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Journal Articles

Recent progress of a code system DEURACS toward deuteron nuclear data evaluation

Nakayama, Shinsuke; Iwamoto, Osamu; Watanabe, Yukinobu*

EPJ Web of Conferences, 239, p.03014_1 - 03014_4, 2020/09

Intensive neutron sources using deuteron accelerators have been proposed for various applications such as irradiation test for fusion reactor materials and production of radioisotopes for medical use. In addition, transmutation system using deuteron-induced spallation reactions has been recently proposed for LLFPs. Accurate and comprehensive deuteron nuclear data are indispensable in the design study of such facilities. Under the above situations, we have been developing a code system dedicated for deuteron-induced reactions, which is called DEURACS. In the present work, calculations using DEURACS are compared with available experimental data up to 200 MeV such as DDXs for emission of neutron or light charged particles. We also analyze isotopic production cross sections of residual nuclei. Validation of the present modelling in DEURACS is discussed through comparison with the experimental data.

Journal Articles

Evaluation of gamma-ray strength function based on measured gamma-ray pulse-height spectra in time-of-flight neutron capture experiments

Iwamoto, Nobuyuki; Nakamura, Shoji; Kimura, Atsushi; Katabuchi, Tatsuya*; Rovira, G.*; Hara, Kaoru*; Iwamoto, Osamu

EPJ Web of Conferences, 239, p.17016_1 - 17016_4, 2020/09

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:1 Percentile:58.8(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.

Journal Articles

Natural isotope abundance and thermal cross section

Iwamoto, Osamu

Aisotopu Techo 12-Han, p.117 - 130, 2020/03

Natural isotope abundance and thermal neutron cross sections are given by a table. The natural isotope abundance is adopted from the IUPAC report and the thermal cross sections are taken from JENDL-4.0. Thermal neutron-capture cross sections and the isomer and ground state production cross sections are given. The other reaction cross section larger than 1 micro-barn are also given.

Journal Articles

Neutron capture cross-section measurement and resolved resonance analysis of $$^{237}$$Np

Rovira, G.*; Katabuchi, Tatsuya*; Tosaka, Kenichi*; Matsuura, Shota*; Terada, Kazushi*; Iwamoto, Osamu; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Nobuyuki; Segawa, Mariko; et al.

Journal of Nuclear Science and Technology, 57(1), p.24 - 39, 2020/01

Journal Articles

JENDL/ImPACT-2018; A New nuclear data library for innovative studies on transmutation of long-lived fission products

Kunieda, Satoshi; Furutachi, Naoya; Minato, Futoshi; Iwamoto, Nobuyuki; Iwamoto, Osamu; Nakayama, Shinsuke; Ebata, Shuichiro*; Yoshida, Toru*; Nishihara, Kenji; Watanabe, Yukinobu*; et al.

Journal of Nuclear Science and Technology, 56(12), p.1073 - 1091, 2019/12

 Times Cited Count:1 Percentile:58.8(Nuclear Science & Technology)

A new nuclear data library, JENDL/ImPACT-2018, is developed for an innovative study on the transmutation of long-lived fission products. Nuclear reaction cross- sections are newly evaluated for incident neutrons and protons up to 200 MeV for 163 nuclides including long-lived nuclei such as $$^{79}$$Se, $$^{93}$$Zr, $$^{107}$$Pd and $$^{135}$$Cs. Our challenge is an evaluation of cross-sections for a number of unstable nuclei over a wide energy range where the experimental data are very scarce. We estimated cross- sections based on a nuclear model code CCONE that incorporates an advanced knowledge on the nuclear structure theory and a model-parameterization based on a new experimental cross-sections measured by the inverse kinematics. Through comparisons with available experimental data on the stable isotopes, it is found that the present data give predictions of cross-sections better than those in the existing libraries.

JAEA Reports

Proceedings of the 2018 Symposium on Nuclear Data; November 29-30, 2018, Tokyo Institute of Technology, Ookayama Campus, Tokyo, Japan

Chiba, Satoshi*; Ishizuka, Chikako*; Tsubakihara, Kosuke*; Iwamoto, Osamu

JAEA-Conf 2019-001, 203 Pages, 2019/11

JAEA-Conf-2019-001.pdf:18.86MB

The 2018 Symposium on Nuclear Data was held at Multi-Purpose Digital Hall and Collaboration Room of Tokyo Institute of Technology, on November 29 and 30, 2018. The symposium was organized by the Nuclear Data Division of the Atomic Energy Society of Japan (AESJ) in cooperation with Sigma Special Committee of AESJ, Nuclear Science and Engineering Center of Japan Atomic Energy Agency, and Laboratory for Advanced Nuclear Energy of Institute of Innovative Research, Tokyo Institute of Technology. In the symposium, there were one tutorial, "Development of nuclear data processing code FRENDY", one special lecture "What the future holds for Nuclear Energy" and seven oral sessions, "Nuclear Data and Future Perspectives", "Current Status and Future Perspectives of Reactor Physics", "Topics", "Nuclear Data Applications", "International Session", "Nuclear Data Measurements and New Technology for Nuclear Reactor Diagnosis", and "Data Needs from New Fields". In addition, recent research progress on experiments, evaluation, benchmark and application was presented in the poster session. Among 82 participants, all presentations and following discussions were very active and fruitful. This report consists of total 35 papers including 13 oral and 22 poster presentations.

