Capture Resonance Integral Research Articles

Investigation of the Cd-Ratio difference method to measure the cross section of 186W(n,γ)187W at the Jordan Research and Training reactor

The neutron capture cross section of 186W(n,γ)187W was measured at different energies, including the thermal capture cross section (0.025 eV) and resonance integral. Neutron capture cross section values were determined using the activation technique and by applying the Cadmium-ratio difference method. Two irradiation locations at the Jordan Research and Training Reactor (JRTR) were used (NAA1 and NAA2). The thermal capture cross section values were determined to be 39.56 ± 0.69 ± 2.58b and 32.17 ± 3.72 ± 2.00b at NAA1 and NAA2, respectively. While resonance integral values were found to be 113.93 ± 8.20 ± 16.87b and 69.35 ± 26.63 ± 29.69b at NAA1 and NAA2, respectively. The present results of the resonance integral are not in good agreement with the most of the previous experimental and evaluated data as well as the theoretical calculations.

Measurements of capture cross-section of 93Nb by activation method and half-life of 94Nb by mass analysis

ABSTRACT The thermal-neutron capture cross section (σ 0 ) and resonance integral (I 0 ) for93Nb were measured by an activation method; a half-life of 94Nb was derived by mass analysis. Niobium-93 samples were irradiated with the use of the hydraulic conveyer installed in the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Gold-aluminum and cobalt-aluminum alloy wires were used to monitor thermal-neutron fluxes and Westcott’s indexes at the irradiation position. A 25-μm-thick gadolinium foil was used to separate reactions ascribed to thermal neutrons. Its thickness provided a cut-off energy of 0.133 eV. In order to attenuate the radioactivity of 182Ta produced by impurities, the Nb samples were cooled for nearly 2 years. The induced radio activity in the monitors and Nb samples was measured by gamma-ray spectroscopy. In the analysis based on Westcott’s convention, the σ 0 and I 0 values were calculated as 1.11 ± 0.04 barns and 10.5 ± 0.6 barns, respectively. After the γ-ray measurements, mass analysis was applied to the Nb samples to obtain the reaction rate. By combining data obtained by both γ-ray spectroscopy and mass analysis, a half-life of 94Nb was determined as (2.00 ± 0.15) ×104 years.

Am-241 thermal neutron capture cross section and neutron capture resonance integral from reactor activation and oscillation measurements

In order to validate the neutron capture cross section in 241Am, comparisons of calculations with activation experiments at the TRIGA reactor at JSI and pile oscillation measurements at the MINERVE reactor at CEA Cadarache were done. The results suggest that the evaluation in the new test library JEFF-4T1 on average provide an improvement of the C/E results compared to the existing nuclear data library releases. However, due to some discrepancies, additional experiments at JSI as well as further development of the computational model of the JSI TRIGA reactor are planned to improve the accuracy and reliability of the neutron activation analysis and the nuclear data inferred from them.

Measurement of neutron capture cross sections for the 174Yb(n,γ)175Yb reaction at thermal and epithermal energies

Herein, we measured the thermal neutron capture cross section (σ0) and resonance integral (I0) of the 174Yb(n,γ)175Yb reaction relative to those of the reference reaction 197Au(n,γ)198Au. Measurements were conducted based on the activation method using pulsed neutrons combined with the Cd ratio method and offline γ-ray spectrometry. Pulsed neutrons were generated on a 100 MeV electron linac of the Pohang Accelerator Laboratory, Korea. Yb samples and Au monitors were irradiated with and without a 0.5 mm Cd cover to absorb thermal neutrons. The neutron flux was determined via the 115In(n,γ)116mIn reaction. The induced activities of the reaction products were measured using a gamma spectrometer based on a well-calibrated HPGe detector. For the 174Yb(n,γ)175Yb reaction, the thermal neutron capture cross section and resonance integral cross-section were obtained as σ0,Yb = 70.5 ± 4.2 b and I0,Yb = 54.1 ± 4.2 b, relative to the corresponding values of σ0,Au = 98.65 ± 0.09 b and I0,Au = 1550 ± 28 b for the 197Au(n,γ)198Au reference reaction. The obtained results were compared with the measured and evaluated data.

NICE - Neutron Induced Charged particle Emission

A new detector setup (NICE-detector) based on an organic plastic scintillator is presented. It will be used during experiments measuring neutron-induced reactions with a charged particle in the exit channel. The proposed design was tested at the Goethe University Frankfurt. One of the test cases was the capture cross-section of 209Bi at different astrophysically important energies, including thermal capture cross-section and resonance integral. This research presents the performance of the detector setup, as well as preliminary results for the calculated cross-sections. The preliminary results demonstrate that the newly developed NICE-detector can be used to determine capture cross-sections with sufficient accuracy, and might be adopted in the future as an alternative for charged particle measurements in different nuclear and astrophysical applications.

