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Journal Articles

Longitudinal measurements and beam tuning in the J-PARC linac MEBT1

Otani, Masashi*; Futatsukawa, Kenta*; Miyao, Tomoaki*; Liu, Y.*; Hirano, Koichiro; Kondo, Yasuhiro; Miura, Akihiko; Oguri, Hidetomo

Journal of Physics; Conference Series, 1350, p.012078_1 - 012078_5, 2019/12

 Times Cited Count:0 Percentile:100

The Japan Proton Accelerator Research Complex (J-PARC) linac is operated with design peak current of 50 mA from 2018. For operation with such a high beam current, itis important to understand transverse and longitudinal beam properties especially in low-velocity region. A medium energy beam transport (MEBT1) line between the 3-MeV radio-frequency quadrupole linac (RFQ) and the 50-MeV drift-tube linac (DTL) is a 3-m-long transport line to match the beam to the DTL and produce a macro pulse configuration for a 3-GeV rapid-cycling synchrotron (RCS). In this paper, recent measurements and beam tuning results in MEBT1 will be presented.

Journal Articles

Dirac surface state-modulated spin dynamics in a ferrimagnetic insulator at room temperature

Tang, C.*; Song, Q.*; Chang, C.-Z.*; Xu, Y.*; Onuma, Yuichi; Matsuo, Mamoru*; Liu, Y.*; Yuan, W.*; Yao, Y.*; Moodera, J. S.*; et al.

Science Advances (Internet), 4(6), p.eaas8660_1 - eaas8660_6, 2018/06

 Times Cited Count:8 Percentile:26.78(Multidisciplinary Sciences)

Journal Articles

Beam tuning for longitudinal profile at J-PARC linac

Miura, Akihiko; Liu, Y.*; Maruta, Tomofumi*; Miyao, Tomoaki*

Proceedings of 5th International Beam Instrumentation Conference (IBIC 2016) (Internet), p.150 - 153, 2017/03

no abstracts in English

Journal Articles

Phase resolution measurement for the Bunch Shape Monitor at J-PARC Linac

Miyao, Tomoaki*; Maruta, Tomofumi*; Liu, Y.*; Miura, Akihiko

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1094 - 1096, 2016/11

no abstracts in English

Journal Articles

Bunch length analysis of negative hydrogen ion beam in J-PARC linac

Miura, Akihiko; Hayashi, Naoki; Maruta, Tomofumi*; Liu, Y.*; Miyao, Tomoaki*; Fukuoka, Shota*

Proceedings of 4th International Beam Instrumentation Conference (IBIC 2015) (Internet), p.386 - 389, 2016/02

We have used bunch shape monitors (BSMs) to measure the longitudinal bunch length of negative hydrogen ion beam in the J-PARC linac. In order to evaluate the measurement errors with peak beam current increasing, we observed waveforms with various beam current. As the result, an RMS bunch length depends on the peak beam current and the bending at the pulse head grows with the peak beam current. We also compared the data taken at an off-center beam to avoid the thermal stress with the ones at an on-center beam, because a target wire will be exposed to a higher peak beam current. In this paper, we introduced the peak beam current dependence of the bunch length waveforms, and an effect of on- /off-centering of the wire position. Finally the new buncher tuning method using one BSM have been discussed.

Journal Articles

Beam monitors for the commissioning of energy upgraded linac

Miura, Akihiko; Maruta, Tomofumi*; Liu, Y.*; Miyao, Tomoaki*; Kawane, Yusuke; Ouchi, Nobuo; Oguri, Hidetomo; Ikegami, Masanori*; Hasegawa, Kazuo

JPS Conference Proceedings (Internet), 8, p.011002_1 - 011002_6, 2015/09

BB2014-1017.pdf:0.51MB

In the J-PARC Linac, an energy upgrade project has started since 2009 using Annular-ring Coupled Structure cavities to achieve design beam power of 1 MW at the exit of the downstream rapid cycling synchrotron. Linac beam parameters of the upgraded Linac is drastically improved especially for the beam energy from 181 to 400 MeV in the project. To meet with the significant upgrades of the Linac, beam monitors to be used for the upgraded beam line are newly designed and fabricated as well as the beam monitor layout is designed with the consideration to the beam commissioning strategies. This paper introduces the beam monitor layout in the new beam line and the commissioning results to confirm the beam monitor functioning.

