Prospects and opportunities for particle physics accelerators at the energy frontier are reviewed. In particular, the main features characterizing hadron and lepton collider facilities proposed at CERN and in other known laboratories are discussed. 

The issues of the international cooperation of Belarusian organizations with the Joint Institute for Nuclear Research within the framework of international projects with the participation of scientists and specialists of Belarus are considered. 

When high energy particles move along the crystal axis or plane, they experience the action of an extended effective field, the strength of which by orders of magnitude exceeds that of any stationary magnet. These fields give rise to wide possibilities of new phenomena observation, particle properties measurement, high energy beam control, generation and polarization. Many of their possibilities have been predicted by Belarusian scientists and observed at CERN, FNAL, IHPEP, etc. The revealed effects of channeling efficiency increase by crystal cutting and multiple volume reflection from different atomic planes of the same bent crystal make it possible to improve the radiation protection of superconducting magnets of both the high luminocity Large hardron collider phase and the Future circular collider. A drastic enhancement of both radiation and pair production processes in crystals can influence the functioning of both the existing Compact muon solenoid electromagnetic calorimeter at CERN and Fermi gamma-telescope as well as can be applied to devise more effective calorimeters and gamma-telescopes in future. A remarkable effect of channeling particle spin rotation in bent crystals enables one to measure both magnetic and electron dipole moments of short-lived charm and beauty hyperons as well as to observe electron magnetic moment modification. 

The signatures of the spin-2 graviton excitations predicted by the Randall – Sundrum model with one warped extra dimension, in dilepton and diphoton production at LHC were studied. By using the center – edge asymmetry, we evaluate the ranges of mass and coupling constant where such gravitons can be discriminated against competitor spin-1 and spin-0 objects that could potentially manifest themselves in these processes. Depending on the value of coupling constants, the numerical results allow one to obtain graviton identification mass ranges of the order of 2.4 TeV and 3.2 TeV for LHC nominal energy of 14 TeV and time-integrated luminosity of 100 fb–1. 

The possibility of introducing coherent states of particles moving in constant homogeneous non-Abelian gauge fields is shown. An important feature of the model considered in the article is that each color degree of freedom corresponds to its characteristic size. 

N. Arkani-Hamed, S. Dimopoulous, and G. Dvali have proposed a model (ADD) of low-scale quantum gravity featuring large extra dimensions. In this model, the exchange of Kaluza – Klein towers of gravitons can enhance a production rate of lepton pairs at high invariant mass in proton-proton collisions at LHC. By considering the present and future LHC energy regimes, we have again analyzed the LHC potential to discover the effects of large extra dimensions and to discriminate between various theoretical models. Specifically, in the latter case we explore the LHC capability to distinguish spin-2 Kaluza – Klein towers of gravitons exchange from other new physics effects which might be conveniently parametrized by the four-fermion contact interactions. We find that LHC with planned energy of 14 TeV and luminosity of 100 fb–1 will be capable of discovering (and identifying) graviton exchange effects in the large extra dimensions with the cutoff parameter of the order MS = 6.2 TeV (4.8 TeV) for d = 6 and MS = 8.8 TeV (6.8 TeV) for d = 3. 

We discuss the existence of new phenomena and properties of nonperturbative evolution of color quarks, gluons and other states in stochastic vacuum of quantum chromodynamics, color dissipation and confinement; instability of movement of color particles in the confinement region; appearance of squeezed and entangled states of strongly interacting particles; correlation properties of strong instanton decays; chaos-assisted instanton tunneling; quark-gluon plasma properties description in terms of the Hagedorn bootstrap statistical model. 

In the present article we discuss a new class of scintillation materials that are prospective for application in high energy physics experiments and for detection of neutrons in a wide energy range. 

Ce-doped Lu3 Al5 O12 (LuAG), and Gd3 Al2 Ga3 O12 (GAGG) crystals with and without codoping by Mg2+ ions have been studied by the nonlinear absorption spectroscopy method. A faster rise time of transient optical absorption has been observed in all crystals codoped with Mg in comparison to Mg-free samples. A significant difference in the time evolution of the differential optical density in GAGG in comparison to LuAG crystals is revealed. in gadolinium garnets an absorption band peaked in the blue-green range and decaying with characteristic time of ~2 ps is observed. This band is considered to be due to absorption of free electrons before their trapping by Ce3+doping ions. A broad transient absorption band in the yellowred region is attributed to absorption from the Ce3+ excited states. 

