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Journal Articles

Upgrade of the 3-MeV linac for testing of accelerator components at J-PARC

Kondo, Yasuhiro; Hirano, Koichiro; Ito, Takashi; Kikuzawa, Nobuhiro; Kitamura, Ryo; Morishita, Takatoshi; Oguri, Hidetomo; Okoshi, Kiyonori; Shinozaki, Shinichi; Shinto, Katsuhiro; et al.

Journal of Physics; Conference Series, 1350, p.012077_1 - 012077_7, 2019/12

 Times Cited Count:0 Percentile:0.07

We have upgraded a 3-MeV linac at J-PARC. The ion source is same as the J-PARC linac's, and the old 30-mA RFQ is replaced by a spare 50-mA RFQ, therefore, the beam energy is 3 MeV and the nominal beam current is 50 mA. The main purpose of this system is to test the spare RFQ, but also used for testing of various components required in order to keep the stable operation of the J-PARC accelerator. The accelerator has been already commissioned, and measurement programs have been started. In this paper, present status of this 3-MeV linac is presented.

Journal Articles

Crystal structure change of katoite, Ca$$_{3}$$Al$$_{2}$$(O$$_{4}$$D$$_{4}$$)$$_{3}$$, with temperature at high pressure

Kyono, Atsushi*; Kato, Masato*; Sano, Asami; Machida, Shinichi*; Hattori, Takanori

Physics and Chemistry of Minerals, 46(5), p.459 - 469, 2019/05

 Times Cited Count:1 Percentile:12.33(Materials Science, Multidisciplinary)

To reveal the decomposition mechanism with temperature under high-pressure, crystal structure of a hydrogrossular, katoite Ca$$_{3}$$Al$$_{2}$$(O$$_{4}$$D$$_{4}$$)$$_{3}$$ has been studied by in-situ neutron diffraction at 8 GPa. Although unusual expansion behavior was discerned at 200-400$$^circ$$C, the unit cell was continuously expanded up to 850$$^circ$$C. At 900$$^circ$$C, katoite was decomposed, indicating that pressure strongly increases dehydration temperature from 300$$^circ$$C to 900$$^circ$$C. On release of pressure, the katoite reappear together with corundum and portlandite. At 8 GPa, CaO$$_{8}$$ and AlO$$_{6}$$ polyhedra expand with temperature up to 850$$^circ$$C by about 8% and 13%, respectively. On the other hand, tetrahedral interstices are isotopically squeezed by about 10%: due to the expansion of above polyhedra. The neighboring D-D distance remains almost unchanged in this temperature range, while the O-D bond distance shrinks drastically just before decomposition. This finding suggests that the shortening of O-D distance caused by the D-D repulsion destabilizes the O-D bond, which induces the thermal decomposition of katoite.

Journal Articles

Holding force tests of Curie Point Electro-Magnet in hot gas for passive shutdown system

Matsunaga, Shoko*; Matsubara, Shinichiro*; Kato, Atsushi; Yamano, Hidemasa; D$"o$derlein, C.*; Guillemin, E.*; Hirn, J.*

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

This paper presents a design of Curie Point Electro-Magnet (CPEM) which will be installed as a passive shutdown system for a French Sodium-cooled Fast Reactor (ASTRID) development program which is conducted in collaboration between France and Japan. To confirm CPEM design validity, a qualification program for CPEM is developed on the basis of past comprehensive test series of Self-Actuated Shutdown System (SASS) in Japan. The main outcome of this paper is results of holding force tests in hot gas, which satisfy design requirements. Moreover, the result of a numerical magnetic field analysis showed the same tendency as that of the holding force test.

Journal Articles

Evaluation of activated nuclides due to secondary particles produced in stripper foil in J-PARC RCS

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 $$gamma$$-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, $$^{65}$$Zn is extremely suitable for a proton beam indicator, and $$^{60}$$Co and $$^{56}$$Co are also suited for a neutron and proton indicator respectively.

Journal Articles

Incorporation of multinuclear copper active sites into nitrogen-doped graphene for electrochemical oxygen reduction

Kato, Masaru*; Muto, Marika*; Matsubara, Naohiro*; Uemura, Yohei*; Wakisaka, Yuki*; Yoneuchi, Tsubasa*; Matsumura, Daiju; Ishibara, Tomoko*; Tokushima, Takashi*; Noro, Shinichiro*; et al.

ACS Applied Energy Materials (Internet), 1(5), p.2358 - 2364, 2018/05

 Times Cited Count:4 Percentile:26.29(Chemistry, Physical)

Journal Articles

New scintillation type beam loss monitor to detect spot area beam losses in the J-PARC RCS

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.

