GeV Deuterons Research Articles

MONTE-CARLO SIMULATION OF QUASI-INFINITE DEPLETED URANIUM TARGET IRRADIATED BY 1…10 GeV DEUTERON AND PROTON BEAM

Simulation of a ~21 t depleted uranium target irradiated by 1…10 GeV proton and deuteron particles with the help of FLUKA simulation package was carried out. Neutron spectra and neutron flux in a target volume were obtained. Total number of 235U (n,f), 238U(n,f) reactions occurred in a target were determined. Beam particle power multiplication are calculated. The calculations were performed for the purpose of planning experiments on irradiation of a uranium target (22 tons of depleted uranium) at JINR (Dubna) within the framework of the international project “Energy and Transmutation of RAW”.

EXPERIMENTAL STUDIES OF THE NUCLEAR-PHYSICAL CHARACTERISTICS OF THE EXTENDED URANIUM TARGET IRRADIATED BY RELATIVISTIC PROTONS, DEUTRONS AND 12C NUCLEI

In 2011-2017 in the framework of the international collaboration project “Energy and Transmutation of RAW”, a series of experimental studies on the deep subcritical uranium assembly QUINTA were carried out. The massive uranium target (512 kg of natU) was irradiated with 0.66 GeV proton, deuterons and 12C nuclei (1 to 4 AGeV) from the Phasotron and Nuclotron accelerators (JINR, Dubna). The main results of experimental studies carried out with the participation of the Kharkov group of collaboration are presented.

Inelastic cross sections in relativistic deuterons on Lead reactions

The inelastic cross section of deuterons hitting a Lead target has been determined by the beam attenuation technique. A spallation neutron source based on Lead target has been irradiated with 1.6 and 2.5 GeV deuterons. Solid state nuclear track detectors as well as the activation method were used in order to obtain the neutron and proton distribution along the surface of the source. The attenuation coefficient was estimated by fitting the experimental data taking into account the build up effect and the beam attenuation. Using the attenuation coefficient, the interaction length and then the inelastic cross section of deuterons on Lead reaction have been determined.

Monitoring mixed neutron-proton field near the primary proton and deuteron beams in spallation targets

At the Joint Institute for Nuclear Research (JINR) we are involved in the Accelerator-Driven-System (ADS) research. We perform experiments with assemblies composed of a spallation target and a subcritical blanket irradiated with high-energy proton or deuteron beams that generate high-energy neutron fields by spallation and fission reactions. In this paper, three uranium assemblies are presented: Energy plus Transmutation (E+T), QUINTA and BURAN. We discuss the results of the E+T and QUINTA irradiations by 1.6 GeV deuterons and 660 MeV protons, respectively. We have focused on the regions close to the primary beam passage through the targets. The field has been measured using activation detectors of 209Bi, 59Co, and natPb. Monte Carlo simulations using MCNPX 2.7.0 have been performed and compared to the experimental results. We discovered that the field intensity near the primary beam is very dependent on the precision of the accelerator beam settings. Therefore, a Monte Carlo-based study of the influence of the uncertainty of primary proton beam parameters on experimental result accuracy of the QUINTA assembly has been carried out. The usage of MCNPX 2.7.0 in the future BURAN irradiations has been assessed.

NEUTRON-PHYSICAL CHARACTERISTICS OF A SYSTEM OF QUASI-INFINITE DEPLETED URANIUM BLANKET – PARTICLE ACCELERATOR. MONTE CARLO SIMULATION

Simulation of a quasi-infinite uranium target irradiated by 1 GeV proton and deuteron particles with the help of FLUKA simulation package was carried out. Neutron spectra and neutron flux in a target volume were obtained. 235U(n,f), 238U(n,f), 238U(n,g) reaction rates in a target were determined. Beam particle power multiplication were calculated.

Spallation reactions induced by 4.4 GeV deuterons on lead isotopes

Independent and cumulative production cross sections for radioactive nuclear fragments from the deuteron-irradiation of isotopically enriched lead (204Pb, 206Pb, 207Pb, and 208Pb) targets were obtained for the first time. The experiment has been performed with a 4.4 GeV deuteron beam from the Nuclotron of the Laboratory of High Energy Physics (LHE), Joint Institute for Nuclear Research (JINR) at Dubna. The production cross sections of target fragments were determined by off-line γ-ray spectroscopy. Charge dispersion and mass-yield distributions were deduced from these data. The results are discussed in terms of the relative importance of different reaction mechanisms (evaporation–spallation, fission and multifragmentation). Comparison of our results with the data from the reaction induced by protons of about the same kinetic energy per nucleon, has been performed. The coexistence of the different decay modes in the formation of the reaction residues, such as spallation, fission and multifragmentation is suggested.

