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A thyristor switch for powering the quadrupole lenses in the Booster–Nuclotron transport channel has been developed. Data on a switching current with an amplitude of up to 500 A are presented. The time stability of the switch is studied using a prototype. The data allow us to conclude that the thyristor switch is a universal device that can be used in other pulsed power supplies of magnetic lenses in accelerators.

In the near future, the Nuclotron at the Joint Institute for Nuclear Research in Dubna will deliver heavy-ion beams with kinetic energies up to 3.8 A GeV. In Au + Au collisions at these beam energies, a dense nuclear fireball will be created, which allows to investigate the high-density equation-of-state (EOS) of nuclear matter in the laboratory, which will shed light on the properties of compact stellar objects. Moreover, signatures for the onset of deconfinement might be observable at the densities reached in those collisions. The Baryonic Matter at the Nuclotron (BM@N) experiment is being upgraded for the measurement of Au + Au collisions at the highest energies and beam intensities available at the Nuclotron. The research and upgrade program together with physics performance studies of the BM@N experiment are presented.

The multi-purpose detector (MPD) is the flagship experiment at NICA (Nuclotron-based Ion Collider fAcility) which is currently under construction at the Joint Institute for Nuclear Research. It is realized in the frame of a large international scientific collaboration. In this work, the status of the preparation of the subdetector components is briefly summarized. The assembly of the solenoidal magnet composed of superconducting coil and iron yoke will be followed by the installation of main subdetectors: time projection chamber, time of flight, electromagnetic calorimeter, fast forward detector and forward hadronic calorimeter. Preparations for the software and computing infrastructure are described. An overview of the MPD physics programme is also given, with emphasis on overall event characteristics and bulk observables, such as single particle spectra, particle identification and basic correlation measurements, as well as dedicated studies of electromagnetic probes and heavy flavor.

We present new ideas on tests of fundamental symmetries in polarization experiments at the NICA facility. Specifically, we explore the possibilities of high precision tests of the Standard Model by parity violation and searches of Beyond the Standard Model semistrong breaking of time reversal invariance in double polarized proton-deuteron scattering, taking advantage of high intensity beams of polarized protons and deuterons available at NICA. In both cases, we propose to use the new technique of polarized beam with precessing horizontal polarizations, and polarized deuterons are the favored choice. An external target in the extracted beam is optional for the parity violation experiment, which requires furnishing Nuclotron and/or new Booster with very modest new instrumentation. One should not overlook this potential for substantial broadening of the spin physics horizon at the NICA facility.

The BM@N (Baryonic Matter at Nuclotron) is the first experiment in operation at the NICA-Nuclotron accelerator complex. The BM@N scientific program comprises the study of dense nuclear matter produced in heavy-ion collisions in the intermediate energy range between the SYS-18 and NICA/FAIR facilities. The first experiments were performed with deuteron and carbon beams with kinetic energy ranging from 3.5 to 4.5 GeV per nucleon on fixed targets. An extended configuration of the BM@N setup was realized in the next runs with argon and krypton beams. First preliminary physics results are presented on $$\Lambda $$ hyperon production in carbon–nucleus interactions at a beam kinetic energy of 4 GeV per nucleon. Signals of $$\Lambda $$ hyperons, charged pions, kaons and light nuclear fragments are identified in argon–nucleus interactions. The performance of the upgraded BM@N central tracker is evaluated for the reconstruction of strange particles and hypernuclei in heavy-ion interactions.

There are strong reasons to bleive that the energy region covered by the Nuclotron-based Ion Collider fAcility (NICA) is an extremely interesting one. We present an overview of theoretical proposals in relativistic heavy ion collisions and show where more and better measurements are needed. The theoretical understanding can be clarified by covering the energy region available to NICA. It would be helpful to determine the strangeness content by covering the full phase space ( $$4\pi $$ ) to determine the thermodynamic parameters.

