Nuclotron-based Ion Collider fAcility Research Articles

Collision energy dependence of source sizes for primary and secondary pions at energies available at the JINR nuclotron-based ion collider facility from Lévy fits

We study the evolution of the two-pion correlation function parameters with collision energy in the context of relativistic heavy-ion collisions within the NICA energy range. To this end, we perform UrQMD simulations in the cascade mode to produce samples of pions from 5×106\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$5\ imes 10^6$$\\end{document} Bi+Bi collisions for each of the studied energies. The effects of the quantum-statistical correlations are introduced using the correlation afterburner code CRAB. We fit the correlation function using Gaussian, exponential and symmetric Lévy shapes and show that for all collision energies the latter provides the best fit. We separate the sample into pions coming from primary processes and pions originating from the decay of long-lived resonances, and show that the source size for the latter is significantly larger than for the former. The source size for the secondaries, is similar but in general larger than the size for the whole pion sample. To further characterize the pion source, we also simulate the effects of a non-ideal detector introducing a momentum smearing parameter, representing the minimum pair momentum and thus a maximum source size that can be resolved. The values of the correlation function intercept parameter are therefore modified from the values they attain for the perfect detector case. Using the core-halo picture of the source, we show that the values of the intercept parameter are influenced by the presence of a significant fraction of core pions coming from the decay of long-lived but slow-moving resonances. These findings serve as a benchmark to compare with future Monte Carlo studies that consider an Equation of State and thus allow for a phase transition within the studied energy domain.

Elliptic flow of inclusive charged hadrons in Au+Au collisions at E lab = 35 A GeV using the PHSD model

Elliptic flow (v 2) of inclusive charged hadrons at mid-rapidity (∣η∣ < 1.0) in Au+Au collisions at E lab = 35 A GeV using the parton hadron string dynamics (PHSD) model are presented as a function of centrality, transverse momentum (p T) and pseudo-rapidity (η). The v 2 results are obtained using the η-sub event plane method with respect to the event plane angle (ψ 2) and participant plane angle (). p T-integrated charged hadron v 2 shows a strong centrality dependence in Au+Au collisions at E lab = 35 A GeV. The eccentricity-scaled elliptic flow (v 2/ε 2) also shows centrality dependence. The higher values of v 2/ε 2 in central collisions suggest the development of stronger collectivity. The calculations are compared with the results from Au+Au collisions at published by the STAR experiment at RHIC. We also compare the results of HSD and PHSD modes to investigate the contribution of hadronic and partonic phases of the medium on the calculated v 2. The current results serve as a prediction of the collective behavior of the matter produced in baryon-rich and moderate temperature conditions for the upcoming multi-purpose detector at the nuclotron-based Ion collider facility (NICA) and compressed baryonic matter experiment at the facility for antiproton and ion research. These predictions are also useful for interpreting data measured at relativistic heavy ion collider (RHIC) beam energy scan program.

Double J/ψ production as a test of parton momentum correlations in double parton scattering

Using the GS09 model we predict the possible impact of the parton momentum correlation on the J/ψ-pair production at the Spin Physics Detector at the Nuclotron-based Ion Collider Facility. The double J/ψ production and the effective cross sections are calculated.

Towards Study of Two-Particle PT Correlations in Hadronic Interactions at NICA

A new method for studying two-particle transverse momentum (PT) correlations in soft hadronic interactions is proposed. It is shown that Monte Carlo models: PYTHIA 6 and Geant4 FTF (FRITIOF), give different predictions for the correlations in proton–proton interactions. The correlations are connected with Schwinger’s mechanism of particle creation. These correlations can be studied in current and future experiments in high energy physics, in particular, at the Nuclotron-based Ion Collider fAcility (NICA).

Elliptic flow of identified hadrons in Au+Au collisions at E_{lab} = 35~text {A}~text {GeV} using the PHSD model

We present predictions of elliptic flow (v_2) of identified hadrons at mid-rapidity (|y| < 1.0) in Au+Au collisions at E_{lab} = 35~text {A}~text {GeV} using the Parton Hadron String Dynamics (PHSD) model. The transverse momentum (p_{textrm{T}}) dependence of identified hadron v_2 in minimum bias (0–80%) and three different centrality intervals (0–10%, 10–40%, and 40–80%) are presented. A clear centrality dependence of v_2(p_{textrm{T}}) is observed for particles and anti-particles. We also present the p_{textrm{T}} dependence of v_2 difference ({Delta } v_2) between particles and corresponding anti-particles. A significant difference in v_2 values for baryons and anti-baryons is observed. Constituent quark scaling (NCQ) of v_{2} is investigated in Au+Au collisions. We also present a v_2(p_{textrm{T}}) ratio between the HSD and PHSD modes to explore the effect of hadronic and partonic interactions in the medium. These predictions are useful for interpreting the data measured in the Beam Energy Scan (BES) program at RHIC. They will also be useful for the future Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR) and Multi-Purpose Detector (MPD) at the Nuclotron-based Ion Collider facility (NICA).