Thermal-neutron capture cross sections and resonance integrals of the 243Am(n,γ)244gAm and 243Am(n,γ)244m+gAm reactions

ABSTRACT The thermal-neutron capture cross sections (σ0) and resonance integrals (I0) were measured for the 243Am(n,γ)244gAm and 243Am(n,γ)244m+gAm reactions by a neutron activation method. Americium-243 samples were irradiated with a pneumatic tube and a hydraulic conveyer installed in the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Alloy wires of Au/Al, Co/Al or Co foils were used as neutron monitors to measure thermal-neutron fluxes and epi-thermal Westcott’s indexes at irradiation positions. A 25-μm-thick gadolinium foil was used to separate reactions due to thermal- and epi-thermal neutron components, and a value of 0.133 eV was taken as a corresponding cut-off energy. Gamma-ray spectroscopy was applied to measure radioactivity of neutron monitors and the ground state of reaction products, while alpha-ray spectroscopy was applied to measure that of target 243Am and final reaction product 244Cm through the decay of 244m, 244gAm. By utilizing Westcott’s convention, the σ0 and I0 values were derived as 4.73 ± 0.27 barn and 96.5 ± 8.9 barn for the 243Am(n,γ)244gAm reaction, and 88.5 ± 4.0 barn and 2.30 ± 0.20 kilobarn for the 243Am(n,γ)244m+gAm reaction, respectively. The present result of σ0 for the production of 244m+gAm agreed with the reported value of 87.7 ± 5.4 barn measured with a time-of-flight method within the limits of uncertainties.

Measurement of the thermal neutron cross section and resonance integral of the 187Re(n,γ)188Re reaction

We measured the thermal neutron capture cross sections (σ0) and resonance integral (I0) of the 187Re(n,γ)188Re reaction relative to that of the 197Au(n,γ)198Au monitor reaction using neutron activation with the Cd ratio method. The investigated samples and monitors were irradiated with and without a 0.5-mm-thick Cd cover for the pulsed neutron source based on the 100-MeV electron linac at the Pohang Accelerator Laboratory (PAL). The induced activities for the reaction products were measured using a high-purity germanium (HPGe) detector. In order to improve the accuracy of the experimental results, the necessary corrections were made. The thermal neutron capture cross sections and resonance integral of the 187Re(n,γ)188Re reaction were determined relative to reference values of σo,Au = 98.65 ± 0.09 barn and Io,Au = 1550 ± 28 barn from the 197Au(n,γ)198Au reaction, respectively. The corresponding values for the 187Re(n,γ)188Re reaction were determined to be σ0,Re = 75.6 ± 3.4 barn and I0,Re = 317 ± 22 barn, respectively. The obtained results are compared with the literature data and discussed.

Measurements of thermal-neutron capture cross-section of Cesium-135 by applying mass spectrometry

ABSTRACTThe thermal-neutron capture cross-section (σ0) and resonance integral (I0) were measured for the 135Cs(n,γ)136Cs reaction by an activation method and mass spectrometry. Because of difficulty in the preparation of pure 135Cs samples, we used 135Cs contained as an impurity in a normally available 137Cs standard solution. An isotope ratio of 135Cs and 137Cs in a standard 137Cs solution was measured by mass spectrometry to quantify 135Cs. Cesium-135 impurity along with the 137Cs standard solution was irradiated at the hydraulic conveyer of the research reactor in the Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as neutron monitors to measure thermal-neutron fluxes and epi-thermal Westcott’s indices at an irradiation position. A gadolinium filter was used to measure the σ0, and a value of 0.133 eV was taken as the cut-off energy. Gamma-ray spectroscopy was used to measure induced activities of 137Cs, 136Cs and monitor wires. On the basis of Westcott’s convention, the σ0 and I0 values were derived as 8.57 ± 0.25 barn, and 45.3 ± 3.2 barn, respectively. The value of σ0 obtained in the present study agreed within the limits of uncertainties with the past-reported value of 8.3 ± 0.3 barn.

