NICA Collider Research Articles

Spin Transparency Mode in the NICA Collider with Solenoid Siberian Snakes for Proton and Deuteron Beam

Two solenoid Siberian Snakes are required to obtain ion polarization in spin transparency mode of the NICA collider. The snake solenoids with a total field integral of 2×50 T·m are placed into the straight sections of the NICA collider. It allows one to control polarization of protons and deuterons up to 13.5 GeV/c and 4 GeV/c respectively. The snakes introduce a strong betatron oscillation coupling. The calculations of orbital parameters of proton and deuteron beams in the NICA collider with solenoid Snakes are presented.

A possible layout of the Spin Physics Detector with toroid magnet.

The Spin Physics Detector project for carrying out experiments at the 2-nd interaction point of the NICA collider is under preparation. The design of the collider allows reaching collision energy in the c.m.s. as high as √s = 26 GeV for polarized proton-proton collisions and √s = 12 GeV for polarized deuteron-deuteron collisons with a luminosity of up to 1032 cm2 s-1 (for protons) and 1031cm2s-1 for deuterons. Such a high luminosity of polarized beams interactions opens unique possibilities to investigate a variety of polarization phenomena including those related to the nucleon spin structure. A proposal for the experimental set-up based on a toroid type magnet is presented.

The design and development of high-current leads on the basis of 2G HTS conductors

The feasibility of creating high-current leads on the basis of second-generation (2G) high-temperature superconductors (HTSs) was demonstrated. A method for graded soldering of 2G HTS tape stacks is proposed. It allows one to avoid negative effects that are related to an inhomogeneous current sharing between parallel HTS conductors. A prototype of HTS-coated current leads (CLs) was designed, manufactured, and tested; its critical current exceeds 18 kА. Prototypes of HTS CLs for the superconducting magnetic system of the Nuclotron accelerator (a part of the NICA collider) with an operating current of 6 kA were developed, manufactured, and tested in liquid helium (the overcurrent was 9 kA).

Rapidity distributions of hadrons in the HydHSD hybrid model

A multistage hybrid model intended for describing heavy-ion interactions in the energy region of the NICA collider under construction in Dubna is proposed. The model combines the initial, fast, interaction stage described by the model of hadron string dynamics (HSD) and the subsequent evolution that the expanding system formed at the first stage experiences at the second stage and which one treats on the basis of ideal hydrodynamics; after the completion of the second stage, the particles involved may still undergo rescattering (third interaction stage). The model admits three freeze-out scenarios: isochronous, isothermal, and isoenergetic. Generally, the HydHSD hybrid model developed in the present study provides fairly good agreement with available experimental data on proton rapidity spectra. It is shown that, within this hybrid model, the two-humped structure of proton rapidity distributions can be obtained either by increasing the freeze-out temperature and energy density or by more lately going over to the hydrodynamic stage. Although the proposed hybrid model reproduces rapidity spectra of protons, it is unable to describe rapidity distributions of pions, systematically underestimating their yield. It is necessary to refine the model by including viscosity effects at the hydrodynamic stage of evolution of the system and by considering in more detail the third interaction stage.

Selection of the elastic scattering events in interactions of the NICA colliding proton (deuteron) beams

The features of the kinematics of elastic pp (dd ) scattering in the collider system, as well as some issues concerning registration and selection of elastic scattering events in the NICA colliding beams are considered. Equality and the opposite direction of the scattered particle momenta provide a powerful selection criterion for elastic collisions. Variants of the organization of the trigger signal for recording tracks of secondary particles and DAQ system are given. The estimates of the characteristics of elastic NN processes are obtained from available dσ /d ΩCM data for the elastic pp and np scattering. The paper presents examples of simulations using the Monte-Carlo of elastic pp scattering in the colliding proton beams and quasi-elastic np scattering in the colliding deuteron beams and evaluates the outputs of these processes at the NICA collider.

Hadron rapidity spectra within a hybrid model

A 2-stage hybrid model is proposed that joins the fast initial state of interaction, described by the hadron string dynamics (HSD) model, to subsequent evolution of the expanding system at the second stage, treated within ideal hydrodynamics. The developed hybrid model is assigned to describe heavy-ion collisions in the energy range of the NICA collider under construction in Dubna. Generally, the model is in reasonable agreement with the available data on proton rapidity spectra. However, reproducing proton rapidity spectra, our hybrid model cannot describe the rapidity distributions of pions. The model should be improved by taking into consideration viscosity effects at the hydrodynamical stage of system evolution.