Probing Gluons with the Future Spin Physics Detector

In this paper, we review the physics studies to be performed with the Spin Physics Detector (SPD) at the Nuclotron-based Ion Collider fAcility (NICA) which is a multi-purpose experiment designed to study nucleon spin structure in the three dimensions. With capabilities to collide polarized protons and deuterons with center-of-mass energy up to 27 GeV and luminosity up to 1032cm−2s−1 for protons (an order of magnitude less for deuterons), the experiment is considered to allow measurements of cross-sections and spin asymmetries of hadronic processes sensitive to the unpolarized and various polarized (helicity, Sivers, Boer-Mulders) gluon distributions inside the nucleons. Results from the SPD will be complimentary to the present high-energy spin experiments at the RHIC (Relativistic Heavy Ion Collider) facility or future experiments such as the Electron-Ion Collider (EIC) at BNL (Brookhaven National Laboratory) and the AFTER experiment at the LHC (Large Hadron Collider) in understanding the spin structure of the basic building blocks of visible matter. Monte Carlo simulation-based results presented here demonstrate the impact of the SPD asymmetry measurements on gluon helicity parton distribution function (PDF) and gluon Sivers functions. With polarized deuteron collisions, the SPD is expected to be the unique laboratory for probing tensor-polarized gluon distributions. Additionally, there are possibilities of colliding other light nuclei, such as carbon, at reduced collision energy and luminosity during the first stage of the experiment.

Algorithm for Enhancing Event Reconstruction Efficiency by Addressing False Track Filtering Issues in the SPD NICA Experiment

This paper introduces methods for parallelizing the algorithm to enhance the efficiency of event recovery in Spin Physics Detector (SPD) experiments at the Nuclotron-based Ion Collider Facility (NICA). The problem of eliminating false tracks during the particle trajectory detection process remains a crucial challenge in overcoming performance bottlenecks in processing collider data generated in high volumes and at a fast pace. In this paper, we propose and show fast parallel false track elimination methods based on the introduced criterion of a clustering-based thresholding approach with a chi-squared quality-of-fit metric. The proposed strategy achieves a good trade-off between the effectiveness of track reconstruction and the pace of execution on today’s advanced multicore computers. To facilitate this, a quality benchmark for reconstruction is established, using the root mean square (rms) error of spiral and polynomial fitting for the datasets identified as the subsequent track candidate by the neural network. Choosing the right benchmark enables us to maintain the recall and precision indicators of the neural network track recognition performance at a level that is satisfactory to physicists, even though these metrics will inevitably decline as the data noise increases. Moreover, it has been possible to improve the processing speed of the complete program pipeline by 6 times through parallelization of the algorithm, achieving a rate of 2000 events per second, even when handling extremely noisy input data.

Centrality Selection Effect on Elliptic Flow Measurements in Relativistic Heavy-Ion Collisions at NICA Energies

The elliptic flow (v2) of produced particles is one of the important observables sensitive to the transport properties of the strongly interacting matter created in relativistic heavy-ion collisions. Detailed differential measurements of v2 are also foreseen in the future Multi-Purpose Detector (MPD) experiment at the Nuclotron based Ion Collider fAcility (NICA) at collision energies sNN = 4–11 GeV. Elliptic flow strongly depends on collision geometry, defined by the impact parameter b. Usually b is an input to theoretical calculations and can be deduced from experimental observables in the final state using the centrality procedure. In this work, we investigate the influence of the choice of centrality procedure on the elliptic flow measurements at NICA energies.

