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Yamamoto, Kazami; Yamamoto, Masanobu; Yamazaki, Yoshio; Nomura, Masahiro; Suganuma, Kazuaki; Fujirai, Kosuke; Kamiya, Junichiro; Nakanoya, Takamitsu; Hatakeyama, Shuichiro; Yoshimoto, Masahiro; et al.
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.277 - 281, 2023/01
The J-PARC 3GeV Rapid Cycling Synchrotron (RCS) is aiming to provide the proton beam of very high power for neutron experiments and the main ring synchrotron. We have continued the beam commissioning and the output power from RCS have been increasing. In recent years, we have been trying continuous supply of 1-MW high-intensity beam, which is the design value, to a neutron target. We tried to operate continuously for over 40 hours in June 2020. However, some trouble occurred and the operation was frequently suspended. In June 2021, we tried again 1-MW operation but it was suspended due to deterioration of the cooling water performance. Last summer shutdown period, we recovered performance of the cooling water system and retried in this June. In the final case, the outside temperature became extremely high. We could not keep 1-MW power, whereas 600 kW beam was delivered in stable.
Np and 
Am gamma ray regionsFukuda, Tatsuo; Kobata, Masaaki; Shobu, Takahisa; Yoshii, Kenji; Kamiya, Junichiro; Iwamoto, Yosuke; Makino, Takahiro*; Yamazaki, Yuichi*; Oshima, Takeshi*; Shirai, Yasuhiro*; et al.
Journal of Applied Physics, 132(24), p.245102_1 - 245102_8, 2022/12
Times Cited Count：1 Percentile：17.38(Physics, Applied)Direct energy conversion has been investigated using Ni/SiC Schottky junctions with the irradiation of monochromatized synchrotron X-rays simulating the gamma rays of Np (30 keV) and Am (60 keV). From current-voltage measurements, electrical energies were obtained for both kinds of gamma rays. The energy conversion efficiencies were found to reach up to 
1.6%, which is comparable to those of a few other semiconducting systems reported thus far. This result shows a possibility of energy recovery from nuclear wastes using the present system, judging from the radiation tolerant nature of SiC. Also, we found different conversion efficiencies between the two samples. This could be understandable from hard X-ray photoelectron spectroscopy and secondary ion mass spectroscopy measurements, suggesting the formation of Ni-Si compounds at the interface in the sample with a poor performance. Hence, such combined measurements are useful to provide information that cannot be obtained by electrical measurements alone.
Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：6 Percentile：84.97(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Yamamoto, Kazami; Yamamoto, Masanobu; Yamazaki, Yoshio; Nomura, Masahiro; Suganuma, Kazuaki; Fujirai, Kosuke; Kamiya, Junichiro; Hatakeyama, Shuichiro; Hotchi, Hideaki; Yoshimoto, Masahiro; et al.
Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.209 - 213, 2020/09
The J-PARC 3GeV Rapid Cycling Synchrotron (RCS) is aiming to provide the proton beam of very high power for neutron experiments and the main ring synchrotron. We have continued the beam commissioning and the output power from RCS have been increasing. In recent years, just before the summer shutdown period, we have been trying continuous supply of 1-MW high-intensity beam, which is the design value, to a neutron target. First trial was 1-hour continuous operation in July 2018, and second trial was 10-hours continuous in July 2019. In both cases, we achieved almost stable operation. Furthermore, in June 2020, we tried to operate continuously for over 40 hours. But in this case, some trouble occurred and the operation was frequently suspended. Through these continuous operation trials, we have identified issues for stable operation of 1 MW. In this presentation, we will report the results of 1-MW continuous operation and issues obtained from these results.
Al
GaO
scintillators by gamma-ray-induced positron annihilation lifetime spectroscopyFujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.
Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08
Times Cited Count：5 Percentile：33.01(Physics, Applied)To clarify the existence of cation vacancies in Ce-doped GdAlGaO (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:YAl
O, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg
ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.
