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Journal Articles

Dependence of charge-exchange efficiency on cooling water temperature of a beam transport line

Yamamoto, Kazami; Hatakeyama, Shuichiro; Saha, P. K.; Moriya, Katsuhiro; Okabe, Kota; Yoshimoto, Masahiro; Nakanoya, Takamitsu; Fujirai, Kosuke; Yamazaki, Yoshio; Suganuma, Kazuaki

EPJ Techniques and Instrumentation (Internet), 8(1), p.9_1 - 9_9, 2021/07

The 3 GeV Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex supplies a high-intensity proton beam for neutron experiments. Various parameters are monitored to achieve a stable operation, and it was found that the oscillations of the charge-exchange efficiency and cooling water temperature were synchronized. We evaluated the orbit fluctuations at the injection point using a beam current of the injection dump, which is proportional to the number of particles that miss the foil and fail in the charge exchange, and profile of the injection beam. The total width of the fluctuations was approximately 0.072 mm. This value is negligible from the user operation viewpoint as our existing beam position monitors cannot detect such a small signal deviation. This displacement corresponds to a 1.63$$times$$10$$^{-5}$$ variation in the dipole magnetic field. Conversely, the magnetic field variation in the L3BT dipole magnet, which was estimated by the temperature change directly, is 4.08$$times$$10$$^{-5}$$. This result suggested that the change in the cooling water temperature is one of the major causes of the efficiency fluctuation.

Journal Articles

High-intensity beam profile measurement using a gas sheet monitor by beam induced fluorescence detection

Yamada, Ippei; Wada, Motoi*; Moriya, Katsuhiro; Kamiya, Junichiro; Saha, P. K.; Kinsho, Michikazu

Physical Review Accelerators and Beams (Internet), 24(4), p.042801_1 - 042801_13, 2021/04

A transverse beam profile monitor that visualizes a two-dimensional beam-induced fluorescent image was developed. The monitor employs a sheet-shaped gas flow formed by a technique of rarefied gas dynamics. A simplified analysis method was developed to reconstruct the beam intensity profile from the obtained image. The developed profile monitor and the analysis method were applied to measure the J-PARC 3 MeV H$$^-$$ beam profile. The root mean square values of the profiles were consistent with the ones obtained by a wire-scanning-type beam profile monitor. The beam loss due to the gas sheet injection was measured as a beam-current reduction. The amount of the beam current decreased in proportion to the gas sheet flux and the reduction ranged from 0.004 to 2.5%. The assembled system was capable of reconstructing a beam profile from a single shot beam pulse (1.7$$times$$10$$^{13}$$ protons in 50 $$mu$$s).

Journal Articles

Simulation study of heavy ion acceleration in J-PARC

Harada, Hiroyuki; Saha, P. K.; Kinsho, Michikazu

JPS Conference Proceedings (Internet), 33, p.011028_1 - 011028_6, 2021/03

Recently, humankind had big discovery about neutron star, which is great big nuclear in the space. They are discovery of neutron star with twice mass of solar in 2010 and detection of gravity wave when two neutron stars incorporate in 2017. In order to understand the high dense matter like the neutron star, project of experimental researches by using accelerated heavy ion beams are planed in the world. The J-PARC facility consists of three accelerators, which are 400 MeV linac, 3 GeV rapid cycling synchrotron and Main Ring synchrotron. The accelerated MW class high intensity proton beams are used in many experiments. We have simulation study of the heavy ion beam in J-PARC to fully utilize high intensity ability of J-PARC. We propose the accelerator scheme of the beam in J-PARC and the intensity will reach to the world record. In my talk, I will introduce the accelerator scheme for the high-intensity heavy ion beam in J-PARC.

Journal Articles

Development of laser system for laser stripping injection

Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Kinsho, Michikazu

JPS Conference Proceedings (Internet), 33, p.011026_1 - 011026_6, 2021/03

The charge-exchange multi-turn injection by using a carbon stripper foil is adopted in high-intensity proton ring accelerators worldwide. It is a beneficial method to compress the pulsed proton beam with high intensity but there are serious issues for high intensity. First issue is a short lifetime of the foil by deformation or breaking itself. Another issue is high radiation dose corresponding to the scattered particles on the foil. Therefore, a non-destructive stripping injection method is required for higher intensity proton beam. We newly propose a non-destructive method of H$$^{-}$$ stripping by using only laser. The new method is called "laser stripping injection". To establish our method, we are preparing for a POP (Proof-of-Principle) experiment of 400 MeV H- stripping to proton at J-PARC. In our presentation we will present the current status of laser system development for laser stripping injection at J-PARC.

