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A. A. Solnyshkin

Publications and source records attributed to A. A. Solnyshkin.

16 recordsLinked to original sources

Experimental and theoretical research of photoneutron reactions in the 181Ta nucleus

Bremsstrahlung fluxes for irradiating tantalum samples were formed by irradiating a tungsten converter with an electron beam with energy up to 130 MeV. The relative yields and flux-averaged cross-sections of multinucleon photonuclear reactions with the emission of up to 9 neutrons in 181Ta nuclei were determined. Monte Carlo simulations to study the yields of photonuclear reactions were performed using Geant4 and TALYS-2.0 codes. The obtained experimental results were compared with the available literature data and calculated results. The comparison showed that the values of the relative reaction yield and the flux-averaged cross-section coincide with the literature data, taking into account the different geometry of the experiments. The calculated results coincide with the experimental ones only for reactions with the emission of up to 5 neutrons from the nucleus.

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Photonuclear reactions on $^{59}$Co at bremsstrahlung end-point energies of 40-130 MeV

Relative yields have been measured in the 40-130 MeV bremsstrahlung induced reactions of 59Co. The experiments have been performed with the beam from the electron linear accelerator LINAC-200 using the activation and off-line {\gamma}-ray spectrometric technique. The bremsstrahlung photon flux has been calculated with the Geant4 program. The cross sections were calculated by using computer code TALYS-1.96 with different models and are found to be in good agreement with the experimental data.

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Interaction of photons with silver and indium nuclei at energies up to 20 MeV

The yields of photonuclear reactions in the 107Ag, 113In, and 115In nuclei have been measured. Monte Carlo simulations have been performed using the Geant4 code, and the results have been compared with the experimental ones. The isomeric ratios of the yields in the reactions 107Ag({\gamma},n)106m,gAg and 113In({\gamma},n)112m,gIn have been determined. The cross sections for the reactions 107Ag({\gamma},n)106gAg and 107Ag({\gamma},2n)105Ag at an energy of 20 MeV have been calculated on the basis of the experimental data.

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Study of secondary neutron interactions with $^{232}$Th, $^{129}$I, and $^{127}$I nuclei with the uranium assembly "QUINTA" at 2, 4, and 8 GeV deuteron beams of the JINR Nuclotron accelerator

The natural uranium assembly, "QUINTA", was irradiated with 2, 4, and 8 GeV deuterons. The $^{232}$Th, $^{127}$I, and $^{129}$I samples have been exposed to secondary neutrons produced in the assembly at a 20-cm radial distance from the deuteron beam axis. The spectra of gamma rays emitted by the activated $^{232}$Th, $^{127}$I, and $^{129}$I samples have been analyzed and several tens of product nuclei have been identified. For each of those products, neutron-induced reaction rates have been determined. The transmutation power for the $^{129}$I samples is estimated. Experimental results were compared to those calculated with well-known stochastic and deterministic codes.

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Production of isomeric states in the deuteron-induced reaction of gold at incident energy 4 GeV

The independent cross section ratio for production of nuclei from 197Au targets irradiated with 4 GeV deuterons have been measured by off-line gamma-spectroscopy. On the basis of the measured independent cross section ratio of 198m, gAu the average intrinsic angular momentum of the primary nucleus was estimated by means of a simple statistical-model analysis based on the formalism developed by Huizenga and Vandenbosch.

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Recoil Properties of Fragments Formed in the 4.4 GeV Deuteron-Induced Reaction on Gold target

The recoil properties of fragments produced by the interaction of 4.4 GeV deuteron with 197Au target have been studied. New experimental data on recoil properties for 90 nuclei, varying from 24Na to 198Au, were obtained. The technique applied was the {thick-target thick-catcher} and induced activity method. The deuteron beam was obtained from the Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR), Dubna. The experimental data were analyzed on the basis of the standard two-step vector model formalism. From this analysis we could find evidence to support the existence of several different mechanisms, such as spallation, fission and fragmentation, in the reaction investigated. Fission contributed appreciably to the formation of products in the mass region of 65 < A < 120. The kinematic characteristics of residual nuclei formed in the present deuteron-induced reaction have been compared to those from proton-induced reactions with gold target.

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Target Residues Formed in the Deuteron-Induced Reaction of Gold at Incident Energy 2.2 AGeV

The cross sections of 110 radioactive nuclide with mass numbers 22 < A < 198 amu from the interaction of 2.2 GeV/nucleon deuterons from the Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR) at Dubna with a 197Au target are investigated using induced activity method. The results including charge and mass distributions are parameterized in terms of 3-parameter equation in order to complete the real isobaric distribution. Using data from charge distribution total mass-yield distribution was obtained. The analysis of the mass-yield distribution allows to suppose existence of different channels of the interaction such as spallation, deep spallation, fission-like and multifragmentation processes.

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Recoil Studies in the Reaction of 12-C Ions with the Enriched Isotope 118-Sn

The recoil properties of the product nuclei from the interaction of 2.2 GeV/nucleon 12-C ions from Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR) at Dubna with a 118-Sn target have been studied using catcher foils. The experimental data were analyzed using the mathematical formalism of the standard two-step vector model. The results for 12-C ions are compared with those for deuterons and protons. Three different Los Alamos versions of the Quark-Gluon String Model (LAQGSM) were used for comparison with our experimental data.

