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Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; et al.
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.574 - 578, 2019/07
no abstracts in English
Yamamoto, Kazami; Yamakawa, Emi*; Takayanagi, Tomohiro; Miki, Nobuharu*; Kamiya, Junichiro; Saha, P. K.; Yoshimoto, Masahiro; Yanagibashi, Toru*; Horino, Koki*; Nakanoya, Takamitsu; et al.
ANS RPSD 2018; 20th Topical Meeting of the Radiation Protection and Shielding Division of ANS (CD-ROM), 9 Pages, 2018/08
The existing beam power of the J-PARC Rapid Cycling Synchrotron is up to 500 kW, and higher radiation doses are concentrated in the injection area. These activations are caused by the interaction between the foil and the beam. To reduce dose exposure to workers near the injection point, we study a new design of the injection scheme. Experience has shown that eddy currents are generated in the metal flange near the magnet owing to the pulsed magnetic field, and the temperature exceeds 100 degrees C. The shield installed in the new injection system needs to have a layer structure, in which an insulator is inserted between iron shields to reduce the eddy current. From the results of the shielding calculation, even if 1 mm of polyethylene was inserted between two 9-mm-thick SUS 316 plates, which serve as shielding material, the shielding performance was reduced only about 5%, and we confirmed that it would function well.
Yoshimoto, Masahiro; Saha, P. K.; Kato, Shinichi; Okabe, Kota; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1048 - 1050, 2018/06
The charge exchange multi-turn beam injection scheme is adopted in the J-PARC 3GeV Rapid Cycling Synchrotron Accelerator (RCS) due to achieve 1MW beam power operation. In the conventional multi-turn beam injection scheme, which is provided by only the septum and bump magnets, injecting turn numbers are limited by the beam losses at the septum. On the other hand, charge exchange multi-turn beam injection does not cause the beam losses at the septum; there is no restriction in principle on the injecting turn number. However, high residual doses are observed around the stripper foil. During the charge exchange multi-turn beam injection, not only the injecting beam but also circulating beam hit the foil, and then a large number of secondary particles, namely protons and neutrons, are generated. PHITS simulation results indicate that the secondary particles cause the high residual doses around the foil. To verify this examination, secondary particles measurement is key issue. Then, a new independent type foil introducing device is installed in the 100-deg dump beam transport line in order to construct a simple experimental system for secondary particle measurements. We plan the two experiments by using this system; one is a directly secondary particle detecting method, and the other is a radioactivation analysis method with metal sample pieces. Now, we started the study of how the identification of species and energies of the secondary particles with PHITS code. Irradiation target of Cu is adopted and irradiated proton or neutron beam with various energy range. Then radio-nuclides emitted the 
-ray are picked up. Moreover, the radio-nuclides, whose reaction efficiencies due to beam species or energy are different, are searched for the indicator of the secondary particles. From the simulation results, 
Zn is extremely suitable for a proton beam indicator, and 
Co and 
Co are also suited for a neutron and proton indicator respectively.
Yoshimoto, Masahiro; Harada, Hiroyuki; Kato, Shinichi; Kinsho, Michikazu; Okabe, Kota
Proceedings of 6th International Beam Instrumentation Conference (IBIC 2017) (Internet), p.461 - 465, 2018/03
In the J-PARC RCS, a large fraction of our effort has been concentrated on reducing and managing beam losses to achieve 1MW high power proton beam operation. Standard beam loss monitor (BLM), which is installed outside of the magnet in every cell of beam optics and detect the beam loss at wide area in each cell, is insufficient to investigate finer beam loss mechanism in the ring. Thus we developed new scintillation type BLM to detect the beam loss at spot area on the vacuum chamber inside the magnet. The new BLM has separating structure a photomultiplier (PMT) from a plastic scintillator and connecting with optical fibres. Because small plastic scintillator is installed on the vacuum chamber directly, it has capability to have high sensitivity for localized spot area beam loss. On the other hand, the PMT can precisely be operated without being affected by magnetic field by keeping the PMT from the magnet. The new BLM leads the RCS to achieve the stable high power beam operation. In this presentation, we report the detail of the performance of the new BLM.
