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Journal Articles

Measurement for thermal neutron capture cross sections and resonance integrals of the $$^{243}$$Am(n,$$gamma$$)$$^{rm 244g}$$Am, $$^{rm 244m+g}$$Am reactions

Nakamura, Shoji; Endo, Shunsuke; Kimura, Atsushi; Shibahara, Yuji*

KURNS Progress Report 2019, P. 132, 2020/08

Research and development were made for accuracy improvement of neutron capture cross section data on $$^{243}$$Am among minor actinides. First, the emission probabilities of decay $$gamma$$ rays were obtained with high accuracy, and the amount of the ground state of $$^{244}$$Am produced by reactor neutron irradiation of $$^{243}$$Am was examinded by $$gamma$$-ray measurement. Next, the total amount of isomer and ground states was examoned by $$alpha$$-ray measurement.

Journal Articles

The Joint evaluated fission and fusion nuclear data library, JEFF-3.3

Plompen, A. J. M.*; Cabellos, O.*; De Saint Jean, C.*; Fleming, M.*; Algora, A.*; Angelone, M.*; Archier, P.*; Bauge, E.*; Bersillon, O.*; Blokhin, A.*; et al.

European Physical Journal A, 56(7), p.181_1 - 181_108, 2020/07

 Times Cited Count:1

The Joint Evaluated Fission and Fusion nuclear data library 3.3 is described. New evaluations for neutron-induced interactions with the major actinides $$^{235}$$U, $$^{238}$$U and $$^{239}$$Pu, on $$^{241}$$Am and $$^{23}$$Na, $$^{59}$$Ni, Cr, Cu, Zr, Cd, Hf, W, Au, Pb and Bi are presented. It includes new fission yileds, prompt fission neutron spectra and average number of neutrons per fission. In addition, new data for radioactive decay, thermal neutron scattering, gamma-ray emission, neutron activation, delayed neutrons and displacement damage are presented. JEFF-3.3 was complemented by files from the TENDL project. The libraries for photon, proton, deuteron, triton, helion and alpha-particle induced reactions are from TENDL-2017. The demands for uncertainty quantification in modeling led to many new covariance data. A comparison between results from model calculations using the JEFF-3.3 library and those from benchmark experiments for criticality, delayed neutron yields, shielding and decay heat, reveals that JEFF-3.3 is excellent for a wide range of nuclear technology applications, in particular nuclear energy.

Journal Articles

Measurement of cesium isotopic ratio by thermal ionization mass spectrometry for neutron capture reaction studies on $$^{135}$$Cs

Shibahara, Yuji*; Nakamura, Shoji; Uehara, Akihiro*; Fujii, Toshiyuki*; Fukutani, Satoshi*; Kimura, Atsushi; Iwamoto, Osamu

Journal of Radioanalytical and Nuclear Chemistry, 325(1), p.155 - 165, 2020/07

 Times Cited Count:0 Percentile:100(Chemistry, Analytical)

The measurements of isotopic ratios of Cs samples by thermal ionization mass spectrometry were performed for the analysis of their samples used to evaluate nuclear data obtained for $$^{135}$$Cs. To obtain a high intensity and stable ion beam, the effects of additive agents on the ionization of Cs were examined. The effect of silicotungstic acid on the ionization of Cs was the largest among the additive agents studied in the present study, while the silicotungstic acid also showed the largest isobaric interference of polyatomic ions. It was demonstrated that as small as 2$$times$$10$$^{-13}$$ g of a Cs sample was sufficient to achieve the analytical precision required to measure the $$^{135}$$Cs/$$^{137}$$Cs ratio in the case where an additive agent of TaO/glucose was employed. After examining of the analytical conditions, such as the interference effect due to Ba, the measurements of the isotopic ratios of two Cs samples used in our study using TIMS were conducted, and it was discussed how much the ratios contributed to evaluation of the neutron capture cross-section of $$^{135}$$Cs.

