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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.
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P7-2025-29 (3.040.235)
Fomichev A. S. et al.
Research of Neutron-Rich Nuclei in Reactions
with Radioactive Beams and a Cryogenic Tritium Target
The work is devoted to the research in the field of fundamental nuclear
physics on the study of the structure of light neutron-rich nuclei in experiments
with radioactive beams (E ∾ 20–50 MeV/nucleon) and a cryogenic tritium
target (gas or liquid) at the ACCULINNA-2@U-400M complex. The main
emphasis in the article is on the uniqueness of the new complex and its
advantages in relation to the ACCULINNA-1 equipment, the prospects of using
direct nuclear reactions (t, α) and (t, p) at these energies for the purpose of
studying such isotopes as 7H, 10Íå, 13Li, 16Âå, etc., and also on the first day
experiments.
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P13-2025-19 (8.433.416)
Verhoglyadov A. E., Kushnir I. V.
Numerical Calculations of Fuel Assemblies Bending in the IBR-2 Reactors
The work is dedicated to study of bending of fuel assemblies (FA) under the
non-uniform temperature distribution in the core of a periodic pulsed reactor.
Numerical calculations of the transverse deformation of the IBR-2 fuel assembly
in full geometry were carried out taking into account the coolant flow. The
shape of the bend, the displacement of fuel pellets and the time dependence of
deformation after pulsed energy release were found. Since the bending of the
FA changes the reactivity and has a negative effect on the reactor dynamics, a
possible method for reducing the bending value is proposed using coolant flow
profiling. The results can be used in the design of a new neutron source.
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P9-2025-16 (8.433.416)
Sumbaev A. P. et al.
Accelerator LUE-200.
Status, Capabilities and Development Problems
The article reports on the status of the accelerator facility of the Laboratory of Neutron Physics (LNP) of the Joint Institute for Nuclear Research (JINR, Dubna) — the
driver of an intense pulsed source of resonant neutrons. The general scheme of the linear electron accelerator and the features of its basic systems are presented.
LUE-200 consists of two accelerating sections on a traveling wave with an operating frequency of 2856 MHz with SLEDtype microwave power compression systems.
The pulsed beam current at the accelerator output reaches 2 A with a pulse duration of 80–120 ns. With an average beam particle energy of 90–110 MeV
and an acceleration cycle frequency of 50 Hz, the average beam power reaches 0.95–1.0 kW. The integral neutron flux (in the thermal and resonance energy range)
from a non-multiplying W-target reaches values of ∼ 1.06 · 1012 s-1. The possibilities of further development of the accelerator are discussed.
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P13-2025-15 (289.266)
Verkhoglyadov A. E., Shabalin E. P.
Model of the Dynamics of the IBR-2 Reactor Based on Two-Component Power Feedback
In the course of the work on studying the dynamics of the IBR-2 reactor, two main effects of reactivity feedback were indicated: the elongation of the column
of fuel pellets and the transverse bending of the fuel assemblies. A model of the dynamics of the IBR-2 reactor is described that takes these effects into account.
It is assumed that the instability of the dynamics occurs due to a change in
the amplitude of one of the effects, which depends on fuel burnout. It is shown
that at a certain value of the burnout parameter the reactor dynamics becomes
unstable.
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E4-2025-14 (628.141)
Efimov A.D., Koval I.V., Izosimov I.N.
Harris Model and IBM for Pu, Cm, Fm, No
For heavy even nuclei Pu, Cm, Fm and No, the description of the energies
of yrast bands in the Harris phenomenological model of the variable moment of inertia and in the interacting boson model (IBM), including IBM phenomenology, is considered. For two nuclei,
244Pu and 248Cm, the results of calculations in the extended IBM version are also presented. Comparison of these results made it possible to identify different characteristics
of the behavior of the moment of inertia as a function of the square of the rotational frequency and obtain corresponding interpretations of their features. In particular, a version
is proposed that explains the weakening of the growth of the moment of inertia for spins of states greater than 24+ in a number of nuclei.
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P9-2025-9 (3.758.571)
Amoskov V. M. et al.