Hadron rapidity spectra within a hybrid model

A 2-stage hybrid model is proposed that joins the fast initial state of interaction, described by the hadron string dynamics (HSD) model, to subsequent evolution of the expanding system at the second stage, treated within ideal hydrodynamics. The developed hybrid model is assigned to describe heavy-ion collisions in the energy range of the NICA collider under construction in Dubna. Generally, the model is in reasonable agreement with the available data on proton rapidity spectra. However, reproducing proton rapidity spectra, our hybrid model cannot describe the rapidity distributions of pions. The model should be improved by taking into consideration viscosity effects at the hydrodynamical stage of system evolution.

Measurement of the magnetic-field parameters of the NICA Booster dipole magnet

Serial assembly and tests of dipole and quadrupole magnets of the NICA Booster have started at the Laboratory of High Energy Physics of the Joint Institute for Nuclear Research (JINR). The accelerator is fitted with Nuclotron-type magnets with a superconducting winding and an iron yoke for shaping the needed magnetic field. The design of magnets for NICA was optimized (based on the experience gained in constructing and operating the JINR Nuclotron) for the production of magnetic fields of the required configuration in terms of the beam dynamics in the accelerator and the collider. Measurements of parameters of the field of each magnet are expected to be performed in the process of assembly and testing of each module of the magnet-cryostat system of the NICA Booster and Collider. The results of magnetic measurements for the NICA Booster dipole magnet are presented.

Intense ion-beam dynamics in the NICA collider

The problems of intense ion-beam dynamics in the developed and optimized optical structure of the NICA collider are considered. Conditions for beam collisions and obtaining the required parameters of luminosity in the operation energy range are discussed. The restriction on collider luminosity is related to effects of the domination of the space charge and intrabeam scattering. Applying methods of cooling, electron and stochastic ones, will permit one to suppress these effects and reach design luminosity. The work also deals with systems of magnetic field correction and problems of calculating the dynamic aperture of the collider.

Start-up configuration of the NICA collider equipment

The start-up version of the NICA/MPD project is determined in accordance with the strategy of its staging. At the initial stage, the elements required for completing the BM@N experiment using an extracted beam and the test of MPD elements at a luminosity no less than 5 × 1025 cm–2 s–1 will be put into operation. The equipment configuration and strategy of the NICA collider operation during its commissioning are presented in this article.

Solving the problem of anomalous J/ $\psi$ suppression by the MPD experiment on the NICA collider

The meassurements of charmonium states production via their decay on lepton pairs by the MPD experiment on the NICA collider at the energies $ \sqrt{s_{NN}}$ = 4-11 GeV per nucleon could provide important data for solving the problem of anomalous J/ $ \psi$ suppression first observed in central Pb-Pb collisions by the NA50 Collaboration at 158 GeV/nucleon. The anomalous J/ $ \psi$ suppression could be due to the formation of the QGP in the central heavy-ion collisions. However, this effect could be also interpreted as the result of the comover interactions in nuclear matter. The recent experiments at the SPS, at the RHIC, and the LHC reviewed in this article indicate a more complicated picture of the J/ $ \psi$ production including the recombination, medium effects, parton shadowing, and the coherent energy loss mechanism. A more simple production mechanism could be expected at low colliding energies. However, no data were obtained at energies below $ \sqrt{s_{NN}}=17$ GeV for heavy-ion collisions. After the short review of the whole set of the data of charmonium states observation the estimation of the production rate for the MPD/NICA is made.

Novel QCD physics at NICA

The NICA collider project at the Joint Institute for Nuclear Research in Dubna will have the capability of colliding protons, polarized deuterons, and nuclei at an effective nucleon-nucleon center-of-mass energy in the range $\sqrt{s_{NN}} = 4 - 11$ GeV. I briefly survey a number of novel hadron physics processes which can be investigated at the NICA collider. The topics include the formation of exotic heavy-quark resonances near the charm and bottom thresholds, intrinsic strangeness, charm, and bottom phenomena, hidden-color degrees of freedom in nuclei, color transparency, single-spin asymmetries, the RHIC baryon anomaly, and non-universal antishadowing.

Multi-purpose detector at the JINR NICA collider in the landscape of heavy-ion projects

The role of the multi-purpose detector at the JINR NICA collider in the landscape of heavy-ion projects is briefly discussed.