Investigation of properties of nuclear matter at extremely high temperature and/or extremely high baryon densities under laboratory conditions is one of the fundamental lines of research in high-energy physics. Throughout the past decades, such investigations have been performed in collisions of ultrarelativistic heavy ions in several experiments at modern accelerator complexes, including the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL, USA) and the Large Hadron Collider (LHC) at CERN (Switzerland). In the near future, it is also planned to launch investigations of this kind at the FAIR (Facility for Antiproton and Ion Research at Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, Germany) and NICA (Nuclotron-based Ion Collider fAcility at Joint Institute for Nuclear Research (JINR), Dubna, Russia) accelerators. In order to implement such investigations, it is necessary to create sophisticated detector systems that are able to record events featuring high-multiplicity product particles and to measure reliably their properties. The present article gives a brief survey of all detector systems that have already been created and are being developed at Laboratory of Relativistic Nuclear Physics at Petersburg Nuclear Physics Institute (National Research Center Kurchatov Institute) for the PHENIX (BNL, USA), ALICE (CERN, Switzerland), and CBM (GSI, Germany) experiments aimed at studying nuclear matter under extreme conditions.

The software for determining charged track parameters of the Spin Physics Detector (SPD) experiment on the future Nuclotron based Ion Collider fAcility (NICA) collider (JINR, Dubna) is presented along with the results obtained. The use of this program allows prompt simulations of various magnetic field configurations and the tracking system of the SPD experiment to determine the optimal structure for better track reconstruction.

A new accelerator complex NICA (Nuclotron-based Ion Collider facility) for the study of the collisions of heavy ions and polarized particles is under construction at JINR (Dubna, Russia). The main goal of the NICA physics program is the experimental investigation of the strongly interacting matter phase diagram in the poorly explored region of the maximal baryon density. As the experimental strategy, a detailed energy and system size scan will be performed with an emphasis to the yields, rapidity spectra, transverse momentum a well as azimuthal angle distributions for multiple probes from gammas to hypernuclei. In order to fulfill all project’s goals, the multipurpose detector MPD is designed as a high acceptance spectrometer allowing full reconstruction of high multiplicity events. In this paper, the MPD project at NICA is described, including the MPD physics cases, the MPD design and the status of project’s realization.

The nonlinear dynamics of the 197Au31+ ion beam in the booster has been studied with the MAD-X program. The numerical computation of the dynamic aperture for the DFO-magnetic lattice of the booster is presented. Resonances of second and third order are taken into account. An analysis of the betatron oscillation frequency spread is carried out. This paper shows that the use of multipole correctors allows one to get beams with the required parameters.

The NICA accelerator complex is developed on the JINR base in Dubna for performing physical experiments on colliding beams of heavy ions. It consists of the injection complex, booster synchrotron, upgraded Nuclotron synchrotron, and heavy-ion collider. The booster is currently under assembly. The system, developed at the LHEP JINR to perform precise temperature measurements of superconducting magnets of the booster synchrotron, is described. The thermometry system includes more than 240 resistive TVO-type temperature sensors, the National Instruments data acquisition system, software based on Tango Controls technology, and a web-client application.

A new accelerator complex with new beam lines for applied research is being constructed at the Joint Institute for Nuclear Research (Dubna, Russia) as part of the Nuclotron-based Ion Collider fAcility (NICA) project. The new beam channels are the link between the NICA accelerators and the new stations for applied studies in the applied research program. The channels provide beam transport and the formation of beams with the required parameters. The floor plans, deflection dipole magnets, and beam-dynamics simulation results for the channels are discussed.

The results from studies of the differential cross section of elastic deuteron–proton scattering at 500–1000 MeV/nucleon on the Nuclotron Internal Targets Station are presented and compared to the available experimental data for similar energies, and to the results of theoretical calculations in the theory of relativistic multiple scattering.

The results of using the FLUKA package to calculate the radiation environment around building no. 1 of the Laboratory of High Energy Physics, which contains the ion injection systems, booster, and Nuclotron of the NICA complex in operation for the collider and for experiments with fixed targets, are presented. The calculation has been performed for the mode of 197Au ion acceleration to an energy of 578 MeV/n The main dose-forming component of the radiation field around the building is neutrons of a wide energy range. Detailed models of an ion acceleration ring and the geometry of shields and building details are used in the calculation. The calculation results indicate that the adopted design decisions with the given rates of ion losses will ensure compliance with radiation-protection norms during the operation of the NICA booster.