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On E0 Transitions in even-even nuclei

The reanimation of the investigations dedicated to 0^{+} states energies and E0 transitions between them is provoked by new and more precise experimental techniques that not only made revision of the previous data but also gave a possibility to obtain a great amount of new 0^{+} states energies and conversion electrons data. We suggest one phenomenological model for estimation of the E0 transition nuclear matrix elements. Recently theoretical calculations [1] predicted existence of a 0^{+} state with energy 0.68 MeV in ^{160}Dy nucleus. Powerful enough arguments in favor of existence of 681.3 keV state in ^{160}Dy nucleus are presented.

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Recoil Products from p+$^{118}Sn$ and d+$^{118}Sn$ at 3.65 GeV/A

The recoil properties of the product nuclei from the interaction of 3.65 GeV/nucleon protons and deuterons with $^{118}Sn$ target have been studied by the method of catching foils on the beams of LHE JINR. The mathematical formalism of the standard two step vector model was used for the analysis of experimental results. The obtained results for the protons are compared with the ones obtained for the deuterons. The total energy of the deuterons beam was 3.65GeV/nucleon. It is interesting to note that the forward velocity v and the recoil nuclei kinetic energy increases linearly with the increase of mass loss of target $ΔA$, but seems to change its slope at around $ΔA=60$. It seems that light and medium mass products are produced partly by a fragmentation mechanism.

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Formation of Light Isotopes by Protons and Deuterons of 3.65 GeV/nucleon on Separated Tin Isotopes

We measure cross sections for residual nuclide formation in the mass range 6 < A < 97 caused by bombardment with protons and deuterons of 3.65 GeV/nucleon energy of enriched tin isotopes (112-Sn, 118-Sn, 120-Sn, 124-Sn). The experimental data are compared with calculations by the codes FLUKA, LAHET, CEM03, and LAQGSM03. Scaling behavior is observed for the whole mass region of residual nuclei, showing a possible multifragmentation mechanism for the formation of light products (6 < A < 31). Our analysis of the isoscaling dependence also shows a possible contribution of multifragmentation to the production of heavier nuclides, in the mass region 39 < A < 81.

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Interacting Vector Boson Model Analysis of the ^{160}Dy Excited States Spectrum

Analysis of the recently obtained experimental data for collective states of ^{160}Dy is presented. The Interacting Vector Boson Model (IVBM) was applied for the classification of low lying states with positive parity 0^{+},2^{+},4^{+},6^{+}and for description of rotational ground, S, γ and two octupole bands. The energies of the bands are reproduced with high accuracy using only one set of the model parameters for all bands.

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Properties of Excited States in the ^{160}Dy Nucleus

Positive-parity levels and 16 rotational bands are theoretically analyzed on the basis of phenomenological models of the atomic nucleus with the use of new experimental data on excited states in the ^{160}Dy nucleus recently gained in the investigation of the decay ^{160}Er → ^{160m,g}Ho → ^{160}Dy.

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Analysis of the JINR p(660 MeV) + 129I, 237Np, and 241Am Measurements with Eleven Different Models

We have analyzed the recent JINR measurements on nuclide production cross sections from interaction of 660 MeV proton beams with radioactive targets of enriched 129I (85% 129I and 15% 127I), 237Np, and 241Am with eleven different models, realized in eight transport codes and event-generators: LAHET (Bertini, ISABEL, INCL+ABLA, and INCL+RAL options), CASCADE, CEM95, CEM2k, LAQGSM+GEM2, CEM2k+GEM2, LAQGSM+GEMINI, and CEM2k+GEMINI. We found out that all these models have problems in a correct description of many of these cross sections, though some of these models describe very well most of the recent measurements done at GSI using inverse kinematics, as well as many other reactions. None of the tested here models is able to reproduce well all the JINR data and all of them should be further improved. Development of a better universal evaporation/fission model should be of a highest priority. We conclude that it is impossible to make a correct choice between fission and fragmentation reaction mechanisms analyzing only measurements on product cross sections; addressing this question would require analysis of two- or multi-particle correlation measurements.

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Study of Proton Induced Reactions in a Radioactive 129-I Target at Ep=660 MeV

Two NaI (85% 129-I and 15% 127-I) targets were exposed to a beam of 660-MeV protons. Cross sections for formation of 76 residual nuclei were obtained by the induced activity method. The results are compared with other experimental data on 127-I and theoretical calculations by eleven models contained in the codes LAHET3 (using the Bertini+Dresner, ISABEL+Dresner, INCL+Dresner, and INCL+ABLA options), CASCADE, CEM95, CEM2K, LAQGSM+GEM2, CEM2k+GEM2, LAQGSM+GEMINI, and CEM2k+GEMINI. Most of the models describe spallation products with masses close to the target reasonably well while the reliability of the codes differs greatly in the deep spallation and fission/fragmentation regions. The difficulties in describing products with A=40-80 by all of the codes tested here except for CEM2k+GEMINI and LAQGSM+GEMINI is related to the neglect of fission (and fragmentation) processes for targets as light as 129-I.

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