Phenomena at the QCD phase transition in nonequilibrium chiral fluid dynamics (N $\chi$ FD)

Heavy-ion collisions performed in the beam energy range accessible by the NICA collider facility are expected to produce systems of extreme net-baryon densities and can thus reach yet unexplored regions of the QCD phase diagram. Here, one expects the phase transition between the plasma of deconfined quarks and gluons and the hadronic matter to be of first order. A discovery of the first-order phase transition would as well prove the existence of the QCD critical point, a landmark in the phase diagram. In order to understand possible signals of the first-order phase transition in heavy-ion collision experiments it is very important to develop dynamical models of the phase transition. Here, we discuss the opportunities of studying dynamical effects at the QCD first-order phase transition within our model of nonequilibrium chiral fluid dynamics.

Numerical calculation of ion polarization in the NICA collider

The NICA Collider with two solenoid Siberian snakes is “transparent” to the spin. The collider transparent to the spin provides a unique capability to control any polarization direction of protons and deuterons using additional weak solenoids without affecting orbital parameters of the beam. The spin tune induced by the control solenoids must significantly exceed the strength of the zero-integer spin resonance, which contains a coherent part associated with errors in the collider's magnetic structure and an incoherent part associated with the beam emittances. We present calculations of the coherent part of the resonance strength in the NICA collider for proton and deuteron beams.

Orbital parameters of proton and deuteron beams in the NICA collider with solenoid Siberian snakes

Two solenoid Siberian snakes are required to obtain ion polarization in the “spin transparency” mode of the NICA collider. The field integrals of the solenoid snakes for protons and deuterons at maximum momentum of 13.5 GeV/c are equal to 2×50 T·m and 2×160 T·m respectively. The snakes introduce strong betatron oscillation coupling. The calculations of orbital parameters of proton and deuteron beams in NICA collider with solenoid snakes are presented.

Релятивистская ядерная физика в ОИЯИ: от синхрофазотрона к коллайдеру NICA

Релятивистская ядерная физика в ОИЯИ: от синхрофазотрона к коллайдеру NICA

Study for a Design of Magnet System for the SPD Detector NICA LHEP JINR

The choice of magnet system for the Spin Physics Detector of the NICA Collider of LHEP JINR is given. The inverse problem of magnetostatics is solved for a magnetic field of 0.5 tesla in the aperture a) ɸ 3 m x 5 m and b) ɸ 3 m x 6 m. We also discuss the design of the magnet with a field of 0.3 T.The paper presents the results obtained for the "warm" and SC versions of the magnetic system: currents (ampere-turns), the geometry (size) of the coil and the iron yoke, weight (on the whole and the individual elements), the magnet transportation and assembly.

Spin Physics at NICA

The NICA-SPD project is under preparation at the 2nd interaction point of the NICA collider. The main purpose of this experiment is the study of the nucleon spin structure with high intensity polarized proton and deuteron beams. The design of the collider can allow us to reach a very high collision proton (deuteron) energy up to [Formula: see text]s [Formula: see text][Formula: see text]26 (12) GeV with the average luminosity up to 10[Formula: see text] (10[Formula: see text] cm[Formula: see text] Both proton and deuteron beams will be effectively polarized. The one gives us unique possibilities to investigate the polarized phenomena and nucleon spin structure at NICA. The comprehensive program of these studies is presented.

Possible measurements of the spin one observables in elastic dN, dd collisions at the NICA deuteron beams

The report shows the possibilities of studying the spin one observables in the elastic dN and dd interactions at the NICA collider of the VBLHEP JINR. The use of the colliding deuteron beams would allow us to carry out the measurements of the differential cross sections I0(dN, dd) of the elastic scattering of unpolarized deuterons and the differential cross sections Ipol(dN,dd) and the vector Ay(Ed,θ) and tensor Ayy(Ed,θ) and Axx(Ed.θ) analyzing powers in elastic collisions of the vector and tensor polarized deuterons. The planned luminosity of the colliding polarized deuteron beams will provide sufficiently high elastic events counting rate. The use of the colliding beams of the polarized deuterons for the spin one >dN and dd observables research has a number of significant advantages in comparison with the experiments with the “fixed” target. The angular acceptance of the collider detector covers the full solid angle 4π radians while the wide ranges of the energies of the dN, dd interactions and the 4-momentum transfer squared are available.