Journal Articles

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

Nakamura, Shoji; Shibahara, Yuji*; Kimura, Atsushi; Iwamoto, Osamu; Uehara, Akihiro*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 57(4), p.388 - 400, 2020/04

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

The thermal-neutron capture cross-section ($$sigma_{0}$$) and resonance integral(I$$_{0}$$) were measured for the $$^{135}$$Cs(n,$$gamma$$)$$^{136}$$Cs reaction by an activation method and mass spectrometry. We used $$^{135}$$Cs contained as an impurity in a normally available $$^{137}$$Cs standard solution. An isotope ratio of $$^{135}$$Cs and $$^{137}$$Cs in a standard $$^{137}$$Cs solution was measured by mass spectrometry to quantify $$^{135}$$Cs. The analyzed $$^{137}$$Cs samples were irradiated at the hydraulic conveyer of the research reactor in 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 $$sigma_{0}$$, and a value of 0.133 eV was taken as the cut-off energy. Gamma-ray spectroscopy was used to measure induced activities of $$^{137}$$Cs, $$^{136}$$Cs and monitor wires. On the basis of Westcott's convention, the $$sigma_{0}$$ and I$$_{0}$$ values were derived as 8.57$$pm$$0.25 barn, and 45.3$$pm$$3.2 barn, respectively. The $$sigma_{0}$$ obtained in the present study agreed within the limits of uncertainties with the past reported value of 8.3$$pm$$0.3 barn.

JAEA Reports

Survey of computational methods of cross sections for thermal neutron scattering by liquids

Ichihara, Akira

JAEA-Review 2019-046, 36 Pages, 2020/03

JAEA-Review-2019-046.pdf:1.55MB

Toward the revision of JENDL-4.0, we conducted a literature survey on how to compute the cross section of thermal neutrons scattered by a liquid. This report summarizes the computational methods for evaluating thermal neutron cross sections with molecular dynamics simulations. The cross section can be expressed with a function called as scattering law. For light and heavy water, the scattering law data instead of the cross sections have been provided in nuclear databases. In this report we review the formulations of the scattering laws. The scattering laws can be derived from both the intermediate scattering function and the space-time correlation function. Features of the derived scattering laws are briefly explained. It is shown that the scattering law data can be evaluated using a molecular dynamics simulation of the liquid that is the target of thermal neutrons.

Journal Articles

Estimation of uncertainty in lead spallation particle multiplicity and its propagation to a neutron energy spectrum

Iwamoto, Hiroki; Meigo, Shinichiro

Journal of Nuclear Science and Technology, 57(3), p.276 - 290, 2020/03

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

This paper presents an approach to uncertainty estimation of spallation particle multiplicity of lead ($$^{rm nat}$$Pb), primarily focusing on proton-induced spallation neutron multiplicity ($$x_{pn}$$) and its propagation to a neutron energy spectrum. The $$x_{pn}$$ uncertainty is estimated from experimental proton-induced neutron-production double-differential cross sections (DDXs) and model calculations with the Particle and Heavy Ion Transport code System (PHITS). Uncertainties in multiplicities for $$(n,xn)$$, $$(p,xp)$$, and $$(n,xp)$$ reactions are then inferred from the estimated $$x_{pn}$$ uncertainty and the PHITS calculation. Using these uncertainties, uncertainty in a neutron energy spectrum produced from a thick $$^{rm nat}$$Pb target bombarded with 500 MeV proton beams, measured in a previous experiment, is quantified by a random sampling technique, and propagation to the neutron energy spectrum is examined. Relatively large uncertainty intervals (UIs) were observed outside the lower limit of the measurement range, which is prominent in the backward directions. Our findings suggest that a reliable assessment of spallation neutron energy spectra requires systematic DDX experiments for detector angles and incident energies below 100 MeV as well as neutron energy spectrum measurements at lower energies below $$sim$$1.4 MeV with an accuracy below the quantified UIs.

