A procedure for separating one- and two-neutron events using the number of active cells and the number and shape of clusters is described. This procedure is effective also in the case of identical neutron energies, when criteria based on time-of-flight information fail. The results of Monte Carlo simulation with the Geant4 toolkit of the interaction of single and pairwise neutrons with energies from 0.5 to 4 GeV in a 16‑layer neutron detector are presented.
An Erratum to this paper has been published: https://doi.org/10.1134/S1547477126040011
The feasibility of allocation of a spectator hadron calorimeter, designed to determine the centrality of collisions, at the NICA collider by using the collider’s magnetic elements is considered. It is shown that the achieved deflection of the proton spectators from the main beam virtually eliminates the ambiguity of the calorimeter data for central and peripheral events.
Various methods to produce Gd-containing nanoparticles (precursors of Gd2O3) were assessed. Their size and morphology are shown to strongly depend on the synthesis technique and composition. The reaction of highly diluted solutions of gadolinium nitrate with ammonium oxalate led to formation of Gd2(C2O4)3 oxalate sol particles with a size of 8 nm in presence of surfactant and 26 nm particles when it was absent. During storage of these sols, the particle size increases to 180–200 nm. Gd(OH)3 particles and Gd2(C2O4)3 particles were synthesized by the sol–gel method. Hydroxide Gd(OH)3 had the morphology of extended broken planes, while oxalate Gd2(C2O4) had the structure of micrometer-sized polyhedra. Subsequent application of SiO2 shells to their surface by the hydrolytic decomposition of tetraethoxysilane led to formation of core–shell particles Gd(OH)3@SiO2 and Gd2(C2O4)3@SiO2, morphologically identical to the Gd(OH)3 and Gd2(C2O4)3 nuclei. Thermal decomposition of Gd(OH)3 and Gd2(C2O4)3 or gadolinium citrate resulted in formation of cubic Gd2O3 particles whose morphology does not depend on that of the precursors.
A mathematical model is formulated to describe the plasma treatment of spent nuclear fuel (SNF) reprocessing wastes, which are fed into an air-plasma flow as dispersed aqueous–salt–organic compositions (ASOCs) containing ethanol or acetone as organic additives. The model describes the coupled kinetics of droplet heating and evaporation, interphase momentum exchange, and heat and mass transfer within a one-dimensional two-phase-flow framework, which is cast in dimensionless form to enable parametric analysis and scale-up. Thermochemical calculations are used to determine optimal ASOC formulations that provide an adiabatic combustion temperature of approximately 1500 K, thereby ensuring energetically efficient plasma operation and complete oxidation of the organic fraction. The influence of key operating parameters—initial plasma temperature and velocity, droplet size and injection velocity, and liquid-to-gas mass ratio—on the spatial extent of droplet evaporation is investigated numerically using a fourth-order Runge–Kutta integration scheme with controlled accuracy. The results show that, at temperatures above about 1500 K, the overall rate of plasma utilization is governed by solvent (water) evaporation, whereas further increases in inlet plasma temperature have only a weak effect on the length of the complete-evaporation zone. In contrast, droplet size and flow hydrodynamics exert a dominant influence: reducing the initial droplet diameter from 100 to 40 μm and decreasing the gas-flow velocity from 90 to 10 m s–1 lead to multi-fold reductions of the evaporation length, allowing complete evaporation within reactor lengths not exceeding 1 m. The resulting model serves as a physically sound and computationally efficient means of forecasting and refining droplet-evaporation dynamics in air-plasma reactors designed for processing wastes from spent nuclear fuel reprocessing and other liquid radioactive waste streams.