Journal Articles

Laser storage ring with high power for realization of laser stripping injection

Harada, Hiroyuki; Yamane, Isao*; Saha, P. K.; Suganuma, Kazuaki; Kinsho, Michikazu; Irie, Yoshiro*; Kato, Shinichi

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.684 - 688, 2017/12

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 can realize high intensity proton beam but the uncontrolled beam losses are caused by scattering between beams and the foil. Additionally, the collision may occur the foil beak. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. In the J-PARC 3GeV RCS, we newly propose and develop a laser stripping injection scheme. However, it is necessary that laser power is two order higher than latest laser one. To realize this big issue, we develop the laser storage ring, which can provide laser pulse of high repetition rate by recycling one. In this presentation, we will introduce the laser stripping injection scheme and describe the concept of the laser storage ring with high repetition rate and report the current status.

Journal Articles

Recent progress of J-PARC RCS beam commissioning; Efforts for realizing a high-intensity low-emittance beam

Hotchi, Hideaki; Harada, Hiroyuki; Kato, Shinichi; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Tani, Norio; Watanabe, Yasuhiro; Yoshimoto, Masahiro

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.95 - 99, 2017/12

no abstracts in English

Journal Articles

Struggle to suppress radio-activation due to multi-turn charge exchange beam injection with stripper foil and its issues

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.

Journal Articles

Status of proof-of-principle experiment for 400 MeV H$$^{-}$$ stripping to protons by using only lasers in the 3-GeV RCS of J-PARC

Saha, P. K.; Harada, Hiroyuki; Yamane, Isao*; Kinsho, Michikazu; Miura, Akihiko; Okabe, Kota; Liu, Y.*; Yoshimoto, Masahiro; Kato, Shinichi; Irie, Yoshiro*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.866 - 870, 2017/12

Journal Articles

A Failure investigation of the beam collimator system in the J-PARC 3 GeV rapid cycling synchrotron

Okabe, Kota; Yamamoto, Kazami; Kamiya, Junichiro; Takayanagi, Tomohiro; Yamamoto, Masanobu; Yoshimoto, Masahiro; Takeda, Osamu*; Horino, Koki*; Ueno, Tomoaki*; Yanagibashi, Toru*; et al.

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.853 - 857, 2017/12

The most important issue is to reduce the uncontrolled beam loss in the high intensity hadron accelerator such as J-PARC proton accelerators. The J-PARC 3 GeV Synchrotron (RCS) has a collimator system which narrows a high intensity beam in the RCS. After startup of RCS in 2007, the collimator system of the RCS worked well. However, in April 2016, vacuum leakage at the collimator system occurred during the maintenance operation. To investigate a cause of the failure, we took apart iron shields of the collimator reducing exposed dose of operators. As a result of inspection, we succeeded to identify the cause of the vacuum leakage failure. In this presentation, we report the failure investigation of the beam collimator system in the RCS.

Journal Articles

Achievement of a low-loss 1-MW beam operation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kato, Shinichi; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Tani, Norio; et al.

Physical Review Accelerators and Beams (Internet), 20(6), p.060402_1 - 060402_25, 2017/06

 Times Cited Count:17 Percentile:87.54(Physics, Nuclear)

The 3-GeV rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) is the world's highest class of high-power pulsed proton driver, aiming for an output beam power of 1 MW. The most important issues in realizing such a high-power beam operation are to control and minimize beam loss for maintaining machine activations within permissible levels. In RCS, numerical simulation was successfully utilized along with experimental approaches to isolate the mechanism of beam loss and find its solution. By iteratively performing actual beam experiments and numerical simulations, and also by several hardware improvements, we have recently established a 1-MW beam operation with very low fractional beam loss of a couple of 10$$^{-3}$$. In this paper, our recent efforts toward realizing such a low-loss high-intensity beam acceleration are presented.

Journal Articles

Realizing a high-intensity low-emittance beam in the J-PARC 3-GeV RCS

Hotchi, Hideaki; Harada, Hiroyuki; Kato, Shinichi; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Tani, Norio; Watanabe, Yasuhiro; Yoshimoto, Masahiro

Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2470 - 2473, 2017/06

For this past year, RCS beam tuning was focused on realizing a high-intensity low-emittance beam required from the downstream facility. The extraction beam emittance including its tail part was successfully decreased by optimizing transverse injection painting, and tune and chromaticity manipulations, where bipolar sextupole field patterns were newly introduced to simultaneously achieve emittance growth mitigation at the early stage of acceleration and beam instability suppression after the middle stage of acceleration. This paper presents the recent experimental results, together with detailed discussions for the emittance growth and its mitigation mechanisms.