A general theoretical description of a magnetic resonance is presented. This description is necessary for a detailed analysis of spin dynamics in electric-dipole-moment experiments in storage rings. General formulas describing a behavior of all components of the polarization vector at magnetic resonance are obtained for arbitrary initial polarization. Quasimagnetic resonances for particles and nuclei moving in non-continuous perturbing fields of accelerators and storage rings are considered. Distinguishing features of quasi-magnetic resonances in storage ring electric-dipole-moment experiments are investigated. The formulas for the effect caused by the electric dipole moment are derived. Main systematical errors are discussed. 

The primordial spectrum of scalar particleʼs density perturbations is calculated. On the assumption of spectrum universality, i.e., a mean energy density and a typical value of inhomogeneity can be chosen arbitrarily, the form of the spectrum turns out to be completely defined. It is close to the flat Harrison – Zeldovich spectrum, but with the suppression of low-frequency modes. 

In the framework of the scalar-tensor theory of gravitation, a scalar field is considered, whose source is the trace of own energy-momentum tensor and the trace of the energy-momentum tensor of matter. The potential that enters the Lagrangian of a scalar field depends on three parameters: scalar interaction constant, scalar field mass, and constant that determines the minimum of the field energy. The representation of the scalar-tensor theory on the Minkowski background with a linear connection between the metric and the tensor gravitational potential is considered, and the additional conditions for field equations are obtained that restriction a tensor field over its spin states. For a cosmological problem, it is shown that additional conditions lead to a spatially flat universe according to observations. Numerical solutions of field equations are obtained and on their basis it is shown that the cosmological parameters of the model well describe modern observational data and the scalar field under consideration can then successfully simulate dark energy. The area of variation of parameters of the cosmological solution was studied and a cosmological scalar-tensor solution was compared with the ΛCDM-model of General Relativity. Depending on the model parameters for cosmological evolution, possible scenarios are analyzed. 

UZrCN fuel is a high-density, high-temperature fuel that has potential for application in different type reactors. In the past, reactor tests using UZrCN HEU (96% U-235) fuel have been performed to low burnup. However, reactor-testing data are still needed at high burnup to confirm the optimal performance of this-type fuel. The SM-3 research reactor, which is a high-flux reactor located at the State Scientific Center – Research Institute of Atomic Reactors, Dimitrovgrad, Russia, will be used to test a UZrCN LEU (19.73% U-235) fuel to ~40% of burnup. The fuel will then be examined to determine its performance during irradiation.

On the “Giacint” and “Kristal” critical facilities located at the Joint Institute for Power and Nuclear Research – SOSNY of the National Academy of Sciences of Belarus, Minsk, Belarus, criticality experiments on multiplying systems modeling physical features of cores with UZrCN LEU (19.75% U-235) fuel have been prepared for use in works on fast reactors with gaseous and liquid-metal coolants. Critical assemblies represent uniform hexagonal lattices of fuel assemblies, each of which consists of 7 fuel rods and has no clad. The active fuel length is 500 mm. Clad material is stainless steel or Nb. Three types of fuel assemblies with different matrix material (air, aluminum and lead) are investigated. These are side radial, top and bottom reflectors – beryllium (internal layer) and stainless steel (external layer).

This article desribes the design of the experiment that will be performed in the SM-3 reactor and discusses the results of different calculations that have been performed to show that the experiment design will meet all objectives. The description of construction and composition of critical assemblies with UZrCN fuel and the calculation results are also presented. 

The problems of state and the next technical maintenance radiotherapy and nuclear medicine evaluation in the Republic of Belarus are discussed. Now the treatment of oncological patients in radiotherapy puts to electron linear accelerators instead of irradiation them on external gamma-therapy units with 60Co. Dosimetric monitoring of new high technological methods of radiotherapy is described. Application of such complex precision methods on linear accelerators increases the efficiency of radiotherapy, practically decreases the complication in normal tissue and critical organs surrounding the volume targets during and after irradiation. Application of the modern diagnostic emission tomography including positron emission tomography units with ultrashort living radionuclides allows one to essentially improve the quality of cancer distribution detection, to develop the optimal treatment of patients, and to control them during the period after treatment. The ways of next technical maintenance evolution in radiotherapy and nuclear medicine are discussed. 

Vladimir Nikolaevich Belyi (To the 70th Anniversary).

List of Publications for 2017 in “Proceedings of the National Academy of Sciences of Belarus. Physics and Mathematics Series”.