Fe Reaction Research Articles

Synthesis, neutron activation and characterization of CsFeO2 Nanoparticles

This research aimed to obtain nanosized magnetic particles with radioactive properties. Cesium ferrite nanoparticles (CsFeO2) were produced using the sol-gel/combustion method and the samples were characterized by FTIR, and showed peaks in the bands 305 cm-1 and 328 cm-1 attributed to g-Fe2O3, peaks at 318 cm-1 and 343 cm-1 reveal a secondary α-Fe2O3 phase, vibrations at 354 cm-1 are attributed to Fe-O in the octahedral sites. The neutral irradiation activated several radionuclides. The irradiation for 2h with the acquisition times of 600s and 7200s yielded Cs-134, Cs-134m and Mn-56, which was produced from the reaction 56Fe (nr, p) 56Mn. The irradiation of 4h with the acquisition times of 18000s yielded Fe-59 with Cs-134. The results of the present work show that it is possible to activate CsFeO2 nanoparticles by neutron irradiation to obtain potentially useful radioisotopes.

Analysis of transport-activation internal coupling method implemented in Monte Carlo code cosRMC

When fusion nuclear reactor is in operation, neutron activation causes a large number of radioisotopes. Activation calculation is a very important step in both of reactor shielding calculation and radiation safety analysis. The capability of transport-activation coupling calculation was developed in Monte Carlo code cosRMC though the built-in burnup solver Depth. In the process of neutron transport, the one-group cross section of activation-related was calculated by internal coupling method and the manipulation and transfer of input file for energy spectrum to external activation code was no longer necessary, which is more efficient and flexible than traditional external coupling. A cuboid iron model is established, and the activation calculation is performed by cosRMC and ALARA respectively. In the constant energy spectrum mode, the relative error of 56Fe atomic density between two codes is 0.0019 %, which verified the accuracy of capability of activation internal coupling calculation in the cosRMC code. The relative errors of 57Fe and 58Fe atomic density are 17.97 % and 36.75 % between constant and variable energy spectrum. This showed that whether energy spectrum remains constant has a significant impact on the results. Moreover, the one-group reaction rate with continuous energy/ multi-group cross section were different, which is because the pre-generated multi-group cross section libraries are independent of the geometry and energy spectrum of the specific problem. The resonance shielding effect of the specific problem cannot be accurately considered when using the multi-group cross section, resulted in relative errors of 60 % for the one-group cross section of 56Fe(n,γ) reaction. cosRMC can directly use the continuous energy method to calculate the problem dependent one-group section, which will give more accurate results.

Demonstration of nuclear gamma-ray polarimetry based on a multi-layer CdTe Compton camera

To detect and track structural changes in atomic nuclei, the systematic study of nuclear levels with firm spin-parity assignments is important. While linear polarization measurements have been applied to determine the electromagnetic character of gamma-ray transitions, the applicable range is strongly limited due to the low efficiency of the detection system. The multi-layer Cadmium-Telluride (CdTe) Compton camera can be a state-of-the-art gamma-ray polarimeter for nuclear spectroscopy with the high position sensitivity and the detection efficiency. We demonstrated the capability to operate this detector as a reliable gamma-ray polarimeter by using polarized 847-keV gamma rays produced by the 56Fe\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{56}\ extrm{Fe}$$\\end{document}(p,p′γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${ p},{ p'}\\gamma $$\\end{document}) reaction. By combining the experimental data and simulated calculations, the modulation curve for the gamma ray was successfully obtained. A remarkably high polarization sensitivity was achieved, compatible with a reasonable detection efficiency. Based on the obtained results, a possible future gamma-ray polarimetery is discussed.