Kamiya, Junichiro; Kinsho, Michikazu; Yamazaki, Yoshio; Yoshimoto, Masahiro; Yanagibashi, Toru*
Journal of the Vacuum Society of Japan, 60(12), p.484 - 489, 2017/12
Multi-turn H
charge exchange injection is employed as a beam injection method in the 3-GeV RCS (Rapid cycling synchrotron) at J-PARC (Japan Proton Accelerator Research Complex). In this method, injection H beam is put on the same orbit as already circulating proton (H
) beam in a dipole magnetic field due to the opposite curvature of the injected and circulating beams. In the straight section, where the two beams coincide with each other, both beams are passed through a thin foil, which strips two weakly bound electrons off each H ion, forming an intense beam of protons. The thin foil, which is mostly made of carbon, would be the source of the outgassing, especially when its temperature rises due to the beam hitting. Therefore it is important to estimate the amount and components of the outgassing from the charge stripping foil. In this paper, we will report the thermal desorption measurement results for the several foil, which is used as the charge stripping foil in the RCS.
Hayashi, Naoki; Harada, Hiroyuki; Horino, Koki; Hotchi, Hideaki; Kamiya, Junichiro; Kinsho, Michikazu; Saha, P. K.; Shobuda, Yoshihiro; Takayanagi, Tomohiro; Tani, Norio; et al.
Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.3833 - 3835, 2014/07
no abstracts in English
Hayashi, Naoki; Harada, Hiroyuki; Hotchi, Hideaki; Kamiya, Junichiro; Saha, P. K.; Shobuda, Yoshihiro; Takayanagi, Tomohiro; Tani, Norio; Yamamoto, Kazami; Yamamoto, Masanobu; et al.
Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3921 - 3923, 2012/05
The injection energy upgrade from 181 to 400 MeV for J-PARC RCS is planned in 2013. One power supply was replaced and using for a normal operation. An IGBT chopper type power supply which has larger switching noise will be changed to a capacitor bank type. New injection system allows the center injection with 400 MeV and switching painting area. As further steps for the leakage field, it begins to diminish the effect from the beam transport line. A quadrupole corrector system is designed and fabricated to compensate the beta beat due to the injection bump as the first step. Two profile monitors will be modified to correct position systematic errors and third one is going to be installed at dispersion free section. It is important to minimize kicker impedance lower, which may cause the beam instability. A diode, which has high reverse breakdown voltage and works with lower forward voltage, has been developed. Using this new diode, an experiment shows the impedance becomes lower.
Yamamoto, Kazami; Yamazaki, Yoshio; Yoshimoto, Masahiro; Kamiya, Junichiro; Harada, Hiroyuki; Saha, P. K.; Hotchi, Hideaki; Kinsho, Michikazu; Kato, Shinichi*
Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.1605 - 1607, 2011/09
In the J-PARC RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. From the beam study, we were certain that these losses were caused by the scattering of the injection and circulating beam at the charge exchange injection foil. In order to mitigate these losses, we started to develop a new collimation system in the H0 branch duct. We present latest study results and overview of this new collimation system.
Hayashi, Naoki; Hotchi, Hideaki; Kamiya, Junichiro; Saha, P. K.; Takayanagi, Tomohiro; Yamamoto, Kazami; Yamamoto, Masanobu; Yamazaki, Yoshio
Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.2730 - 2732, 2011/09
The J-PARC RCS is a high beam power Rapid-Cycling Synchrotron (RCS). The original designed injection energy is 400 MeV, although presently it is 181 MeV, and its beam power is limited to 0.6 MW. Works to recover the Linac energy are ongoing and injection magnets power supplies upgrade for two bump and new knob are required in the RCS. In order to achieve 1 MW designed beam power, new instrumentation, like quadrupole corrector or to reduce kicker impedance, are also planned simultaneously. Activities related injection energy recovery in the J-PARC RCS are presented.
Yamamoto, Kazami; Yamazaki, Yoshio; Yoshimoto, Masahiro; Kamiya, Junichiro; Harada, Hiroyuki; Saha, P. K.; Hotchi, Hideaki; Kinsho, Michikazu; Kato, Shinichi*
Proceedings of 8th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.312 - 316, 2011/08
In the J-PARC RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. From the beam study, we were certain that these losses were caused by the scattering of the injection and circulating beam at the charge exchange injection foil. In order to mitigate these losses, we started to develop a new collimation system in the H0 branch duct. We present latest study results and overview of this new collimation system.