Yoshimoto, Masahiro; Kato, Shinichi; Okabe, Kota; Harada, Hiroyuki; Kinsho, Michikazu
Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.877 - 881, 2017/12
It is key issue to reduce the level of the radio-activation of the devices in high power proton accelerator, to achieve MW class high power beam operation. The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) adopted a beam collimation system which aims to localize the beam loss at the collimators and to reduce the level of residual doses at the other devices. However, relatively high residual doses are detected in not only the beam collimator area but also a vicinity of the stripper foil. The results of previous work, measurements of the detailed residual dose distribution and simulations of the radio-activation by the PHITS, indicate that the high level residual dose around the stripper foil is caused by secondary particles due to nuclear reaction at the foil. In order to suppress the secondary particles from foil, we try hard to reduce the number of foil hitting particles during the beam injection period. As a result, the level of the radio-activation around the foil can be decreased. At the same time, new beam loss monitor to detect the secondary particles from the foil is developed. In this presentation, we report the secondary particles detections and estimations of number of the foil hitting particles. In addition, we discuss the reduction of the radio-activation.
Yoshimoto, Masahiro; Harada, Hiroyuki; Kinsho, Michikazu; Yamamoto, Kazami
Proceedings of 5th International Beam Instrumentation Conference (IBIC 2016) (Internet), p.673 - 677, 2017/03
The most important issue in realizing such a MW-class high-power routine beam operation is to keep machine activations within a permissible level, that is, to preserve a better hands-on-maintenance environment. Thus, a large fraction of our effort has been concentrated on reducing and managing beam losses. To validate the beam loss optimizations, residual radiation measurement along the ring provide us with further information. By relating signals of the beam loss monitors with the measured distribution of the residual radiation, achievements of the high power beam operation will be described. In this presentation, we will report on the measurement results of residual radiation distribution along the ring together with the relation with the beam loss signals.
Yoshimoto, Masahiro; Takeda, Osamu; Harada, Hiroyuki; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1097 - 1101, 2016/11
In the 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), a beam collimation system which aims to localize the beam loss at the collimators and to reduce the level of residual doses at the other devices is installed in the ring to achieve a 1MW high power beam operation. However vacuum leakage due to the collimator trouble occurred in April, 2016. Therefore an absorber No.5 in the collimation system had to be removed from the ring. Before resuming the beam operation, a new beam loss situation was simulated by using the particle tracking code. In the beam tuning, the transition of the beam loss distribution was measured by the beam loss monitors. We verified that the new beam situation was permissible, and the beam operation can be resumed. By following-up the transition of the residual dose distribution along the ring, the detailed beam loss structure can be understood. In this presentation, we report an influence of ring-collimator malfunction on beam loss localization in the J-PARC RCS.
Hotchi, Hideaki; Harada, Hiroyuki; Kato, Shinichi; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Tani, Norio; Watanabe, Yasuhiro; et al.
Proceedings of 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2016) (Internet), p.480 - 485, 2016/08
The J-PARC 3-GeV RCS has achieved a 1-MW beam acceleration in January 2015. Since then, a large fraction of our effort has been focused on reducing and managing beam losses. In the beam test in October 2015, we successfully minimized space-charge induced beam loss by optimizing the injection painting technique, as well as suppressed beam instability by controlling the tune and the chromaticity. In addition, in the recent beam test, the transverse painting area was successfully expanded by introducing both quadrupole correctors and anti-correlated painting scheme, by which a foil scattering part of beam loss during charge-exchange injection was further reduced. By such recent efforts, the 1-MW beam operation is now estimated to be established within a permissible beam loss level. In this talk, recent progresses of RCS beam commissioning are reported with particular emphasis on our approaches to beam loss issues.