The future gold beams with energies of up to 3.8A[Formula: see text]GeV from the Nuclotron at JINR in Dubna are well suited to study the equation of state of dense baryonic matter, and to explore the microscopic degrees-of-freedom emerging at neutron star densities. The relevant observables in heavy-ion collisions at these energies include yield and multidifferential distributions of (multi-) strange particles, collective flow of identified particles, fluctuation of conserved quantities and hypernuclei. In order to measure these observables in Au [Formula: see text] Au collisions with rates of up to 50[Formula: see text]kHz, the Baryonic Matter@Nuclotron setup will be upgraded with a highly granulated and fast hybrid tracking system, and a forward calorimeter for event plane determination. The physics program, the detector upgrades and physics performance studies will be presented.

—The results of a statistical and harmonic analysis of the magnetic measurement data of structural elements (dipole magnets) of the Nuclotron Booster at an injection and extraction current are presented.

This article presents the general layout, requirements for main elements, design of main elements, overall design, and calculation of the magnetic fields of the Nuclotron injection kicker.

The design of a high-voltage collet with movable external and internal conductors is considered. The design of the grip connection, the choice of material for the grips, and the conditions for ensuring reliable electrical contact in it are described in detail. The results of tests of the high-voltage collet are presented.

In the BM@N experiment (for Baryonic Matter at the Nuclotron), nucleus–nucleus collisions under extreme conditions will be investigated for elements up to gold. The high collision rate and a large charged-particle multiplicity per collision dictate that the employed detectors should show high spatial and time resolutions and stable operation at occupancies up to 106/cm2. Multilayer GEM (Gas Electron Multiplier) devices that satisfy these criteria have therefore been chosen as constituent elements of the main tracking system. In this paper, we describe the design of the GEM detector employed in the BM@N experiment and report the results of its characterization.

The current source of the IP-2500 type is intended to feed the SP-41 magnet, one of the key elements in the beamline for transporting the charged-particle beam to the experimental zone of the BM@N facility (baryonic matter at the Nuclotron) at the NICA collider complex that is created at the Joint Institute for Nuclear Research (Dubna). The inductance of the magnet is 2.3 H, and its active resistance is 0.0896 Ω. The source is used for powering the SP-41 magnet with a current of 2500 A and a relative accuracy of 10−4.

NICA is an international project accelerator collider complex under construction at the Joint Institute for Nuclear Research in Dubna. The facility is aimed at providing collider experiments with heavy ions up to gold in the center of mass energy from 4 to 11 GeV/u and an average luminosity up to 1 $\times\, 10^{27}$ cm $^\mathbf {-2}$ s $^\mathbf {-1}$ for Au $^{79+}$ . Collision experiments with polarized deuterons and protons are also foreseen. The facility includes two injector chains, a new superconducting booster synchrotron, the existing 6 AGeV superconducting synchrotron Nuclotron, and a new superconducting collider consisting of two rings, each 503 m in circumference. The planned FAIR synchrotron SIS100 has to deliver high-intensity beams for the FAIR project at GSI, Darmstadt. This machine will use fast-cycling 4 T/s magnets with a magnetic field up to 2 T. The NICA booster synchrotron, the NICA collider, and the heavy ion synchrotron SIS100 are based on iron-dominated window frame-type magnets with a hollow superconductor winding analogous to the Nuclotron magnet. Progress in the manufacturing and testing of the NICA magnets and the SIS100 superconducting magnets is presented.

Characteristics of the neutron detector are investigated at the MARUSYA facility in the region of the F4 focus using an extracted deuteron beam from the Nuclotron accelerator (Laboratory of High Energy Physics, Joint Institute for Nuclear Research (LHEP JINR)). It is shown that the neutron detection efficiency is about 27%. With its time characteristics, the detector can be used in the SCAN-3 experimental facility for detecting nucleons from the decay of the η nucleus via the πn and pn channels.