Genetic Algorithm for Determination of the Event Collision Time and Particle Identification by Time-of-Flight at NICA SPD

Particle identification is an important feature of the future SPD (Spin Physics Detector) experiment at the NICA (Nuclotron-based Ion Collider fAcility) collider. In particular, the identification of particles with momenta up to a few GeV/c (with c the speed of light) by their time-of-flight facilitates the reconstruction of events of interest. The high time resolution of modern TOF (Time-Of-Flight) detectors demands the need to obtain the event collision time, t0, with comparable accuracy. While the determination of the collision time is feasible through the use of TOF signals supplemented by track reconstruction, it proves to be computationally expensive. In the presented study, a dedicated Genetic Algorithm is developed as a fast and accurate method to determine the proton–proton collision time by the measurements of the TOF detector at the SPD experiment. By using this reliable method for the t0 determination we compare different approaches for the particle identification procedure based on TOF signals.

Feasibility Study of Hypernucleus Production at NICA/MPD

The NICA (Nuclotron-based Ion Collider fAcility) project at the Joint Institute for Nuclear Research (JINR, Dubna, Russia) is aimed at the construction of a new accelerator complex for heavy ions and polarized particles. Heavy-ion collisions at NICA are planned to be studied in the region of the highest net-baryon density, which favors the formation of bound nuclear systems with strangeness hypernuclei. The multipurpose detector (MPD) at NICA is designed to reconstruct interactions of relativistic nuclei in a high-multiplicity environment. In this paper, we report the feasibility study results for the reconstruction of Λ3H, Λ4H and Λ4He in Bi+Bi collisions at the nucleon-nucleon center-of-mass energy, sNN= 9.2 GeV.

Helicity and vorticity in heavy-ion collisions at energies available at the JINR Nuclotron-based Ion Collider facility

Heavy-ion collisions at center-of-mass nucleon collision energies 4.5--11.5 GeV are analyzed within the parton-hadron-string dynamics (PHSD) transport model. Spectator nucleons are separated, and the transfer of the initial angular momentum of colliding nuclei to the fireball formed by participants is studied. The maximal angular momentum is carried by the fireball in gold-gold collisions with the impact parameter about 5 fm corresponding to centrality class 10--20%. The obtained participant distributions were fluidized and the energy and baryon number densities, temperature, and velocity fields are obtained in the Landau frame. It is shown that the velocity field has dominantly Hubble-like transversal and longitudinal expansion with the vortical motion being only a small correction on top of it. The vorticity field is calculated and illustrated in detail. The formation of two oppositely rotating vortex rings moving in opposite directions along the $z$ axis is demonstrated. Other characteristics of the vortical motion such as the Lamb vector field and the kinematic vorticity number are considered. The magnitude of the latter one is found to be smaller than that for the Poiseuille flow and close to the pure shear deformation corresponding to just a flattening of fluid cells. The field of hydrodynamic helicity, which is responsible for the axial vortex effect, is calculated. The separation of positive and negative helicities localized in upper and lower semiplanes with respect to the reaction plane is shown. It is proved that the areas with various helicity signs can be probed by the selection of $\mathrm{\ensuremath{\Lambda}}$ hyperons with positive and negative projections of their momenta orthogonal to the reaction plane.

Prospects for the (Hyper)Nuclei Study in the Nica Energy Range

The production of nuclei and hypernuclei is of interest for experimental and theoretical studies: it is a big question how such weakly bound objects survive in a hot, dense environment and which new insights on the heavy-ion collisions dynamics they can bring us. We present the results on the hypernuclei feasibility study for the flagship Nuclotron-based Ion Collider fAcility (NICA)/Multi-Purpose Detector (MPD) experiment at the Joint Institute for Nuclear Research (JINR) in Dubna using the Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) transport approach and a realistic reconstruction chain.

Implementation of the Event Metadata System for physics analysis in the NICA experiments

NICA (Nuclotron-based Ion Collider fAcility) is a new accelerator complex, which is under construction at the Joint Institute for Nuclear Research in Dubna to study properties of dense baryonic matter. The experiments of the NICA projects have already generated and obtained substantial volumes of event data, and it is expected that the overall number of stored events will increase from the current value of hundreds of millions to several billion events per year. The developed Event Metadata System is required to store and index experimental event records obtained at NICA facilities, allowing to quickly search for only necessary events based on various criteria for further processing and physics analyses. The main aim of the information system that is described is to speed up desired physics analyses and data quality checks. In addition, it allows reducing the load of the NICA computing infrastructure. The Event Metadata System, which is presented in the paper, is integrated with other experimental and software systems, in particular, NICA ROOT-based frameworks and implemented Condition Database. An access and management of the event metadata in the Event Catalogue being used to select only events for a particular physics analysis are provided via several interfaces, such as REST API, Web UI, and a dedicated C++/ROOT interface. The detailed architecture of the system and developed services including monitoring are also presented.

