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Yee-Rendon, B.; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Tamura, Jun
Proceedings of 12th International Particle Accelerator Conference (IPAC 21) (Internet), p.790 - 792, 2021/08
The Medium Energy Beam Transport (MEBT) will transport a CW proton beam with a current of 20 mA and energy of 2.5 MeV from the exit of the normal conducting Radiofrequency Quadrupole (RFQ) to the superconducting Half-Wave resonator (HWR) section. The MEBT must provide a good matching between the RFQ and HWR, effective control of the emittance growth and the halo formation, enough space for all the beam diagnostics devices, among others. This work reports the first lattice design and the beam dynamics studies for the MEBT of the JAEA-ADS.
Yee-Rendon, B.; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Tamura, Jun; Cicek, E.*
Proceedings of 12th International Particle Accelerator Conference (IPAC 21) (Internet), p.793 - 795, 2021/08
The Five-cell Elliptical Superconducting Radio-Frequency Cavities (SRFC) provide the final acceleration in the JAEA-ADS linac (from 600 MeV to 1.5 GeV); thus, their performance is essential for the success of the JAEA-ADS project. After their optimization of the cavity geometry to achieve a high-acceleration gradient with lower electromagnetic peaks, the next step in the R&D strategy is the accurate estimation of beam-cavity effects which can affect the performance of the cavities. To this end, multipacting studies were developed to investigate its effect in the cavity operation regimen and find countermeasures. The results of this study will help in the development of the SRFC models and in the consolidation of the JAEA-ADS project.
Takei, Hayanori; Tsutsumi, Kazuyoshi*; Meigo, Shinichiro
Journal of Nuclear Science and Technology, 58(5), p.588 - 603, 2021/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The Japan Atomic Energy Agency (JAEA) has designed a Transmutation Physics Experimental Facility (TEF-P) as an experimental facility in the Japan Proton Accelerator Research Complex (J-PARC). The TEF-P is a critical assembly driven by a low-power proton beam, a maximum of 10 W, which is extracted from a high-power beam source, such as 250 kW of 400 MeV proton beam of the J-PARC Linac. To extract such a low-power proton beam from the high-power proton beam, we developed a laser charge exchange (LCE) device and employed its technique, which is one of the non-contact beam extraction techniques. For the proof of performance of the LCE device to the TEF-P, a low-power proton beam was extracted using a negative-hydrogen (H
) Linac having an energy of 3 MeV, and a bright continuous laser. Proton beam with the power of 0.57 mW was successfully extracted with a laser stripping efficiency of 
. These experimental values are in good agreement with the estimated ones.
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
Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Hasegawa, Kazuo; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Konomi, Taro*
JPS Conference Proceedings (Internet), 33, p.011049_1 - 011049_6, 2021/03
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.
Yee-Rendon, B.; Tamura, Jun; Kondo, Yasuhiro; Hasegawa, Kazuo; Maekawa, Fujio; Meigo, Shinichiro; Oguri, Hidetomo
JPS Conference Proceedings (Internet), 33, p.011043_1 - 011043_5, 2021/03
The Japan Atomic Energy Agency (JAEA) has been working in the research and development of an Accelerator Driven Subcritical System (ADS) for the transmutation of nuclear waste. The ADS proposed by JAEA consists of a CW proton linac of 30 MW coupling with a subcritical core reactor. The accelerator will be operated with a beam current of 20 mA. Normal conducting Radio-Frequency Cavities (NRFC) and Superconducting Radio-Frequency Cavities (SRFC) will be used to achieve final energy of 1.5 GeV, and the SRFC will be employed for the main part of the acceleration: from 2 MeV to 1.5 GeV. In the first stage of the accelerator development, the focus was the design and optimization of the SRFC models and the beam optics. For the SRFC sections, the acceleration will be done by using Half Wave Resonators (HWR), Single Spokes (SS), and Elliptical cavities (Ellip) operating with a frequency of 162, 324, and 648 MHz, respectively. The beam optics were optimized satisfying the equipartitioning condition to control the emittance growth, which helped to reduce the beam halos and the beam loss.
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.
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.