BM@N (Baryonic Matter at Nuclotron) is the first experiment undertaken at the accelerator complex of NICA-Nuclotron. The aim of the BM@N experiment is to study interactions of relativistic heavy ion beams with fixed targets. The scientific program of the BM@N experiment comprises studies of nuclear matter in the intermediate energy range between experiments at the SIS and NICA/FAIR facilities. The BM@N experiment has recorded first experimental data in December 2016. The experimental runs were performed in the deuteron and carbon beams of kinetic energy per nucleon ranging from 3.5 to 4.5 GeV. The extended configuration of the BM@N set-up was realized in recent runs with the argon and krypton beams. The first measurement of short range correlations of nucleons in carbon nucleus was performed in inverse kinematics with the carbon beam and liquid hydrogen target. The experimental program covering physics of heavy ion collisions as well as first experimental results on the production of hyperons are presented.

We consider the capability of flexible spin-transparent polarization control and manipulation in conventional synchrotrons at integer spin resonances by means of spin navigators. The latter are designed as a couple of small solenoids separated by a constant beam bend. We formulate the requirements to the navigator design considering the criteria for stability of the spin motion in the presence of synchrotron energy oscillations. We propose the design of a novel spin-flipping system free of resonant beam depolarization based on such a spin navigator. We discuss the possibilities of testing spin-flipping systems at an integer spin resonance with protons in the Nuclotron ring at JINR in Dubna, Russia, and with deuterons in the RHIC rings at BNL in Upton, New York. The results are relevant to the existing and future facilities where the spin transparency mode can be applied for polarization control.

Universe 7(6), 171 - (2021). doi:10.3390/universe7060171, Published by MDPI, Basel

The differential cross sections of the charge exchange reaction $$dp \rightarrow (pp)n$$ has been measured at 1.75 GeV/c per nucleon for small transferred momenta using the one arm magnetic spectrometer STRELA at the Nuclotron accelerator in JINR Dubna. The ratio of the differential cross section of the charge exchange reaction $$dp \rightarrow (pp)n$$ to that of the $$np \rightarrow pn$$ elementary process is discussed in order to estimate the spin-dependent part of the $$np \rightarrow pn$$ charge exchange amplitude. The $$np \rightarrow pn$$ amplitude turned out to be predominantly spin-dependent.

A precision hybrid magnetic three-arm «SCAN-3» spectrometer is being developed at the Joint Institute for Nuclear Research. The spectrometer is designed to detect charged particles (π±, K±, p) and neutrons produced in the target by collisions of the NUCLOTRON high-interactive beam particles with target nuclei. One of the tasks of the spectrometer is to detect neutrons from the decay of the η-meson nucleus via nπ- and pn- channels. To complete this task, two arms of the spectrometer will be created that consist of six multilayer neutron detectors based on scintillation blocks. The characteristics of a neutron detector that consists of five scintillation blocks are considered. The detector was studied using the cosmic rays and the neutron beam produced by the stripping reaction of the NUCLOTRON extracted deuteron beam on a fixed target.

The aim of the deuteron spin structure (DSS) experiment is to obtain polarization observables in dp elastic scattering and in dp breakup at large CMS angles (> 60°). The dp breakup reaction has been investigated by the scintillation detectors placed at the vicinity of the Internal Target Station (ITS) of Nuclotron. Calibration data have been obtained at the deuteron energy of 300 - 500 MeV. The main goal of this report is to present the calibration procedure of the ΔE - E detectors. Calibration coefficients are used to recover the deposited particle energy.

Properties of spectator matter created in central (of 0-5% centrality) 197Au– 197Au and 208Pb– 208Pb collisions with energies typical for the Nuclotron based Ion Collider fAcility (NICA) accelerator complex are calculated with a recently developed Abrasion-Ablation Monte Carlo for Colliders (AAMCC) model. The sensitivity of cross-sections of emission of spectator neutrons to the nuclear deformation of 197Au and to the presence of neutron skin in 208Pb is demonstrated. The influence of the nuclear deformation of the 197Au on the forward-backward asymmetry of free spectator nucleons and on the asymmetry of the total volume of spectator matter is investigated.

