Neutron Interactions Research Articles

Interaction Parameters of Some Polymers Used in Nuclear Power Plants with Ionizing Radiation, Produced Secondary Radiations and Radiation Damages

AbstractThe primary interactions of polypropylene (PP), poly(vinyl acetate) (PVA), ethylene‐vinyl acetate (EVA), polyvinyl chloride (PVC), polychloroprene (CR) and polyurethane (PUR) polymers preferred in the nuclear industry with gamma and neutron radiations, secondary radiations formed after neutron interactions and damages given to polymers by these ionizing radiations are investigated. The gamma interaction parameters Were determined in the photon energy range of 0.03‐20 MeV using WinXCOM, GEANT4 and FLUKA methods. Also, energy absorption and exposure buildup factors and Kerma parameters are calculated at different photon energies. To investigate the interactions of the studied polymers with neutron, the effective removal cross‐section for fast neutrons with theoretical and the partial neutron rates passing through the studied polymer at 4.5 MeV, 100 eV and 0.025 eV energies are determined with simulation codes. The numbers of secondary gamma‐rays and neutrons Were obtained with GEANT4. The Total Ionizing Dose and Displacements per Atom parameters are studied with the help of FLUKA simulation. It is observed that the interaction of PVC polymer with gamma radiation and PP polymer with neutron particles is higher than the others. The secondary radiation from PVC and CR is less. The PP, PVA, and EVA exhibit superior resistance to radiation damage.

Subshell gaps and onsets of collectivity from proton and neutron pairing gap correlations

Throughout the nuclear chart, particle-hole correlations give rise to giant resonances and, together with the proton–neutron interaction, deformation and rotational bands. In order to shed light on many-body correlations in open-shell nuclei, I explore macroscopic properties that could manifest from the collective behaviour of protons and neutrons. Intuitively, the correlation of proton and neutron Cooper pairs can be inferred from the respective pairing gaps, that can precisely be extracted from the AME 2020 atomic mass evaluation through odd-even atomic mass differences. This work shows that the combination of large and close-lying proton and neutron pairing gaps is sensitive to onsets of collectivity and subshell gaps in superfluid nuclei, away from major shell closures. Trends of reduced transition probabilities or B(E2) values — which describe the collective overlap between the wave functions of initial and final nuclear states — are revealed in overall agreement with data. Specially interesting is the peak of collectivity in the tin isotopes at 110Sn, instead of at midshell, as expected by large-scale shell-model calculations; a situation that has astounded the nuclear physics community for quite some time.

Measurement of γ-rays generated by neutron interaction with 16O at 30 MeV and 250 MeV

Abstract Deep understanding of γ-ray production from the fast neutron reaction in water is crucial for various physics studies at large-scale water Cherenkov detectors. We performed test experiments using quasi-mono energetic neutron beams (En = 30 and 250 MeV) at Osaka University’s Research Center for Nuclear Physics to measure γ-rays originating from the neutron-oxygen reaction with a high-purity germanium detector. Multiple γ-ray peaks which are expected to be from excited nuclei after the neutron-oxygen reaction were successfully observed. We measured the neutron beam flux using an organic liquid scintillator for the cross section measurement. With a spectral fitting analysis based on the tailored γ-ray signal and background templates, we measured cross sections for each observed γ-ray component. The results will be useful to validate neutron models employed in the on-going and future water Cherenkov experiments.

A comparative investigation of neutron and gamma radiation interaction properties of zircaloy-2 and zircaloy-4 with consideration of mechanical properties

Abstract This study has established the radiation shielding efficacy of zircaloy-2 and zircaloy-4 over a wide spectrum of energy levels. Using the Monte Carlo N-Particle (MCNP) method, the gamma and neutron transmission factors (TF and nTF) were calculated for various energy levels. Zircaloy-2 demonstrated the highest gamma-ray absorption capacity and the lowest neutron absorption capacity among the investigated alloys. The results indicate that zircaloy-2 and zircaloy-4 have nearly the same neutron transmission characteristics. Although many studies have examined the structure and physical characteristics of these materials, there has been a lack of Monte Carlo simulations to comprehensively investigate the correlation between gamma absorption, neutron absorption parameters, and mechanical qualities. This research aims to examine the ability of zirconium and its zircaloy-2 and zircaloy-4 alloys, which are critical materials used in the nuclear industry, to absorb gamma and neutron radiation over a broad spectrum of frequencies. According to the results, zircaloy-2 has the best ability to absorb secondary gamma rays and the highest level of resistance to them. Despite the minimal disparity in the nTF between the two alloys, simulation results have shown that zircaloy-2 has a higher level of neutron transmittance. These results have the potential to expedite the development of novel materials with enhanced attributes for various applications.

