Progress in development of Nuclotron accelerator complex

The Nuclotron superconducting synchrotron was constructed in 1987–1992 [1]; it is the world’s first synchrotron based on fast cycling “window frame” electromagnets with a superconducting coil. For a design field of dipole magnets of 2 T, the magnetic rigidity is 45 T m, which corresponds to the energy of heavy nuclei (for example, gold) of 4.5 GeV/nucleon. The Nuclotron accelerator complex is currently being upgraded (the Nuclotron-M project); this upgrade is considered a key part of the first stage of fulfilling the new Joint Institute for Nuclear Research (JINR) project: the Nuclotron-based Ion Collider fAcility and Multi-Purpose Detector (NICA/MPD). The most important task of this new project is the preparation of basic Nuclotron systems for its reliable operation as part of the NICA accelerator complex. Basic results of activity on the project, which started in 2007, are presented and the results of the last Nuclotron runs are analyzed.     

Upgrade of Nuclotron power supply system

One of the trends of Nuclotron development lies in modifying the power supply system and upgrading the energy evacuation system of structural magnets in order to provide reliable durable operation of the synchrotron at a dipole magnet field level of 2 T. This is necessary for Nuclotron operation as part of the injection chain of the heavy-ion NICA collider under design at JINR and for the current program of physical studies. The principles of construction and specific features of the existing system based on a separate power supply of structural dipole and quadrupole magnetic elements are considered. The main provisions of the upgrade of the power supply system, structural and schematic diagrams, control schemes, and energy evacuation switch schemes from superconducting elements are presented.     

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.     

Beam transportation lines for the NICA project

A heavy-ion collider, i.e., the Nuclotron-based Ion Collider Facility (NICA), is being developed at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The aim of this project is to construct a new accelerator complex for conducting experiments with colliding ion beam (at the first stage of the project) and with polarized proton and deuteron beams (at the second stage). The NICA accelerator complex will consist of two linear accelerators, two synchrotrons, two collider rings, and beam transportation lines. The magnetic lattice and diagnostic and correction systems for the NICA beam transportation lines are described in this report.     

Simulations of a superconducting ion gantry

Medical carbon-ion synchrotron is being developed at JINR on the basis of the in-house technology of Nuclotron superconducting magnets. The key element of the facility is a superconducting gantry that consists of two 67.5° and one 90° bending sections, each including two identical low-aperture (about 120 mm) dipole magnets with a magnetic field of 3.2 T. Such gantries are intended for multiple raster scanning with a wide carbon beam or for the technique of layerwise irradiation with a spread-out (several mm) Bragg peak. Simulations of the dipole magnets are the subject of this work.     

The State of the Magnetic Measurements of the NICA Collider Twin-Aperture Dipoles

Physics of Particles and Nuclei Letters - The lattice of the NICA collider includes 80 twin-aperture superconducting dipole magnets. Measurements of the magnetic field parameters should be done for...     

HIRFL-CSRe二极铁积分磁场测量

 介绍了兰州重力加速器冷却储存环实验环二极磁铁积分长线圈测磁装置的构成，描述了实验环二极铁的分散性测量、横向分布测量、传递函数等测量内容及测量方法。实验环二极铁采用不断地加减硅钢铁片垫补和加调整线圈电流的方法来调整二极磁铁的有效长度来改变分散性。通过垫补和测量，二极磁铁的分散性在优化磁场时达到±2×10^-4。同时给出了二极铁的横向分布和传递函数的测量结果。对二极铁的设计和加工进行了修正。     

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.     

Start of Electron Cooling System for the NICA Booster

In order to achieve the required beam parameters in the NICA booster, the electron cooling system (ECS) was designed and manufactured at the Institute of Nuclear Physics (INP), Novosibirsk. In 2017, the system was shipped to JINR and its assembly and commissioning started. A specific feature of this system is that, for the first time ever, the electron cooling method with a magnetized e-beam is applied at the superconducting synchrotron; this imposes some additional requirements for the design and start of the ECS, operating at room temperature. This paper describes the main steps of the ECS assembly and start at the straight section of the booster, including mounting mechanical, electrical, and plumbing systems (water, electricity, air, and oil system) and geodetic works on installing the system on site. The measured magnetic field homogeneity for the straight solenoid is given. The assembly of vacuum and magnet systems takes several steps because of the ECS design features. At the final assemblage stage of the vacuum system, the vacuum chamber is baked up and the bulk getters and the cathode of the electron gun are activated. Upon completing assembly and testing the high voltage system, the E-beam is conducted from the gun to the collector.     

Beam-cooling methods in the NICA project

The Nuclotron-based Ion Collider Facility (NICA) is a new accelerator complex under construction at the Joint Institute for Nuclear Research (JINR) for experiments with colliding beams of heavy ions up to gold at energies as high as 4.5 × 4.5 GeV/u aimed at studying hot and dense strongly interacting nuclear matter and searching for possible indications of the mixed phase state and critical points of phase transitions. This facility comprises an ion source of the electron-string type, a 3-MeV/u linear accelerator, a 600-MeV/u superconducting booster synchrotron (Booster), a Nuclotron (upgraded superconducting synchrotron with a maximum energy of 4.5 GeV/u for ions with the charge-to-mass ratio Z/A = 1/3), and a collider consisting of two vertically separated superconducting rings with an average luminosity of 10²⁷ cm^?2 s^?1 in an energy range over 3.0 GeV/u. Beam cooling is supposed to be used in two NICA elements, the Booster, and the collider rings. The Booster is intended for the storage of ¹⁹⁷Au³¹⁺ ions to an intensity of about 4 × 10⁹ particles; their acceleration to the energy 600 MeV/u, which is sufficient for the complete stripping of nuclei (an increase in the injection energy and the charge state of ions makes the requirements for vacuum conditions in the Nuclotron less stringent); and the formation of the necessary beam emittance using the electron cooling system. Two independent beam-cooling systems, a stochastic one and an electron one, are supposed to be used in the collider. The parameters of the cooling systems, the optimum mode of operation for the collider, and the arrangement and design of the elements of the systems are discussed.     

