NICA Collider Research Articles

Bayesian approach to particles identification in the MPD experiment

Identification of particles generated by ion collisions in the NICA collider is one of the basic functions of the Multipurpose Detector (MPD). The main means of identification in MPD are the time-of-flight system (TOF) and the time-projection chamber (TPC). The article considers the optimization of the algorithms of particles identification by these systems. Under certain conditions, the use of the statistical Bayesian approach has made it possible to achieve an optimal ratio of the efficiency of particle identification and contamination by incorrectly defined particles.

From Nuclotron Synchrotron to NICA Collider—Common Cryogenic Concept for Various Superconducting Magnets, Their Design Specifics and Test Results

From Nuclotron Synchrotron to NICA Collider—Common Cryogenic Concept for Various Superconducting Magnets, Their Design Specifics and Test Results

The State of Magnetic Axis Measurement of the Nica Collider Quadrupoles

The State of Magnetic Axis Measurement of the Nica Collider Quadrupoles

Quasi-Frozen Spin Structures at the NICA Collider as an Option to Search for the Electric Dipole Moment of Deuterons and Axion Dark Matter

Quasi-Frozen Spin Structures at the NICA Collider as an Option to Search for the Electric Dipole Moment of Deuterons and Axion Dark Matter

Prompt polarized J/ψ production at NICA within NRQCD and generalized parton model

In our work we consider prompt J/ψ and ψ′ production within the approaches of nonrelativistic quantum chromodynamics and generalized parton model. We use various experimental data (√s = 200 GeV and √s =19.4 GeV) of charmonium production to fit octet nonperturbative matrix elements and averaged values of initial partons’ transverse momenta. Further, we make evaluation with the extracted parameters and predict J/ψ production cross section and polarization of J/ψ and ψ′ at NICA collider energy √s = 27 GeV.

Dense Cold Quark–Gluon Matter Clusters and Their Study at the NICA Collider

In this paper, the production of particles outside the region of nucleon–nucleon kinematics due to interactions involving dense cold clusters of quark-gluon matter in nuclei is calculated. The possibility of observing this process in the region of central rapidities and large transverse momenta in heavy ion collisions at low energies with MPD detector at the NICA collider is demonstrated.

First Measurements of the Magnetic Axis of Quadrupole Magnets for the NICA Collider

First Measurements of the Magnetic Axis of Quadrupole Magnets for the NICA Collider

ASSOCIATIVE PRODUCTION OF J/ψ -MESONS AND DIRECT PHOTONS
 AT THE ENERGY OF THE NICA COLLIDER

The article considers the associated production of J/-mesons and direct photons at the energy of the NICA collider, s =27 GeV, in the Generalized Parton Model in the leading order of perturbation theory of the quantum chromodynamics. Hadronization of a pair of cc-quarks to a J/-meson is described in terms of two approaches: the color singlet model and the color evaporation model. Nonperturbative parameters of the models are fixed from comparison with the available experimental data on inclusive production of J/-mesons obtained at energies from s = 19 up to s = 200 GeV. It is shown that the processes of the associative production of J/ + can be used to study of gluon distribution functions depending on the transverse momentum in a proton.

Status of the Time-of-Flight System of the MPD Experiment at the NICA Collider

Status of the Time-of-Flight System of the MPD Experiment at the NICA Collider

Instanton induced spin–spin correlations

The QCD instanton can be observed at relatively low energies at Nica collider by studying the spin-spin correlations between the incoming proton and the produced Lambda or Sigma hyperons (or the Lambda and bar{Lambda } hyperons). Low Nica energy will allow to better record and to measure the polarization of the hyperon originated by the polarized valence quark(s) in the proton fragmentation region.

Elliptic Flow and Its Fluctuations from Transport Models for Au+Au Collisions at sNN = 7.7 and 11.5 GeV

The elliptic flow v2 is one of the key observables sensitive to the transport properties of the strongly interacting matter formed in relativistic heavy-ion collisions. In this work, we report on the calculations of v2 and its fluctuations of charged hadrons produced in Au+Au collisions at center-of-mass energy per nucleon pair sNN = 7.7 and 11.5 GeV from several transport models and provide a direct comparison with published results from the STAR experiment. This study motivates further experimental investigations of v2 and its fluctuations with the Multi-Purpose Detector (MPD) at the NICA Collider.

PRODUCTION OF ηc WITH TWO-PHOTON DECAY IN THE GPM AT THE ENERGIES OF NICA COLLIDER

The article discuss the production of c-mesons with decays into the photon pairs at the energy of the NICA collider, s =27 GeV, in the generalized parton model and the leading order approximation of the perturbation theory of quantum chrodynamics. The hadronization of a cc-pair into c-meson is described in the color singlet model and in the color evaporation model. In the calculation of the background process of two photon production with invariant mass near the mass of c-meson, we take into account direct as well as fragmentation mechanisms of the prompt photon production. The results of calculations are compared with predictions of the collinear parton model. We study the signal/background ratio as a function of thedifferent kinematical variables.

