Pepan Letters
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Preprints and Communications

Here you can find JINR preprints and communications in pdf format starting from 1999.
File size is given in bytes in round brackets.

Subject Categories for JINR Publications Archive (1999 - 2021)

E3-2022-43 (1.179.334)
Sukhovoj A. M., Mitsyna L. V.
A Possibility of Simultaneous Obtaining of the Nuclear Level Density and Radiative Strength Functions When Analyzing (n,2γ) Reaction

For 43 compound nuclei from the 40 ⩽ A ⩽ 200 mass region,the most probable nuclear-physical parameters (the radiative strength functions and nuclear level density) were accumulated obtained by the empirical method of analysis of precise experimental intensities of the two-step γ cascades in nucleus decaying after thermal neutron capture. The method allows obtaining the strongly correlated nuclear-physical parameters from indirect experiment simultaneously which enables to investigate the intranuclear processes. The results of the empirical analysis are presented for all investigated nuclei when testing versions of model representations of energy dependences of the required nuclear-physical parameters.

P13-2022-40 (396.114)
Avdeev S. P. et al.
Detector for Setting Up Beam Convergence and Determining Luminosity at the Interaction Point on the MPD NICA

A detector for adjusting the convergence of beams at the point of interaction of the MPD (Multi-Purpose Detector) installation at the NICA collider (Nuclotron-based Ion Collider fAcility) is discussed. Simulation of the detector operation for Au + Au collisions at √SNN = 11 GeV is performed. It is shown that background events from scattering on residual gas give a negligible contribution to the detector's samples. The question of how to use a detector to adjust beam alignment is discussed. The calibration procedure for obtaining absolute luminosity in the MPD interaction zone with the help of this detector is considered.

P13-2022-33 (537.588)
Artukh A. G. et al.
Precision High Voltage Sources for Nuclear Radiation Detectors on POL-12012 (KST-POL-12012) Transformers

Precision high-voltage sources have been developed for nuclear radiation detectors (semiconductor detectors, based on photomultipliers, etc.). Instead of a specialized high-voltage source, an AC line voltage transformer (∾220 V) POL-12012 together with a voltage multiplier was used. Electrical parameters of the units: range 0...+/2,5 kV, power ⪯10 W, efficiency 77%, ripple factor (2 kV/1 mA) 1 mV, conversion frequency 80150 kHz, temperature drift ⪯004%/°, operating temperature 40...+ 60°, manual/external control, smooth rise/fall of voltage, shutdown during overload. Structurally, the blocks are made in two versions: Euromechanics 3U or stand-alone module 80x80x40 mm. They are used in a number of experiments and industrial installations, where they provide quality, reliability, temperature range and the necessary functionality.

P11-2022-32 (301.110)
Amirkhanov I. V. et al.
Numerical Investigation of the Influence of Finite Sample Thickness on Laser Ablation of Materials

In previous works, numerical simulations of laser ablation of materials that occurs under the action of ultrashort laser pulses in semi-constrained samples were carried out. In the present work, a similar numerical study was carried out in samples of a finite size. The action of the laser is taken into account through the source functions in the heat conduction equation, setting the coordinate and time dependences of the laser source. During laser ablation of the material, the thickness of the sample changes. By passing to the moving coordinate system, the problem with moving boundaries is transferred to the problem with fixed boundaries. In this case, in the heat conduction equation, along with the diffusion term, a convective heat transfer term arises. The effective speed of the convective term involves the speeds of displacements of the first and second boundaries, as well as the variable thickness of the sample. In our new formulation of the problem, the variable thickness of the sample affects not only the convective term, but it affects the diffusion term, the source functions, and the boundary conditions of the heat equation. These influences are visible from the mathematical formulation of the problem itself. Other effects are established by numerical simulation.

P11-2022-31 (797.241)
Amirkhanov I. V., Sarkhadov I., Tukhliev Z. K.
Simulation of Thermal Processes Appearing in Materials under the Action of Laser Pulses within the Hyperbolic Thermal Peak Model

The paper proposes a modification of the thermal spike model (TSM) based on a system of two coupled hyperbolic heat conduction equations. The action of the laser in the electron gas is taken into account through the source function, which was chosen in the form of a double femtosecond laser pulse. In the hyperbolic TSM, in contrast to the parabolic TSM, there are additional parameters that characterize the relaxation times of the heat flux in the electron gas and the crystal lattice. In addition, there are additional terms in the sources of the hyperbolic TSM derivatives from the sources of parabolic equations and from the temperatures difference between the electron gas and the crystal lattice. This means that the temperatures of the electron gas and the crystal lattice are influenced not only by the sources, but also by their rates of change. Assuming that the thermophysical parameters of the sample material are independent of temperatures, the hyperbolic TSM equations are linear. Using this property of the equations in the present work, the contributions of each term of the common source in the electron gas to the temperatures of the electron gas and the crystal lattice are established.