Journal Articles

Report of 31st Meeting of the Working Party on International Nuclear Data Evaluation Co-operation (WPEC)

Iwamoto, Osamu; Iwamoto, Nobuyuki; Kimura, Atsushi; Yokoyama, Kenji; Tada, Kenichi

Kaku Deta Nyusu (Internet), (124), p.23 - 34, 2019/10

The 31st annual meeting and the subgroup meeting of the Working Party on International Nuclear Data Evaluation Co-operation (WPEC) under the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development (OECD/NEA) was held at the head quarter of OECD/NEA located at Boulogne-Billancourt near Paris from 24 to 28 in June in 2019. The activities about nuclear data measurement and evaluation of each region or country were reported at the annual meeting, and the SG activities were discussed at the subgroup meetings. The summary of these meetings are reported.

Journal Articles

Consistent description of light composite particle emission in deuteron-induced reactions

Nakayama, Shinsuke; Iwamoto, Osamu; Watanabe, Yukinobu*

Physical Review C, 100(4), p.044603_1 - 044603_8, 2019/10

 Times Cited Count:1 Percentile:100(Physics, Nuclear)

The weakly-bound nature of the deuteron brings the complexity of deuteron-induced reactions compared to nucleon-induced ones, and is expected to affect various physical quantities observed in deuteron-induced reactions. Aiming to deep understanding and accurate prediction for the emission of light composite particle (LCP) in deuteron-induced reactions, we revise the computational system dedicated to deuteron-induced reactions, called DEURACS. The model by Iwamoto and Harada describing pre-equilibrium cluster emission which was successfully applied to LCP emission innucleon-induced reactions is integrated into the framework of DEURACS, in which the breakup processes of incident deuteron are explicitly taken into account. The phenomenological model by Kalbach is also adopted to estimate the contribution from the direct pickup process. Using the revised DEURACS, we analyze the $$(d,xt)$$, $$(d,xmathrm{^{3}He})$$, and $$(d,xalpha)$$ reactions in the target mass range $$27 leqslant A leqslant 90$$. Regardless of the targets, the calculation results successfully reproduced the experimental data for each reaction, simultaneously. These results demonstrates that the LCP emission from the pre-equilibrium and compound nucleus processes in deuteron-induced reactions,which occupies a large part of the total LCP emission,can be described by the same theoretical models as used in nucleon-induced reactions when the breakup processes of incident deuteron are properly considered.

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

Statistical properties of thermal neutron capture cross sections calculated with randomly generated resonance parameters

Furutachi, Naoya; Minato, Futoshi; Iwamoto, Osamu

Physical Review C, 100(1), p.014610_1 - 014610_7, 2019/07

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

We investigated the probability distribution of thermal neutron capture cross sections ($$sigma_{rm th}$$) deduced stochastically with the resonance parameters randomly sampled from Wigner and Porter-Thomas distributions. We found that the typical probability distribution has an asymmetric shape. While there is a long tail on the large $$sigma_{rm th}$$ side due to a resonance happening to be close to the thermal energy, the multiresonance contribution considerably reduces the probability on the small $$sigma_{rm th}$$ side. We also found that the probability distributions have a similar shape if nuclei have an average resonance spacing sufficiently larger than an average radiation width. We compared the typical probability distribution with the distribution of the experimental values of 193 nuclei and found a good agreement between them.

Journal Articles

Present status and future prospect of high energy nuclear data used for radiation therapy

Iwamoto, Osamu; Kunieda, Satoshi; Iwamoto, Nobuyuki

Isotope News, (763), p.4 - 7, 2019/06

no abstracts in English

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:1 Percentile:58.8(Nuclear Science & Technology)

Journal Articles

International Conference on Nuclear Data for Science and Technology (ND2019), 3; Evaluation and theory

Nakayama, Shinsuke; Iwamoto, Osamu; Iwamoto, Nobuyuki; Hashimoto, Shintaro

Kaku Deta Nyusu (Internet), (123), p.53 - 59, 2019/06

The 2019 International Conference on Nuclear Data for Science and Technology (ND2019) was held at the China National Convention Center on May 19-24, 2019. The series of the ND conferences are the largest conferences in nuclear data research field that are held every three years. In this paper, as a part of the conference reports of ND2019, the authors gave summaries of the presentations on nuclear data evaluation and theory conducted at the conference.