Generalized Integral Method for Solving the Neutron Transport Equation with the Hybridized Discontinuous Galerkin Method

Accurate modeling of the neutron transport equation (NTE) with anisotropic scattering is crucial to the understanding of neutron interactions within various mediums. The primary challenges in this domain are (1) the considerable computational resources demanded by anisotropic calculations and (2) the numerical instabilities that arise due to the transport correction approximation. This study introduces a novel, generalized integral method based on the hybridized discontinuous Galerkin framework for solving the second-order NTE with anisotropic scattering. This method employs a spherical harmonics expansion to define the partial current at the mesh interface and applies an angular integral approach to the flux treatment within the mesh. This dual approach facilitates an efficient computational process while preserving accuracy. The integral method has been validated through comparisons with the standard discrete ordinates method (SN) using two eigenvalue problems. The integral method showcases several significant improvements over the traditional SN method. First, it repositions the P0 scattering sources during the formulation process, effectively circumventing the convergence issues associated with transport correction. Second, this strategic repositioning substantially enhances the convergence rates of iterative calculations. Last, a standout feature of the integral method is its capability to perform angular integrals during assembling matrices, successfully reducing the floating-point operations for local flux retrieval and eliminating the ray effect.

New physics at a neutron beam dump

We find a new utility of neutrons, usually treated as an experimental nuisance causing unwanted background, in probing new physics signals. The new physics signals can either be radiated from neutrons (neutron bremsstrahlung) or appear through secondary particles from neutron-on-target interactions, dubbed “neutron beam dump.” As a concrete example, we take the FASER/FASER2 experiment as a “factory” of high-energy neutrons that interact with the iron dump. We find that if new physics particles had the same interaction strength to protons and neutrons, their production rate via neutron-initiated bremsstrahlung would be comparable to that via proton-initiated ones, in terms of the resulting flux and the range of couplings that can be probed. The neutron bremsstrahlung can be used, for instance, to probe dark gauge bosons with nonzero neutron coupling. In particular, we investigate protophobic gauge bosons and find that FASER/FASER2 can probe new parameter space. We also illustrate the possibility of neutron-induced secondary particles by considering axionlike particles with electron couplings. We conclude that the physics potential of FASER/FASER2 in terms of new physics searches can be greatly extended and improved with the inclusion of neutron interactions. Published by the American Physical Society 2024

Evaluating the risk of data loss due to particle radiation damage in a DNA data storage system

DNA data storage is a potential alternative to magnetic tape for archival storage purposes, promising substantial gains in information density. Critical to the success of DNA as a storage media is an understanding of the role of environmental factors on the longevity of the stored information. In this paper, we evaluate the effect of exposure to ionizing particle radiation, a cause of data loss in traditional magnetic media, on the longevity of data in DNA data storage pools. We develop a mass action kinetics model to estimate the rate of damage accumulation in DNA strands due to neutron interactions with both nucleotides and residual water molecules, then utilize the model to evaluate the effect several design parameters of a typical DNA data storage scheme have on expected data longevity. Finally, we experimentally validate our model by exposing dried DNA samples to different levels of neutron irradiation and analyzing the resulting error profile. Our results show that particle radiation is not a significant contributor to data loss in DNA data storage pools under typical storage conditions.

