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Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*; Fuwa, Yasuhiro; Tongu, Hiromu*; Hayano, Hitoshi*; Geng, R. L.*
Journal of Instrumentation (Internet), 19(9), p.P09037_1 - P09037_15, 2024/09
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)Iwashita, Yoshihisa*; Kuriyama, Yasutoshi*; Fuwa, Yasuhiro
IEEE Transactions on Applied Superconductivity, 34(5), p.4904504_1 - 4904504_4, 2024/08
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)A permanent magnet can be used to generate an axisymmetric uniform magnetic field over a long distance. To satisfy Ampere's law, which states that the line-integral value of the magnetic field is zero, a magnetic field region of opposite polarity appears somewhere along the axis while maintaining uniformity in a certain range along the axis. Using this configuration, a magnetic field generator for a Faraday rotation device for laser light was fabricated. This device has a large bore of 30 mm in diameter to handle ultra-high-power lasers and can hold a large crystal disc for Faraday rotation. The irregularity in the central plane is less than 1% within the bore diameter. This configuration can also be applied to long axisymmetric beam transport magnets. This technique can be extended to control the gradient of the magnetic field distributions, such as the focusing field of a klystron.
Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*; Fuwa, Yasuhiro; Terunuma, Nobuhiro*
IEEE Transactions on Applied Superconductivity, 34(5), p.4004005_1 - 4004005_5, 2024/08
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)We are developing a correction magnet for charged particle beams using permanent magnets. By rotating the rod of the permanent magnet that generates the magnetic field, the magnetic field can be changed to bipolarity. To verify the principle of this bi-polarity change, a prototype was built, and its performance was evaluated. The performance evaluation of the prototype machine revealed that the inhomogeneity of the remanent magnetization of the permanent magnet has a significant effect on the multipole component. To suppress this effect, a compensating magnet with additional anisotropic intermediate poles is being considered.
Yoshimoto, Masahiro; Takahashi, Hiroki; Harada, Hiroyuki; Chimura, Motoki; Fuwa, Yasuhiro; Hayashi, Naoki; Kuriyama, Yasutoshi*; Sawabe, Yuki*; Hatakeyama, Shuichiro*
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.839 - 843, 2023/11
In the J -PARC 3GeV synchrotron accelerator (RCS), a new signal processing system for beam monitors is been developing to replace the existing system for the main beam monitors that monitor the stability of the accelerator: beam loss monitor, beam position monitor and beam current monitor. The new system will consist of a TAG server and an ADC module that can be used commonly for the three main monitors. The main design concepts of the new system are: (1) the TAG server divides various beam J-PARC tag information to each ADC module, (2) the ADC module converts acquisition data from beam monitors to digital signals by ADC and performs high-speed analysis by FPGA with switching analysis methods to suit each monitor, (3) the ADC module periodically outputs the analysis data with tag information by packing the signal processing data of all shots for about 10 seconds, and also outputs any one shot data on-demand, and (4) the raw waveform data, the latest four shots of FFT-related data in the process of analysis and bunch data for each cycle are stored in the internal memory of the ADC module, and the data can be read out as needed. In this presentation, we will report on the progress of the data acquisition test of tag information reading and beam monitor signals using the prototype under development.
Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta*; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.
EPJ Web of Conferences, 284, p.01023_1 - 01023_4, 2023/05
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)For accurate prediction of neutronic characteristics for accelerator-driven systems (ADS) and a source term of spallation neutrons for reactor physics experiments for the ADS at Kyoto University Critical Assembly (KUCA), we have launched an experimental program to measure nuclear data on ADS using the Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University. As part of this program, the proton-induced double-differential thick-target neutron-yields (TTNYs) and cross-sections (DDXs) for iron, lead, and bismuth have been measured with the time-of-flight (TOF) method. For each measurement, the target was installed in a vacuum chamber on the beamline and bombarded with 107-MeV proton beams accelerated from the FFAG accelerator. Neutrons produced from the targets were detected with stacked, small-sized neutron detectors for several angles from the incident beam direction. The TOF spectra were obtained from the detected signals and the FFAG kicker magnet's logic signals, where gamma-ray events were eliminated by pulse shape discrimination. Finally, the TTNYs and DDXs were obtained from the TOF spectra by relativistic kinematics. The measured TTNYs and DDXs were compared with calculations by the Monte Carlo transport code PHITS with its default physics model of INCL version 4.6 combined with GEM and those with the JENDL-4.0/HE nuclear data library.
Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.
