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Am neutron capture and total cross sections with ANNRI at J-PARCKimura, 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：14 Percentile：84.54(Nuclear Science & Technology)
Am with ANNRI at J-PARCTerada, 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：18 Percentile：88.27(Nuclear Science & Technology)Mizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu; Terada, Kazushi; Nakao, Taro
JAEA-Conf 2017-001, p.163 - 168, 2018/01
GdMizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu; Hasemi, Hiroyuki*; Kino, Koichi*; Kimura, Atsushi; Kiyanagi, Yoshiaki*
EPJ Web of Conferences, 146, p.11042_1 - 11042_4, 2017/09
Times Cited Count：2 Percentile：78.04(Nuclear Science & Technology)Gadolinium has been used as neutron-absorbing material in a thermal reactor since have large thermal neutron capture cross sections. Nevertheless, there is a discrepancy between RPI data and JENDL-4.0 data for 
Gd. The criticality in the reactor is very sensitive to the capture cross section. The RPI data made the criticality of Gd-loaded thermal systems in ICSBEP overestimated. Recently, the neutron capture cross sections of Gd were measured by the neutron time-of-flight (TOF) method using the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) in the J-PARC/MLF. The pulsed neutron beam from the Japan Spallation Neutron Source (JSNS) was used with a double-bunch structure in this measurement, since the incident proton beam is normally delivered in a double-bunch scheme in the J-PARC. In addition to this, it is necessary to take into account the energy resolution of the pulsed neutron beam at the JSNS for the accurate derivation of resolved resonance parameters. In this study, using the least-squares multilevel R-matrix code REFIT modified to include the double bunch structure and the resolution function for the ANNRI, we fitted the calculated capture cross sections of Gd to the experimental data at the ANNRI. We derived the resonance parameters for some low-lying resonances of the two Gd isotopes.
Harada, Hideo; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kimura, Atsushi; Terada, Kazushi; Nakao, Taro; Nakamura, Shoji; Mizuyama, Kazuhito; Igashira, Masayuki*; Katabuchi, Tatsuya*; et al.
EPJ Web of Conferences, 146, p.11001_1 - 11001_6, 2017/09
Times Cited Count：2 Percentile：78.04(Nuclear Science & Technology)Am obtained by the Westcott conventionMizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu
Journal of Nuclear Science and Technology, 54(1), p.74 - 80, 2017/01
Mizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu
JAEA-Conf 2016-004, p.35 - 39, 2016/09
Improvement of the accuracy of neutron nuclear data for minor actinides (MAs) is required for the nuclear transmutation technique. The purpose of our study is development of evaluation method for improvement of nuclear data accuracy in MA isotopes. For the accurate evaluation, it is necessary to find out the reason of the discrepancy in previous data, to development of the accurate analysis method of the resonance parameters. So far, we found out the reason of the discrepancy of the thermal neutron capture cross section in previous measurements, and succeeded the correction. However the discrepancy of the resonance integral was not improved. The energy dependence of the epithermal neutron flux which has been used for the Cd ratio method can be different from the realistic experimental condition. This may be the reason for the discrepancy among the resonance integrals. For the accurate analysis of the resonance parameters, the precise resolution function's parameters are necessary. We are planning to obtain them by using the well-known stable nucleus and will apply them to the analysis of MAs.
Mizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu
Proceedings of International Conference on the Physics of Reactors; Unifying Theory and Experiments in the 21st Century (PHYSOR 2016) (USB Flash Drive), p.2437 - 2443, 2016/05
The accurate data of the minor actinides (MAs) is required for the nuclear waste problem. However, there is large discrepancy among the previous data. Especially such large discrepancy can been seen between the activation and the time-of-flight measurements. In the activation measurements, the Cd-ratio method based on the Westcott convention has been used in order to obtain the thermal neutron capture cross section 
and the resonance integral 
or the s-factor 
. By reviewing the Westcott convention and the Cd-ratio method, we found that the large discrepancy of can be made smaller by introducing a correction term for the resonance integral or the s-factor in order to correct the contribution of the resonances near the Cd cut-off energy. However, the discrepancy of the resonance integral and the s-factor still remains. In the original Westcott convention, the epithermal component of the neutron flux has been supposed to be proportional to 
, but it may not be true in the realistic condition of the neutron flux. Supposing 
for the epithermal component, we found that 
dependence is not negligible. For the fully consistent and more accurate evaluation of the previous activation measurements for MAs, the detailed information of the neutron flux is necessary and very important.
Am using JENDL-4.0Mizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu
JAEA-Conf 2015-003, p.245 - 250, 2016/03
The management of the nuclear waste problem requires the high precision of the neutron capture cross section for minor actinides. One of the important reaction is the neutron capture reaction of Am. However, the thermal neutron capture cross section of Am is not optimized yet. Especially the values of thermal cross sections measured by the activation technique are around 20% bigger than the other methods (TOF, 
& spectroscopy etc.). In the activation method, the Westcott conventional representation and the Cd-ratio method are used for the analysis of the cross section. However, it may not work well due the special resonance structure of Am. In our study, we verify the Cd-ratio method using the JENDL-4.0, and try to correct the experimental cross section based on our verification of the Cd-ratio method. Consequently we obtained the very close value of the cross section to the JENDL-4.0.
Harada, Hideo; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kimura, Atsushi; Terada, Kazushi; Nakao, Taro; Nakamura, Shoji; Mizuyama, Kazuhito; Igashira, Masayuki*; Katabuchi, Tatsuya*; et al.
