NICA Accelerator Complex Research Articles

HTS current leads for the NICA accelerator complex

The international project “NICA” (Nuclotron-based Ion Collider fAcility) is an accelerator complex which is under construction at the Joint Institute for Nuclear Research (Dubna, Russia). Basing on the NICA project demands NRC “Kurchatov Institute” (Moscow, Russia) designed and manufactured two trial 12 kA 1G current leads (CLs) intended for powering of the JINR superconducting magnets test bench. The main requirements for the CLs were: a reliable and robust design, usage of liquid nitrogen from the NICA cooling circuits as a resistive section coolant, low resistance joints, current ramp rates up to 10 kA/s and the total heat load to the 5 K end not exceeding 0.4 W/kA per one CL. An in-situ cold test of the trial 12 kA CLs held at JINR in 2015 demonstrated the operational reliability of our technological approaches. Following the successful test results the serial production of 20 pairs of 10.5 kA HTS CLs with very few design updates for the accelerator powering started. The first 10 pairs were fabricated, tested and shipped to JINR as a part of the NICA commissioning framework in June 2017. All the CLs fulfilled the acceptance test requirements. The production of the remaining 10 pairs is to be finished in 2018. The paper gives an overview of the 12 kA and 10.5 kA HTS CLs’ design, discusses their thermal, magnetic and electrical characteristics and presents the acceptance tests results. We also compare our CLs with earlier works by other groups in the context of HTS stack-and-soldering technique, joints’ resistances, relative heat loads into the cryogenic environment etc.

Mock Data Challenge for the MPD/NICA Experiment on the HybriLIT Cluster

Simulation of data processing before receiving first experimental data is an important issue in high-energy physics experiments. This article presents the current Event Data Model and the Mock Data Challenge for the MPD experiment at the NICA accelerator complex which uses ongoing simulation studies to exercise in a stress-testing the distributed computing infrastructure and experiment software in the full production environment from simulated data through the physical analysis.

Remote Toggle On/Off of Slow Control System Cabinet Racks at JINR Accelerator Complex NICA

Remote Toggle On/Off of Slow Control System Cabinet Racks at JINR Accelerator Complex NICA

Front-end electronics development for TPC detector in the MPD/NICA project

The article is aimed at describing the development status, measuring results and design changes of the TPC front-end electronics. The TPC is placed in the middle of Multi-Purpose Detector (MPD) and provides tracing and identifying of charged particles in the pseudorapidity range |η| < 1.2. The readout system is one of the most complex parts of the TPC. The electronics of each readout chamber is an independent system. The whole system contains 95232 channels, 1488 64-channel—front-end cards (FEC), 24 readout control units (RCU). The front-end electronics (FEE) is based on ASICs, FPGAs and high-speed serial links. The concept of the TPC front-end electronics has been motivated from one side—by the requirements concerning the NICA accelerator complex which will operate at the luminosity up to 1027 cm−2 s−1 for Au79+ ions over the energy range of 4 < √SNN < 11 GeV with the trigger rate up to 7 kHz and from the other side—by the requirements of the 4-π geometry to minimize the substance on the end-caps of the TPC.

Investigating the adiabatic beam grouping at the NICA accelerator complex

The NICA complex comprises the Booster and Nuclotron synchrotrons for accelerating particle beams to the required energy and the Collider machine, in which particle collisions are investigated. The experimental heavy-ion program deals with ions up to Au+79. The light-ion program deals with polarized deuterons and protons. Grouping of a beam coasting in an ion chamber is required in many parts of the complex. Beam grouping may effectively increase the longitudinal emittance and particle losses. To avoid these negative effects, various regimes of adiabatic grouping have been simulated and dedicated experiments with a deuteron beam have been conducted at the Nuclotron machine. As a result, we are able to construct and optimize the beam-grouping equipment, which provides a capture efficiency near 100% either retaining or varying the harmonic multiplicity of the HF system.

Lambertson magnet with shortened loop for nuclotron injection and extraction systems

Systems of beam injection from the Booster and fast beam extraction for injection into the collider will be developed in order for the Nuclotron to operate in the framework of the NICA accelerator complex. All systems are based on the Lambertson magnets. The shortened superconducting loop is used for compensating scattered fields in the circulating beam chamber. The finite weld resistance (on an order of several nΩ) results in gradual current storage in the loop, which influences the beam upon injection. To eliminate this effect, a heater for converting the loop into the normal conducting state in the pause between cycles is applied.