Journal Articles

1.2-MW-equivalent high-intensity beam tests in J-PARC RCS

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; et al.

JPS Conference Proceedings (Internet), 33, p.011018_1 - 011018_6, 2021/03

no abstracts in English

Journal Articles

Flexible chopper gate pulse generation for the J-PARC RCS

Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Sugiyama, Yasuyuki*; Hotchi, Hideaki; Saha, P. K.; Yoshimoto, Masahiro; Harada, Hiroyuki

JPS Conference Proceedings (Internet), 33, p.011021_1 - 011021_6, 2021/03

Chopped beam injection is employed in the J-PARC RCS to avoid the longitudinal beam losses. A fast beam chopper is installed in the MEBT section of the linac. The chopper is driven by the gate pulses sent from the LLRF control system of the RCS. The delay from the zero crossing of the RCS rf and the width are set so that the beam pulse is injected into the proper phase position of the rf bucket. A unique feature of the J-PARC chopper gate pulse generation is thinning of the pulses. The thinning is useful to control the beam intensity without changing much the condition of the longitudinal painting. Also, the beam macro pulse can be trimmed down to a single intermediate pulse by setting the parameters. In this poster, we present the overview of the generation of the chopper gate pulse in the LLRF control system and various beam commissioning results utilizing the flexibility of it. Also, we discuss the upgrade of the chopper gate pulse generation.

Journal Articles

Studies of laser power reduction for the laser stripping of 400 MeV $$H^{-}$$ beam at J-PARC RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Liu, Y.*

JPS Conference Proceedings (Internet), 33, p.011025_1 - 011025_7, 2021/03

Journal Articles

Analysis of J-HBC stripper foil for the J-PARC RCS

Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*

JPS Conference Proceedings (Internet), 33, p.011019_1 - 011019_7, 2021/03

The multi-turn charge-exchange H$$^{-}$$ beam injection scheme with stripper foils is one of the key techniques to achieve a MW-class high power proton beam. The J-PARC RCS adopts Hybrid type Boron-doped Carbon (HBC) stripper foil, which was developed in KEK to improve the lifetime. Indeed, the RCS user operation confirmed that HBC foil has the great advantage of a longer lifetime against high beam irradiation. To examine characteristics of the HBC foils, various beam studies were performed, such as the stripping efficiency measurement and long-term observation with an H$$^{-}$$ beam in the J-PARC RCS, foil analysis using RBS, EDR and PIXE methods, and SEM and TEM observation after the ion beam irradiation in Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) on National Institutes for Quantum and Radiological Science and Technology (QST). Recently, the deposition apparatus for the HBC foils from the KEK Tsukuba-site was relocated to the JAEA Tokai-site, and we started fabrication of new HBC foil in 2017. (The new one fabricated in JAEA we call J-HBC foil.) And, we continue investigations in TIARA with the J-HBC foils. Furthermore, in-depth researches by changing the process parameters of the foil deposition are carried on. Recent results suggest that the amount of the boron doped in the foil is more important parameter than the ratio of the discharge amount of carbon from cathode and anode electrodes. In this presentation, we will report the details of recent analysis of the J-HBC foil.

Journal Articles

Status of laser development for laser stripping experiment at J-PARC

Harada, Hiroyuki; Saha, P. K.; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.441 - 445, 2020/09

The high-intensity proton accelerator adopts a charge exchange injection scheme, which injects with exchanging from negative Hydrogen ion to proton by using carbon foil. This scheme is destructive-type method by using the foil and can accumulate high intensity proton beam. However, the uncontrolled beam losses by scattering at the foil and the foil breaking by the beam collision are a key issue of high-intensity proton accelerator. In order to realize higher intensity, new injection scheme of non-destructive type is needed instead of the foil. We newly propose laser stripping injection scheme by using laser pulse. We plan proof of principle experiment at J-PARC and are developing the laser system. In my presentation, we introduce the overview of laser stripping injection scheme and report the status of laser development.

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

First measurement and online monitoring of the stripper foil thinning and pinhole formation to achieve a longer foil lifetime in high-intensity accelerators

Saha, P. K.; Yoshimoto, Masahiro; Hatakeyama, Shuichiro; Hotchi, Hideaki; Harada, Hiroyuki; Tamura, Fumihiko; Yamamoto, Kazami; Yamazaki, Yoshio; Kinsho, Michikazu; Irie, Yoshiro*

Physical Review Accelerators and Beams (Internet), 23(8), p.082801_1 - 082801_13, 2020/08

 Times Cited Count:1 Percentile:35.83(Physics, Nuclear)

Journal Articles

J-PARC 3-GeV RCS; 1-MW beam operation and beyond

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; et al.