Kato, Shinichi*; Yamamoto, Kazami; Yamazaki, Yoshio; Yoshimoto, Masahiro; Kamiya, Junichiro; Harada, Hiroyuki; Kinsho, Michikazu
Proceedings of 8th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.296 - 300, 2011/08
In the J-PARC RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. These losses were caused by the large angle scattering of the injection and circulating beam at the charge exchange foil. To realize high power operation, we have to mitigate these losses. So, we started to develop a new collimation system in the H0 branch duct. In order to optimize this system efficiently, we primarily focused on the relative angle of collimator block from scattering particles. We simulated behavior of particles scattered by foil and produced by collimator block and researched most optimized position and angle of the collimator block. These simulation were performed by SAD and GEANT4. We present simulation results and anticipated performance of this new collimation system.
Hayashi, Naoki; Hotchi, Hideaki; Kamiya, Junichiro; Saha, P. K.; Takayanagi, Tomohiro; Yamamoto, Kazami; Yamamoto, Masanobu; Yamazaki, Yoshio
Proceedings of 8th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.306 - 308, 2011/08
The J-PARC RCS is a high beam power Rapid-Cycling Synchrotron (RCS). The original designed injection energy is 400MeV, although presently it is 181MeV, and its beam power is limited to 0.6MW. Works to recover the Linac energy are ongoing and injection magnets power supplies upgrade are required in the RCS. In order to achieve 1MW designed beam power, new instrumentation is also planned simultaneously. Activities related injection energy recovery in the J-PARC RCS is presented.
Kamiya, Junichiro; Kinsho, Michikazu; Kuramochi, Masaya; Takayanagi, Tomohiro; Takeda, Osamu; Ueno, Tomoaki; Watanabe, Masao; Yamamoto, Kazami; Yamazaki, Yoshio; Yoshimoto, Masahiro
IEEE Transactions on Applied Superconductivity, 18(2), p.293 - 296, 2008/06
Times Cited Count：3 Percentile：26.1(Engineering, Electrical & Electronic)The kicker magnets are installed in the extraction section in the Rapid Cycling Synchrotron (RCS) of J-PARC and they extract a proton beam accelerated up to 3 GeV. We performed the mapping in the air applying one third of operational voltage after checking linear dependence of magnetic field with excitation current. A short search coil with the 3-axias stage was used to measure the magnetic field distribution. The results showed that the distribution in the medium plane of the same type of kicker magnet is in good agreement with each other. The excitation test with the operational charging voltage of 60 kV was also performed in a vacuum. At the first stage, we were bothered by the electric breakdown. It was noticed that the reduction of outgassing rate by baking is very effective to suppress the discharge. Pressure and mass spectrum measured during the excitation test showed that the excitation of the kicker magnet has conditioning effect.
Takayanagi, Tomohiro; Kanazawa, Kenichiro; Ueno, Tomoaki; Someya, Hirohiko*; Harada, Hiroyuki*; Irie, Yoshiro; Kinsho, Michikazu; Yamazaki, Yoshishige; Yoshimoto, Masahiro; Kamiya, Junichiro; et al.
IEEE Transactions on Applied Superconductivity, 18(2), p.306 - 309, 2008/06
Times Cited Count：10 Percentile：50.78(Engineering, Electrical & Electronic)The four shift bump magnets (BUHS01-04) of the 3-GeV RCS in J-PARC, which are located at the long straight section, produce a fixed main bump orbit to merge the injection beam into the circulating beam. They are realized with four magnets connected in series to form the accurate closed bump orbit. However, the total integrated magnetic field of the four magnets is not zero because of the magnetic field interferences between the shift bump magnet and the adjacent quadrupole magnet (Q magnet). In order to decrease the imbalance of the integrated magnetic field, 0.3mm insulators were inserted at the median plane of the return yoke of the second and third shift bump magnets (BUHS02 and BUHS03). The integrated field has been decreased from 2358.0 Gauss-cm to -71.6 Gauss-cm, resulting in the closed orbit distortion of the beam to be decreases from 6.0 mm to less than 1.0 mm.