The paper presents measurements of the noise characteristics of silicon photomultipliers in the temperature range from 27.7 °C to 39.1 °C, as well as study of the response of the detector prototypes with Ketek and Hamamatsu SiPM readout to the light source at different voltages. The prototype with SiPM readout from Ketek was tested at the Joint Institute for Nuclear Research Nuclotron deuteron beam at the energy of 4 GeV/nucleon. Time resolution and amplitude of the signal have been estimated.

Analyzing power in elastic proton-proton scattering was obtained at the Nuclotron Internal Target Station using a polarized deuteron beam and a polyethylene target. The selection of useful events was performed using the time and amplitude information from scintillation counters. The asymmetry on hydrogen was obtained by the subtraction of the carbon background. The obtained analyzing power values are compared with the predictions of the partial-wave analysis SAID at the beam energies of 500 and 650 MeV/nucleon.

The the polarimeter upgrade program at the Nuclotron internal target is presented. This polarimeter is intended for polarization experiments to study of the spin structure of two- and three-nucleon systems. The simulation of the pd-elastic and pp-elastic scattering for 500 - 1000 MeV proton energy to optimize the experimental setup and the first test of new detectors are performed.

The Forward Hadron Calorimeter (FHCal) is one of the sub-detectors of MPD/NICA (Nuclotron-based Ion Collider fAcility). FHCal consists of two arms, each containing 44 modules. Modules have longitudinal segmentation and are divided into 7 equal sections. Each section contains 6 pairs of lead-scintillator plates. FHCal’s main goal is to determine geometry of ion collision by measuring the energy distribution of spectators. In order to determine the energy distribution in FHCal, modules were calibrated with cosmic muons. Another important goal facing FHCal is determination of ion collision point in MPD during first stage of MPD’s operation, when no precise ways of doing this will be available. Two methods are presented in this work: using energy distribution in FHCal and using difference in time pulses from opposite FHCal arms.

Within the framework of the Nuclotron–based Ion Collider fAcility (NICA) project an Innovation Block is being constructed. It includes an applied research station for microchips with a package for radiation resistance testing. The ions up to Au with the energy range of 150-350 MeV/n are available for researches. The detailed overview of a technical station for irradiation by long-range ions is presented. A concept for reconstruction of the capsulated microchip structure at it’s interaction with high-energy ions was proposed.

The Baryonic Matter at Nuclotron (BM@N) is the first experiment with a fixed target at the Nuclotron-based Ion Collider fAcility (NICA) in Dubna (Russia). Along with baryonic matter study, the BM@N physics program includes the study of Short-Range Correlations (SRC) in nuclei. The SRC measurement was carried out in 2018. We used 12C beam with the momentum of 48 GeV/c and a liquid hydrogen target. The quasi-free scattering of 12C on protons was recorded with the BM@N spectrometer, which was slightly modified for the SRC experiment. Particularly, the target proton and knocked out proton under the condition of scattering at 90 degrees in the center-of-mass coordinate system were recorded in the arm spectrometer using time-of-flight and coordinate detectors. After interaction, the residual nucleus continued moving along the beam and passed through the scintillator and coordinate detectors as well as the analyzing magnet. This contribution describes the track reconstruction in Multiwire Proportional Chambers (MWPC) and Silicon Detector systems (Si), as well as a method of obtaining combined tracks after the target using the information from MWPC and Si. This is a basis for the identification of nuclear fragments described in the first physics analysis, which was submitted for publication.

We present a concept for control of the ion polarization, called a transparent spin method. The spin transparency is achieved by designing such a synchrotron structure that the net spin rotation angle in one particle turn is zero. The polarization direction of any ions including deuterons can be efficiently controlled using weak quasistatic fields. These fields allow for dynamic adjustment of the polarization direction during an experiment. The main features of the transparent spin method are illustrated in a figure-eight collider. The results are relevant to the electron-ion collider considered in the U.S., the nuclotron-based ion collider facility constructed in Russia, and a polarized electron-ion collider planned in China.