Yoshimoto, Masahiro; Harada, Hiroyuki; Okabe, Kota; Kinsho, Michikazu
Proceedings of 4th International Beam Instrumentation Conference (IBIC 2015) (Internet), p.575 - 579, 2016/01
In the J-PARC RCS, transverse beam profiles including both the beam core and halo at extraction beam transport line (3NBT) were measured by using a combination with a wire scanner type beam scraper and some beam loss monitors (BLMs). Our final goal of this halo monitor is to measure the intra-bunch beam halo of extracted two bunches from the RCS. Thus the plastic scintillator and photomultiplier (PMT) assemblages were adopted as the BLMs with quick time response. However, we found that the BLMs detected not only the radiation from the wire but also reflected one from other devices and wall. Therefore we tried to develop new-type BLMs, which are scintillation-type BLM of lead glass and Cherenkov-type BLM of quartz or UV acrylic. In this presentation, we will report on the overview and experimental results of the new-type BLMs together with the outline of halo monitor system.
Yoshimoto, Masahiro; Harada, Hiroyuki; Hotchi, Hideaki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Kinsho, Michikazu
Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.944 - 946, 2015/06
In the J-PARC RCS, the beam tuning toward the design output beam power of 1MW were started after the completing of the beam energy and beam current upgrades in the LINAC. One of the important issues to achieve the 1MW beam operation is the optimization of the injection beam from the LINAC. Due to the longitudinal beam tuning in the LINAC, the momentum spread of the injected beam into the RCS was measured with the longitudinal tomography method. Our longitudinal tomography tool had been developed using the simple algorithm with the Convolution Back Projection (CBP) method for the beam storage mode of the RCS. Accordingly, we improved this tool to expand into the acceleration mode. By tuning the tank level of the debuncher 2 in the LINAC, it can be measured the momentum spread was shifted from 0.06% to 0.15%. Moreover, these distributions of the momentum spread are consistent with the simulation results.
Tomisawa, Tetsuo; Kishiro, Junichi; Hiroki, Fumio; Sato, Susumu; Igarashi, Zenei*; Lee, S.*; Nigorikawa, Kazuyuki*; Toyama, Takeshi*
Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.165 - 167, 2004/08
It proceeds with the beam monitor production of the beam diagnosis system with J-PARC. In this paper, the present status of beam position monitors (BPM) for the SDTL is described. The impedance of strip line monitor have been adjusted in the construction of housing and electrodes of the BPM. The 4-stripline BPM has already been examined in the medium energy beam transport (MEBT) line. Preliminary results of beam position measurement for various beam conditions are reported.
Tomisawa, Tetsuo; Kishiro, Junichi; Igarashi, Zenei*; Lee, S.*; Hiroki, Fumio
Proceedings of 28th Linear Accelerator Meeting in Japan, p.428 - 430, 2003/08
It is an important factor whether to have a beam loss held how, and the part of the beam diagnosis is important with the accurate beam transport, the occurrence of the high quality beam to accelerate a high intensity proton beam to handle with J-PARC linac accelerator safely. It responds to the purpose, and the beam monitor used for this beam diagnosis has it variously. There are an electric current monitor, a phase monitor, a beam position monitor, a profile monitor, a beam size monitor, a screen monitor, a beam loss monitor, and so on. Report it about these beam monitors in the present condition.
Kinsho, Michikazu; Noda, Fumiaki*
JAERI-Tech 99-011, 46 Pages, 1999/02
no abstracts in English
Chishiro, Etsuji*; Ino, H.*; Ouchi, Nobuo; *; Mizumoto, Motoharu
Proc. of 11th Symp. on Accelerator Sci. and Technol., p.215 - 217, 1997/00
no abstracts in English
Mizumoto, Motoharu; Kusano, Joichi; Hasegawa, Kazuo; Ouchi, Nobuo; Oguri, Hidetomo; Kinsho, Michikazu; Touchi, Y.*; Honda, Yoichiro*; Mukugi, Ken*; Ino, H.*; et al.