Fast and Thermal Neutron Removal Cross-Section for Ceramic Glass Aluminum Oxynitride

This study investigates the effectiveness of transparent aluminum oxynitride (AlON) in neutron shielding, focusing on both fast and thermal neutrons. Using conventional radiation attenuation parameters, the macroscopic neutron removal cross-sections of AlON were calculated for varying neutron energies and material thicknesses. The Geant4 simulation toolkit was employed to model and analyze the neutron interactions with AlON. The results indicate that AlON exhibits a high neutron shielding capacity for fast neutrons, performing better than traditional shielding materials such as concrete and lead. However, for thermal neutrons, AlON's performance was less effective, only surpassing lead but not concrete or water. The findings suggest that while AlON is highly effective for fast neutron shielding, it may require complementary materials to adequately shield thermal neutrons. This could involve using AlON in combination with other materials to create a more comprehensive neutron shielding solution. AlON shows significant potential as a neutron shielding material, particularly for fast neutrons. Its integration with additional shielding materials could enhance its overall effectiveness, making it suitable for various nuclear and radiation protection applications.

Volume fraction detection in multiphase systems using neutron activation analysis and artificial neural network

This study presents an application of an Artificial Neural Network (ANN) to detect fluids in an annular flow regime using Prompt-Gamma Neutron Activation Analysis (PGNAA). The ANN was trained using gamma-ray spectra resulting from neutron interactions with chemical elements found in fluids typical of multiphase flow in oil exploration. These spectra were generated through mathematical simulation using the MCNP6 Monte Carlo computer code to model nuclear particle transport. A241Am-Be polyenergetic neutron source was simulated for these calculations. Several combinations of fluid fractions were developed to create a dataset used for both training and evaluation of the ANN. The ANN demonstrated robust generalization capabilities by accurately predicting the volume fraction of the three investigated fluids (saltwater, oil, and gas), even for cases not included in the training phase. The combination of ANN and PGNAA proved effective for analyzing multiphase systems, with over 92% of all showing errors of less than 5%.

Stochastic differential equations for non-analog Monte Carlo model of point kinetics equations

The stochastic form of one-point and two-point reactor kinetics models have been extensively investigated in the literature. We have noticed that, in some studies, the probabilistic nature of neutron interaction mechanisms was not incorporated truly. For instance, in the case of negative reactivity insertions, one of the presented probability functions becomes negative, making the Monte Carlo (MC) simulation impossible. In this manuscript, the non-analog stochastic point reactor kinetics models are developed to simulate the stochastic behavior of nuclear systems. To reduce the imposed variance from the leakage and capture of neurons, both capture and leakage events are sampled implicitly. Precursors are also forced to decay in each simulation step. The true variances of the neutron’s and delayed neutron precursor’s populations are determined from the solution of the developed non-analog stochastic models. Also, they are compared with those of both analog and non-analog Monte Carlo methods. The results show that the analog Monte Carlo (MC) has a larger variance than the non-analog MC.

Texture measurements of archaeological objects at STRESS-SPEC neutron diffractometer

The main advantage of neutron diffraction over X-ray diffraction, arises from the fact that the interaction of neutrons with material is relatively weak and not related to the number of electrons, and consequently the penetration depth of neutrons is about 102-103 larger than that of laboratory X-ray diffraction. This is particular essential for the non-destructive texture analysis of archaeological objects as no additional surface treatments of the samples (e.g. polishing) are necessary. STRESS-SPEC at MLZ is designed as a state of the art multi-purpose diffractometer for strain and texture analysis. Besides the optimized high neutron flux the available large variability in gauge volume definition systems together with the robotic sample handling option offer high flexibility for bulk or gradient texture measurements. Since 2014, local and bulk textures of iron and gold artefacts collected by Bavarian State Archaeological Collection (Munich, Germany) have been thoroughly investigated at STRESS-SPEC. Results showed that heat treatment of iron artefacts at high temperatures can re-orientate the inner crystallites. In the gold foil artefacts, the texture represented by the measured pole figures shows a high symmetry – the so-called Cube component, which is commonly found in annealed fcc materials. For comparison, laboratory samples were produced by rolling, flat hammering, and pin / round hammering and also measured in order to elucidate possible manufacturing and processing routes. In turned out that both rolling and pin / round hammering followed by a high temperature annealing can produce similar pole figures to those of the gold artefacts foils.

