion interactions, the spectators carry important information about the geometry of the collisions, namely, the reaction plane and the collision centrality. In this work, we discuss the experimental methods of the spectators’ measurements as well as Monte Carlo simulations of the spectators’ applications for the reconstruction of the heavy-ion collision geometry.