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Iwamoto, Hiroki
Kaku Deta Nyusu (Internet), (129), p.19 - 25, 2021/06
no abstracts in English
Meigo, Shinichiro; Iwamoto, Yosuke; Matsuda, Hiroki
Isotope News, (774), p.27 - 31, 2021/04
no abstracts in English
Iwamoto, Hiroki; Meigo, Shinichiro
JPS Conference Proceedings (Internet), 33, p.011046_1 - 011046_6, 2021/03
no abstracts in English
Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
JPS Conference Proceedings (Internet), 33, p.011050_1 - 011050_6, 2021/03
R&D of the beam window is crucial in the ADS, which serves as a partition between the accelerator and the target region. Although the displacement per atom (DPA) is used to evaluate the damage on the window, experimental data on the displacement cross section is scarce in the energy region above 20 MeV. We started to measure the displacement cross section for the protons in the energy region between 0.4 to 3 GeV. The displacement cross section can be derived by resistivity change divided by the proton flux and the resistivity change per Frankel pair on cryo-cooled sample to maintain damage. Experiments were conducted at the 3 GeV proton synchrotron at the J-PARC Center, and aluminum and copper was used as samples. As a result of comparison between the present experiment and the calculation of the NRT model, which is widely used for calculation of the displacement cross section, it was found that the calculation of the NRT model overestimated the experiment by about 3 times.
Takeshita, Hayato; Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Hiroki; Maekawa, Fujio; Watanabe, Yukinobu*
JPS Conference Proceedings (Internet), 33, p.011045_1 - 011045_6, 2021/03
To improve accuracy of nuclear design of accelerator driven nuclear transmutation systems, nuclide production cross sections on Ni and Zr, which were candidate materials to be used in ADS, were measured for GeV energy protons. The measured results were compared with PHITS calculations and JENDL/HE-2007.
Fe for 0.4-3.0 GeV protons in J-PARCMatsuda, Hiroki; Takeshita, Hayato*; Meigo, Shinichiro; Maekawa, Fujio; Iwamoto, Hiroki
JPS Conference Proceedings (Internet), 33, p.011047_1 - 011047_6, 2021/03
Accurate nuclide production cross-section data are required for the design of Accelerator-Driven nuclear transmutation System (ADS) such as the design of radioactive waste disposal, design of remote-handling procedure of highly activated components, and evaluation of exposure doses of rad-workers. Although much efforts have been devoted to nuclide production cross-section measurements so far, uncertainties of the measured data are sometimes large as several tens percentage, and there is no experimental data in the GeV energy region even for some of important nuclides. In this study, proton induced nuclide production cross-section of iron, which is the most important constituent element of steel, was measured. The present experiment was compared with calculations by the PHITS code with several physics models including Bertini and INCL4.6 and evaluated nuclear data JENDL-HE/2007. The most significant discrepancy found in this study was the production cross sections via the (p,xn) reaction. It was suggested that further improvements, such as the in-medium effect on the nucleon-nucleon scattering and the Pauli blocking, were required in the intra-nuclear cascade models used in this study.
Iwamoto, Yosuke; Yoshida, Makoto*; Matsuda, Hiroki; Meigo, Shinichiro; Satoh, Daiki; Yashima, Hiroshi*; Yabuuchi, Atsushi*; Shima, Tatsushi*
Materials Science Forum, 1024, p.95 - 101, 2021/03
To predict the lifetime of target materials in high-energy radiation environments at spallation neutron sources, radiation transport codes such as PHITS are used to calculate the displacements per atom (DPA) value. In this work, to validate calculated DPA values of tungsten, we implemented 0.25-mm-diameter wire sample of tungsten in a proton irradiation device with a Gifford-McMahon cryocooler and measured the defect-induced electrical resistivity changes related to the displacement cross section using 389-MeV protons at 10 K. As well as our previous results for aluminum and copper, calculated results with defect production efficiencies provided good agreements with experimental data. Based on measurements of recovery of the defects through annealing, about 85% of the damage remained at 60 K, and the same tendency is observed in other experimental result for reactor neutron irradiation.