Thermal neutron capture cross sections and resonance integrals of ruthenium isotopes- 96Ru, 102Ru and 104Ru

Thermal neutron capture cross sections and resonance integrals of 96Ru, 102Ru and 104Ru are measured with reference to a 55Mn monitor. The experiments are carried out using the neutrons from an Am–Be neutron source kept inside a concrete bunker. The thermal neutron capture cross sections measured are in good agreement with the evaluations as well as with one of the recent measurements. The resonance integral of 102Ru measured in the present study is in good agreement with older measurements.

Measurements of thermal-neutron capture cross-section and resonance integral of neptunium-237

ABSTRACT The thermal-neutron capture cross-section (σ 0) and resonance integral (I 0) were measured for the 237Np(n,γ) 238Np reaction by an activation method. A method with a Gadolinium filter, which is similar to the Cadmium difference method, was used to measure the σ 0 with paying attention to the first resonance at 0.489 eV of 237Np, and a value of 0.133 eV was taken as a cut-off energy. Neptunium-237 samples were irradiated at the pneumatic tube of the Kyoto University Research Reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as monitors to determine thermal-neutron fluxes and epi-thermal Westcott’s indices at an irradiation position. A γ-ray spectroscopy was used to measure activities of 237Np, 238Np and neutron monitors. On the basis of Westcott’s convention, the σ 0 and I 0 values were derived as 186.9 ± 6.2 barn, and 1009 ± 90 barn, respectively.

Reactor production of promethium-147

In this paper, we describe the 147Pm production yields and level of impurities from several targets that consisted of milligram quantities of highly enriched 146Nd oxide irradiated at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory for durations ranging from 24 to 180 h. A comparison between theoretical and experimental data are also presented, and attempts were made to empirically evaluate the neutron capture cross-sections of 41.3-d 148mPm and 5.4-d 148gPm. For a one-cycle irradiation (~24 days), 147Pm yield reaches a maximum value of 101.8 MBq/mg (2.75 mCi/mg) at 60 days after the end of bombardment. Because of large neutron capture cross-sections of 147Pm, the yield of 147Pm does not significantly increase with longer irradiation. Our estimates of the thermal neutron capture cross-section and resonance integral for 146Nd at 1.48 ± 0.05 b and 2.56 ± 0.25 b, respectively, were consistent with the reported values. The effective neutron capture cross-section of 147Pm to 148mPm was 53.3 ± 2.7 b–a factor of 2 lower than the 98.7 ± 6.5 b calculated from reported cross-sections. The measured σeff to the ground state (5.37-d 148gPm) was 82.0 ± 4.1 b; ~34% lower than the value of 139 ± 10 b calculated from reported cross-sections. In this work, we also describe the development of a chemical process based on extraction and ion-exchange chromatography for separation of 147Pm from milligram quantities of 146Nd and other impurities. Sequential separation of Pm from the Nd target and from other radioisotopic impurities (153Gd and 154&155Eu, 192Ir, and 60Co) was achieved using a LN extraction resin in HCl media followed by further purification of Pm from 60Co and 192Ir using a low cross-linking cation exchange resin. Based on these data, we estimated that two rounds of purification under our experimental conditions can provide a mass separation factor of >104 between Pm and Nd. Our data indicate that curie quantities of 147Pm with suitable chemical and radioisotopic purity for applications in beta voltaic batteries can be produced by irradiating gram quantities of highly enriched 146Nd in the flux trap of HFIR for one cycle.

Neutron Transmission and Capture Measurements of 133Cs from 0.01 to 600 eV

Neutron capture and transmission measurements were carried out from 0.01 to 600 eV on both solid and liquid samples containing elemental cesium (133Cs). Only s-wave resonances were observed in these measurements. These data were analyzed for resonance parameters utilizing the SAMMY Bayesian analysis code to simultaneously fit both the capture and transmission data. Parameters were obtained for 31 cesium resonances up to 600 eV. The thermal capture cross section and capture resonance integral were determined. The thermal capture cross section is 10% larger than the ENDF, JENDL, and JEFF evaluated values but lies within the uncertainty of the most recent measurement by Yoon and Lee [New Phys.: Sae Mulli (Korean Phys. Soc.)., Vol. 61, p. 7 (2011)]. The capture resonance integral has a statistical 1σ error of 2% and lies 1.4σ above the JENDL value, 5.5σ above the ENDF value, and 3.9σ above the JEFF value. The s-wave strength function was determined.