Journal Articles

Activation measurement for thermal-neutron capture cross-section of Cesium-135

Nakamura, Shoji; Kimura, Atsushi; Iwamoto, Osamu; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*

KURNS Progress Report 2018, P. 106, 2019/08

Under the ImPACT project, the neutron capture cross-section measurements of Cesium-135 ($$^{135}$$Cs) among the long-lived fission products have been performed at Kyoto University. This paper reports measurements of the thermal-neutron capture cross-section of $$^{135}$$Cs at the Kyoto University Research Reactor (KUR).

Journal Articles

Measurements of the $$^{243}$$Am neutron capture and total cross sections with ANNRI at J-PARC

Kimura, Atsushi; Nakamura, Shoji; Terada, Kazushi*; Nakao, Taro*; Mizuyama, Kazuhito*; Iwamoto, Nobuyuki; Iwamoto, Osamu; Harada, Hideo; Katabuchi, Tatsuya*; Igashira, Masayuki*; et al.

Journal of Nuclear Science and Technology, 56(6), p.479 - 492, 2019/06

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

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

Nakamura, Shoji; Kitatani, Fumito; Kimura, Atsushi; Uehara, Akihiro*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 56(6), p.493 - 502, 2019/06

 Times Cited Count:1 Percentile:50.57(Nuclear Science & Technology)

The thermal-neutron capture cross-section($$sigma_{0}$$)and resonance integral(I$$_{0}$$) were measured for the $$^{237}$$Np(n,$$gamma$$)$$^{238}$$Np reaction by an activation method. A method with a Gadolinium filter, which is similar to the Cadmium difference method, was used to measure the $$sigma_{0}$$ with paying attention to the first resonance at 0.489 eV of $$^{237}$$Np, 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 $$gamma$$-ray spectroscopy was used to measure activities of $$^{237}$$Np, $$^{238}$$Np and neutron monitors. On the basis of Westcott's convention, the $$sigma_{0}$$ and I$$_{0}$$ values were derived as 186.9$$pm$$6.2 barn, and 1009$$pm$$90 barn, respectively.

Journal Articles

Measurement of neutron scattering cross section of nano-diamond with particle diameter of approximately 5 nm in energy range of 0.2 meV to 100 meV

Teshigawara, Makoto; Tsuchikawa, Yusuke*; Ichikawa, Go*; Takata, Shinichi; Mishima, Kenji*; Harada, Masahide; Oi, Motoki; Kawamura, Yukihiko*; Kai, Tetsuya; Kawamura, Seiko; et al.

Nuclear Instruments and Methods in Physics Research A, 929, p.113 - 120, 2019/06

 Times Cited Count:2 Percentile:26.15(Instruments & Instrumentation)

A nano-diamond is an attractive neutron reflection material below cold neutron energy. The total neutron cross section of a nano-diamond was derived from a neutron transmission measurement over the neutron energy range of 0.2 meV to 100 meV because total neutron cross section data were not available. The total cross section of a nano-diamond with particle size of approximately 5 nm increased with a decrease in neutron energy to 0.2 meV. It was approximately two orders of magnitude larger than that of graphite at 0.2 meV. The contribution of inelastic scattering to the total cross section was to be shown negligible small at neutron energies of 1.2, 1.5, 1.9, 2.6, and 5.9 meV in the inelastic neutron scattering measurement. Moreover, small-angle neutron scattering measurements of the nano-diamond showed a large scattering cross section in the forward direction for low neutron energies.

Journal Articles

Unified description of the fission probability for highly excited nuclei

Iwamoto, Hiroki; Meigo, Shinichiro

Journal of Nuclear Science and Technology, 56(2), p.160 - 171, 2019/02

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

We present a new model to describe the fission probability of the high-energy fission model, as deduced from the intranuclear cascade calculation with the Intra-Nuclear Cascade model of Li$`{e}$ge (INCL) version 4.6 and Prokofiev's phenomenological systematics of the proton-induced fission cross sections. This model is implemented in the de-excitation model of the Generalized Evaporation Model (GEM), and applied to Monte Carlo spallation reaction simulation using the Particle and Heavy Ion Transport code System (PHITS). Comparing with experimental data for subactinide nuclei shows that this model can provide a unified prediction of the proton-, neutron-, and deuteron-induced fission cross sections with markedly improved accuracy. The calculated fission fragments tend to shift to higher mass numbers. To account for the isotopic distributions of fission fragments within the framework of a coupled INCL/GEM, modification of INCL is required, especially for description of the highly-excited states of residual nuclei.