Iwamoto, Yosuke; Meigo, Shinichiro
EPJ Web of Conferences, 239, p.20011_1 - 20011_4, 2020/09
Times Cited Count：0 Percentile：0.19PHITS including the NRT model can calculate displacement cross sections of materials for various particle irradiations in wide energy range. Recently, Nordlund et al. provided the athermal recombination corrected (arc) displacement per atom (dpa) function providing more physically realistic descriptions of primary defect creation in materials. Therefore, the arc-dpa will be used for efficient predictions of the usable lifetime of materials in various accelerator facilities. In this work, the arc-dpa function related with the defect production efficiency was implemented in the radiation damage model in PHITS. As a result, for the displacement cross sections of Cu and W under proton irradiations with energies above 100 MeV, the arc-dpa cross sections are smaller than the NRT-dpa cross sections by a factor of about 3. In this presentation, we will present the arc-dpa cross sections for proton, deuteron and heavy-ion irradiations in the energy region between 100 MeV/u and 3 GeV/u.
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, Yosuke; Meigo, Shinichiro; Hashimoto, Shintaro
Journal of Nuclear Materials, 538, p.152261_1 - 152261_9, 2020/09
Times Cited Count：2 Percentile：66.08(Materials Science, Multidisciplinary)The displacements-per-atom (dpa) is widely used as an exposure unit to predict the operating lifetime of materials in radiation environments. Because the athermal-recombination-corrected dpa (arc-dpa) model is a more realistic model than the standard Norgertt-Robinson-Torrens (NRT) model, new evaluation of radiation damage will be performed using the arc-dpa model as a standard. In this work, the recent arc-dpa model of various materials are incorporated in PHITS, and the rescaling factors (NRT-dpa/arc-dpa) over a wide energy range are reported. For neutron incidences with the energy spectrum determined in selected nuclear facilities and proton incidences with energies of 600 MeV-50 GeV, the rescaling factor for each material is independent of these irradiation conditions with almost the same value for each material. Our findings will be beneficial for rescaling the NRT-dpa model used for radiation damage applications over a wide energy region.
Yee-Rendon, B.; Tamura, Jun; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Oguri, Hidetomo
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.33 - 37, 2020/09
Japan Atomic Energy Agency (JAEA)- Accelerator Driven System (ADS) linac consists of a CW proton accelerator with a beam current of 20 mA driven with the energy of 1.5 GeV. Most of the beam acceleration is achieved by using superconducting cavities to obtain high acceleration efficiency at CW mode. The main superconducting linac is composed of five families of cavities (Half Wave resonators, Spokes resonators, and Elliptical cavities) with theirs respectively magnets. Due to the large beam power in the linac of 30 MW and the high reliability required for the ADS project, a robust beam optic designed is necessary to have a stable beam operation and control the beam loss power. The JAEA-ADS linac is composed of several sections and components; thus, the misalignment of these elements together with field errors enhance the beam loss rate and compromises the safety of the linac. To this end, an error linac campaign was launched to estimate the error tolerance of the components and implement a correction scheme to reduce the beam loss power around the linac.
Meigo, Shinichiro; Oi, Motoki; Fujimori, Hiroshi*
Physical Review Accelerators and Beams (Internet), 23(6), p.062802_1 - 062802_24, 2020/06
Times Cited Count：0 Percentile：0.02(Physics, Nuclear)As hadron accelerators for such as the ADS and spallation neutron source achieve increasing beam power, damage to targets is becoming increasingly severe. To mitigate this damage, nonlinear beam optics based on octupole magnets is attractive. Nonlinear optics can decrease the beam-focusing hazard due to failure of the rastering magnet. As a side effect of nonlinear optics, the beam size is known to expand drastically compared with linear optics. Nonlinear effects have been studied via a simplified filament model that ignores beam-divergence spread at the octupole magnet. In this study, a new generalized model is proposed for application to an octupole magnet, regardless of the filament-model approximation. It is found that the transverse distribution obtained by beam tracking can be specified by the introduction of only two parameters, namely the normalized octupole strength of 
and the 
of the phase advance. To achieve the two antagonistic requirements of reduction of the beam-peak density and minimization of the beam loss, the transverse distribution is surveyed for a large range of beam position. It is found that a bell-shaped distribution with 
1 and 
3 can satisfy requirements. This result is applied to beam transport in the spallation neutron source at J-PARC. The calculation result given by the present model shows good agreement with the experimental data, and the peak current density is reduced by 50% compared with the linear-optics case.