Iwamoto, Hiroki
Kaku Deta Nyusu (Internet), (128), p.13 - 25, 2021/02
no abstracts in English
for a mercury target induced by 3-GeV protonsMatsuda, Hiroki; Iwamoto, Hiroki; Meigo, Shinichiro; Takeshita, Hayato*; Maekawa, Fujio
Nuclear Instruments and Methods in Physics Research B, 483, p.33 - 40, 2020/11
Times Cited Count：0 Percentile：0.02(Instruments & Instrumentation)A thick target neutron yield for a mercury target at an angle of 180 from the incident beam direction is measured with the time-of-flight method using a 3-GeV proton beam at the Japan Proton Accelerator Research Complex (J-PARC). Comparing the experimental result with a Monte Carlo particle transport simulation by the Particle and Heavy Ion Transport code System (PHITS) shows that there are apparent discrepancies. We find that this trend is consistent with an experimental result of neutron-induced re- action rates obtained using indium and niobium activation foils. Comparing proton-induced neutron-production double-differential cross-sections for a lead target at backward directions between the PHITS calculation and experimental data suggests that the dis- crepancies for our experiments would be linked to the neutron production calculation around 3 GeV by the PHITS spallation model and/or the calculation of nonelastic cross-sections around 3 GeV in the particle transport simulation.
Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
Journal of Nuclear Science and Technology, 57(10), p.1141 - 1151, 2020/10
Times Cited Count：3 Percentile：66.08(Nuclear Science & Technology)To estimate the structural damages of materials in accelerator facilities, displacement per atom (dpa) is widely employed as a damage index, calculated based on the displacement cross-section obtained using a calculation model. Although dpa is applied as standard, the experimental data of the displacement cross-section for a proton in the energy region above 20 MeV are scarce. Among the calculation models, difference of about factor 8 exist, so that the experimental data of the cross-section are crucial to validate the model. To obtain the displacement cross-section, we conducted experiments at J-PARC. The displacement cross-section of copper and iron was successfully obtained for a proton projectile with the kinetic energies, 0.4 - 3 GeV. The results were compared with those obtained using the widely utilized Norgertt-Robinson-Torrens (NRT) model and the athermal-recombination-corrected (arc) model based on molecular dynamics. It was found that the NRT model overestimates the present displacement cross-section by 3.5 times. The calculation results obtained using with the arc model based on the Nordlund parameter show remarkable agreement with the experimental data. It can be concluded that the arc model must be employed for the dpa calculation for the damage estimation of copper and iron.
) reaction for the development of accelerator-based neutron sourcesWatanabe, Yukinobu*; Sadamatsu, Hiroki*; Araki, Shohei*; Nakano, Keita*; Kawase, Shoichiro*; Kin, Tadahiro*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; et al.
EPJ Web of Conferences, 239, p.20012_1 - 20012_4, 2020/09
Times Cited Count：1 Percentile：91.61Accelerator-based neutron sources induced by deuteron beams are attractive for study of nuclear transmutation of radioactive waste as well as radiation damage for fusion reactor materials. In the present work, we have carried out a Double Differential cross section (DDX) measurement for Li at 200 MeV in the Research Center for Nuclear Physics (RCNP), Osaka University. A deuteron beam accelerated to 200 MeV was transported to the neutron experimental hall and focused on a thin Li target. Emitted neutrons from the target were detected by two different-size EJ301 liquid organic scintillators located at two distances of 7 m and 20 m, respectively. The neutron DDXs were measured at six angles from 0 to 25). The neutron detection efficiencies of the detectors were calculated by SCINFUL-QMD code. We will present the results of the present DDX measurement and compare them with theoretical model calculations with DEURACS and PHITS.
Iwamoto, Hiroki; Meigo, Shinichiro; Matsuda, Hiroki
EPJ Web of Conferences, 239, p.06001_1 - 06001_6, 2020/09
Times Cited Count：0 Percentile：0.19no abstracts in English
Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Hiroki; Maekawa, Fujio
EPJ Web of Conferences, 239, p.06004_1 - 06004_4, 2020/09
Times Cited Count：0 Percentile：0.19For the Accelerator-Driven nuclear transmutation System (ADS), nuclide production yield estimation in the lead-bismuth target is important to manage the target. However, experimental data of nuclide production yield by spallation and high-energy fission reactions are scarce. In order to obtain the experimental data, we experimented in J-PARC using Pb and 
Bi samples. The samples were irradiated with protons at various kinematic energy points between 0.4 and 3.0 GeV. After the irradiation, the nuclide production cross section over 
Be to 
Re was obtained by spectroscopic measurement of decay gamma-rays from the samples with HPGe detectors. The present experimental results were compared with the evaluated data (JENDL-HE/2007) and the calculation with the PHITS code and the INCL++ code. The present experiment data showed consistency with other experimental data with better accuracy than other ones. In reactions to produce light nuclides, JENDL and calculation with the PHITS and INCL++ for Be production agreed with the data.
Na production, however, underestimated about 1/10 times. For middle to heavy nuclide productions cases, both calculations agreed with the experiment by a factor of two. JENDL showed lower energy having a maximum value of excitation function maximal value than the experimental data.
Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
EPJ Web of Conferences, 239, p.06006_1 - 06006_4, 2020/09
Times Cited Count：0 Percentile：0.19R&D of the beam window is crucial in the ADS, which serves as a partition between the accelerator and the target region. Although the displacement per atom (DPA) is used to evaluate the damage on the window, experimental data on the displacement cross section is scarce in the energy region above 20 MeV. We started to measure the displacement cross section for the protons in the energy region between 0.4 to 3 GeV. The displacement cross section can be derived by resistivity change divided by the proton flux and the resistivity change per Frankel pair on cryo-cooled sample to maintain damage. Experiments were conducted at the 3 GeV proton synchrotron at the J-PARC Center, and copper was used as samples. As a result of comparison between the present experiment and the calculation of the NRT model, which is widely used for calculation of the displacement cross section, it was found that the calculation of the NRT model overestimated the experiment by about 3 times.
Iwamoto, Hiroki
Journal of Nuclear Science and Technology, 57(8), p.932 - 938, 2020/08
Times Cited Count：4 Percentile：66.08(Nuclear Science & Technology)We present a new approach to generate nuclear data from experimental cross section data by Gaussian process regression. This paper focuses on generating proton-induced nuclide production cross sections for nickel target. Our results provide reasonable fitting curves together with their uncertainties and suggest that this approach appears to be effective in generating or evaluating the nuclear data. Besides, our results suggest that our approach could be available for experimental design in terms of reducing the generated nuclear data uncertainty.
Iwamoto, Hiroki; Meigo, Shinichiro
Journal of Nuclear Science and Technology, 57(3), p.276 - 290, 2020/03
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)This paper presents an approach to uncertainty estimation of spallation particle multiplicity of lead (
Pb), primarily focusing on proton-induced spallation neutron multiplicity (
) and its propagation to a neutron energy spectrum. The 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 
, 
, and 
reactions are then inferred from the estimated uncertainty and the PHITS calculation. Using these uncertainties, uncertainty in a neutron energy spectrum produced from a thick 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 
1.4 MeV with an accuracy below the quantified UIs.
Iwamoto, Yosuke; Yoshida, Makoto*; Matsuda, Hiroki; Meigo, Shinichiro; Satoh, Daiki; Yashima, Hiroshi*; Yabuuchi, Atsushi*; Kinomura, Atsushi*; Shima, Tatsushi*
JPS Conference Proceedings (Internet), 28, p.061003_1 - 061003_5, 2020/02
To predict the lifetime of target materials in high-energy radiation environments at spallation neutron sources, radiation transport codes such as PHITS are used to calculate the displacements per atom (DPA) value. In this work, to validate calculated DPA values of tungsten, we implemented 0.25-mm-diameter wire sample of tungsten in a proton irradiation device with a Gifford-McMahon cryocooler and measured the defect-induced electrical resistivity changes related to the displacement cross section using 389-MeV protons at 10 K. In comparison with experimental data under 1.1 and 1.9 GeV proton irradiation, we found that damage rate of tungsten increases with proton energy due to increase the number of secondary particle s produced by nuclear reactions.
Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
JPS Conference Proceedings (Internet), 28, p.061004_1 - 061004_6, 2020/02
no abstracts in English
Iwamoto, Hiroki; Meigo, Shinichiro
Journal of Nuclear Science and Technology, 56(2), p.160 - 171, 2019/02
Times Cited Count：1 Percentile：24.18(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
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.
Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Hiroki
Progress in Nuclear Science and Technology (Internet), 6, p.171 - 174, 2019/01
Activation cross sections of various materials are strongly required for the improvement of the accuracy of nuclear design and the reduction of the construction costs for spallation neutron sources and transmutation systems. Activation cross sections have been measured in several facilities. However, they have low accuracy and precision. Especially, there are merely experimental data with 3 GeV protons which are used for spallation neutron source (MLF) in J-PARC, the experimental data is required for the improvement of the target materials. Thus, we measured cross sections of tungsten, gold, indium, and beryllium with 0.4 GeV to 3.0 GeV protons. Moreover, ones of aluminium that are set with materials were also measured for a variation of this experiment. It was found that more accurate data than current ones would be measured by using precise beam controls and highly accurate beam monitoring. We compared the experimental data, the evaluated data (JENDL-HE/2007), and the calculations with several intra-nuclear cascade models by PHITS code. Although the experimental data agreed with JENDL-HE/2007, the calculations underestimated about 40%. This could come from the evaporation model (GEM) being included in PHITS code. We found that the calculations agreed with the experimental data by upgrading PHITS code. The cross sections for the other materials have been analysed so far.
