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BM@N (Baryonic Matter at the Nuclotron) is the fixed target experiment aimed to study nuclear matter in the relativistic heavy ion collisions at the Nuclotron accelerator in JINR. Detectors based on Gas Electron multipliers (GEM) have been identified as appropriate for the BM@N tracking system, which is located inside the BM@N analyzing magnet. The structure of the GEM detectors and the results of study of their characteristics are presented. The GEM detectors are integrated into the BM@N experimental setup and data acquisition system. The performance of the GEM tracking system in the first technical run with the deuteron beam is shortly reviewed.

BM@N (Baryonic Matter at the Nuclotron) is a fixed target experiment aimed to study nuclear matter in the relativistic heavy-ion collisions at the Nuclotron accelerator in JINR. The BM@N tracking system is based on Gas Electron Multipliers (GEM) detectors mounted inside the BM@N analyzing magnet. The Cathode Strip Chamber (CSC) is installed outside the magnet. The CSC is used for improvement of particles momentum identification. The structure of the GEM detectors and the CSC prototype and the results of study of their characteristics are presented. The GEM detectors and CSC are integrated into the BM@N experimental setup and data acquisition system. The results of first tests of the GEM tracking system and CSC in last runs are shortly reviewed.

Data on hadron multiplicities from inelastic proton-proton interactions in the energy range of the NICA collider have been compiled. The compilation includes recent results from the NA61/SHINE and NA49 experiments at the CERN SPS accelerator. New parameterizations for excitation functions of mean multiplicities π ± , K ± , K 0 S , Λ , p , p are obtained in the region of collision energies 3 < √ s N N < 31 GeV. The energy dependence of the particle yields, as well as variation of rapidity and transverse momentum distributions are discussed. A standalone algorithm for hadron phase space generation in pp collisions is suggested and compared to model predictions using an example of the PHQMD generator. The investigation has been performed at the Laboratory of High Energy Physics, JINR PACS: 13.75.Cs; 13.85.Ni; 25.60.Dz * Vadim.Kolesnikov@cern.ch IntroductionThe NICA accelerator complex is under construction at JINR (Dubna). It would offer a record luminosity (reaching 10 27 cm −2 c −1 ) for heavy-ion collisions in the energy range 4 < √ s N N < 11 GeV [1]. Proton-proton collisions at NICA can be studied in the energy range from 4 to 25 GeV. The physics program of the MultiPurpose Detector (MPD) at the NICA collider is aimed at experimental exploration of a yet poorly known region of the QCD phase diagram of the highest net-baryon density with an emphasis on the nature of the transition from hadronic to quark-gluon degrees of freedom, modification of hadron properties in dense nuclear matter, and search for the signals about the critical end point [2]. However, the interpretation of experimental results from nucleus-nucleus interactions showing novel phenomena has to rely on comparison to the corresponding data from elementary collisions. For example, the excitation function of the strangeness-to-entropy ratio, which behaves differently in heavy-ion and pp collisions, may serve as an important probe in the study of the deconfinement phase [3] or can be related to chiral symmetry restoration in the dense hadronic matter [4].Microscopic models of nucleus-nucleus collisions, which utilize multiple physics phenomena in strongly interacting matter, are useful tools for explaining experimental results and making new predictions. Data on hadron yields from elementary inelastic collisions are the essential input for such kind of models permitting to establish details of the evolution of particle inclusive production from elementary to nuclear interactions. Experimental studies of hadron production in pp collisions have been performed at many laboratories over 60 th -80 th of the last century. There are also several review papers, which summarize data and discuss the excitation function of hadron yields in a range of collision energies from several GeV up to LHC energies (see for example [5][6][7]). These old papers, however, rely on a too broad region of energies as compared to the NICA range and do not include the recent measurements from CERN/SPS [9][10][11][12][13][14]. Moreover, early bubble chamber applications are typic...

Abstract. BM@N is the fixed target experiment at the accelerator complex NICA-Nuclotron aimed to study nuclear matter in the relativistic heavy ion collisions. Triple-GEM detectors were identified as appropriate for the BM@N tracking system located inside the analyzing magnet. Seven GEM chambers are integrated into the BM@N experimental setup and data acquisition system. GEM construction, main characteristics and first obtained results of the GEM tracking system performance in the technical run with the deuteron beam are shortly reviewed.