Achieving the Desired Field Gradient in PM-Based Quads through Computerized Sort-Out of PM Units with Measured Parameters
The study is focused on the optimized design and fabrication of a PM-based quadrupole for beam transportation and focusing in the DC140 cyclotron. The quad has
a modular configuration with a set of geometrically similar PM bricks in every module. Prior to assembly, geometrical and magnetic parameters were measured over the whole set of PMs.
The measured data were used to adjust positions and orientations of PM bricks. A generalized procedure is proposed in a form of a program module to retrieve, sort out,
and group specifications of individual PMs from the measurement database. This procedure can be applied to compare and select parameters for various magnets based on PM assemblies
without limitation on the PM nomenclature.
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P9-2025-8 (1.532.364)
Amoskov V. M. et al.
Inspection of Geometric and Magnetic Parameters of PM-Based Quads in Precision Transport System for Accelerator Application
The study is focused on performance of permanent magnet–based quadrupoles (PMQ) used for beam transportation and focusing in the DC140 cyclotron.
An inspection procedure is examined, which combines 3D field simulation and measurement for geometric and magnetic parameters of PM units. The results are used to
guide practical measurement technique and instrumentation decisions. A set of supplied PM units has been measured and an optimum intramagnet PMQ
configuration has been determined. As a result, the prototype, reference, and test magnets have been assembled.
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P3-2025-7 (1.235.980)
Verhoglyadov A. E. et al.
Calculation of the Reactivity of a Pulsating Reactor Taking into Account the Thermoelastic Deformation of the Fuel
The paper studies the change of the reactivity of the pulsed reactor IBR-2 due to the thermal expansion of the fuel caused by a single power pulse.
In the accepted model, the temperature is found by solving a system of two-dimensional nonstationary heat equations.
The deformation of fuel pellets is calculated in 3D geometry using the finite element method. Critical calculations were performed using the Monte Carlo method
in the full geometry of the reactor. It is shown that the reactivity of the reactor has a complex dependence on time. The obtained results will be used for accurate calculations
of the dynamics of a pulsed reactor.
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E4-2025-4 (537.889)
Efimov A.D., Koval I.V., Izosimov I.N.
Comparison of the Description of Yrast Bands in the Harris and IBM Models for Even Nuclei Th and U
For even Th and U nuclei, the description of the energies of yrast bands in the Harris variable moment of inertia model is studied in its phenomenological
application. For some of these nuclei, the results obtained in the IBM microscopic
version are presented, in which high-spin excitation modes are also considered.
For other nuclei, in cases where high-spin orbits are not so significant in
describing the properties of yrast bands, in addition to the Harris model, IBM
with a full standard Hamiltonian constructed only from s, d bosons is utilized.
Since the Harris model is considered with no more than four parameters, it can
be used for both heavy and superheavy nuclei to approximate the energies of
high-spin states. The study of the properties of nuclei in various models will
reveal the possibilities of describing different behavior of the moments of inertia
in IBM and outline additional criteria for the implementation of band crossing.
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P13-2025-2 (2.515.072)
Mitrofanov S.V. et al.
Beam Profile Measurement at the Entrance of the Gas-Filled Solenoid GASSOL
A beam profilometer has been developed and tested for use at the entrance
of the gas-filled solenoid GASSOL during its commissioning and adjustment.
The profilometer is constructed as a mosaic of cathodes, each measuring current
generated by secondary emission during bombardment by accelerated ions being
measured from each cathode. A corresponding number of current amplifier
channels is used to measure the currents from the cathodes. A software program
has been developed for visualizing the beam profile. During an experiment with
a 40Ar+4 ion beam at an energy of 4 MeV per nucleon, the lower sensitivity limit
of the profilometer was found to be less than 0.001 pnA. The upper sensitivity
limit, determined through thermal calculations, is 100 pnA. A critical factor is
the risk of signal cable contact failures due to heating. The accuracy of beam
centre determination, ∓1 mm, falls within the specified tolerance for radial
displacement of the beam axis relative to the magnetic axis of the solenoid.
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