Deuteron spin structure program is aimed on extraction of two and three nucleon forces information, including their spin dependent parts, from dp elastic and dp breakup processes investigated at intermediate energies. The dp elastic data were obtained at Internal Target Station of Nuclotron (JINR) in the energy range 400-1800 MeV using polarized deuteron beam. Strong sensitivity to the short range spin structure of the isoscalar nucleon-nucleon correlations is observed in deuteron analyzing powers. Preliminary results of the the cross section for the dp breakup reaction have been obtained at 400 MeV of deuteron energy.

Time evolution of shear viscosity $\ensuremath{\eta}$, entropy density $s$, and their ratio $\ensuremath{\eta}/s$ in the central area of central gold-gold collisions at energies available at the Nuclotron-based Ion Collider fAcility (NICA) are studied within the ultrarelativistic quantum molecular dynamics (UrQMD) transport model. The extracted values of energy density, net baryon density, and net strangeness density are used as input to (i) the statistical model of an ideal hadron gas to define temperature, baryochemical potential, and strangeness chemical potential, and to (ii) a UrQMD box with periodic boundary conditions to study the relaxation process of highly excited matter. During the relaxation stage, the shear viscosity is determined in the framework of the Green-Kubo approach. The procedure is performed for each of 20 time slices, corresponding to conditions in the central area of the fireball at times from 1 to $20\mathrm{fm}/c$. For all tested energies the ratio $\ensuremath{\eta}/s$ reaches its minimum, ${\left(\ensuremath{\eta}/s\right)}_{\mathrm{min}}\ensuremath{\approx}0.3$ at $t\ensuremath{\approx}5\phantom{\rule{4pt}{0ex}}\mathrm{fm}/c$. Then it increases up to the late stages of the system evolution. This rise is accompanied by the drop of both temperature and strangeness chemical potential and by the increase of baryochemical potential.

The new accelerator complex NICA (Nuclotron-based Ion Collider fAcility) is under construction at JINR (Dubna, Russia). The main physics goal of the NICA project is the experimental exploration of the properties of nuclear matter under extreme condition. The MPD experiment is foreseen for study heavy-ion collisions at the NICA collider. The current status of the NICA project is presented.

A new generation of experiments on relativistic nuclear physics is planned to be started in the nearest years at the Nuclotron-based Ion Collider facility (NICA) under construction at the Joint Institute for Nuclear Research in Dubna. The fixed target experiment BM@N (Baryonic Matter at Nuclotron) is considered as a first stage towards the implementation of the physics program available at NICA. For a successful accomplishment of the BM@N physics program, a well-developed and tested software package for simulation, digitization, reconstruction and analysis of collision events and other supporting tasks is of utmost importance. The data flow scheme of the experiment is shown. Offine and online software systems, such as the main BmnRoot framework, databases of the experiment, data monitoring and others providing information support for the experiment are presented. The implementation of the software systems is a necessary stage for the successful operation of the BM@N experiment.

Over 30 years there has been no comprehensive understanding of the mechanism of soft photons (energy smaller than 50 MeV) formation. Experimental data indicate an excess of their yield in hadron and nuclear interactions in comparison with calculations performed in QED. For a more thorough study of this phenomenon at the Nuclotron (a superconducting accelerator in JINR), preliminary measurements have been carried out with using an electromagnetic calorimeter based on BGO crystals. These results are consistent with the world data. In JINR, in connection with the building of a future accelerator complex NICA, it has become possible to carry out such studies in pp, pA and AA interactions at energies up to 25 A GeV. Our group develops the conception of an heterogeneous electromagnetic calorimeter as “spaghetti” and “shashlik” types based on gadolinium gallium garnet (GaGG) crystals with a low threshold for registration of photons. The first tests of prototypes of them manufactured at JINR on the basis of the GaGG and a mixture of tungstate and copper as an absorber are reported.