Journal Articles

Phenomenological level density model with hybrid parameterization of deformed and spherical state densities

Furutachi, Naoya*; Minato, Futoshi; Iwamoto, Osamu

Journal of Nuclear Science and Technology, 56(5), p.412 - 424, 2019/05

 Times Cited Count:2 Percentile:34.3(Nuclear Science & Technology)

A phenomenological level density model that has different level density parameter sets for the state densities of the spherical and the deformed states, and the optimization of the parameters using the experimental data of the average s-wave neutron resonance spacing are presented. The transition to the spherical state from the deformed one is described using the parameters derived from a microscopic nuclear structure calculation. The nuclear reaction calculation has been performed by the statistical model using the present level density. Resulting cross sections for various reactions with the spherical, deformed and transitional target nuclei shows a fair agreement with the experimental data, which indicates the effectiveness of the present model. The role of the rotational collective enhancement in the calculations of those cross sections is also discussed.

Journal Articles

Measurements of neutron capture reaction cross-sections at ANNRI of MLF in J-PARC

Iwamoto, Osamu

ImPACT Fujita Puroguramu Kokai Seika Hokokukai "Kaku Henkan Niyoru Koreberu Hoshasei Haikibutsu No Ohaba Na Teigen, Shigenka" Seika Hokokusho, Shiryoshu, p.78 - 81, 2019/03

Measurements of Neutron Capture Reaction Cross-Sections at ANNRI of MLF in J-PARC have been conducted as a part of the ImPACT Fujita Program titled "Reduction and Resource Recycling of High-level Radioactive Wastes through Nuclear Transmutation". A resonance cross section of the neutron capture reaction with Cs-135 was measured. In addition, a thermal cross section and a resonance integral have been deduced by an activation experiment at KUR. Summary of this study will be reported.

Journal Articles

Development of the standard evaluated database of nuclear reactions for long lived fission products

Iwamoto, Osamu

ImPACT Fujita Puroguramu Kokai Seika Hokokukai "Kaku Henkan Niyoru Koreberu Hoshasei Haikibutsu No Ohaba Na Teigen, Shigenka" Seika Hokokusho, Shiryoshu, p.102 - 105, 2019/03

Study on the development of the standard evaluated database of nuclear reactions for long lived fission products has been conducted as a part of the ImPACT Fujita Program titled "Reduction and Resource Recycling of High-level Radioactive Wastes through Nuclear Transmutation". The database of the neutron and proton induced reactions on LLFPs and their neighbor nuclei has been developed taking account of the up-to-date theoretical and experimental knowledges. In addition, the update of the calculation methods of deuteron induced reactions has also conducted. Summary of this study will be reported.

Journal Articles

Impulsing paradigm change through disruptive technologies program, ImPACT; Reduction and resource recycling of high-level radioactive waste through nuclear transmutation

Iwamoto, Osamu; Fujita, Reiko*; Niita, Koji*; Watanabe, Yukinobu*

Kaku Deta Nyusu (Internet), (122), p.33 - 43, 2019/02

A program related to the transmutation of long-lived fission products (LLFPs) entitled "Reduction and Resource Recycling of High-level Radioactive Wastes through Nuclear Transmutation" has been conducted under the Impulsing Paradigm Change through Disruptive Technologies Program (ImPACT) organized by the Cabinet Office since 2014 and it will be finished in FY 2018. Various activities from acquisition of basic data to examination of transmutation scenario are being carried out as the five separated projects. R&Ds related to nuclear data are also conducted and many outcomes are being produced. This article describes results of the two projects related nuclear data with a short introduction of the whole project.

Journal Articles

Measurements of gamma-ray emission probabilities in the decay of americium-244g

Nakamura, Shoji; Terada, Kazushi*; Kimura, Atsushi; Nakao, Taro*; Iwamoto, Osamu; Harada, Hideo; Uehara, Akihiro*; Takamiya, Koichi*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 56(1), p.123 - 129, 2019/01

 Times Cited Count:1 Percentile:58.8(Nuclear Science & Technology)

Accurate data of $$gamma$$-ray emission probabilities are frequently needed when one quantitatively determines the amount of isotope by $$gamma$$-ray measurements or obtains neutron capture cross-sections using them. Americium-243, one of the most important minor actinides, produces $$^{244}$$Am after neutron capture. The 744-keV $$gamma$$-ray decaying from the ground state of $$^{244}$$Am has a relatively large $$gamma$$-ray emission probability c.a. 66%, however, its uncertainty is as large as 29%. The uncertainty of the $$gamma$$-ray emission probability leads to a major factor of the systematic uncertainty on determining an amount of isotope, and therefore the $$gamma$$-ray emission probability was measured by using an activation method and an examined level structure of $$^{244}$$Cm. In this study, the emission probability of 744-keV $$gamma$$ ray was derived as 66.5$$pm$$1.1%, and its uncertainty was improved from 29% to 2%.

261 (Records 1-20 displayed on this page)