An effective gauge field theory of the nucleon interactions

We discuss the possibility of constructing an effective gauge field theory of the nucleon interactions based on the ideas of isotopic invariance as well as hypercharge invariance as a local gauge symmetry and spontaneous breaking of this symmetry. The constructed effective field theory predicts the structure of interactions of protons and neutrons with ρ- and σ-mesons, and with pi-mesons and photons, as well as interactions of these particles with each other. The Lagrangian of the theory consists of several parts involving dimension 4 and 5 gauge invariant operators. Feynman rules for physical degrees of freedom that follow on from the Lagrangian define the structure of diagrams for one-boson exchanges between nucleons, predicting the internucleon one-boson-exchange potential as well as nucleon scattering amplitudes. The range of applicability of the effective theory is discussed and estimates are made of the resulting coupling constants. The theory predicts the mass of the neutral ρ 0-meson to be about 1 MeV larger than the mass of the charged mesons ρ ±. The vector ω-meson, which is a sterile particle with respect to the considered gauge group SU I (2) × U Y (1), can be added to the scheme via a gauge-invariant operator of dimension 5, as shown in the appendix.

Characterization of diamond and organic scintillation detectors utilizing radiation sources for continuous plasma operation.

This paper provides a comprehensive study of neutron calibration methodologies, specifically highlighting the capabilities for n-γ discrimination in diamond and EJ-309, and stilbene scintillation detectors. The calibration process detailed in this study includes pulse height analysis and pulse shape discrimination, relying on the analysis of charge deposition resulting from both γ and neutron interactions. Utilizing 60Co and 252Cf radiation sources, the energy spectra of these sources are obtained. The characterized detectors were used in ST40 experiments and allowed acquiring neutron signal during a plasma shot with good agreement among diamond and scintillation detectors. Then, the diamond detector was cross-calibrated against indium activation foils placed at the same location in proximity to the ST40 during plasma shots: both detectors measured a neutron flux of ≈106 cm-2 s-1 at ≈1 m distance from the tokamak center, and the discrepancy between the diamond detector and the activation foils is ≈25%.

Combined X-ray Diffraction Analysis and Quantum Chemical Interpretation of the Effect of Thermal Neutrons on the Geometry and Electronic Properties of CdTe

Objective: Substantiation of the result of the interaction of thermal neutrons with CdTe crystals by quantum-chemical methods and comparison of the experimental results with the results of quantum-chemical calculations. Methods: Single crystal samples of cadmium telluride (CdTe) were obtained by a modified Bridgman method. The plates cut from the single crystal were subjected to mechanical grinding with abrasive paper of the type P1,200-P4,000, mechanical polishing with silver paste. To clean the surface of the plate from contamination, it was washed in ethyl alcohol. In the experimental part of the work, the influence of low thermal neutron fluxes on the structural parameters of CdTe was studied. The samples were irradiated with a thermal neutron flux in the range from 2.64×107 neutron/cm2 to 1.85×109 neutron/cm2. To study the structure of CdTe crystals, the method of X-ray structural analysis was used, using a DRON-3 X-ray diffractometer. In the second part of the work, computer modeling of the process of interaction of thermal neutrons on CdTe crystals was carried out. Results: X-ray diffraction analysis of the crystals showed that as a result of irradiation with low thermal neutron fluxes, the structural parameters of CdTe improve, as evidenced by the ordering of the crystallites. In addition, in this region of the thermal neutron flux the resistance of the crystals decreases. Conclusion: Calculations of the crystal lattice parameters of CdTe are in good agreement with experimental data. The electronic and optical properties of CdTe have been studied. A decrease in the band gap after irradiation with thermal neutrons has been shown.

Simulations on the performances of neutron shielding glass materials and secondary radiation risks

Glasses with neutron shielding properties are extremely important for nuclear industries. Neutron interactions with ten different neutron shielding glass types were simulated by using GEANT4 Monte Carlo simulation toolkit. Simulation results were evaluated in terms of shielding performances, deposited energy properties and produced secondary radiation. Important evaluations were made in view of radiation safety, especially on secondary particles and radioactivity resulting from interactions between neutrons and glass samples. All simulated glass samples were found to emit risky secondary particles and radioactive nuclei after interacting with fast neutrons.