Cross-section measurements for the 58,60,61Ni(n, α)55,57,58Fe reactions at 8.50, 9.50 and 10.50 MeV neutron energies * *Supported by the National Natural Science Foundation of China (11775006) and China Nuclear Data Center and the Science and Technology on Nuclear Data Laboratory

Cross sections of the 58,60,61Ni(n, α)55,57,58Fe reactions were measured at 8.50, 9.50 and 10.50 MeV neutron energies based on the HI-13 tandem accelerator of China Institute of Atomic Energy (CIAE) with enriched 58Ni, 60Ni, and 61Ni foil samples with backings. A twin gridded ionization chamber (GIC) was used as the charged particle detector, and an EJ-309 liquid scintillator was used to obtain the neutron energy spectra. The relative and absolute neutron fluxes were determined via three highly enriched 238U3O8 samples inside the GIC. The uncertainty of the present data of the 58Ni(n, α)55Fe reaction is smaller than most existing measurements. The present data of 60Ni(n, α)57Fe and 61Ni(n, α)58Fe reactions are the first measurement results above 8 MeV. The present experimental data could be reasonably reproduced by calculations with TALYS-1.9 by adjusting several default values of theoretical model parameters.

Cross-section measurements for 58,60,61Ni(n, α)55,57,58Fe reactions in the 4.50 – 5.50 MeV neutron energy region * * Supported by the National Natural Science Foundation of China (11775006) and China Nuclear Data Center and the Science and Technology on Nuclear Data Laboratory

The cross sections at 5 energy points of the 58Ni(n, α)55Fe reaction were measured in the 4.50 MeV ≤ En ≤ 5.50 MeV region while those for the 60Ni(n, α)57Fe and 61Ni(n, α)58Fe reactions were measured at En = 5.00 and 5.50 MeV using the 4.5 MV Van de Graaff accelerator at Peking University. A gridded twin ionization chamber (GIC) was used as the detector, and enriched 58Ni, 60Ni, and 61Ni foil samples were prepared and mounted at the sample changer of the GIC. Three highly enriched 238U3O8 samples inside the GIC were used to determine the relative and absolute neutron fluxes. The neutron energy spectra were obtained through unfolding the pulse height spectra measured by the EJ-309 liquid scintillator. The interference from the low-energy neutrons and impurities in the samples has been corrected. The present data of the 60Ni(n, α)57Fe reaction are the first measurement results below 6.0 MeV, and those of the 61Ni(n, α)58Fe reactions are the first measurement results in the MeV region. The present results have been compared with existing measurements, evaluations, and TALYS-1.9 calculations.

Double-, energy-, angle- differential and total yield cross section data of 58Ni(n,a)55Fe reaction

The double-, energy-, angle- differential cross section data, and the total yield of 58Ni(n,α)55Fe reaction is investigated in the neutron energy range between 2 and 9 MeV. The measurements were performed with the prompt detection method, detecting the alpha particles of the reaction with a multitelescope consisted of five ΔΕ-ΔΕ-Ε telescopes, placed at angles 14, 51, 79, 109 and 141 degrees relative to the neutron beam direction. The normalisation to the absolute units was made using the known total yield of the reference reactions 27Al(n,α)24Na and 58N(n,p)58Co. The cross section measurements were compared with previous measurements and with theoretical calculations performed with the STAPRE-H [1-4] code.

Coherent and incoherent channels of neutrino-nucleus reactions

Inelastic neutrino-nucleus scattering cross sections at low and intermediate energies are investigated for currently interesting nuclei employed in neutrino-detection experiments. This is an extension to charged current processes of our previous QRPA calculations referred to neutral current neutrino/antineutrino-nucleus reactions. Our preliminary results for the reactions 56Fe(νe, e−)56Co and 40Ar(νe, e−)40K compare rather well with similar calculations obtained in the context of continuum RPA.

Evaluation of the nuclear excitation functions of fast neutron-induced reactions on 52Cr and 56Fe isotopes