This study investigates proton-induced reactions on enriched selenium targets, focusing on the production of bromine radioisotopes, which are of significant medical relevance for both diagnostic imaging and therapeutic applications. The study employs Monte Carlo samples to evaluate for experimental uncertainty in energy and cross-section simulations, then enters corrected energy into TALYS 2.0 and compares corrected cross-sections to predictions. The relative variance technique was used for assessing experimental data from the EXFOR database using nuclear level density models that are included of the TALYS 2.0 code. The results demonstrated that the 77Se(p,2n)76Br and 78Se(p,2n)77Br reactions are among the most significant production routes, yielding 224.4 and 284.1 mCi/(µA h), respectively, with radionuclidic purities of 96.8 and 85.5
Superfluid He-4 can serve as a tool for neutrino and dark matter detection. Low-energy neutrino interactions with superfluid He-4 can take place in the form of coherent elastic neutrino-atom scattering (CEvAS), a process that has not been observed so far. The first experimental study of CEvAS is in preparation in the National Center for Physics and Mathematics in Sarov. Using a high-intensity tritium neutrino source and a superfluid He-4 detector, it will have a rich potential to test the neutrino physics of the Standard Model and beyond it at unprecedentedly low energies. For example, one of the observable effects of the physics beyond the Standard Model in CEvAS can be neutrino millicharge and magnetic moment. In this study, we apply the formalism of open quantum systems to describe the evolution of the recoil helium atom after neutrino scattering on superfluid helium. In particular, we have obtained the Lindblad equation for a helium atom with an initial recoil energy of higher than 2 meV, which suffices to remove the atom from the condensate.
For the first time, we have measured the flux-weighted average yields of (γ, α) reactions on targets of natural osmium and iridium for a bremsstrahlung beam with a cutoff energy of 55.5 MeV. Theoretical calculations including an α-particle preproduction factor of 10–2 provide a satisfactory description of experimental data. It has been established that at photon energies below 55 MeV, nonstatistical mechanisms of charged particle emission predominate.
This work presents comprehensive calculations of resonance energies and quantum defects associated with photoabsorption and photoionization of singly ionized strontium (Sr II) over a wide energy range, using the modified atomic orbital theory (MAOT). The study focuses on Rydberg series originating from inner-shell transitions of the type 4p65s 2S1/2 → 4p45s (1,3P)ns/nd, as well as from doubly excited transitions 4p65s 2S1/2 → 4p54d (1,3P,3D)ns/nd. For the first time, resonance energies are determined for a wide range of principal quantum numbers n, including highly excited states of astrophysical relevance. The MAOT results show excellent agreement with experimental measurements obtained using the double laser plasma (DLP) technique and with multiconfiguration Hartree–Fock (MCHF) calculations reported by Banahan et al. [14]. These findings validate previously uncertain experimental assignments and clarify spectral features affected by strong overlap between the 4d and 5s orbitals and by pronounced configuration interaction. The present results significantly improve the reliability of available spectroscopic data and provide valuable atomic parameters for modeling astrophysical and laboratory plasmas.
In this paper, we consider the features of the figure-8 accelerator from the spin dynamics point of view. Some of the main advantages of such a structure are: the absence of spin resonance crossing during beam acceleration and the ability to manipulate polarization in the spin-transparent mode. In this paper, we numerically verify the hypothesis that the figure-8 ring is characterized by a spin coherence time of several hours; we consider the influence of second-order deviations in phase coordinates on decoherence. The modifications of the figure-8 ring to search for a signal of axion-like particles and the electric dipole moment of light nuclei are also presented.
The paper investigates the phenomenon of transverse bending of rod fuel elements of the active zone under the influence of temperature, which plays an important role in the dynamics of a periodic pulse reactor. Analytical calculation of thermoelastic deformation showed that positive feedback is directly related to the method of fixing the fuel elements. The possibility of fixing, eliminating the positive effect of reactivity, is demonstrated, and ways of technical solution of the problem are proposed.
A separator for the real-time beneficiation of iron ore on a conveyor belt has been developed. The method of tagged neutrons is used to determine the elemental composition of ore. A portable neutron generator ING-27 is used as a neutron source. Characteristic gamma quanta are detected by 14 gamma detectors based on BGO crystal. Ore is separated into marketable product and tailings by a gate device controlled by neutron-analyzer signals, which checks on-line the compliance of elemental concentrations of ore with the required values. The results of the separation are discussed.