Analysis of the Results of Magnetic Measurements of the Structural Elements of the Nuclotron Booster

Physics of Particles and Nuclei Letters - —The results of a statistical and harmonic analysis of the magnetic measurement data of structural elements (dipole magnets) of the Nuclotron Booster...     

Results of the Nuclotron-M project

The main goal of the Nuclotron-M project, approved in 2007, was formulated as follows: modernization of the main accelerator systems for reliable and safe operation of the Nuclotron as a part of the accelerator facility NICA (Nuclotron-based Ion Collider Facility) being constructed at JINR. Demonstration of heavy-ion beam acceleration (with atomic mass number higher than 100) as well as safe and stable operation of the main superconducting system operation at a magnetic field of up to 2 T had been defined as criteria of successful project fulfillment. Another very important issue is performance of stable, long-term beam runs and increase of the accelerated beam intensity. All the main goals of the Nuclotron-M project had been successfully achieved by the end of 2010. In this report we give an overview of the project realization chronology and present the main experimental results obtained at LHEP Nuclotron accelerator facility in the period from 2007 to early 2011.     

Multipurpose Detector MPD for the Study of Strongly Interacting Matter at the NICA Collider

Physics of Atomic Nuclei - 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...     

一种粒子谱仪用高均匀性高磁通密度永磁组件

研制的永磁组件采用主辅永磁体和匀场技术相结合的改进C型磁路结构,利用计算机仿真技术对组件磁路结构进行验证及优化。仿真分析及实验结果表明:采用这种磁路结构扩大了均匀区的范围,提高了磁场均匀性。按这种结构制造的永磁组件在20 mm气隙、中心平面200 mm120 mm均匀区内气隙磁通密度达到0.75 T,不均匀度为0.67%。另外,也对永磁组件在高低温下的磁性能进行了仿真计算,结果表明:在-55~70 ℃温度范围内均匀区的气隙磁通密度变化为4%左右。     

Thermometry System of NICA Booster Superconducting Magnets

Physics of Particles and Nuclei Letters - 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...     

Cycling Equipment for the NICA Booster Accelerator

Physics of Particles and Nuclei Letters - Cycling equipment was developed for the Booster accelerator of the NICA complex in the form of a VME3U crate with a set of digital and optical input/output...     

Analysis of the magnetic field, force, and torque for two-dimensional Halbach cylinders

The Halbach cylinder is a construction of permanent magnets used in applications such as nuclear magnetic resonance apparatus, accelerator magnets and magnetic cooling devices. In this paper the analytical expression for the magnetic vector potential, magnetic flux density and magnetic field for a two dimensional Halbach cylinder are derived. The remanent flux density of a Halbach magnet is characterized by the integer p. For a number of applications the force and torque between two concentric Halbach cylinders are important. These quantities are calculated and the force is shown to be zero except for the case where p for the inner magnet is one minus p for the outer magnet. Also the force is shown never to be balancing. The torque is shown to be zero unless the inner magnet p is equal to minus the outer magnet p. Thus there can never be a force and a torque in the same system.     

Permanent magnet applications

Rare-earth permanent magnets are ideally suited to generate magnetic fields comparable to their spontaneous polarization J_S. Near-square hysteresis loops and large values of the coercivity and anisotropy fields greatly simplify magnet design, as each magnet block is effectively transparent to the magnetic fields produced elsewhere in the magnet assembly. The fields generated by compact and efficient magnet structures requiring no continuous expenditure of energy can be static or variable, uniform or nonuniform. Permanent magnets are fully competitive with electromagnets for fields up to 2 T, and fields as high as to 5 T can be produced in a small volume. When a field with a rapid spatial variation is required, permanent magnets may offer the only practicable solution. Both permanent magnet structures and the uses to which they are put are reviewed, classifying the magnet applications in terms of the nature of the field, the effect on the magnet and the physical effect exploited.     

Development of an Algorithm for Magnet Sorting and Field Shimming for TPS Elliptically Polarized Undulators

A spatially periodic magnetic field is essential to cause an electron beam to wiggle and to emit electromagnetic radiation in a synchrotron (SR) source of radiation, and to provide fully coherent light in free electron lasers (FEL). To create this field, permanent magnets (PM) or electromagnets are patterned in a device commonly called an insertion device for SR and a radiator or modulator for FEL. In reality, magnet blocks or iron poles are not identical, in terms of geometry and magnetic properties, even with progressive manufacture. Compensatory methods are thus desired to recover the magnetic field and also to decrease the duration of construction. Magnet sorting is a pre-process that aims to eliminate the effect of manufacturing error. Before assembly of an insertion device, data of each component, especially the magnetic properties of each magnet block and the gap variation of mechanical structure, are organized to optimize the performance of the magnetic field. After that process, there is sometimes an optimization to shim the magnetic field. An effective algorithm of both processes is significant, particularly for a long undulator and an elliptically polarized undulator (EPU).