In this article, we present the nuclear excitation functions of the fast neutron-induced reactions 52Cr(n,p)52V, 52Cr(n,α)49Ti, 52Cr(n,2n)51Cr, 56Fe(n,p)56Mn, 56Fe(n,α)53Cr, and 56Fe(n,2n)55Fe, because these measurements are critical to estimate the level of the neutron activation for the fusion reactor structural materials. The theoretical computer codes TALYS-1.8 and EMPIRE-3.2.2 have been used for the calculation of the excitation functions. The theoretical calculations consider different nuclear reaction models, level density models and optical model potentials. The calculated excitation function results are compared with the existing experimental data obtained from the IAEA-EXFOR database, as well as with those available in the TENDL-2017 and ENDF/B-VIII.0-evaluated nuclear data libraries. The obtained results show the variation in excitation functions for different level density models. Moreover, we have studied the contribution from different reaction mechanisms in total reaction cross-section which varies with the incident neutron energy. These excitation function results can be useful to estimate the important parameters of nuclear reactors, such as nuclear heating, nuclear transmutation rates, and waste management etc. This kind of information can enhance the basic understanding of the mechanism of the fast neutron-induced nuclear reactions.

New Results on Excited States in the one-particle one-hole nucleus 56Co measured with MINIBALL detectors

The non-yrast states of the odd-odd nucleus 56Co have been investigated by studying the γ-rays induced in the predominantly fusion-evaporation reaction 56Fe(p,n γ)56Co at an incident energy of 10 MeV. The γ-rays were measured in-beam with four high-resolution MINIBALL-triple germanium (Ge) detectors. The experiment provided excellent data in γ-γ coincidences. The complex level scheme of 56Co was constructed mainly based on the analysis of these γ-γ coincidences. The angular distributions of the γ-rays were also analysed and allowed us to assign spin-parity values to most of the excited states in this nucleus. Despite the extensive work previously done studying the 56Co nucleus, the analysis presented in this work has resulted in a large improvement in the knowledge of its structure.

Enrichment of 57Fe isotope in neutron flux of nuclear reactors observed by Mössbauer spectroscopy

The abundance of 57Fe isotope in nuclear reactor core materials can be considerably enriched by neutron-capture 56Fe(n,γ) reactions. This is demonstrated using the sections of Zr-2.5 wt.%Nb pressure tubes removed from two CANDU* reactors. The tubes contained 0.11 and 0.04wt% Fe and were irradiated for about 10 effective full power years (EFPY) up to ~1026n/m2 fast neutron (E > 1MeV) fluencies. The Mössbauer spectra of 57Fe in irradiated samples indicated up to 10 times larger areas than unirradiated off-cuts from the same pressure tubes. The observed effect is in accord with the values calculated for known thermal neutron-capture cross-sections and resonance capture integrals, neutron flux profiles and spectra, and times of irradiation. The build-up of 57Fe facilitated recording Mössbauer absorption spectra of alloys with minor amount of Fe down to ~ 400ppm, despite intense background radiation emitted by samples. These findings can open new possibilities in post-irradiation studies of alloys used in nuclear reactors and in other objects subjected to large neutron fluencies.

Nuclear data sensitivity and uncertainty analysis of effective neutron multiplication factor in various MYRRHA core configurations

A sensitivity and uncertainty analysis was carried out to estimate the uncertainty in the neutron multiplication factor keff and to identify the most important nuclear data for neutron induced reactions for criticality calculations of the latest MYRRHA designs. Sensitivity profiles, i.e. sensitivity to the nuclear data as a function of incoming neutron energy, were derived for both a critical and sub-critical core. They were calculated using codes that are based on different methodologies including stochastic and deterministic calculations (i.e. SCALE, MCNP and XSUN). The neutron induced nuclear data sensitivity analysis outlined the following quantities to be of special importance for the MYRRHA reactor concept: 239Pu(n,γ) both in resonance and fast energy region, (n,f) fast, χ and ν fast; 238U(n,n′) fast, (n,γ) resonance and fast, (n,n) resonance and fast; 240Pu ν fast; 238Pu(n,f) both resonance and fast; 56Fe(n,γ) both resonance and fast. Differences of less than 4% between codes were obtained for these quantities, with few exceptions (238Pu(n,f), 238U(n,n) and 56Fe(n,γ) reactions). Nuclear data covariance matrices of different libraries (SCALE-6, COMMARA-2 and JENDL-4.0m) were used to derive the uncertainty in keff based on the calculated sensitivities. This study reveals that the largest contributions to keff uncertainty result from the uncertainty in the average prompt neutron fission multiplicity of 239Pu, in the 238U inelastic scattering cross section and 239Pu fission cross section, using the covariances from SCALE-6, COMMARA-2 and JENDL-4.0m, respectively.