Journal Articles

Cross section measurements of $$^{155,157}$$Gd(n,$$gamma$$) induced by thermal and epithermal neutrons

Mastromarco, M.*; Manna, A.*; Aberle, O.*; Andrzejewski, J.*; Harada, Hideo; Kimura, Atsushi; n_TOF Collaboration*; 116 of others*

European Physical Journal A, 55(1), p.9_1 - 9_20, 2019/01

 Times Cited Count:6 Percentile:6.97(Physics, Nuclear)

Journal Articles

Progress of neutron-capture cross-section measurements promoted by ImPACT project at ANNRI in MLF of J-PARC

Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu; Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*

JAEA-Conf 2018-001, p.199 - 203, 2018/12

Study on cross-section measurements has been promoted for $$^{135}$$Cs among long-lived fission products in ImPACT Project. The feasibility study on $$^{79}$$Se sample preparation also has been conducted to measure its cross sections in future. During the feasibility study, we started the neutron-capture cross-section measurements of stable Se isotopes. This paper reports research progresses on preparation of a radioactive $$^{135}$$Cs sample, neutron irradiation experiments with the Cs sample, and cross-section measurements of stable Se isotopes.

Journal Articles

Analysis of $$^{135}$$Cs/$$^{137}$$Cs isotopic ratio for samples used for neutron capture cross section measurement project by thermal ionization mass spectrometry

Shibahara, Yuji*; Uehara, Akihiro*; Fujii, Toshiyuki*; Nakamura, Shoji; Kimura, Atsushi; Hales, B. P.; Iwamoto, Osamu

JAEA-Conf 2018-001, p.205 - 210, 2018/12

In the ImPACT project, high-precision mass analysis was performed on a $$^{137}$$Cs standard solution for using $$^{135}$$Cs included in the standard solution as an impurity to measure the $$^{135}$$Cs cross-sections. A $$^{137}$$Cs standard solution of only 10Bq (pg order) was analyzed, and the isotope ratio of $$^{135}$$Cs and $$^{137}$$Cs was obtained with an accuracy of 0.5%.

Journal Articles

Measurements of neutron total and capture cross sections of $$^{241}$$Am with ANNRI at J-PARC

Terada, Kazushi*; Kimura, Atsushi; Nakao, Taro*; Nakamura, Shoji; Mizuyama, Kazuhito*; Iwamoto, Nobuyuki; Iwamoto, Osamu; Harada, Hideo; Katabuchi, Tatsuya*; Igashira, Masayuki*; et al.

Journal of Nuclear Science and Technology, 55(10), p.1198 - 1211, 2018/10

 Times Cited Count:3 Percentile:35.66(Nuclear Science & Technology)

Journal Articles

Proton-induced activation cross section measurement for aluminum with proton energy range from 0.4 to 3 GeV at J-PARC

Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Hiroki

Journal of Nuclear Science and Technology, 55(8), p.955 - 961, 2018/08

 Times Cited Count:1 Percentile:72.34(Nuclear Science & Technology)

We have started an experimental program to measure activation cross sections systematically in the proton-induced spallation reaction in structural materials commonly used in high-intensity proton accelerator-based facilities, such as Japan Proton Accelerator Research Complex (J-PARC). As the first step of the program, aluminum (Al) was chosen to verify the adequacy of the measurement technique implemented in a J-PARC proton beam environment because data of Al have been relatively well studied both by experimental measurement and simulation. Activation cross sections of $$^{7}$$Be, $$^{22}$$Na, and $$^{24}$$Na in Al were measured at proton energy points from 0.4, 1.3, 2.2 to 3.0 GeV, which could be delivered smoothly from the synchrotron. The validity of experimental data has been verified by introducing an effective proton numbers determination procedure. We compared the measured data with existing experimental data, the evaluated data (JENDL-HE/2007), and the calculations with several intra-nuclear cascade models by the Particle and Heavy Ion Transport code System (PHITS) code. Although the experimental data agreed with JENDL-HE/2007, the calculations underestimated about 40%. This could come from the evaporation model (generalized evaporation model) being implemented in the PHITS code. We found that the calculations agreed with the experimental data by an upgraded PHITS code.