Collective phenomena in hadron and nuclear interactions at high multiplicity

Multiparticle production is described in the language of quarks and gluons. In the experiment the real hadrons are registered. For transfer from quarks and gluons to observed hadrons, various phenomenological models are used. In order to describe the high multiplicity region, we have developed a gluon dominance model. It represents a convolution of two stages. First stage is described by QCD. For second one (hadronisation), the phenomenological model is used. The description of topological cross sections inp$ \bar p $ collisions within of our model testifies that in hadron collisions the mechanism of hadronisation is being replaced by the recombination one. At that point, gluons play an active role in the multiparticle production process, and valence quarks are passive. They stay in the leading particles, and only the gluon splitting is responsible for the region of high multiplicity. The model with inclusion of intermediate quark charged topologies describes topological cross sections in annihilation. We observe the significant growth of a scaled variance of number of neutral pions with increasing of the total multiplicity at U-70 accelerator at IHEP (Protvino). The following experiment with 3.5 A GeV deuteron, lithium and carbon beams of the Nuclotron (JINR, Dubna) falling at a carbon target is carried out at the NIS-GIBS setup. The noticeable excess yield of soft photons(pT< 50 MeV/c) is observed. The existing models based on Monte Carlo simulation and theoretical estimations predict a lower yield. Our Collaboration plans to study excess of soft photon yield and other phenomena at the SPD (Spin Physics Detector) setup at JINR, Dubna with polarised beams of proton and light nuclei up to 25 GeV.

Activation measurement of neutron production and transport in a thick lead target and a uranium blanket during 4 GeV deuteron irradiation

Several simple accelerator-driven system (ADS) setups were irradiated by relativistic proton and deuteron beams in last years at the Nuclotron synchrotron site of the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. This paper is dedicated to a 4 GeV deuteron irradiation of a setup called Energy plus Transmutation (E+T), consisting of a lead target, natural uranium blanket, and polyethylene shielding. This paper represents the finalization of data analysis and concludes systematics of the proton and deuteron experiments carried out with the E+T setup. Activation detectors served for monitoring of proton and deuteron beams and for measurements of neutron field distribution in model ADS studies. Products of reactions with thresholds up to 106 MeV as well as non-threshold reactions were observed in the samples. The yields of the produced isotopes were determined using the gamma-ray spectrometry and compared with Monte Carlo simulations performed with the MCNPX transport code.

Interactions of secondary particles with thorium samples in the setup QUINTA irradiated with 6 GeV deuterons

The natural uranium assembly, QUINTA, was irradiated with 6GeV deuterons. The 232Th samples were placed at the central axis of the setup QUINTA. The spectra of gamma rays emitted by the activated 232Th samples have been analysed and more than one hundred nuclei produced have been identified. For each of those products, reaction rates have been determined. The ratio of the weight of produced 233U to 232Th is presented. Experimental results were compared with the results of Monte Carlo simulations by FLUKA code.

Isomer production in intermediate-energy deuteron-induced reactions on a gold target

Residual nuclei formed at ground and isomeric states from the interaction of 4.4 GeV deuteron with a gold target have been measured and investigated by the induced-activity method. Eight isomeric and ground-state pairs of target residues in the mass range of $44lAl198$ were identified by off-line $\ensuremath{\gamma}$-spectroscopy analysis and their isomer ratios were obtained from the cross-section production. From the isomer ratio data of the formed $^{196}\mathrm{Au}$ and $^{197}\mathrm{Hg}$ nuclei, the average intrinsic angular momentum of the composite system was estimated by means of a simple statistical model based on the formalism developed by Huizenga and Vandenbosch.

Study of secondary neutron interactions with 232Th, 129I, and 127I 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 8GeV deuterons. The 232Th, 127I, and 129I 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 232Th, 127I, and 129I 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 129I samples is estimated. Experimental results were compared to those calculated with well-known stochastic and deterministic codes.

Study of 232Th(n,[formula omitted]) and 232Th(n,f) reaction rates in a graphite moderated spallation neutron field produced by 1.6 GeV deuterons on lead target

The Gamma-3 assembly of the Joint Institute for Nuclear Research (JINR), Dubna, Russia is designed to emulate the neutron spectrum of a thermal Accelerator Driven System (ADS). It consists of a lead spallation target surrounded by reactor grade graphite. The target was irradiated with 1.6GeV deuterons from the Nuclotron accelerator and the neutron capture and fission rate of 232Th in several locations within the assembly were experimentally measured. 232Th is a proposed fuel for envisaged Accelerator Driven Systems and these two reactions are fundamental to the performance and feasibility of 232Th in an ADS. The irradiation of the Gamma-3 assembly was also simulated using MCNPX 2.7 with the INCL4 intra-nuclear cascade and ABLA fission/evaporation models. Good agreement between the experimentally measured and calculated reaction rates was found. This serves as a good validation for the computational models and cross section data used to simulate neutron production and transport of spallation neutrons within a thermal ADS.

Target residues formed in the 4.4 GeV deuteron-induced reaction on gold

The production cross sections for 110 radioactive nuclides, with mass numbers $22\ensuremath{\le}A\ensuremath{\le}198$, were obtained from the interaction of 4.4 GeV deuteron with a $^{197}\mathrm{Au}$ target using the induced-activity method. The deuteron beam was obtained from the Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR) at Dubna. Using the charge distribution data, we derived the total mass-yield distribution. The analysis of the mass-yield distribution allowed us to consider the coexistence of different channels in the interaction such as evaporation, fission, and multifragmentation.