Assessment of the 153Eu and 154Eu neutron capture cross sections from the integral data assimilation of used nuclear fuel experiments

The purpose of this paper is to make the most of a large set of used nuclear fuel experiments for determining integral trends on the 153Eu(n,γ) and 154Eu(n,γ) reactions cross sections. The assimilation of the integral trends is based on a linear least-square fitting procedure relying on the Bayes’ theorem. Realistic uncertainties are obtained thanks to a marginalization technique. The method is applied to the 153Eu and 154Eu capture cross sections recommended in the evaluated nuclear data library JEFF-3.1.1. Our results indicate an underestimation of both capture cross-sections of approximately 4.9% and 7.1%, respectively. For 153Eu, our study suggests to increase the capture resonance integral from I0 = 1409 barns to I0 = 1502 ± 68 barns. This trend is consistent with the capture resonance integral I0 = 1560 ± 4 barns obtained from recent time-of-flight measurements carried out at the Renssealer Polytechnic Institute. The trend obtained in this work on 154Eu capture cross section is also consistent with a recent analysis that confirms its underestimation.

Measurements of the thermal neutron cross-section and resonance integral for the 108 Pd(n,γ) 109 Pd reaction

Abstract The thermal neutron capture cross-section (σ0) and resonance integral (I0) of the 108Pd(n,γ)109Pd reaction have been measured relative to that of the monitor reaction 197Au(n,γ)198Au. The measurements were carried out using the neutron activation with the cadmium ratio method. Both the samples and monitors were irradiated with and without cadmium cover of 0.5 mm thickness. The induced activities of the reaction products were measured with a well calibrated HPGe γ-ray detector. In order to improve the accuracy of the results, the necessary corrections for the counting losses were made. The thermal neutron capture cross-section and resonance integral of the 108Pd(n,γ)109Pd reaction were determined to be σ0,Pd = 8.68 ± 0.41 barn and I0,Pd = 245.6 ± 24.8 barn, respectively. The obtained results are compared with literature values and discussed.

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.

Neutron capture measurements and resonance parameters of dysprosium

Neutron capture yields of dysprosium isotopes ( 161Dy, 162Dy, 163Dy, and 164Dy were measured using the time-of-flight method with a 16 segment sodium iodide multiplicity detector. The measurements were made at the 25m flight station at the Gaerttner LINAC Center at Rensselaer Polytechnic Institute. Resonance parameters were obtained using the multilevel R-matrix Bayesian code SAMMY. The neutron capture data for four enriched dysprosium isotopes and one natural dysprosium sample were sequentially fitted. New resonances not listed in ENDF/B-VII.1 were observed. There were 29 and 17 new resonances from 161Dy and 163Dy isotopes, respectively. Six resonances from 161Dy isotope, two resonances from 163Dy, and four resonances from 164Dy were not observed. The capture resonance integrals of each isotope were calculated with the resulting resonance parameters and those of ENDF/B-VII.1 in the energy region from 0.5eV to 20MeV and were compared to the capture resonance integrals with the resonance parameters from ENDF/B-VII.1. A resonance integral value of the natural dysprosium calculated with present resonance parameters was $ 1405 \pm 3.5$ barn. The value is $ \sim 0.3\%$ higher than that obtained with the ENDF/B-VII.1 parameters. The distributions of the present and ENDF/B-VII.1 neutron widths were compared to a Porter-Thomas distribution. Neutron strength functions for 161Dy and 163Dy were calculated with the present resonance parameters and both values were in between the values of “Atlas of Neutron Resonances” and ENDF/B-VII.1. The present radiation width distributions of 161Dy and 163Dy were fitted with the $ \chi^{2}$ distribution by varying the degrees of freedom.

Rhenium resonance parameters from neutron capture and transmission measurements in the energy range 0.01 eV to 1 keV

Rhenium is a refractory metal with potential uses in nuclear reactor applications, particularly those at very high temperatures. Measurements have been made using natural samples. Natural rhenium consists of two isotopes: 185Re (37.40%) and 187Re (62.60%). The electron linear accelerator (LINAC) at the Rensselaer Polytechnic Institute (RPI) Gaerttner LINAC Center was used to explore neutron interactions with rhenium in the energy region from 0.01 eV to 1 keV. Neutron capture and transmission measurements were performed by the time-of-flight technique. Two transmission measurements were performed at flight paths of 15 m and 25 m with 6Li glass scintillation detectors. The neutron capture measurements were performed at a flight path of 25 m with a 16-segment sodium iodide multiplicity detector. Resonance parameters were extracted from the data using the multilevel R-matrix Bayesian code SAMMY. A table of resonance parameters and their uncertainties is presented. The uncertainties in resonance parameters were propagated from a number of experimental quantities using a Bayesian analysis. Uncertainties were also estimated from fitting each Re sample measurement individually. The measured neutron capture resonance integral for 185Re is (4 ± 1)% larger than ENDF/B-VII.1. The capture resonance integral for 187Re is (3 ± 1)% larger than ENDF/B-VII.1. Other findings from these measurements include: a decrease in the thermal capture cross section for 185Re of (2 ± 2)% from ENDF/B-VII.1; a decrease in the thermal capture cross section for 187Re of (3 ± 4)% from ENDF/B-VII.1; a decrease in the thermal total cross section for 185Re of (2 ± 2)% from ENDF/B-VII.1; and a decrease in the thermal total cross section for 187Re of (6 ± 5)% from ENDF/B-VII.1. Considering the uncertainties, none of the indicated changes in thermal cross sections represents a statistically significant change from ENDF/B-VII.1.