Proc. of 11th Symp. on Accelerator Sci. and Technol., p.130 - 132, 1997/00
no abstracts in English
Kinsho, Michikazu; Noda, Fumiaki*; Kusano, Joichi; Mizumoto, Motoharu
Proc. of 11th Symp. on Accelerator Sci. and Technol., p.341 - 343, 1997/00
no abstracts in English
Meigo, Shinichiro; Oi, Motoki; Fujimori, Hiroshi*; Kawasaki, Tomoyuki; Nishikawa, Masaaki; Fukuda, Shimpei
no journal, ,
no abstracts in English
Harada, Hiroyuki; Saha, P. K.; Kinsho, Michikazu
no journal, ,
J-PARC facility consists of three accelerators, which are 400 MeV Linac, 3 GeV Rapid Cycling Synchrotron (RCS), 50 GeV Main Ring synchrotron (MR). These accelerators provides MW-class high intensity proton beam to multipurpose experiments where the produced secondary particles at targets are used. RCS successfully achieved 1 MW output of designed beam power with high repetition rate of 25 Hz for a short time. In user operation, RCS achieved to provide high power beam up to 500 kW. I will report present status. Additionally, I will mention future plan under design work.
Yoshimoto, Masahiro; Takeda, Osamu; Harada, Hiroyuki; Yamamoto, Kazami; Kinsho, Michikazu
no journal, ,
Suppression of device radiations due to beam losses in the high intensity proton accelerators is one of the key issues to achieve MW class high power beam operation. In the J-PARC RCS, Ring collimator system which can localize the beam loss in the ring is adopted to suppress the device radiations. However, high residual doses are observed around the stripper foil. During the multi-turn charge exchange beam injection, not only the injecting beam but also circulating beam hit the foil, and then a large number of secondary particles, namely protons and neutrons, are generated. PHITS simulation results indicate that the secondary particles cause the high residual doses around the foil. Thus, we developed a new BLM which can detect the beam loss at the localized spot area. This new BLM can relate the beam loss with the radio activation of the device at the spot area. Detected radiations by this new BLM are occurred during the beam injection period and the total amount of the signal is directly proportional to the frequency of both the injecting and the circulating beam irradiation. Beam loss evaluation method combining the detailed residual dose survey by the GM counter after the beam stop into the radiations measurement by the BLM during the beam operation is effectively to reveal the beam losses structure from the point of view of the beam dynamics in the accelerator. In this presentation, we report the relation between the BLM signals and residual doses, and the beam losses structure and the mechanism.
Yoshimoto, Masahiro; Okabe, Kota; Harada, Hiroyuki; Kinsho, Michikazu; Kato, Shinichi*
no journal, ,
The charge exchange multi-turn beam injection scheme is adopted in the J-PARC 3GeV Rapid Cycling Synchrotron Accelerator (RCS) due to achieve 1MW beam power operation. In the conventional multi-turn beam injection scheme, which is provided by only the septum and bump magnets, injecting turn numbers are limited by the beam losses at the septum. On the other hand, charge exchange multi-turn beam injection does not cause the beam losses at the septum; there is no restriction in principle on the injecting turn number. However, high residual doses are observed around the stripper foil. During the charge exchange multi-turn beam injection, not only the injecting beam but also circulating beam hit the foil, and then a large number of secondary particles, namely protons and neutrons, are generated. PHITS simulation results indicate that the secondary particles cause the high residual doses around the foil. To verify this examination, secondary particles measurement is key issue. But injection system is too complex to detect the pure signals of the secondary particles from the stripper foil. Thus, a new independent type foil introducing device is installed in the 100
dump beam transport line in order to construct a simple experimental system for secondary particle measurements. We plan the two experiments by using this system; one is a directly secondary particle detecting method, and the other is a radioactivation analysis method with metal sample pieces. Now, we started the study of how the identification of species and energies of the secondary particles with PHITS code. In this presentation, we report the simulation results of the utility of the radioactivation analysis method.