Takayanagi, Tomohiro; Kanazawa, Kenichiro; Ueno, Tomoaki; Someya, Hirohiko*; Harada, Hiroyuki*; Irie, Yoshiro; Kinsho, Michikazu; Yamazaki, Yoshishige; Yoshimoto, Masahiro; Kamiya, Junichiro; et al.
IEEE Transactions on Applied Superconductivity, 18(2), p.310 - 313, 2008/06
Times Cited Count：2 Percentile：20.19(Engineering, Electrical & Electronic)The beam painting injection system of the 3-GeV RCS in J-PARC, which realizes the uniform beam distributions in the ring, consists of four horizontal paint bump magnets and two vertical paint magnets. Each paint bump magnet power supply is required to excite the current with high accuracy that varies from 17.6 kA to zero during 0.5 msec. The IGBT chopper units, the switching frequency of which is 50 kHz each, are multiple connected to achieve the effective carrier frequency of 600 kHz. The output accuracy is then achieved to be less than 1 %. The measurements of the magnetic field with the actual current waveform were performed and the good performance was confirmed.
Yoshimoto, Masahiro; Ueno, Tomoaki; Togashi, Tomohito; Takeda, Osamu; Kanazawa, Kenichiro; Watanabe, Masao; Yamazaki, Yoshio; Kamiya, Junichiro; Takayanagi, Tomohiro; Kuramochi, Masaya; et al.
IEEE Transactions on Applied Superconductivity, 18(2), p.297 - 300, 2008/06
Times Cited Count：4 Percentile：30.89(Engineering, Electrical & Electronic)Yoshimoto, Masahiro; Ueno, Tomoaki; Togashi, Tomohito; Toyokawa, Ryoji; Takeda, Osamu; Watanabe, Masao; Yamazaki, Yoshio; Yamamoto, Kazami; Kamiya, Junichiro; Takayanagi, Tomohiro; et al.
IEEE Transactions on Applied Superconductivity, 18(2), p.301 - 305, 2008/06
Times Cited Count：1 Percentile：12.89(Engineering, Electrical & Electronic)Kamiya, Junichiro; Kinsho, Michikazu; Ogiwara, Norio; Kuramochi, Masaya; Ueno, Tomoaki; Takayanagi, Tomohiro; Takeda, Osamu; Watanabe, Masao; Yamazaki, Yoshio; Yoshimoto, Masahiro
Shinku, 50(5), p.371 - 377, 2007/05
Kicker magnets in Rapid Cycling Synchrotron (RCS) of Japan Proton Accelerator Research Complex (J-PARC) are now under construction. The kicker magnets are short pulse magnets with high charging voltage of 60 kV or more which is installing in vacuum chambers. The kicker magnet mainly consists of aluminum alloy as electric plates and ferrite as magnetic cores. The outgas reduction from those components is very important to prevent not only electrical discharge but also interaction between the proton beam and residual gas in the vacuum. We thoroughly reduced the outgas from the components. Surface of the aluminum alloy was finished by pit-free electropolishing. Aluminum and ferrites were baked in vacuum before construction of the magnet. They were baked each other until water, which was the main component of outgas, was reduced. We will discuss the effects of above processes on the discharge in the vacuum.
Takayanagi, Tomohiro; Kamiya, Junichiro; Watanabe, Masao; Yamazaki, Yoshishige; Irie, Yoshiro; Kishiro, Junichi; Sakai, Izumi*; Kawakubo, Toshimichi*
IEEE Transactions on Applied Superconductivity, 16(2), p.1358 - 1361, 2006/06
Times Cited Count：16 Percentile：60.93(Engineering, Electrical & Electronic)The injection bump system of the 3-GeV RCS in J-PARC consists of the pulse bending magnets for the injection bump orbit, which are four horizontal bending magnets (shift bump), four horizontal painting magnets (h-paint bump), and two vertical painting magnets (v-paint bump). In this paper, the design of the magnets and power supply of the injection bump system are reported.