D17-2022-30 (3.533.537)
Shukrinov Yu. M., Nashaat M.
JINR Collaboration with Scientific Institutions of Egypt in the Field of Theoretical Research of Superconducting Josephson Nanostructures

An overview of the results obtained in the framework of JINR collaboration with Egyptian scientific institutions in the field of theoretical research and modeling of various superconducting Josephson nanostructures is presented. In particular, systems of coupled Josephson junctions with various types of shunting are considered, and results are presented that reflect their phase dynamics and current-voltage characteristics for various resonance phenomena. Much attention is paid to the study of superconducting structures with ferromagnetic materials, which make it possible to control the magnetic properties of the system by a superconducting current. An important place is occupied by joint studies of topological and chaotic phenomena in Josephson structures.

E1-2022-29 (796.223)
Yurevich V. I.
Phenomenological Model of Nucleon-Induced Fission Cross Sections in High-Energy Region

A phenomenological model was developed for approximation and numerical estimation of fission cross sections in interactions of high-energy nucleons with heavy nuclei. The model predictions are compared with the most reliable experimental data, available estimations and theoretical calculations for different nuclei from 181Ta to 239Pu. The model reproduces well the experimental results above 50 MeV and has good prediction potential.

E1-2022-22 (287.247)
Sovd M. et al.
Thermodynamic Characteristics of Particles Produced in πC Interactions at 40 GeV/c as a Function of the Cumulative Number and the van der Waals Equation of State

In this paper we have determined constants a and b of the van der Waals equation of state using the experimentally obtained critical parameters Tc, Vc and Pc for πC mesons and protons from πC interactions. The PV diagrams have also been analyzed.

E1-2022-21 (267.611)
Sovd M. et al.
On the Possibility of Pion Condensation from π-C Interactions at 40 GeV/c

In this paper we consider an opportunity of observing the π-meson condensation on the basis of the dependence of temperature (T) on the target mass (mt )and chemical potential (μsec(μB,T)) obtained for π+C interactions at 40 GeV/c.

E1-2022-20 (267.611)
Baatar Ts. et al.
Two Different Distance Scales of q2 and VQCD Potential of Protons from π-C Interactions at 40 GeV/c

In this paper we have expressed the formula for the four-momentum squared q2 as a function of two different distance scales r1 and r2. This procedure necessitates taking into account an additional derivative from the formula for q2 (or the running coupling constant of αs(q2)). We have calculated the force using the potential VQCD(r2). The impact of r2 parameter on the force has also been studied.

E6-2022-19 (270.279)
Efimov A. D., Izosimov I. N.
Extrapolation of the Energies of the 21+, 41+, 61+ States in the Superheavy EvenEven Nuclei

Based on the existing correlation between the deformation energy and the lowest excitation energy, estimates were obtained for energy of the 21+ states. The considered systematics of the energy ratios in the rotational band also made it possible to obtain estimates for the 41+ and 61+ states. A comparison with the results of other works was carried out.

P3-2022-13 (496.940)
Dubois M. et al.
Enhanced Directional Extraction of Very Cold Neutrons Using a Diamond Nanoparticle Powder Reflector

For more than a decade, Detonation NanoDiamond (DND) powders have been actively studied as a material for efficient reflectors of Very Cold Neutrons (VCNs) and Cold Neutrons (CNs). During this time, the storage of VCNs in traps with walls made of DND powder and the quasi-specular reflection of CNs from layers of DND powder have been experimentally demonstrated. The quality of DND powder has been improved by reducing the fraction of impurities causing neutron losses, as well as by choosing the powder parameters that correspond to the most efficient reflection of neutrons. Methods for calculating the transport of neutrons in real powders have been developed. In this work, we experimentally demonstrate the possibility of shaping a VCN beam using a reflector made of fluorinated DND (F-DND) powder. With respect to the flux from an isotropic source located at the bottom of the reflector cavity, the gain in the VCN flux density along the beam axis is ∼ 10 for the neutron velocities of 57 m/s and 75 m/s. The gain in the total flux at the exit from the reflector cavity is ∼ 14 for the fastest VCNs from the interval 4692 m/s and increases with decreasing VCN velocity, reaching ∼ 33 for the slowest VCNs.