Journal of Nuclear Science and Technology, 60(4), p.435 - 449, 2023/04
Times Cited Count：3 Percentile：50.01(Nuclear Science & Technology)Double-differential thick target neutron yields (TTNYs) for Fe, Pb, and Bi targets induced by 107-MeV protons were measured using the fixed-field alternating gradient accelerator at Kyoto University for research and development of accelerator-driven systems (ADSs) and fundamental ADS reactor physics research at the Kyoto University Critical Assembly (KUCA). Note that TTNYs were obtained with the time-of-flight method using a neutron detector system comprising eight neutron detectors; each detector has a small NE213 liquid organic scintillator and photomultiplier tube. The TTNYs obtained were compared with calculation results using Monte Carlo-based spallation models (i.e., INCL4.6/GEM, Bertini/GEM, JQMD/GEM, and JQMD/SMM/GEM) and the evaluated high-energy nuclear data library, i.e., JENDL-4.0/HE, implemented in the particle and heavy iontransport code system (PHITS). All models, including JENDL-4.0/HE, failed to predict high-energy peaks at a detector angle of 5
. Comparing the energy- and angle-integrated spallation neutron yields at energies of 
20 MeV estimated using the measured TTNYs and the PHITS indicated that INCL4.6/GEM would be suitable for the Monte Carlo transport simulation of ADS reactor physics experiments at the KUCA.
Iwamoto, Hiroki; Nakano, Keita; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; Yashima, Hiroshi*; Nishio, Katsuhisa; et al.
JAEA-Conf 2022-001, p.129 - 133, 2022/11
For accurate prediction of neutronic characteristics for accelerator-driven systems (ADS) and a source term of spallation neutrons for reactor physics experiments for the ADS at Kyoto University Critical Assembly (KUCA), we have launched an experimental program to measure nuclear data on ADS using the Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University. As part of this program, the proton-induced double-differential thick-target neutron-yields (TTNYs) and cross-sections (DDXs) for iron have been measured with the time-of-flight (TOF) method. For each measurement, the target was installed in a vacuum chamber on the beamline and bombarded with 107-MeV proton beams accelerated from the FFAG accelerator. Neutrons produced from the targets were detected with stacked, small-sized neutron detectors composed of the NE213 liquid organic scintillators and photomultiplier tubes, which were connected to a multi-channel digitizer mounted with a field-programmable gate array (FPGA), for several angles from the incident beam direction. The TOF spectra were obtained from the detected signals and the FFAG kicker magnet's logic signals, where gamma-ray events were eliminated by pulse shape discrimination applying the gate integration method to the FPGA. Finally, the TTNYs and DDXs were obtained from the TOF spectra by relativistic kinematics.
Fuwa, Yasuhiro; Iwashita, Yoshihisa*; Kuriyama, Yasutoshi*; Tongu, Hiromu*; Hayano, Hitoshi*; Geng, R. L.*
Proceedings of 20th International Conference on RF Superconductivity (SRF 2021) (Internet), p.323 - 325, 2022/05
In order to evaluate the performance of a superconducting cavity, we are developing a mapping system to measure the distribution of cavity temperature, field emission X-rays, and trapped magnetic flux with high positional resolution. In order to construct a system with high positional resolution, a large number of sensors are required. However, as the number of sensors increases, so does the amount of wiring, which increases the complexity of the wiring in the cryogenic apparatus, and also increases the heat transfer through the wiring, which disturb efficient operation of cavity tests. We are developing an efficient mapping system with a multiplexer that scans the readout signal on the same circuit as the sensor in the cryogenic dewar where the cavity test is conducted. In this presentation, we report the outline and test results of the mapping system under development
Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*; Hirota, Katsuya*; Hayano, Hitoshi*; Fuwa, Yasuhiro
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.32 - 35, 2019/10
Research and development of gradient enhancement of superconducting RF accelerating cavity is carried out by accelerator research institute in the world, but defects on the cavity surface limit accelerating electric field. Therefore, development of "Inside inspection system for superconducting accelerated cavity" that optically visualizes the state of the inner surface of the superconducting cavity has been carried out, and results have been achieved. In this research, we apply image processing technology that has developed remarkably in recent years to the internal inspection system, and advanced the defect recognition method. Extraction of depth information and image synthesis were performed from images obtained with different focal positions with the camera for internal surface inspection. Also, by performing pattern recognition processing on the images, automatic detection of defects has become possible. By integrating these techniques into the cavity inner surface inspection system, it becomes possible to shorten the scan time for defect search and acquire the defect shape.
Np and 
Am by accelerator-driven system at Kyoto University Critical AssemblyPyeon, C. H.*; Yamanaka, Masao*; Oizumi, Akito; Fukushima, Masahiro; Chiba, Go*; Watanabe, Kenichi*; Endo, Tomohiro*; Van Rooijen, W. G.*; Hashimoto, Kengo*; Sakon, Atsushi*; et al.
