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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.

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:47.15(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


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:0 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:0 Percentile:100(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:23.33(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:0 Percentile:100(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%.

JAEA Reports

Proceedings of the 2017 Symposium on Nuclear Data; November 16-17, 2017, iVil, Tokai-mura, Ibaraki, Japan

Nishio, Katsuhisa; Utsuno, Yutaka; Chiba, Satoshi*; Koura, Hiroyuki; Iwamoto, Osamu; Nakamura, Shoji

JAEA-Conf 2018-001, 226 Pages, 2018/12


The 2017 Symposium on Nuclear Data was held at iVil in Tokai on November 16-17, 2017. The symposium was hosted by the Nuclear Data Division of the Atomic Energy Society of Japan (AESJ) and Advanced Science Research Center of Japan Atomic Energy Agency, and co-hosted by Japanese Nuclear Data Committee of AESJ and North Kanto Branch of AESJ. In the symposium, a tutorial was given by Prof. Rykaczewski (ORNL) "New nuclear data from total absorption spectroscopy and beta-delayed neutron measurements", as well as six oral sessions, "Nuclear Physics and Nuclear Data" (two sessions), "Nuclear Theory and Nuclear Data", "Reactors" and "Nuclear Data and Their Applications" (two sessions). In addition, recent advances in experiment, theory, evaluation, benchmark, and application were presented in the poster session. The symposium had 79 participants, who contributed to very active and fruitful discussions. This report consists of 37 papers, including those of 14 oral and 23 poster presentations.

Journal Articles

Present status and future plan of JENDL

Iwamoto, Osamu

JAEA-Conf 2018-001, p.87 - 91, 2018/12

Status and plan of JENDL will be presented. After the release of JENDL-4.0 in 2010, six special purpose files have been developed. Four of them were already released and two are under preparation for the release. New decay and yield data for fission products were released as JENDL/FPD-2011 and JENDL/FPY-2011 in 2011, respectively. JENDL-4.0/HE released in 2015 includes proton and neutron induced reaction data up to 200 MeV. Comprehensive decay data were released as JENDL/DDF-2015 which contains data for 3,237 nuclides. New photonuclear reaction data JENDL/PD-2016 and an activation file JENDL/AD-2017 are under preparation for release. Regarding general purpose file, two activities are in progress. One is JENL-4.0u which is created for maintenance of JENDL-4.0 and the other is development of next version of JENDL. For the next JENDL, evaluation for light nuclei and structure material are in progress. It is planed that next version of JENDL will be JENDL-5 which contains nuclear data for all nuclei having natural abundance. Addition of covariance data will be one of the main targets.

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.

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