E7-2022-12 (413.769)
Isaev A. V. et al.
Spontaneous Fission of 246Fm

An experiment on the study of the 246Fm spontaneous fission was conducted using the SHELS separator. The isotope was synthesized in the complete fusion reaction of 40Ar beam ions and 208Pb target nuclei. The neutron yields of 246Fm spontaneous fission (¯ν = 3,79±0,30, σ2nu = 2,1) were obtained using the SFiNx detector system. The multiplicity distribution of emitted prompt neutrons was restored using the Tikhonov method of statistical regularisation (¯νr = 3,79 ± 0,20, σ2νr= 2,8). The spontaneous fission branching ratio (bSF = 0,061 ± 0,005) and the half-life (T1/2 = 1,50+0,08-0,07 s) of the isotope were determined. The experimental data were compared with scission point model predictions. Excellent convergence was observed in the average number of neutrons per spontaneous fission process. However, the forms of the experimental and model prompt neutron multiplicity distributions differ significantly.

9-2022-10 (927.586)
Teterev Yu. G. et al.
Estimation of the Yield and Angular Distribution of Neutrons for Calculating the Biological Protection of Reconstructed Heavy Ion Accelerators with Energies from 1 to 6 MeV/nucleon

Simple analytical formulas are presented for the operational estimation of the yield and angular distribution of neutrons, which are necessary for calculating the biological protection of heavy ion accelerators with energies from 1 to 6 MeV/nucleon. The results of the calculation were compared with the results of calculations using the LIZE++ and FLUKA programs and with the available experimental data in the literature. As a result of the comparisons, it can be argued that the proposed method for calculating the yield and angular distribution of neutrons from thick targets can be used to quickly assess the necessary biological protection of heavy ion accelerators under construction and reconstruction with energies from 1 to 6 MeV/nucleon. The deviation of the results of these calculations from the more accurate ones does not exceed a factor of two, which is comparable with the results of deviations in the calculation of biological shielding associated with a certain variety of spectra of produced neutrons and deviations in the protective properties of the materials used or their thickness.

P10-2022-5 (496.940)
Kirilov A.S., Murashkevich S.M.
Adaptation of the Sonix+ Software Package to Work with DAQ Controllers DeLiDAQ-2 and Digitizer N6730 by CAEN

Before the use of DeLiDAQ-2 controllers and Digitizer N6730 on the IBR-2 reactor instruments, the main form of DAQ output data was spectral distributions of intensities in matrix form, which, in particular, was used in the Sonix$+$ software package for online visualization. Due to the fact that output data from considered controllers are available only in the events list form, the construction of spectral distributions (histogramming) must be done by programs.The work is devoted to adaptation of the complex for use of the controllers specified, algorithms of data histogramming for them, as well as to tests results carried out at the GRAINS instrument (beam 10 of the IBR-2) in October 2021 consideration.

P10-2022-4 (496.940)
Kirilov A. S., Truntova L. A.
Enhancement of Experiment Control in the Sonix+ Software Package

The work is devoted to enhancing the Sonix+ software package at the IBR-2 instruments to minimize the loss of measurement time when including mathematical operations (summing matrices, building spectral distributions of intensity based on data from the list of events, etc.) directly in the experimental procedure in the Python language (script). For this purpose, the execution of all such operations was separated from the main script into one or more background scripts. A special device class has been added to the complex structure to execute background scripts. Besides this, the checkpoint mechanism previously used to connect the user interface with the script has been replaced by a new one based on Python language decorators and context managers. This significantly simplified the script, improved its reliability, and reduced the time of its development or modification.

2022-2 (20.032.428)
Brief Review of Topmost Scientific Results Obtained in 2021 at the Joint Institute for Nuclear Research

9-2022-1 (2.030.431)
Kozlov O. S. et al.
Actual Tasks of Beam Dynamics Analysis in the NICA Collider

The NICA project is under development at the Joint Institute for Nuclear Research (Dubna). The accelerator complex is in the stage of step-by-step assembly and commissioning. The complex consists of two superconducting synchrotrons and a superconducting ion collider. Numerous studies of beam dynamics, performed at the design stage, formed the basis of R&D of the collider systems. Most part of tasks was done in detail and totally completed. However, a number of tasks are not finished and actual to date. Some of them, being fundamental, need detailed analysis using three-dimensional particle tracing with taking into account all the main physical effects and nonlinearities of electromagnetic fields of the structure. Key task in the NICA collider is study of collective phenomena, to which this work is mainly devoted. The paper describes the current status of numerical and analytical calculations of beam stability in the NICA collider and possible plans of solution of noncompleted tasks.