Journal of Nuclear Science and Technology, 56(8), p.684 - 689, 2019/08
Times Cited Count：12 Percentile：75.51(Nuclear Science & Technology)This study demonstrates, for the first time, the principle of nuclear transmutation of minor actinide (MA) by the accelerator-driven system (ADS) through the injection of high-energy neutrons into the subcritical core at the Kyoto University Critical Assembly. The main objective of the experiments is to confirm fission reactions of neptunium-237 (Np) and americium-241 (Am), and capture reactions of Np. Subcritical irradiation of Np and Am foils is conducted in a hard spectrum core with the use of the back-to-back fission chamber that obtains simultaneously two signals from specially installed test (Np or Am) and reference (uranium-235) foils. The first nuclear transmutation of Np and Am by ADS soundly implemented by combining the subcritical core and the 100 MeV proton accelerator, and the use of a lead-bismuth target, is conclusively demonstrated through the experimental results of fission and capture reaction events.
Iwamoto, Yosuke; Matsuda, Hiroki; Meigo, Shinichiro; Satoh, Daiki; Nakamoto, Tatsushi*; Yoshida, Makoto*; Ishi, Yoshihiro*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Yashima, Hiroshi*; et al.
Proceedings of 61st ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2018) (Internet), p.116 - 121, 2018/07
The radiation damage model in the radiation transport code PHITS has been developed to calculate the basic data of the radiation damage including the energy of the target Primary Knock on Atom (PKA). For the high-energy proton incident reactions, a target PKA created by the secondary particles was more dominant than a target PKA created by the projectile. To validate the radiation damage model in metals irradiated by 
100 MeV protons, we developed a proton irradiation device with a Gifford-McMahon cryocooler to cryogenically cool wire samples. By using this device, the defect-induced electrical resistivity changes related to the DPA cross section of copper and aluminum were measured under irradiation with 125 and 200 MeV protons at cryogenic temperature. A comparison of the experimental data with the calculated results indicates that the DPA cross section with defect production efficiencies provide better quantitative descriptions.
Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.
Journal of Nuclear Materials, 458, p.369 - 375, 2015/03
Times Cited Count：15 Percentile：73.26(Materials Science, Multidisciplinary)To validate Monte Carlo codes for the prediction of radiation damage in metals irradiated by 100 MeV protons, defect-induced electrical resistivity changes of copper related to the displacement cross-section were measured with 125 MeV proton irradiation at 12 K. The cryogenic irradiation system was developed with a Gifford-McMahon cryocooler to cool the sample via an oxygen-free high-conductivity copper plate by conduction cooling. The sample was a copper wire with a 250
m diameter and 99.999% purity sandwiched between two aluminum nitride ceramic sheets. The resistivity increase did not change during annealing after irradiation below 15 K. The experimental displacement cross-section for 125 MeV irradiation shows similar results to the experimental data for 1.1 and 1.94 GeV. Comparison with the calculated results indicated that the defect production efficiency in Monte Carlo codes gives a good quantitative description of the displacement cross-section in the energy region 100 MeV.
Iwamoto, Yosuke; Yoshida, Makoto*; Nakamoto, Tatsushi*; Ogitsu, Toru*; Yoshiie, Toshimasa*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Mori, Yoshiharu*
no journal, ,
We measured the electrical resistivity under irradiation of 125 MeV proton in copper sample (0.2 um thickness) at cryogenic temperature at the FFAG accelerator facility in Kyoto university. Resistivity was measured by the four-terminal method. As a result, we measured the resistivity of copper at 7.3 K within 20 micro-ohm and temperature of sample. We measured the electrical resistivity under irradiation of 125 MeV proton in copper sample (0.2 um thickness) at cryogenic temperature at the FFAG accelerator facility in Kyoto university. Resistivity was measured by the four-terminal method. As a result, we measured the resistivity of copper at 7.3 K within 20 micro-ohm and temperature of sample.
Iwamoto, Hiroki; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta; Nakano, Keita; Nishio, Katsuhisa; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; et al.
no journal, ,
For the purpose of research and development of accelerator-driven nuclear transmutation systems, neutron yields of 107-MeV proton incident on iron, lead and bismuth targets were measured by the flight time method using the FFAG accelerator at Kyoto University. The energy spectra of the neutron yield obtained by the measurements were compared with results of particle transport analysis with the nuclear reaction models (INCL4.6/GEM, Bertini/GEM, JQMD/GEM and JQMD/SMM/GEM) incorporated in the Monte Carlo particle transport calculation code PHITS and the nuclear data library JENDL-4.0/HE. As a result, it was found that the INCL4.6/GEM, which was the reference model of PHITS, best reproduced the experimental values.