COMPARISON OF DPA AND HELIUM PRODUCTION IN CANDIDATE FUEL CLADDING MATERIALS FOR THE CANADIAN SCWR

Harsh conditions associated with high-temperature, high-pressure supercritical-water coolant in the Canadian supercritical water-cooled reactor (SCWR) necessitate the use of stainless steel or nickel-based alloys as fuel cladding material rather than more conventional zirconium-based alloys. In-core neutron irradiation is expected to produce helium in nickel-bearing alloys through the 2-step 58Ni(n,γ)59Ni(n,α)56Fe reaction. Increases in displacements per atom (DPA) associated with this reaction will also occur. It is important to quantify neutron-irradiation induced helium production and DPA to assess the consequences for fuel sheath material integrity. In this paper, neutron-flux induced helium production and displacement damage are estimated from lattice physics calculations for 5 candidate SCWR fuel clad materials, alloys 214, 625, 800 H, 347, and zirconium-modified 310 stainless steel, and compared for 2 fuel options, plutonium-thorium dioxide, (Pu–Th)O2, and low enriched uranium-thorirum dioxide, (LE...

Nuclear-level densities in the 49V and 57Co nuclei on the basis of evaporated-neutron spectra in (p, n) and (d, n) reactions

The spectra of neutrons from the reactions 49Ti(p, n)49V and 57Fe (p, n)57Co were measured in the range of proton energies between 8 and 11 MeV along with their counterparts from the reactions 48Ti(d, n)49V and 56Fe (d, n)57Co at the deuteron energies of 2.7 and 3.8 MeV. These measurements were conducted with the aid of a time-of-flight fast-neutron spectrometer on the basis of the EGP-15 pulsed tandem accelerator of the Institute for Physics and Power Engineering (IPPE, Obninsk). An analysis of measured data was performed within the statistical equilibrium and preequilibrium models of nuclear reactions. The respective calculations based on the Hauser–Feshbach formalism of statistical theory were carried out with nuclear-level densities given by the generalized superfluid model of the nucleus, the backshifted Fermi-gas model, and the Gilbert–Cameron composite formula. The nuclear-level densities of 49V and 57Co and their energy dependences were determined. The results were discussed together with available experimental data and data recommended by model systematics.

Nuclear data for fusion: Validation of typical pre-processing methods for radiation transport calculations

Nuclear data form the basis of the radiation transport codes used to design and simulate the behaviour of nuclear facilities, such as the ITER and DEMO fusion reactors. Typically these data and codes are biased towards fission and high-energy physics applications yet are still applied to fusion problems. With increasing interest in fusion applications, the lack of fusion specific codes and relevant data libraries is becoming increasingly apparent. Industry standard radiation transport codes require pre-processing of the evaluated data libraries prior to use in simulation. Historically these methods focus on speed of simulation at the cost of accurate data representation. For legacy applications this has not been a major concern, but current fusion needs differ significantly. Pre-processing reconstructs the differential and double differential interaction cross sections with a coarse binned structure, or more recently as a tabulated cumulative distribution function. This work looks at the validity of applying these processing methods to data used in fusion specific calculations in comparison to fission. The relative effects of applying this pre-processing mechanism, to both fission and fusion relevant reaction channels are demonstrated, and as such the poor representation of these distributions for the fusion energy regime. For the natC(n,el) reaction at 2.0MeV, the binned differential cross section deviates from the original data by 0.6% on average. For the 56Fe(n,el) reaction at 14.1MeV, the deviation increases to 11.0%. We show how this discrepancy propagates through to varying levels of simulation complexity. Simulations were run with Turnip-MC and the ENDF-B/VII.1 library in an effort to define a new systematic error for this range of applications. Alternative representations of differential and double differential distributions are explored in addition to their impact on computational efficiency and relevant simulation results.