MiniSPD Stand for Testing Si-Detectors

SPD (Spin Physics Detector) collaboration proposes to install a universal setup in the second interaction point of the NICA collider under construction (JINR, Dubna) to study the spin structure of the proton and deuteron. It plans to carry out research of spin-related phenomena with polarized proton and deuteron beams at a collision energy up to 27 GeV and a luminosity up to 1032 cm−2 s−1. MiniSPD stand is manufactured as a setup for testing SPD detector prototypes with cosmic muons at LHEP. It allows to carry out checkout of the Data Acquisition System (DAQ), the Detector Control System (DCS). Young physicists and students working at this test bench gain experience of work with real detectors of the future SPD setup. In this report, we give some information about the basic tasks of SPD projects. The results of simulation and comparison with data on cosmic rays at this stand for three modules of silicon plates are also presented.

Topical Problems of Beam Dynamics in the NICA Collider

Topical Problems of Beam Dynamics in the NICA Collider

New Technologies for the Vertex Detectors in the NICA Collider Experiments

A review is presented of the latest technologies for vertex detectors that can be used in experiments at the NICA collider. These technologies include both the novel pixel detectors with new ultralight radiation-transparent carbon composite structures and cooling systems. The efficiency of reconstructing D meson decay is estimated for the developed detector complexes, and the possibility of using these complexes to study the formation of clusters of cold, dense quark-gluon matter inside nuclei are studied.

Particle Multiplicity Fluctuations and Spatiotemporal Properties of Particle-Emitting Source of Strongly Interacting Matter for NICA and RHIC Energies

The results of the model analysis of hadron femtoscopic correlations and factorial moments of particle multiplicity in heavy ion collisions for the energy range of the Beam Energy Scan (BES) program at RHIC and future NICA collider are presented. For this purpose, the simulation of Au+Au collisions at center-of-mass energies 7.7 and 11.5 GeV per nucleon pair using the UrQMD, vHLLE+UrQMD (with the crossover and first-order equation of states), and HYDJET++ event generators was performed. The sensitivity of pion and kaon correlation radii and the dependence of the factorial moments on heavy ion beam energy to quark–hadron phase transition details was studied. In addition, the possible influence of some relevant detector effects on the corresponding experimental observables is discussed.

Ultraperipheral production of lepton pairs (perturbative and nonperturbative effects)

Perturbative and nonperturbative terms of the cross-sections of ultraperipheral production of lepton pairs in ion collisions are taken into account. It is shown that production of low-mass [Formula: see text] pairs is strongly enhanced (compared to perturbative estimates) due to the nonperturbative Sommerfeld–Gamow–Sakharov (SGS) factor. Coulomb attraction of the nonrelativistic components of those pairs leads to the finite value of their mass distribution at lowest masses. Their annihilation can result in an increased intensity of 511 keV photons. It can be recorded at the NICA collider and is especially crucial in astrophysical implications regarding the 511 keV line emitted from the Galactic center. The analogous effect can be observed in lepton pairs production at LHC. Energy spectra of lepton pairs created in ultraperipheral nuclear collisions and their transverse momenta are calculated.

Probing the properties of dense nuclear matter with photon conversions at NICA

Photons serve as valuable probes of the properties of the hot and dense nuclear matter created in collisions of heavy ions. Thermal photon spectra at RHIC and LHC energies indicate that the temperature of the produced medium far exceeds the temperature of the phase transition to the quark-gluon plasma in lattice QCD calculations. Measurements of thermal photon spectra in heavy ion collisions at lower energies at the future NICA collider may help to trace the transition from partonic to hadronic degrees of freedom. In this contribution, feasibility studies on thermal photon measurements using the photon conversion method in the future MPD experiment at NICA will be reviewed. In this work, a possibility to increase photon reconstruction efficiency with a dedicated conversion layer is presented and feasibility to probe the material budget of the experiment with converted photons is discussed.

Yield of Particles in the Cumulative Region at Central Rapidities and Large Transverse Momenta at the NICA Collider

Yield of Particles in the Cumulative Region at Central Rapidities and Large Transverse Momenta at the NICA Collider

Production and quality control of NICA-MPD shashlik electromagnetic calorimeter in Tsinghua University

The Multi Purpose Detector (MPD) is one of the detectors at the NICA collider and the Electromagnetic Calorimeter (ECal) is an important part of MPD. The cylindrical ECal system consists of 2400 ECal modules. In the first stage (2020–2024), Tsinghua University (THU) will produce 460 ECal modules for MPD project. This article mainly introduces the production, quality control and cosmic ray test of ECal modules in THU. The process flow, quality control standards, and testing system of ECal production have been established, which guarantees the high-quality completion of mass production on schedule. Up to now, nearly 360 modules have been manufactured, and a total of 460 modules will be produced by June 2022.