Journal of Instrumentation (Internet), 15(7), p.P07022_1 - P07022_16, 2020/07

 Times Cited Count:1 Percentile:27.17(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Progress status in fabrication of HBC stripper foil for 3-GeV RCS at J-PARC in Tokai site

Yoshimoto, Masahiro; Yamazaki, Yoshio; Nakanoya, Takamitsu; Saha, P. K.; Kinsho, Michikazu

EPJ Web of Conferences, 229, p.01001_1 - 01001_7, 2020/02

In the 3-GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), we adopted thick Hybrid type Boron-doped Carbon (HBC) stripper foil for the multi-turn H$$^{-}$$ charge-exchange injection. The HBC stripper foil developed at KEK has been successfully demonstrated to improve the foil lifetime significantly. Early manufacturing process of the stripper foil in the J-PARC had been carried out in following two steps: foil fabrication in KEK Tsukuba-site and foil preparation in JAEA Tokai-site. However, to proceed with the foil manufacturing in a same place efficiently, the carbon discharge arc-evaporation system for HBC stripper foil was removed from the Tsukuba-site and relocated in the Tokai-site. After reassembling of the carbon discharge arc-evaporation system, performance evaluation tests of new HBC foil which are produced at the JAEA Tokai site (J-HBC) are implemented at the TIARA facility of QST-Takasaki. As results of argon beam irradiation for lifetime evaluation, components analysis with RBS method, and impurity evaluation with micro-PIXE method, we can verify that the J-HBC foil performs pretty much equally to the original HBC foil. After the irradiation test by using 400MeV H$$^{-}$$ beam in the J-PARC RCS, user operation by using the J-HBC foil was successfully demonstrated for 10 days.

Journal Articles

Beam dynamics study for beam loss mitigation in the J-PARC RCS

Hotchi, Hideaki; Harada, Hiroyuki; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yoshimoto, Masahiro

Kasokuki, 16(2), p.109 - 118, 2019/07

no abstracts in English

Journal Articles

Recent progress of the J-PARC RCS beam commissioning and operation; Efforts to realize a higher beam power beyond 1 MW

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

Journal Articles

Development of two-mirror multi-pass laser system to reduce laser power for laser stripping injection at J-PARC 3-GeV RCS

Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Sato, Atsushi*; Yoneda, Hitoki*; Michine, Yurina*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.841 - 845, 2019/07

Journal Articles

Study of heavy ion acceleration in J-PARC

Harada, Hiroyuki; Saha, P. K.; Kinsho, Michikazu

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.179 - 182, 2019/07

Recently, humankind had big discovery about neutron star, which is great big nuclear in the space. They are discovery of neutron star with twice mass of solar in 2010 and observation of gravity wave when two neutron start incorporate in 2017. In order to understand the high dense matter like the neutron star, project of experimental researches by using accelerated heavy ion beams become heated in the world, such RHIC-BES-II program, FAIR project, NICA project, etc. The J-PARC provides MW class high intensity proton beams to many experiments and researches. We have study of the heavy ion beam in J-PARC to fully utilize high intensity ability of J-PARC. We propose the accelerator scheme of the beam in J-PARC and the intensity will reach to the world record. In our talk, we will report the current status of proton beam and the accelerator scheme for the high-intensity heavy ion beam in J-PARC.

Journal Articles

Dynamic variation of chromaticity for beam instability mitigation in the 3-GeV RCS of J-PARC

Saha, P. K.; Hotchi, Hideaki; Shobuda, Yoshihiro; Harada, Hiroyuki; Tamura, Fumihiko; Watanabe, Yasuhiro; Takayanagi, Tomohiro

Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.171 - 173, 2019/06

Journal Articles

$$g$$-factor measurement of the 2738 keV isomer in $$^{135}$$La

Laskar, Md. S. R.*; Saha, S.*; Palit, R.*; Mishra, S. N.*; Shimizu, Noritaka*; Utsuno, Yutaka; Ideguchi, Eiji*; Naik, Z.*; Babra, F. S.*; Biswas, S.*; et al.

Physical Review C, 99(1), p.014308_1 - 014308_6, 2019/01

 Times Cited Count:5 Percentile:69.53(Physics, Nuclear)

no abstracts in English

Journal Articles

Activation in injection area of J-PARC 3-GeV rapid cycling synchrotron and its countermeasures

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.

151 (Records 1-20 displayed on this page)