Digital LLRF controller for NICA booster

The digital LLRF controller based on embedded microcontroller for the booster of the Dubna superconducting accelerator complex NICA is presented. It allows setting the frequency in accordance with the magnetic field value in the 0.5–5 MHz range with an inaccuracy ± 110 Hz. A novel method of frequency calculation based on the derivative is proposed. The specialized tester module allows tuning up and checking the RF system during comissioning and operation.

The thermometry system of superconducting magnets test bench for the Nica accelerator complex

Precise temperature control in various parts of the magnet and thermostat is one of the vital problems during cryogenic tests. The report describes design of the thermometry system, developed at LHEP JINR. This system is the operational prototype for the NICA thermometry system. Besides, the report describes generic software tools, developed for the TANGO-based control system web client software design.

Supporting the search for the CEP location with nonlocal PNJL models constrained by lattice QCD

We investigate the possible location of the critical endpoint in the QCD phase diagram based on nonlocal covariant PNJL models including a vector interaction channel. The form factors of the covariant interaction are constrained by lattice QCD data for the quark propagator. The comparison of our results for the pressure including the pion contribution and the scaled pressure shift $\Delta P / T^4$ vs $T/T_c$ with lattice QCD results shows a better agreement when Lorentzian formfactors for the nonlocal interactions and the wave function renormalization are considered. The strength of the vector coupling is used as a free parameter which influences results at finite baryochemical potential. It is used to adjust the slope of the pseudocritical temperature of the chiral phase transition at low baryochemical potential and the scaled pressure shift accessible in lattice QCD simulations. Our study, albeit presently performed at the meanfield level, supports the very existence of a critical point and favors its location within a region that is accessible in experiments at the NICA accelerator complex.

From soft photon study at Nuclotron and U-70 to NICA

Experimental and theoretical studies of direct photon production in hadronic collisions essentially expand our insights in multiparticle production mechanisms. These photons are useful probes to investigate nuclear matter at all stages of the interaction. Soft photons play a particular role in these studies. Until now we have no explanation for the experimentally observed excess of soft photons. These photons have low transverse momenta \( p_{T} < 0.1\) GeV/c, \( \vert x\vert < 0.01\) . In this domain their yield exceeds the theoretical estimates by 5-8 times. The registration of soft photons at Nuclotron (LHEP, JINR) has been carried out by the electromagnetic calorimeter built by the SVD-2 Collaboration. Soft photon electromagnetic calorimeter was tested at U-70, IHEP (Protvino). For the first time the soft photon yield at interactions of 3.5A GeV/c per nucleon deuterium and lithium beams has been measured. The obtained energy spectra confirm the increased yield of soft photons with their energy less than 50MeV (in the laboratory system) in comparison with theoretical predictions and agree with previous experiments at high-energy interactions. It is planned to continue soft photon study at the future accelerator complex NICA with heavy-ion beams.

Light cluster production at NICA

Light cluster production at the NICA accelerator complex offers unique possibilities to use these states as "rare probes" of in-medium characteristics such as phase space occupation and early flow. In order to explain this statement, in this contribution theoretical considerations from the nuclear statistical equilibrium model and from a quantum statistical model of cluster production are supplemented with a discussion of a transport model for light cluster formation and with results from hydrodynamic simulations combined with the coalescence model.

Development of the MRPC for the TOF system of the MultiPurpose Detector

The Multipurpose Detector (MPD) [1] is designed to study of hot and dense baryonic matter in collisions of heavy ions over the atomic mass range 1–197 at the centre of mass energy up to √SNN = 11 GeV (for Au79+). The MPD experiment will be carried out at the JINR accelerator complex NICA [2] which is under construction. The barrel part of the MPD consists of various detectors surrounding the interaction point. It includes a precise tracking system (time projection chamber (TPC) and silicon inner tracker (IT)) and high-performance particle identification system based on time-of-flight (TOF) and calorimeter (ECal). The triple-stack multigap resistive plate chamber is chosen as an active element of the TOF. It provides good time resolution and long term stability. This article presents parameters of the MRPC obtained using the deuteron beam of JINR accelerator Nuclotron. The time resolution is 0∼4 ps with efficiency of 99%. Rate capability studies resulted with a time resolution of 60 ps and efficiency higher than 90% on the beam with particle flux densities up to 2 kHz/cm2.