The spatial distribution of thermal and epithermal neutrons in a graphite moderated spallation neutron field

The Gamma-3 assembly is located at the Joint Institute for Nuclear Research, Dubna, Russia. It consists of a cylindrical lead target (ø = 8 cm, L = 58.8 cm) surrounded by reactor grade graphite (110 × 110 × 60 cm). The target was irradiated with a beam of 1.6 GeV deuterons from the Nuclotron accelerator and CR-39 track detectors coupled to LR-115 2B film were used to measure the slow neutron distribution on the surface of the graphite. The detection efficiency of the CR-39 in the CR-39/LR-115 2B system was measured using a custom made calibration setup and found to be (1.12 ± 0.05) × 10−3 and (6.1 ± 1.2) × 10−4 tracks per neutron, for thermal and epithermal neutrons respectively, under the etching and counting procedures described in this work. The irradiation of the Gamma-3 was also simulated using MCNPX 2.7 Monte Carlo code and good agreement between the experimental and calculated track densities was found. This serves as a good validation for the computational models used to simulate spallation neutron production, transport and moderation.

Recoil properties of fragments formed in 4.4 GeV deuteron-induced reactions on a 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.

Measurements of High Energy Neutron Spectrum (> 10 MeV) by Using Yttrium Foils in a U/Pb Assembly

Study of deep subcritical electronuclear systems and radioactive waste transmutation using relativistic beams were performed. This work is a preliminary step toward the study of the physical properties of Accelerator Driven Systems, in which a deeply subcritical active core is irradiated by a pulsed beam of relativistic ions. The long-range goal of the project is to study the capabilities of such systems with a hard neutron spectrum, for transmutation of radioactive nuclear wastes. Two experimental assemblies, “Energy plus Transmutation” (2006-2009) and “Quinta” (2011-), were irradiated by 1 to 6 GeV deuteron beams using the JINR NUCLOTRON accelerator. The main difference between the two experimental setups is the spallation target - lead or natural uranium. We attempt to obtain neutron energy spectra inside the volume of these assemblies using threshold reactions in natural yttrium (89Y) foils. Some results from three different experiments are presented.

Reconstruction of the fast neutron spectrum using deformation of a reference spectrum represented as a Legendre polynomial expansion

This paper proposes a method for reconstructing the fast neutron spectra in the range 0.2 MeV to 100 MeV based on modified methods of the effective threshold cross sections and the deformation of a reference spectrum using the Legendre polynomial expansion of a deforming function. In contrast to the deformation method traditionally used to determine the desired differential spectrum φ(E), we propose the use of a deforming function as a Legendre polynomial expansion in order to determine the integrated spectrum F(E). Since F(E) is a monotonic decreasing function that tends to zero when approaching the maximum spectral energy, it can be represented by a shorter series; i.e., the number M of the sought series coefficients am will not be large. The developed program was used to calculate fast neutron spectra in a QUINTA nuclear setup that was irradiated with 1–8 GeV deuterons of Nuclotron-M at the Laboratory of High Energies of the Joint Institute for Nuclear Research.

Activation of 197Au and 209Bi in a fast spectrum sub-critical assembly composed of 500 kg natural uranium irradiated with 1 and 4 GeV deuterons

The Quinta assembly of the Joint Institute for Nuclear Research (JINR), Dubna, Russia consists of 512kg of natural uranium rods arranged hexagonally and surrounded by a lead reflector. The setup was irradiated with 1 and 4GeV deuterons and the (n,γ) and (n,xn) reaction rates of gold and bismuth samples located inside the assembly were determined through gamma spectrometry. The experimental reaction rates were compared to those calculated via the MCNPX code using the INCL4-ABLA physics models. Cross section data for neutron, proton and deuteron induced reactions were retrieved from the literature where available and some neutron cross sections were calculated using the TALYS code. The good agreement between experimental and calculated reaction rates serves as a validation for the computational models used to simulate fast Accelerator Driven Systems.

Spatial distribution of thorium fission rate in a fast spallation and fission neutron field: An experimental and Monte Carlo study

The Energy plus Transmutation (EpT) set-up of the Joint Institute for Nuclear Research (JINR), Dubna, Russia is composed of a lead spallation target surrounded by a blanket of natural uranium. The resultant neutron spectrum is a combination of spallation and fission spectra, modified by a reflective external layer of polyethylene and an internal absorbing layer of cadmium. The EpT set-up was irradiated with a beam of 4 GeV deuterons from the Nuclotron Accelerator at JINR. The spatial distribution of thorium fission rate within the assembly was determined experimentally, using a fission track detector technique, and compared with Monte Carlo predictions of the MCNPX code. Contributions of neutrons, protons, deuterons, photons and pions to total fission were taken into account. Close agreement between the experimental and calculated results was found.

Time-Dependent Spectra of Neutrons Emitted in Interaction of 1 and 4 GeV Deuterons with Massive Natural Uranium and Lead Targets

Time-Dependent Spectra of Neutrons Emitted in Interaction of 1 and 4 GeV Deuterons with Massive Natural Uranium and Lead Targets