The knowledge of the stress and strain state in rock sample is of importance in the understanding of the rock properties for the interpretation of geodynamic processes and for geotechnical applications such as mining and tunneling. Recently, the topic of induced seismicity has become a major issue in geoenergy production (gas production, geothermal). Thus, the role of tectonic stress for the initiation of rock failure is of high scientific but also economic interest. The investigation of deformation with conventional lab scale experiments allows the determination of macro-strain in the cm- to m-range. On the nano to micro-scale, the application of diffraction methods offers the investigation of the strain which is localized in the crystal lattice, the so-called intra-crystalline strain. This localization of strain in a sample with dimensions in cm-range is achieved by strain scanning. Because of the low absorption properties of neutrons in matter, like metals and minerals, neutron diffraction is an excellent method for the investigation of strain in bulk samples, especially in multiphase samples, like rocks. The neutron time-of-flight strain diffractometer EPSILON operated at the pulsed neutron source IBR-2M at the JINR Dubna is designed for the investigation of residual and applied intra-crystalline strain of bulk samples. Because of the large wavelength-range (up to λ = 7.8 ) diffraction pattern with d spacings up to d = 5.6 can be investigated. Using the long flight path of about 107.03 m a good spectral resolution is achieved. That allows the investigation of multiphase rocks containing minerals with lower crystal symmetry. The diffractometer is equipped with an uniaxial applied stress device, allowing load states up to 100 kN, e.g., 150 MPa with sample diameters of 30 and 60 mm length. The investigations concentrated on 3 locations within the sample: in the centre, at the rim and at a location in-between (half-radius). To avoid immediate rock failure a pre-experiment to determine the failure stress has been performed. Sample OU-2 (sandstone) has been scanned for 4 load steps (0, 11.65, 23.5, 35.21 MPa axial load). For each load level, the intra-crystalline strain has been determined in the direction of σ_1 and σ_3 . A newly developed analysis tool which uses all diffraction peaks for detection of the lattice deformations has been applied to determine the in situ modulus of elasticity and the Poisson´s ratio at different positions (rim, half-radius, center) within the sample.
A mobile analyzer of the elemental composition of soil based on the tagged neutron method has been developed. The analyzer consists of a neutron module towed across the field by a transport platform. Elemental analysis of the soil is carried out in real time without sampling. The results of field tests of the analyzer are discussed.
This work presents the general concept of a storage ring structure for the investigation of the electric dipole moment (EDM) of the proton and deuteron. The main features of frozen-spin and quasi-frozen-spin structures, designed to suppress spin rotation due to the magnetic dipole moment (MDM), are described. For the implementation of the proposed methods, the dependence of the fields in spin-compensating elements is determined.
Results of studies on variations in neutron intensity in different energy ranges (slow and high-energy ≥100 MeV) obtained at the high-mountain Tien Shan cosmic ray station near the Zailiysky fault are presented. The analysis of atmospheric pressure influence on neutron intensities reveals a common origin between slow and high-energy components. A significant contribution of the lithosphere to the flux of slow neutrons during seismic activity has been established, reaching up to 10–12
Dating is one of the most important tasks in archaeology. Studies of elemental composition using neutron activation analysis, combined with statistical data treatment, enable the establishment of indirect dating for the investigated artifacts. In this study, 11 mortar samples were studied. The samples were collected from buildings located on the territory of the Yuryev Monastery (Veliky Novgorod, Russia). For irradiation, the IREN facility at Joint Institute for Nuclear Research (Russia) and the WWR-K reactor at Institute of Nuclear Physics (Kazakhstan) were used. Using neutron activation analysis, mass fractions of 34 chemical elements were obtained. By applying multivariate statistical methods (hierarchical cluster analysis, principal component analysis, and factor analysis), it was established that the elemental composition of mortars from various historical periods differs significantly. This enabled the identification of groups corresponding to specific historical periods. It was shown that the content of rare earth elements in samples dating back to the pre-Mongol period is elevated compared to samples with later dating. The obtained data enabled the classification of samples with unknown dating using the method of indirect dating.
The article presents a fundamental approach to figure-8 ring structure for multiple physical programs. Firstly, the unique shape of the ring resolves the issue of spin resonance crossings during the acceleration of a polarized beam. Secondly, this structure can be used for electric dipole moment (EDM) measuring experiments and axion search. Thirdly, the structure can be adapted for heavy-ion beam acceleration.
The work presents preliminary results of a theoretical analysis and modeling of proton spin sensitivity in a quasi-frozen spin lattice, used as a broadband axion antenna, with an emphasis on the constraints from the axion field local phase coherence time and the polarized beam spin coherence time. Three major topics include: axion field resonance conditions; the proposal to use (quasi-)frozen spin technologies to improve the axion field local phase coherence time; the impact of sextupole fields used to improve the beam spin coherence time.
