Performance and Radiation Damage of the Heavy-Ion Silicon Beam Tracker in the BM@N Experiment

Abstract

The Silicon Beam Tracker (SiBT) of the BM@N experiment at the NICA complex (JINR, Dubna) is designed to reconstruct trajectories of beam ions upstream of the target. It consists of three stations based on double-sided silicon strip detectors (DSSDs) installed directly in the relativistic heavy-ion beam. The SiBT performance and radiation damage were studied using data from the 2026 experimental run with $^{124}$Xe beams at~$1.6$,~$2.2$, and~$3.0$~AGeV. During the run, the leakage current of the DSSD of the third station of SiBT increased by $28.95~μ\mathrm{A}$, while the charge collection efficiency in the beam center decreased to approximately $68\%$ at the nominal bias voltage of 30~V. Increasing the bias voltage to 90~V restored the charge collection efficiency to approximately $95\%$. Despite the radiation-induced signal degradation, the tracking efficiency remained close to $99\%$. The accumulated radiation damage was also used to reconstruct the spatial distribution of the integrated beam fluence from strip-by-strip leakage-current measurements, yielding an average fluence of approximately $1.3\times10^{12}~\mathrm{n_{eq}/cm^2}$.