Methods for centrality determination in nucleus-nucleus collisions with forward hadron calorimeters at the BM@N experiment

Abstract

The BM@N (Baryonic Matter at Nuclotron) is the fixed target experiment at the Nuclotron (JINR, Dubna, Russia) accelerator complex. The main goal of the BM@N experiment is studying properties of dense nuclear matter produced in the ion-ion collisions at beam energies up to 4.5 AGeV. First experiments were done for carbon, argon and krypton ions beams with C, Al, Cu and Pb targets. The methods of central events selection on event-by-event base with ZDC (Zero Degree Calorimeter) for these reactions are presented. The new Forward Hadron Calorimeter (FHCal) with transverse and longitudinal segmentation will be used to measure the collision centrality in heavy ion experiments after the BM@N upgrade. The FHCal has the beam hole in the center due to expected high beam intensities. New forward quartz hodoscope is been developed to be placed in the beam hole to measure the charge of fragments. New methods of centrality determination with the FHCal and forward quartz hodoscope are discussed.