BM@N (Baryonic Matter at Nuclotron) is the first experiment operating and taking data at the Nuclotron/NICA ion-accelerating complex.The aim of the BM@N experiment is to study interactions of relativistic heavy-ion beams with fixed targets. We present a technical description of the BM@N spectrometer including all its subsystems.

The Silicon Tracking System (STS) of the BM@N experiment will be based on modules with Double-Sided microstrip Silicon Detectors (DSSD) which have been initially developed for the CBM experiment at FAIR. Each module consists of a DSSD, two front-end boards with 8 ASICs each, and a set of low-mass aluminum microcables. During the module assembly the microcables are tab-bonded to the sensor and readout ASICs. The module has 1024 channels on each side of the sensor. For the quality assurance of the ultrasonic bonding process a dedicated procedure based on the noise per channel measurements with a Pogo Pin test device was developed.

First physics results of the BM@N experiment at the Nuclotron/NICA complex are presented on π+ and K+ meson production in interactions of an argon beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 A GeV. Transverse momentum distributions, rapidity spectra and multiplicities of π+ and K+ mesons are measured. The results are compared with predictions of theoretical models and with other measurements at lower energies.

To study the high-density nuclear equation-of-state in collisions between gold nuclei at Nuclotron beam energies (2–4.5 A GeV), the existing BM@N experiment at JINR in Dubna has to be substantially upgraded. The measurement of high-multiplicity events at interaction rates up to 5 MHz requires the installation of four large-aperture tracking stations equipped with double-sided micro-strip silicon sensors, which have been developed for the CBM experiment at FAIR. It has been demonstrated by simulations that the hybrid tracking system comprising four of such silicon stations (STS) situated in-front of seven GEM tracking detectors will be able to identify charged particles including hyperons emitted in Au + Au collisions with good efficiency and high signal-to-background ratio. The results of the simulations and the status of the STS detector development are presented.