Uncertainty Study of Nuclear Model Parameters for the n+56Fe Reactions in the Fast Neutron Region below 20 MeV

In this work we study the uncertainty of nuclear model parameters for neutron induced 56Fe reactions in the fast neutron region by using the Total Monte Carlo method. We perform a large number of TALYS runs and compare the calculated results with the experimental data of the cross sections to obtain the uncertainties of the model parameters. Based on the derived uncertainties another 1000 TALYS runs have been performed to create random cross section files. For comparison with the experimental data we calculate a weighted χ2 value for each random file as well as the ENDF/B-VII.1, JEFF-3.1, JENDL-4.0 and CENDL-3.1 data libraries. Furthermore, we investigate the optical model parameters correlation obtained by way of this procedure.

Beta decay of exoticTZ= -1, -2 nuclei: the interesting case of56Zn

The β decay properties of the Tz = -2, 56Zn isotope and other proton-rich nuclei in the fp-shell have been investigated in an experiment performed at GANIL. The ions were produced in fragmentation reactions and implanted in a double-sided silicon strip detector surrounded by Ge EXOGAM clovers. Preliminary results for 56Zn are presented .The 56Zn decay proceeds mainly by β delayed proton emission, but β delayed gamma rays were also detected. Moreover, the exotic β delayed gamma-proton decay was observed for the first time. The 56Zn half-life and the energy levels populated in the 56Cu daughter have been determined. Knowledge of the gamma de-excitation of the mirror states in 56Co and the comparison with the results of the mirror charge exchange process, the 56Fe(3He,t) reaction (where 56Fe has Tz = +2), were important in the interpretation of the 56Zn decay data. The absolute Fermi and Gamow-Teller strengths have been deduced.

Evidence for the Dipole Nature of the Low-EnergyγEnhancement inFe56

The γ-ray strength function of 56Fe has been measured from proton-γ coincidences for excitation energies up to ≈11 MeV. The low-energy enhancement in the γ-ray strength function, which was first discovered in the (3He,αγ)56Fe reaction, is confirmed with the (p,p'γ)56Fe experiment reported here. Angular distributions of the γ rays give for the first time evidence that the enhancement is dominated by dipole transitions.

A new CVD diamond mosaic-detector for (n, [formula omitted]) cross-section measurements at the n_TOF experiment at CERN

At the n_TOF experiment at CERN a dedicated single-crystal chemical vapor deposition (sCVD) Diamond Mosaic-Detector has been developed for (n,α) cross-section measurements. The detector, characterized by an excellent time and energy resolution, consists of an array of 9 sCVD diamond diodes. The detector has been characterized and a cross-section measurement has been performed for the 59Ni(n,α)56Fe reaction in 2012. The characteristics of the detector, its performance and the promising preliminary results of the experiment are presented.

Nuclear interaction dynamics in the 56Fe (α, xn) reaction

Neutron spectra and angular distributions in the 56Fe (α, xn) reaction are measured at α-particle energies of 12.5, 16.3, 18.3, 26.8, and 45.2 MeV. The measurements are performed using time-of-flight fast neutron spectrometers on pulsed accelerators. The measured data are analyzed in the context of equilibrium, preequilibrium, and direct nuclear reaction mechanisms. The contributions from equilibrium, preequilibrium, and direct mechanisms of neutron emission are studied over a wide range of α-particle energies.

Model calculation of neutron kerma coefficient for n+ 56Fe below 20 MeV

Model calculations for the n+ 56Fe reaction have been performed by using extended UNF code, which is based on the unified Hauser–Feshbach and exciton model. Based on the excellent agreement with the experimental double-differential cross-sections of neutron, alpha and proton, the total kerma coefficients are derived naturally with the formula K Φ = ∑ i K Φ i = N ∑ ijk E ¯ ijk ( E n ) σ ijk ( E n ) ( Sun et al., 2008), which contains more comprehensive parameter information. The discrepancies of total kerma coefficients between the experimental data, evaluated data and the calculated results of this paper have been further analyzed, and one can have some confidence in predicting the kerma coefficients derived naturally by this model calculation.