Feasibility Study of ϕ(1020) Production at NICA

The goal of this article is to provide overview of the new accelerator complex NICA at JINR and to present the current results of the Multi-Purpose Detector (MPD) performance for ϕ-meson production. In our study we use the channel decay ϕ→ K+K- to detect the formation of the ϕ-meson. UrQMD event generator is used and central events at√s = 11 GeV are analyzed. The obtained values of the parameters from the invariant mass distribution are consistent with the PDG values. This study shows that the measurement of ϕ-meson is feasible at NICA/MPD.

Optimization of Distributed Data Processing System for NICA BM@N Experiment by Using Simulation

Superconducting accelerator complex NICA is now in a developing stage at the Joint Institute for Nuclear Research11Russian Federation, Moscow region, Dubna (JINR). The development of the NICA computing complex is carried out at the JINR's Laboratory of Information Technologies (LIT) with the aim to process, analyze, store experimental data and simulate its sophisticated design and evolution. NICA includes the BM@N experiment first run of which is planned to be performed in 2017. Therefore, it is necessary to develop a computing system for distributed data storing and processing for the experiment. The simulation program SyMSim is used to choose a proper architecture of the BM@N computing system infrastructure. SyMSim facilitates making a decision regarding a required equipment. The paper presents the results obtained by simulating a process of receiving and processing data from the BM@N experiment involving a model of the computing complex.

The Cooling, the Regulation and the Temperature Stabilization System for MPD Detector at JINR Accelerator Complex NICA

The Cooling, the Regulation and the Temperature Stabilization System for MPD Detector at JINR Accelerator Complex NICA

Development of the distributed computing system for the MPD experiment at the NICA collider

Experimental data processing and storing are topical issues in modern high energy physics experiments. Development of a distributed cluster based on the server farm of the Laboratory of high energy physics was started to accomplish these tasks in the MPD experiment at the NICA accelerator complex. This article describes the design approaches and methods of cluster development for storing and processing data obtained at the multipurpose detector. The current cluster scheme and structure are presented; software for building data storage and parallelization of the MPD event processing is noted. The article introduces two methods to parallelize data processing: using PROOF software tool of the ROOT environment and a scheduling system under development by the author.

Conceptual design of the system of heavy-ion beam injection into the Booster of the NICA accelerator complex

A project of the system of heavy-ion beam injection into the Booster synchrotron of the NICA accelerator complex developed at the Joint Institute for Nuclear Research (Dubna) is considered. The proposed system provides multivariant injection for accumulating beams with required intensity. The main methods of beam injection into the Booster are described. These are the methods of one-turn, multiturn, and multiple injections. The results of beam dynamics simulations are presented.

A conceptual design of a power-supply system of deflecting plates for multivariate injection into the NICA accelerator complex booster

The design of the complex envisions the installation of three pairs of electric deflecting plates in the booster ring. These plates are designed to carry out the ion-beam injection into the booster in regimes of single-turn, multiturn, and multiple injection. We present a feasible scheme of a power-supply circuit that allows for all the prospective injection regimes through independent unipolar charging and discharging of the plates.

Cryogenics for the future accelerator complex NICA at JINR

The NICA cryogenics will be based on the modernized liquid helium plant that was b uilt in the early 90’s for the superconducting synchrotron known as the Nuclotron. The main goals of the modernization are: increasing of the total refrigerator capacity from 4000 W to 8000 W at 4.5 K, making a new distribution system of liquid helium, and ensuring the shortest possible cool down time. These goals will be achieved by means of an additional 1000 l/hour helium liquefier and “satellite” refrigerators located near the accelerator rings. This report describes the design choices of the NICA, demonstrates helium flow diagrams with major new components and briefly informs of the liquid nitrogen system that will be used for shield cooling at 77 K and at the first stage of cooling down of three accelerator rings with the total length of about 1 km and “cold” mass of 290 tons.

Quench detector for superconducting elements of the NICA accelerator complex

A universal quench detector is designed for new superconducting accelerators of the NICA accelerator complex under construction at JINR. The presence of a two-channel digital input permits the detector to be used both for comparing voltage across two nearest magnets by a bridge scheme and for separating a resistive constituent of the voltage across a controlled element.