Fuwa, Yasuhiro; Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*; Hirota, Katsuya*; Yamada, Masako*; Kitaguchi, Masaaki*; Shimizu, Hirohiko*
no journal, ,
A neutron mirror with a magnetic repulsive wall is under development. Since neutrons have a magnetic dipole moment, they are subject to forces in a magnetic field gradient. Using this phenomenon, a potential wall for neutrons can be formed by arranging permanent magnets in a planar configuration of a Halbach array. This potential wall acts as a mirror for a polarized neutron beam. A prototype mirror 20 mm high and 30 mm wide was fabricated, and preliminary neutron reflection experiments were conducted at the MINE2 port of JRR-3. As the next step, we plan to fabricate a mirror with a larger size and conduct experiments at the J-PARC MLF. In this presentation, the principle of the mirror, the results of preliminary experiments at JRR-3, and the status of the mirror fabrication for the experiment at J-PARC will be reported.
Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.
no journal, ,
To validate Monte Carlo code PHITS for the prediction of radiation damage in metals, the damage rate (defect-induced electrical resistivity changes / particle fluence) related to the displacement cross-section of copper were measured with 125 MeV proton irradiation under 12 K at the FFAG facility in the Kyoto University Research Reactor Institute. The sample was a copper wire with a 250-m diameter and 99.999% purity and was cooled by conduction cooling. After 125 MeV proton irradiation with 1.45
10
protons/m
at 12 K, the total resistivity increase was 4.9410
m (resistance increase: 1.53), while the resistivity of copper before irradiation was 9.49 10
m (resistance: 29.41). Comparison with other experimental results indicated that the damage rate by 125 MeV protons is almost same with those by 1.1 GeV protons and is higher than the damage rate by 14 MeV neutrons by a factor of 1.4. For the comparison with the PHITS results, the experimental data is smaller than the calculated result without the defect production efficiency by a factor of about 2.5 and that with the defect production efficiency by a factor of about 1.4, respectively. It indicates that the defect production efficiency in PHITS gives a good quantitative description of the displacement cross-section.
Iwamoto, Hiroki; Meigo, Shinichiro; Nishio, Katsuhisa; Ishi, Yoshihiro*; Hirose, Kentaro; Iwamoto, Yosuke; Kuriyama, Yasutoshi*; Maekawa, Fujio; Makii, Hiroyuki; Nakano, Keita; et al.
no journal, ,
no abstracts in English
Nakano, Keita; Iwamoto, Hiroki; Meigo, Shinichiro; Nishio, Katsuhisa; Ishi, Yoshihiro*; Hirose, Kentaro; Iwamoto, Yosuke; Kuriyama, Yasutoshi*; Maekawa, Fujio; Makii, Hiroyuki; et al.
no journal, ,
For accurate prediction of neutronic characteristics for accelerator-driven system (ADS), an experimental program to measure nuclear data on ADS using the Fixed Field Alternating Gradient (FFAG) accelerator at Kyoto University has been launched. As a part of this program, energy spectra of spallation neutron from 100-MeV proton-induced reactions on Fe, Pb, and Bi are plan to be measured. In this report, the results of the measurement on Fe target will be presented.
Fuwa, Yasuhiro; Kuriyama, Yasutoshi*; Iwashita, Yoshihisa*
no journal, ,
Radiation demagnetization by neutron irradiation has been measured using the Kyoto University research reactor to evaluate the radiation resistance of permanent magnet materials used for beam optics of accelerators. In the demagnetization evaluation, it is essential to measure the magnetization before and after neutron irradiation accurately, but in the case of measuring the magnetic field using a Hall probe, the displacement of the measured value due to the probe position is relatively large and causes errors in the demagnetization evaluation. In order to realize magnetization measurement with less systematic error, we have developed a method to measure the magnitude of magnetization from the induced electromotive force on coils by rotating the magnet near the coil. By adopting this rotating-magnet method for magnetization measurements, the error of the measured value can be reduced to 0.1%, and the measurement accuracy of radiation demagnetization has been improved.
Np fission chamberIwamoto, Hiroki; Meigo, Shinichiro; Satoh, Daiki; Iwamoto, Yosuke; Sugihara, Kenta*; Ishi, Yoshihiro*; Uesugi, Tomonori*; Kuriyama, Yasutoshi*; Yashima, Hiroshi*; Nishio, Katsuhisa; et al.
no journal, ,
no abstracts in English