Direct Photon Production in Heavy-Ion Collisions: Theory and Experiment

Direct photons provide a possibility to test properties of hot matter created in proton–proton (pp), proton–nucleus (p–A) or nucleus–nucleus (A–A) collisions. As they are created in charged particles’ scatterings and freely escape the hot region, they provide a tool to test all stages of the collision: the scattering of the partons of incoming nucleons, pre-equilibrium evolution and collective expansion of hot quark–gluon matter created in nucleus–nucleus collisions. Comparing direct photon production in pp, p–A and A–A collisions, one can check the scaling with the number of binary collisions expected at a high transverse momentum range and obtain insight into the hot and cold hadronic matter properties with soft photons. The collective elliptic flow of direct photons is a unique possibility to trace the collective flow formation and space–time evolution of the fireball. We review the experimental results on direct photon production in pp, p–A and A–A collisions at the Super Proton Synchroton (SPS), the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) energies and discuss an agreement of theoretical predictions with measurements. Finally, we present predictions of direct photon spectra and collective flow for lower energy collisions expected at the Nuclotron-based Ion Collider fAcility (NICA) and the Facility for Antiproton and Ion Research (FAIR).

Color coherence effects in the reaction H2(p,2p)n

The hard proton knock-out by the proton from the deuteron at relativistic energies is considered with a focus on the color transparency (CT) effect which influences the initial- and final-state interactions. The calculations are performed in the framework of the generalized eikonal approximation supplemented by the quantum diffusion model of CT. The main results of the previous calculations [Frankfurt et al., Phys. Rev. C 56, 2752 (1997)] at the beam momentum below 20 $\mathrm{GeV}/\mathrm{c}$ are confirmed, including the dependence of the nuclear transparency on the transverse momentum of the spectator neutron, ${p}_{st}$, and on the relative azimuthal angle $\ensuremath{\phi}$ between proton and neutron: absorption at ${p}_{st}&lt;0.2\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}/\mathrm{c}$ and enhancement at ${p}_{st}&gt;0.3\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}/\mathrm{c}$ due to rescattering on the neutron, the change of $\ensuremath{\phi}$ dependence between these two regions, and the enhancement of CT effects with ${p}_{\mathrm{lab}}$. The study is then generalized to higher beam momenta, up to 75 $\mathrm{GeV}/\mathrm{c}$. It is shown that such behavior of the transparency is mainly preserved up to ${p}_{\mathrm{lab}}\ensuremath{\simeq}50\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}/\mathrm{c}$, but changes significantly at higher beam momenta due to the interference of valence quark configurations of small and large sizes. As a result, the transparency at small ${p}_{st}$ exhibits oscillations as a function of the beam momentum (the nuclear filtering effect). The tensor analyzing power due to the longitudinal polarization of the deuteron is calculated. The event rate at Nuclotron-based Ion Collider fAcility (NICA) is estimated.

RETRACTED: Quasi-frozen spin concept of magneto-optical structure of NICA adapted to study the electric dipole moment of the deuteron and to search for the axion

The “frozen spin” method is based on the idea that at certain parameters of the ring, the particle spin rotates with the frequency of the momentum, creating conditions for the continuous growth of the electric dipole moment signal. The Nuclotron-based Ion Collider fAcility (NICA) is under construction in Joint Institute for Nuclear Research [1]. Since a straightforward implementation of the frozen spin regime at NICA is impossible, we suggest an alternative “quasi-frozen spin” concept. In this new regime, the reference particle’s spin-vector precesses with a spin phase advance π ⋅ γG/2 per beam revolution, locally recovering the longitudinal orientation at the location of the electric-magnetic elements, Wien filters, placed in the straight sections. In the deuterons case, thanks to the small magnetic anomaly G, the spin-vector continuously oscillates relative to the direction of the momentum-vector with a small amplitude of a few degrees and the expected EDM effect is reduced only by a few percent. In this paper, we study the spin-orbital motion with the aim of using the NICA collider to measure the EDM. We also comment on the potential of NICA as an axion antenna in both the quasi-frozen spin regime and beyond.