Journal Articles

Comparative study on prediction accuracy improvement methods with the use of integral experiments for neutronic characteristics of fast reactors

Yokoyama, Kenji; Kitada, Takanori*

Proceedings of 2018 International Congress on Advances in Nuclear Power Plants (ICAPP 2018) (CD-ROM), p.1221 - 1230, 2018/04

no abstracts in English

Journal Articles

Dimension-reduced cross-section adjustment method based on minimum variance unbiased estimation

Yokoyama, Kenji; Yamamoto, Akio*; Kitada, Takanori*

Journal of Nuclear Science and Technology, 55(3), p.319 - 334, 2018/03

 Times Cited Count:2 Percentile:50.63(Nuclear Science & Technology)

A new formulation of the cross-section adjustment methodology with the dimensionality reduction technique has been derived. This new formulation is proposed as the dimension reduced cross-section adjustment method (DRCA). Since the derivation of DRCA is based on the minimum variance unbiased estimation (MVUE), an assumption of normal distribution is not required. The result of DRCA depends on a user-defined matrix that determines the dimension reduced feature subspace. We have examine three variations of DRCA, namely DRCA1, DRCA2, and DRCA3. Mathematical investigation and numerical verification have revealed that DRCA2 is equivalent to the currently widely used cross-section adjustment method. Moreover, DRCA3 is found to be identical to the cross-section adjustment method based on MVUE, which has been proposed in the previous study.

Journal Articles

Benchmark of neutron production cross sections with Monte Carlo codes

Tsai, P.-E.; Lai, B.-L.*; Heilbronn, L. H.*; Sheu, R.-J.*

Nuclear Instruments and Methods in Physics Research B, 416, p.16 - 29, 2018/02

 Times Cited Count:1 Percentile:72.34(Instruments & Instrumentation)

Fifteen thin target experiments were selected for this benchmark study of the neutron production cross sections. The studied cases include a mix combination of $$^{12}$$C, $$^{20}$$Ne $$^{40}$$Ar, $$^{84}$$Kr, and $$^{132}$$Xe ions bombarding $$^{nat}$$Li, $$^{nat}$$C, $$^{nat}$$Al, $$^{nat}$$Cu, and $$^{nat}$$Pb target with projectile energies between 135 and 600 MeV/nucleon. The experimental data were compared to the model calculations performed by (1) PHITS version 2.73 with JQMD and GEM model, (2) PHITS version 2.82 with revised JQMD 2.0 and GEM model, (3) FLUKA version 2011.2c with RQMD 2.4 and FLUKA's own de-excitation model, and (4) MCNP6 version 1.0 with LAQGSM 03.03 and GEM2 model. This study provides useful information not only for code users but also for model developers, and it will lead to future improvements of the PHITS - JQMD model for heavy-ion induced reactions, which is important for accelerator facilities, heavy-ion radiotherapy, and space radiation.

Journal Articles

Radiative neutron capture on $$^{242}$$Pu in the resonance region at the CERN n_TOF-EAR1 facility

Lerendegui-Marco, J.*; Guerrero, C.*; Mendoza, E.*; Quesada, J. M.*; Eberhardt, K.*; Junghans, A. R.*; Kimura, Atsushi; n_TOF Collaboration*; 126 of others*

Physical Review C, 97(2), p.024605_1 - 024605_21, 2018/02

 Times Cited Count:8 Percentile:14.75(Physics, Nuclear)

300 (Records 1-20 displayed on this page)