NATURAL OR ARTIFICIAL TRITIUM IN RIVERS – THE ASSESSMENT USING SYMMETRICAL INDEX

Tritium, hydrogen isotope, with a half-life of 12.3 years, is produced in two ways: naturally and artificially. Naturally, tritium is generated through the interaction of cosmic radiation protons and neutrons with gases in the upper atmosphere. Artificially, tritium origins from the atmospheric nuclear tests, production from nuclear reactors, future fusion reactors, fuel reprocessing plants, heavy water production facilities and commercial production for medical diagnostics, radiopharmaceuticals, luminous paints. Elevated concentrations of tritium in the environment are of great public concern. Considering the fact that nuclear power plants are located on rivers, knowing the activity concentration of this isotope in rivers is of great importance. This work presents the results for tritium determination in Danube and Sava River in Belgrade, Serbia. The origin of tritium was estimated using a mathematical parameter, symmetrical index.

Investigation of gamma and neutron interaction parameters of synthesized diketone derivatives as potential anti-cancer

Investigation of gamma and neutron interaction parameters of synthesized diketone derivatives as potential anti-cancer

Optimizing the composition of barium-borate glasses for enhancing thermal neutron shielding efficiency: Monte Carlo simulation

A transparent window with thermal neutron shielding properties was an important part of the stations of the nuclear reactors and the particle accelerators. The borate glass with a high neutron cross section was a candidate as a glass network for the neutron shielding window. In order to slow down thermal neutrons, they were trapped by boron and subsequently emitted secondary radiation, such as alpha particles and gamma-ray radiation. This work was to optimize the content between a ratio of borate with a high cross-section neutron interaction and barium for shielding alpha and gamma ray. The barium-borate glasses were successfully synthesized using the melting technique in the atmosphere. Measurements of mechanical and optical glass properties were presented. The measured results showed that an increase in barium oxide content in the glass ratio enhanced the glass density and the transmittance at a visible wavelength. In the calculation of radiation shielding properties, FLUKA code based on Monte Carlo Simulation was demonstrated. The calculated results revealed that an increase in the barium oxide content in the glass composition reduced the thermal neutron shielding properties of the glass samples. In contrast, the glass with barium contents enhanced the photon-shielding efficiency, as indicated by the mass attenuation coefficient and half-value layer. Not only the ratio of the barium and borate contents affected the shielding properties, but the increased glass thickness also enhanced the shielding properties. Thus, the utilization of cooperative borate glasses and barium with appropriate thickness could potentially serve as a viable option for simultaneously protecting against thermal neutrons and photons. The barium-borate glasses with our composition might be used as a window in a thermal neutron station as well as for photon radiation.

Gamma emission from interaction of fission neutrons on nickel and zirconium

Gamma emission induced by the irradiation of nickel and zirconium with fission neutrons was investigated with the FaNGaS (Fast Neutron–induced Gamma-ray Spectrometry) instrument operated at Heinz Maier-Leibnitz Zentrum. Measurements were done at an angle of 90° with respect to the direction of the fission neutron beam (average neutron energy of 2.18 MeV). We report on the relative intensities and production cross sections of 265 gamma lines (163 for nickel and 102 for zirconium). Consistency with available literature data was evaluated. The cross section of the 90Zr(n,n′)90mZr reaction was determined to be 88 ± 8 mb. For a counting time of 12 h, the detection limits of 0.7 and 1.3 mg were estimated for nickel and zirconium, respectively.

Dynamic diffraction of thermal neutrons in crystals with continuous deformation field

The purpose of the work is to consider the basics of the formation of a diffraction wave field of thermal neutrons in the case of Laue transmission geometry of a limited beam of neutrons in the crystal, taking into account the peculiarities of the interaction of thermal neutrons with a continuously and slowly changing deformation field of the crystal net. The conditions of both diffraction blurring and diffraction contraction (focusing) up to the practical restoration of the original shape of the packet will be studied.An integral form for determining the quasi-amplitudes of diffracted waves within the framework of the original spatially inhomogeneous beams is formulated, based on the constructed functions of the influence of a point source of thermal neutron waves for crystals with a continues deformation field. It has been shown that neutron focusing is effective, which is revealed by a smaller half-width of the focal spot, an increase in the resolving power of the energy spectrum and focusing efficiency.