Thermal neutron capture cross-section and resonance integral measurements of 139La(n, $ \gamma$ γ )140La and 140Ce(n, $ \gamma$ γ )141Ce using a Am-Be neutron source

Thermal neutron capture cross-sections and resonance integrals of 139La(n,\( \gamma\))140La and 140Ce (n,\( \gamma\))141Ce are measured with respect to reference reactions 197Au(n,\( \gamma\))198Au and 55Mn(n,\( \gamma\))56Mn using the neutron activation technique. Measurements are carried out using neutrons from an Am-Be source located inside a concrete bunker. Two different methods are used for determining self-shielding factors of activation foils as well as for finding the epithermal neutron spectrum shape factor. For 139 La with reference to 197 Au and 55 Mn the measured thermal cross sections are \( 9.24 \pm 0.25\) b and \( 9.28 \pm 0.37\) b, respectively, while the measured resonance integrals are \( 12.18 \pm 0.67\) b and \( 11.81 \pm 0.94\) b, respectively. For 140 Ce with reference to 197 Au and 55 Mn the measured thermal cross sections are \( 0.44 \pm 0.01\) b and \( 0.44 \pm 0.02\) b, respectively, while the measured resonance integrals are \( 0.55 \pm 0.03\) b and \( 0.54 \pm 0.04\) b, respectively. The present measurements are compared with earlier measurements and evaluations. Presently estimated values confirm the established 139La(n,\( \gamma\))140La cross-sections. The presently measured thermal capture cross-section 140Ce(n,\( \gamma\))141Ce , though lower than the evaluated data, is having higher accuracy compared to previous measurements with large uncertainties. The resonance integral measured is higher (like most previous measurements) than most evaluations requiring a revision of the evaluated data.

Resonance region measurements of dysprosium and rhenium

Neutron capture and transmission measurements have been performed, and resonance parameter analysis has been completed for dysprosium, Dy, and rhenium, Re. The 60 MeV electron accelerator at RPI Gaerttner LINAC Center produced neutrons in the thermal and epithermal energy regions for these measurements. Transmission measurements were made using 6 Li glass scintillation detectors. The neutron capture measurements were made with a 16-segment NaI multiplicity detector. The detectors for all experiments were located at ≈25 m except for thermal transmission, which was done at ≈15 m. The dysprosium samples included one highly enriched 164 Dy metal, 6 liquid solutions of enriched 164 Dy, two natural Dy metals. The Re samples were natural metals. Their capture yield normalizations were corrected for their high gamma attenuation. The multi-level R-matrix Bayesian computer code SAMMY was used to extract the resonance parameters from the data. 164 Dy resonance data were analyzed up to 550 eV, other Dy isotopes up to 17 eV, and Re resonance data up to 1 keV. Uncertainties due to resolution function, flight path, burst width, sample thickness, normalization, background, and zero time were estimated and propagated using SAMMY. An additional check of sample-to-sample consistency is presented as an estimate of uncertainty. The thermal total cross sections and neutron capture resonance integrals of 164 Dy and Re were determined from the resonance parameters. The NJOY and INTER codes were used to process and integrate the cross sections. Plots of the data, fits, and calculations using ENDF/B-VII.1 resonance parameters are presented.

Neutron transmission and capture measurements and analysis of Dy from 0.01 to 550 eV

Neutron capture and transmission measurements were carried out from 0.01 to over 600 eV on both natural Dy and samples highly enriched in 164Dy. These data were analyzed for resonance parameters utilizing the SAMMY Bayesian analysis code to simultaneously fit both the capture and transmission data. Parameters were obtained for 17 resonances in Dy isotopes up to 18 eV and for the 164Dy resonances near 147, 450 and 540 eV. The thermal capture cross section (at 0.0253 eV) and capture resonance integral were determined for 164Dy.