Performance and Upgrade of Trigger Detectors for the BM@N Experiment

A system of trigger detectors was developed and successfully operated in the BM@N experiment during the 2023 run with 124Xe ion beams at 3.8 A GeV. The trigger detectors are based on plastic scintillators with specialized PMTs and SiPMs operating in the strong magnetic field of the BM@N magnet. The detector characteristics obtained in the run are discussed. Some degradation of the detector response due to radiation damage in the scintillators was observed during prolonged operation at a beam intensity of 106 ions per spill. A further upgrade program aims to improve the design of the detectors, their performance characteristics, and to minimize beam-line materials.