Heavy ion collider NICA at JINR

Abstract

Main scientific goal of the NICA/MPD project (Nuclotron-based Ion Collider fAcility/ Multi Purpose Detector) under construction at JINR (Dubna) is exploration of the phase diagram of strongly interacting matter in the region of high compression. The planned experimental program includes studies of possible signs of the phase transitions and critical phenomena in heavy ion (up to Au) collisions at the center-of-mass energies up to 11 GeV/u. The collider experiment provides optimum conditions for efficient energy scan measurements. Attainment of the required average luminosity of the order of 1027 cm-2·s-1 for such physics experiment faces several accelerator physics and technology challenges. Contrary to high energy colliders, the luminosity of NICA case will be mostly limited by the Laslett tune shift, while the beam-beam tune shift parameter will be negligibly small. Flexible operational procedures for the beam storage and short bunch formation have been developed to provide maximum peak luminosity over wide energy range. Beam cooling is critical to counteract luminosity decay due to intra-beam scattering. NICA collider design addresses these issues and satisfies all the requirements for the colliding beams experiments.

The applicability of hydrodynamics in heavy ion collisions at $\sqrt{s_{\rm NN}}$= 2.4-7.7 GeV

“…The axes x and z span the reaction plane [77], with z parallel to the beam direction. We use natural units, distance and time are expressed in fm, while energy density and pressure are expressed in GeV/fm 3 or MeV/fm 3 . SMASH sets time t=0 fm at the moment in which two Lorentz contracted spherical nuclei would touch in a perfectly central collision [11].…”

“…Fig. 15 shows the time evolution of the fraction of the system satisfying the constraints X,Y < 0.3 and ε > 1 MeV/fm 3 for the reactions in Table 1. We notice that even in small systems like C+C there is an interval of time in which most of the system satisfies the set of constraints.…”

“…Fig. 11b shows how replacing X ebe with X dramatically shifts the distribution towards X values below 0.2, leading to a dense 2D histogram region for ε < 0.2 GeV/fm 3 , with a secondary pattern that extends up to 0.8 GeV/fm 3 .…”

“…Fig. 12 shows the time evolution of the fraction of the total system for central Au+Au collisions at E lab = 1.23, 3.4, 8, 12 AGeV and √ s NN = 7.7 GeV, under the constraints X,Y < 0.3 and ε > 1 MeV/fm 3 . We notice that, after an initial equilibration phase which is shorter for more energetic collisions, most of the volume satisfies the imposed constraints.…”

“…Heavy ion collisions are a mesmerizing tool to deepen our understanding of how matter interacts, clumps and collectively behaves at nuclear and hadronic scales. Experimental programs, like HADES at GSI [1], BES at RHIC [2] and the upcoming NICA at JINR [3] and CBM at FAIR [4], aim at exploring the QCD phase diagram [5,6] in the high net baryon density region, around the critical point. With the aid of transport approaches like UrQMD [7,8], PHSD [9,10] or SMASH [11], it is possible to derive phenomenological predictions from the theory that can be quantitatively tested in experiments.…”