The BM@N (Baryonic Matter at Nuclotron) is the first experiment undertaken at the accelerator complex of NICA-Nuclotron. The BM@N scientific program comprises studies of dense nuclear matter in heavy ion beams of the intermediate energy range between the SYS-18 and NICA/FAIR facilities. The first experimental runs were performed with the deuteron and carbon beams of kinetic energy per nucleon ranging from 3.5 to 4.5 GeV with fixed targets. The extended configuration of the BM@N set-up was realized in recent runs with the argon and krypton beams. First physics results are presented on \(\varLambda \) hyperon production in carbon-nucleus interactions at the beam kinetic energy of 4.0 AGeV.

Polarized and unpolarized data for the dp breakup reaction at deuteron energies of 270, 400 MeV and 300–500 MeV using \(\varDelta E - E\) technique are obtained. Dp elastic scattering has been investigated using polarized deuteron beam under various kinematic configurations in the angular range (\(65^{\circ }\)–\(135^{\circ }\)) in c.m. at deuteron energies of 400, 700, 800, 1000, 1100, 1300, 1500 and 1800 MeV. Preliminary results of analyzing powers obtained in dp elastic scattering at 800 MeV of deuteron energy are compared with the calculations based on relativistic multiple scattering model.

A source of polarized deuterons and protons (SPI) has been created as part of the experimental program on accelerated polarized beams at the Nuclotron superconducting synchrotron. The electrostatic accelerating tube has been replaced by an accelerator with spatially homogeneous quadrupole focusing (RFQ linac), and the power-supply system of the ion sources has been also replaced to work with the source of polarized ions on the preinjector of the LU-20 linear accelerator. This article presents the results of 52–54 experiments on the acceleration of polarized protons and light ions in the Nuclotron.

BPM system for transport channel Booster–Nuclotron at NICA facility [1] is developing now at Budker Institute of Nuclear Physics (BINP). The system consists of 6 electrostatic 2-coordinate BPMs and processing electronics. It is capable to measure ion beam trajectory after each shot. The electronics consists of Preamplifiers installed near BPMs and signal processing modules located in safe room. At present a prototype of BPM electronics is fabricated and tested. Software on base of TANGO is developing now for BPM system control.

The quality of booster closed-orbit correction is estimated. The distribution of the maximum orbit distortion in both directions and the results of numerical simulation using the singular value decomposition method are given. The estimation of closed-orbit distortion with the worst correction quality is given.

Two fast interaction trigger systems based on fast detectors with MCP-PMTs and SiPMs readout have been developed for fixed target experiment Baryonic Matter at Nuclotron and collider experiment Multi-Purpose Detector at Laboratory of High Energy Physics, Joint Institute for Nuclear Research. These detectors provide the effective L0 trigger for nucleus–nucleus collisions and the start pulse T0 for TOF detectors with picosecond time resolution. Important requirement to the detectors is good operation in a strong magnetic field.

Methods for processing a digital signal proportional to the longitudinal intensity of charged particles bunches during their acceleration in a synchrotron are discussed. Computerized tomography is used to reconstruct a longitudinal two-dimensional distribution function of particles in the bunch from its profiles depending on the synchrotron motion of particles. Examples of tomographic studies of ion bunches at the Nuclotron are given.

The new NICA (Nuclotron-based Ion Collider fAсility) accelerator complex being built at the Joint Institute for Nuclear Research (Dubna, Russia) is intended for experiments with 197Au79+ gold nuclei at energies in the range of 1–4.5 GeV/n. The RF system of the collider should provide the capture of bunches to be injected from the nuclotron, the accumulation of the necessary number of particles, their acceleration (if necessary), and the formation of bunches. For this, in each ring of the collider, three types of accelerating stations are used: one barrier station and two harmonic stations. The barrier station accumulates the particles and can used to accelerate them up to the energy of the experiment. The harmonic RF stations operating at the 22th and 66th harmonics of the revolution frequency are used for the formation of bunches. This paper describes the operating modes of the RF system and the design features of the RF stations.

Problems connected with the Nuclotron virtual simulation model within MADX are considered. The main objective of the study is a more precise specification of the exiting accelerator model, so that the numerical results obtained using MADX are as close as possible to the experimental data obtained in the last Nuclotron runs. The groups of parameters that bring theoretical calculations closer to the experimental data are found via analyzing the impact of the model characteristics on the numerical results.