Journal Articles

Laser storage ring with high power for realization of laser stripping injection

Harada, Hiroyuki; Saha, P. K.; Yamane, Isao*; Kato, Shinichi; Kinsho, Michikazu; Irie, Yoshiro*

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.983 - 986, 2016/11

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 can realize high intensity proton beam but the uncontrolled beam losses are caused by scattering between beams and the foil. Additionally, the collision may occur the foil beak. Therefore, a new injection scheme for higher intensity is needed as an alternative to the foil. In the J-PARC 3GeV RCS, we newly propose and develop a laser stripping injection scheme However, it is necessary that laser power is two order higher than latest laser one. To realize this big issue, we develop the laser storage ring, which can provide laser pulse of high repetition rate by recycling one. In this presentation, we will introduce the laser stripping injection scheme and describe the concept of the laser storage ring with high repetition rate.

Journal Articles

Improvement of the IPM for the high-intensity beam profile measurement in the J-PARC RCS

Kato, Shinichi; Harada, Hiroyuki; Hatakeyama, Shuichiro; Kawase, Masato; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1089 - 1093, 2016/11

In the J-PARC RCS, the residual gas ionization profile monitor (IPM) is adopted for the nondestructive detection of the 1D transverse distribution of the circulating proton beam. The IPM mainly consists of the divided electrodes generating the external electric field and the detection unit. For the profile measurement, the residual gas ionized by the beam is transported to the detection unit by the external transverse electric field and amplified by the Multi-Channel Plate (MCP) as the electron. After that, these electrons are detected and the 1D distribution is reconstructed. To improve IPM performance, some updates have been performed continuously such as the optimization of the electric field potential and the introduction of the new MCP which has the gradual gain response to the applied voltage. As a result, the IPM shows intended performance in the beam commissioning with the low current condition. However, the distribution cannot be measured in the high current condition such as over 100 kW because the noise increases and hides the signal. To solve this problem, we investigated the source of this noise and examined measures. To compare the simulation and the noise measurement results, we identified the cause of the noise as the electric field from the beam. Therefore, we developed additional electrode component to shield that field based on the simulation result. This component will be installed in 2016 summer. It is expected that the noise is reduced to be 1/100 compared with present one by the new component and the distribution measurement can be performed in the high current condition.

Journal Articles

Development of a control system at a 3 MeV linac in J-PARC

Sawabe, Yuki*; Ishiyama, Tatsuya; Takahashi, Daisuke; Kato, Yuko; Suzuki, Takahiro*; Hirano, Koichiro; Takei, Hayanori; Meigo, Shinichiro; Kikuzawa, Nobuhiro; Hayashi, Naoki

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.647 - 651, 2016/11

In the J-PARC, a 3 MeV linac has been developed for the tests of beam scraper irradiation and charge exchange by high-power laser. To accomplish tests efficiently and safely, the control system for 3 MeV was designed and developed, and this system consists of four subsystems, personal protection system, machine protection system, timing system, and remote control system using the EPICS. In this paper, the details of control system for a 3 MeV linac are presented.

Journal Articles

1 MW beam tuning for beam loss mitigation in the J-PARC 3 GeV 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 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.61 - 65, 2016/11

After the RF power supply upgrade, the J-PARC 3-GeV RCS restarted a 1-MW beam test in October 2015. In the beam test in October, we successfully removed longitudinal beam loss by beam loading compensation as well as minimized space-charge induced beam loss by injection painting. In addition, in this beam test, beam instability was also well suppressed by controlling the tune and the chromaticity. Furthermore, in the following 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 these recent efforts, the 1-MW beam operation is now estimated to be established within a permissible beam loss level. This paper presents recent progresses of 1-MW beam tuning with particular emphasis on our approaches to beam loss issues.

Journal Articles

The Path to 1 MW; Beam loss control in the J-PARC 3-GeV 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.

Journal Articles

An Experimental plan for 400 MeV H$$^{-}$$ stripping to proton by using only lasers in the J-PARC RCS

Saha, P. K.; Harada, Hiroyuki; Kato, Shinichi; Kinsho, Michikazu; Irie, Yoshiro*; Yamane, Isao*

Proceedings of 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2016) (Internet), p.310 - 314, 2016/08

Journal Articles

Angle-resolved photoemission analysis of electronic structures for thermoelectric properties of off-stoichiometric Fe$$_{2-x}$$V$$_{1+x}$$Al alloys

Soda, Kazuo*; Harada, Shota*; Hayashi, Toshimitsu*; Kato, Masahiko*; Ishikawa, Fumihiro*; Yamada, Yu*; Fujimori, Shinichi; Saito, Yuji

Materials Transactions, 57(7), p.1040 - 1044, 2016/06

 Times Cited Count:2 Percentile:16.67(Materials Science, Multidisciplinary)

125 (Records 1-20 displayed on this page)