Heavy  ion  collisions  at  high  energies  provide  a  unique  opportunity  to  study  the  nuclear matter  under extreme  density  and  temperature.  These  extreme  conditions  are  well  suited  to  the investigation  of the  compressibility  of  the  nuclear matter,  in  particular,  the  stiffness  of  the nuclear equation-of-state (EOS). The theoretical models suggest different possible scenarios for these modifications, so that new experimental data with high resolution and statistics are needed in order to disentangle the different theoretical predictions. The research program on heavy-ion collisions  at  the  Nuclotron  of  the  Joint  Institute  for  Nuclear  Research  includes investigation  of the  reaction  dynamics  and  nuclear  EOS,  study  of  the  in-medium  properties  of  hadrons, production of (multi)-strange hyperons at the threshold and search for hyper-nuclei.

        Figure 1. MPD experiment at extracted Nuclotron beam

The figure 2 presents the three-dimensional scheme of the MPD facility. It proposed to explore phase diagram of strongly interacting matter in a high track multiplicity environment has to cover a large phase space, be functional at high interaction rates and comprise high efficiency and excellent particle identification capabilities.

       Figure 2. 3D view of the MPD solenoid with the withdrawn pole

The NICA/MPD detector combining the large phase space coverage and excellent PID. capabilities offer the exciting possibility to study in great detail transverse mass (mt) and rapidity (y) dependence of hadron production. Detailed measurements of the excitation of the effective temperature of the kaon spectra in different colliding systems (from p+p to central A+A) may help to identify a possible phase transition.

One of the main goals of the experiments on heavy ion beams is to discover and study a new form of QCD matter, the quark-gluon plasma (QGP) In recent years advances in theory led to a significant complication of the QCD phase diagram, in particular, to the appearance of a critical point. The discovery of critical point at intermediate temperature and density is considered as one of the most important goals of FAIR and NICA projects. The region of low temperature and extreme baryon density is considered as hardly achievable in laboratory conditions, whereas it is probably realized in nature, in neutron stars. At high density and low temperature the first order phase transition and existence of color superconductivity phase are expected.

Categories: Experiments