EPJ Web of Conferences, 93, p.06001_1 - 06001_5, 2015/05
Times Cited Count：4 Percentile：85.29(Physics, Multidisciplinary)Improvement of accuracy of neutron nuclear data for minor actinides (MAs) and long-lived fission products (LLFPs) is required for developing innovative nuclear system transmuting these nuclei. In order to meet the requirement, the project entitled as "Research and development for Accuracy Improvement of neutron nuclear data on Minor ACtinides (AIMAC)" has been started as one of the "Innovative Nuclear Research and Development Program" at October 2013. The AIMAC project team is composed of researchers in four different fields: differential nuclear data measurement, integral nuclear data measurement, nuclear chemistry, and nuclear data evaluation. By integrating all of the forefront knowledge and techniques in these fields, the team aims at improving the accuracy of the data. The background, overall plan, and recent progress of the AIMAC project will be reviewed.
Iwamoto, Osamu; Iwamoto, Nobuyuki; Mizuyama, Kazuhito
no journal, ,
Under Innovative Nuclear Research and Development Program, "R&D for accuracy improvement of neutron nuclear data on minor actinides", present status of measurements and evaluations for MA nuclear data has been reviewed for "High quality evaluation via bouncing ideas off measurement and evaluation". The important MAs of Np-237 and Am-241, 243 were investigated in the thermal to fast neutron region. It was found that measured data for the thermal neutron cross sections of Np-237 and Am-241 were converging to a value with 5 to 6% discrepancies. The errors in evaluated nuclear data library were checked by comparing with the experimental data. Data for important FPs of Tc-99, I-129 etc. were also reviewed. In this presentation, a plan and result of review for a part of nuclear data evaluation of the program will be reported.
Harada, Hideo; Iwamoto, Osamu; Nakamura, Shoji; Kimura, Atsushi; Iwamoto, Nobuyuki; Terada, Kazushi; Nakao, Taro; Mizuyama, Kazuhito; Igashira, Masayuki*; Katabuchi, Tatsuya*; et al.
no journal, ,
The research project has been started for improving accuracy of neutron nuclear data for minor actinides (MAs) and long-lived fission products (LLFPs), which is required for developing innovative nuclear system transmuting these nuclei. The project consists of 5 items: (1) Accurate measurements of thermal neutron capture cross-sections (2) High-precision quantification of sample amount used for TOF measurement (3) Resonance parameter determination by combining total and capture cross sections (4) Extension of capture cross sections to high energy neutrons (5) High quality evaluation based on iterative communication with experimenters. The overall plan of the project is presented.
Harada, Hideo; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kimura, Atsushi; Terada, Kazushi; Nakao, Taro; Nakamura, Shoji; Mizuyama, Kazuhito; Igashira, Masayuki*; Katabuchi, Tatsuya*; et al.
no journal, ,
Improvement of accuracy of neutron nuclear data for minor actinides (MAs) and long-lived fission products (LLFPs) is required for developing innovative nuclear system transmuting these nuclei. In order to meet the requirement, the project entitled as "Research and development for Accuracy Improvement of neutron nuclear data on Minor ACtinides (AIMAC)" has been started as one of the "Innovative Nuclear Research and Development Program" at October 2013. The background, overall plan, and expected achievements of the AIMAC project will be reviewed.
AmMizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu
no journal, ,
The accuracy of nuclear data for the minor actinides (MAs) included in the high level radioactive wastes which have the long term radiotoxicity is required to be improved for the environmental load reduction technique. However, there is large discrepancy among the previous measurements for MAs. The Cadmium(Cd)-ratio method is the analysis method to deduce the and the s-factor by using the Cd-ratio given by the reaction rates without(with) the Cd-filter. The s-factor is defined by the normalized resonance integral by after subtracting 1/v component. Since there are lower resonances than the cut-off energy in Am, it is necessary to correct the effect of them in order to deduce the accurately. In this study, we evaluated the effect of the lower resonances than the cut-off energy as the correction of s-factor from the JENDL-4.0, and corrected the existing the data. As a result, the consistency among the measurements was improved.
Terada, Kazushi; Nakao, Taro; Kimura, Atsushi; Nakamura, Shoji; Mizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu; Harada, Hideo
no journal, ,
Measurements of the neutron total and capture cross sections of Am-241 have been performed using a time-of-flight method with a Li-glass detector and Ge spectrometers located on the ANNRI of the MLF in the J-PARC. The neutron total cross sections of Am-241 were determined in the neutron energy region from 4 meV to 2 eV. Comparisons of the present result with previous experimental data and evaluations were made. This contribution presents the obtained results.
TcIwamoto, Nobuyuki; Mizuyama, Kazuhito; Iwamoto, Osamu
no journal, ,
no abstracts in English
Am with ANNRI at J-PARCTerada, Kazushi; Nakao, Taro; Kimura, Atsushi; Nakamura, Shoji; Mizuyama, Kazuhito; Iwamoto, Nobuyuki; Iwamoto, Osamu; Harada, Hideo
no journal, ,
Measurements of neutron capture cross sections of Am have been performed with Ge spectrometers at ANNRI in the J-PARC. We obtained capture cross sections of Am in neutron energy region from the thermal to 100 eV. The results were compared with previous measurements and evaluations.
Harada, Hideo; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kimura, Atsushi; Terada, Kazushi; Nakao, Taro; Nakamura, Shoji; Mizuyama, Kazuhito; Igashira, Masayuki*; Katabuchi, Tatsuya*; et al.
no journal, ,
To improve accuracy of neutron nuclear data on minor actinides, a Japanese nuclear data project entitled as "Research and development for Accuracy Improvement of neutron nuclear data on Minor ACtinides (AIMAC)" has been performed by integrating all of the forefront knowledge and techniques in four different fields, such as, differential nuclear data measurement, integral nuclear data measurement, nuclear chemistry, and nuclear data evaluation. Highlights of the AIMAC project and their impacts are outlined.
