Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 28

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Results of 1-MW operation in J-PARC 3 GeV rapid cycling synchrotron

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.

Journal Articles

Visualizing cation vacancies in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ scintillators by gamma-ray-induced positron annihilation lifetime spectroscopy

Fujimori, 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:1 Percentile:24.67(Physics, Applied)

To clarify the existence of cation vacancies in Ce-doped Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ (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:Y$$_{3}$$Al$$_{5}$$O$$_{12}$$, 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$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Journal Articles

Thermal desorption characteristics of several charge stripper carbon films for J-PARC RCS

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.

Journal Articles

Progress of injection energy upgrade project for J-PARC 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

Journal Articles

Status of injection energy upgrade for J-PARC RCS

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.

Journal Articles

Foil scattering loss mitigation by the additional collimation system of J-PARC RCS

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.

Journal Articles

Injection energy recovery of J-PARC RCS

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.

Journal Articles

Foil scattering loss mitigation by the additional collimation system of J-PARC RCS

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.

Journal Articles

Optimization for the additional collimation system of J-PARC RCS

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.

Journal Articles

Injection energy recovery of J-PARC RCS

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.

Journal Articles

Magnetic field mapping and excitation test in vacuum for the kicker magnet in J-PARC RCS

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:27.14(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.

Journal Articles

Improvement of the shift bump magnetic field for a closed bump orbit of the 3-GeV RCS in J-PARC

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:8 Percentile:47.25(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.

Journal Articles

Measurement of the paint magnets for the beam painting injection system in the J-PARC 3-GeV RCS

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:1 Percentile:13.42(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.

Journal Articles

Design and construction of septum magnets at 3-GeV RCS in J-PARC

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:3 Percentile:27.14(Engineering, Electrical & Electronic)

Journal Articles

Field measurement of DC magnets at 3-GeV RCS in J-PARC

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:13.42(Engineering, Electrical & Electronic)

Journal Articles

Reduction of outgassing for suppressing electrical breakdown in the kicker magnet of J-PARC RCS

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.

Journal Articles

Design of the injection bump system of the 3-GeV RCS in J-PARC

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:14 Percentile:59.24(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.

Journal Articles

Design of the shift bump magnets for the beam injection of the 3-GeV RCS in J-PARC

Takayanagi, Tomohiro; Kamiya, Junichiro; Watanabe, Masao; Ueno, Tomoaki*; Yamazaki, Yoshishige; Irie, Yoshiro; Kishiro, Junichi; Sakai, Izumi*; Kawakubo, Toshimichi*; Tounosu, Shigeki*; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.1366 - 1369, 2006/06

 Times Cited Count:7 Percentile:42.11(Engineering, Electrical & Electronic)

The injection system of the 3-GeV RCS in J-PARC is composed of four main orbit bump magnets (shift bump) to merge the injection beam with the circulating beam. The magnetic field design and the structural analysis of the shift bump magnets have been performed using 3D magnetic and mechanical codes. In this paper, the design of the bending magnets is reported.

Journal Articles

Experimental results of the shift bump magnet in the J-PARC 3-GeV RCS

Takayanagi, Tomohiro; Ueno, Tomoaki; Irie, Yoshiro; Kinsho, Michikazu; Takeda, Osamu; Yamazaki, Yoshishige; Yoshimoto, Masahiro; Kamiya, Junichiro; Watanabe, Masao; Kuramochi, Masaya

Proceedings of 10th European Particle Accelerator Conference (EPAC 2006) (CD-ROM), p.1762 - 1764, 2006/00

The shift bump magnet produces a fixed main bump orbit to merge the injection beam into the circulating beam. In order to control the injection beam for the short injection time (500 microseconds) with sufficient accuracy, the shift bump magnet needs a wide uniform magnetic field and the high speed exciting pattern of the high current. The magnetic field design and the structural analysis of the shift bump magnet have been performed using the three-dimensional electromagnetic analysis code and the mechanical analysis code, respectively. The magnetic field distributions were measured with a long search coil, thus giving a BL product over the magnet gap area. The temperature distributions at the various points of the magnet were measured by the thermocouples over 24 hours till they saturated. General trend of these measurements agrees well with calculations.

Journal Articles

Experimental and analysis of the injection bump system of the 3-GeV RCS in J-PARC

Takayanagi, Tomohiro; Ueno, Tomoaki; Kinsho, Michikazu; Takeda, Osamu; Yamazaki, Yoshio; Yoshimoto, Masahiro; Kamiya, Junichiro; Watanabe, Masao; Kuramochi, Masaya; Irie, Yoshiro

Proceedings of 3rd Annual Meeting of Particle Accelerator Society of Japan and 31st Linear Accelerator Meeting in Japan (CD-ROM), p.74 - 76, 2006/00

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). The magnetic field distributions of the shift bump magnet were measured with a long search coil, thus giving a BL product over the magnet gap area. Future more, the temperature distributions at the various points were measured by the thermocouples over 24 hours till they saturated. The good performance at the 181 MeV injection beam design was confirmed.

28 (Records 1-20 displayed on this page)