Effect of various particlization scenarios on anisotropic flow and particle production using UrQMD hybrid model

We discuss the effect of various particlization scenarios available in the hybrid ultrarelativistic quantum molecular dynamics (UrQMD) event generator on different observables in non-central (b = 5–9 fm) Au + Au collisions in the beam energy range 1A-158A GeV. Particlization models switch fluid dynamic description to the transport description using various hypersurface criteria. In addition to particlization models, various equations-of-state (EoS) provided by the UrQMD hybrid model were employed. The observables examined in this paper include the excitation function of anisotropic coefficients such as directed (v1) and elliptic flow (v2), particle ratios of the species, and the shape of net-proton rapidity spectra at mid-rapidity. Our findings in this article suggest which particlization scenario among gradual freeze-out (GF, default), isochronous freeze-out(ICF), and iso-energy density freeze-out(IEF) hypersurface, is more reasonable in predicting the available experimental results. The results obtained here can help predict and compare the measurements provided by future experiments at the Facility for Antiproton and Ion Research (FAIR) and the Nuclotron-based Ion Collider fAcility (NICA) once the data becomes available.

Performance of BeBe, a proposed dedicated beam-beam monitoring detector for the MPD-NICA experiment at JINR

The Multipurpose Detector (MPD) is an experimental array, currently under construction, designed to study the nuclear matter created during the collisions that will be provided by the Nuclotron-based Ion Collider fAcility (NICA) at JINR. The MPD-NICA experiment consists of a typical array of particle detectors as those used to study heavy-ion collisions at LHC and RHIC. To increase the trigger capabilities of MPD for stage 2 of NICA operation, a detector constituted by two arrays of 80 plastic scintillator cells each located symmetrically at opposite sides of the interaction point of MPD is proposed (BeBe). Based on Monte Carlo simulations, a discussion of the potential physics performance of BeBe detector is given for triggering tasks and for the resolution in the determination of the event plane reaction and the centrality of the collisions at NICA. Also, laboratory measurements to estimate the time resolution of individual BeBe cells prototypes are presented. It is shown that a time resolution between 0.47 and 1.39 ns can be reached depending on the number of photosensors employed to collect the scintillation photons. The BeBe detector will be complementary to FFD and FHCAL forward detectors.

A 13 Gbps 1:16 deserializer ASIC for NICA multi purpose detector project

This paper presents the design and test results of a 13 Gbps 1:16 deserializer ASIC fabricated in a 55 nm CMOS technology for Nuclotron-based Ion Collider fAcility (NICA) Multi Purpose Detector (MPD) project. The deserializer would be used in the downlink data transmission of MPD readout system to recover the serial data from the back-end to the parallel data for the front-end. The ASIC adopts a tree-type structure, consisting of a high-speed data receiver (RXDATA), a high-speed clock receiver (RXCLK), four levels of demultiplexer (DEMUX) modules, clock dividers and 16 Low-Voltage Differential Signaling (LVDS) drivers. The demultiplexer modules are composed of different numbers of high-speed DEMUX unit and low-speed DEMUX unit. The high-speed DEMUX unit and the high-frequency clock divider adopt an optimized compressed current mode logic (CML) differential structure to ensure the bandwidth with limited voltage headroom. The low-speed DEMUX unit and the low-frequency clock divider use CMOS latch to save power consumption. The duty cycle correction (DCC) circuit and the clock aligner are employed in the clock paths to ensure the correct duty cycle and aligned clock edges. In the chip test, the ASIC receives 13 Gbps serial data and outputs 16 channels of 812.5 Mbps data correctly with wide-open eye diagram. The tested power consumption is 203 mA with 1.2 V power supply including the RXDATA, the RXCLK and the 16 channels of LVDS drivers, and the core power consumption is 122.7 mA.

The NICA-SPD project: a new tool to investigate the hadron structure

SPD is an international Collaboration gathering around the Spin Physics Detector at the Nuclotron-based Ion Collider FAcility (NICA), presently under construction at the Joint Institute per Nuclear Research, in Dubna. The project is briefly presented with special focus to the opportunities opened by the collision of high luminosity polarized proton and deuteron beams with total energy up to $\sqrt{s}$=27 GeV. Examples of the foreseen research program are highlighted, in connection with the spin structure of light nuclei, the proton gluon content and the spin dependence of the nucleon-nucleon interaction. The unicity of NICA-SPD makes the future results complementary to the studies that have been or will be performed at other polarized hadron machines in different energy domains.