Journal Articles

Bunch shape measurement of 181 MeV beam in J-PARC linac

Miura, Akihiko; Feschenko, A. V.*; Mirzojan, A. N.*; Miyao, Tomoaki*; Ouchi, Nobuo; Maruta, Tomofumi*; Liu, Y.*; Oguri, Hidetomo; Ikegami, Masanori*; Hasegawa, Kazuo

JPS Conference Proceedings (Internet), 8, p.011003_1 - 011003_6, 2015/09

BB2014-1018.pdf:0.45MB

In J-PARC Linac, an energy upgrade project has started since 2009 using Annular-ring Coupled Structure (ACS) cavities. We have decided to use the bunch shape monitors (BSM) as the monitors of the longitudinal beam width measurement in order to take the longitudinal matching using two bunchers located in the upstream of ACS cavities, where the RF frequency jumps from 324 to 972 MHz. Three BSMs were completely fabricated and installed in the beam line. The BSMs were commissioned with the beam and their operability was demonstrated. We found the vacuum degradation during the measurement. We once removed all BSMs to have a vacuum conditioning and postponed the longitudinal matching at the establishment of 400-MeV operation of the energy upgraded Linac. In this paper, we introduce the mechanism of the BSM, its operability, the measurement results with the 181 MeV beam and consistency check with the respect cavity amplitude. We also describe the operational vacuum conditions and the outline of the improvement of the vacuum system for the BSMs.

Journal Articles

Beam loss mitigation by the modification of the beam pulse definition in the J-PARC LINAC

Sawabe, Yuki; Maruta, Tomofumi*; Liu, Y.*; Miura, Akihiko; Miyao, Tomoaki*; Ishiyama, Tatsuya; Kikuzawa, Nobuhiro; Hayashi, Naoki

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1202 - 1205, 2015/09

no abstracts in English

Journal Articles

Recent progress of beam study in the J-PARC linac

Maruta, Tomofumi*; Liu, Y.*; Futatsukawa, Kenta*; Miyao, Tomoaki*; Miura, Akihiko; Ikegami, Masanori*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.432 - 436, 2015/09

no abstracts in English

Journal Articles

Installation and performance check of beam monitors for energy upgraded J-PARC linac

Miura, Akihiko; Ouchi, Nobuo; Oguri, Hidetomo; Hasegawa, Kazuo; Maruta, Tomofumi*; Liu, Y.*; Miyao, Tomoaki*; Ikegami, Masanori*

Proceedings of 27th International Linear Accelerator Conference (LINAC 2014) (Internet), p.1059 - 1061, 2014/12

An energy upgrade project has started in the J-PARC Linac since 2009. In the upgraded project, beam energy in the Linac has increased from original 181 MeV to 400 MeV using the additional 21 Annular-ring Coupled Structure Linac (ACS) cavities. The new beam monitors as the beam current monitors, the phase monitors, the beam position monitors and the transverse profile monitors (wire scanner monitors) were designed and fabricated. By the end of November, 2013, all beam monitors were completely installed. From the middle of December, we started the beam commissioning to achieve the beam energy as 400 MeV, as well as to confirm the beam monitor functioning. We achieved the 400 MeV beam acceleration at the middle of January, 2014 using newly installed beam monitors. This paper describes the beam monitor installation and the beam commissioning results of beam monitor functioning.

Journal Articles

Present status of J-PARC linac

Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10

no abstracts in English

Journal Articles

Upgrade of power supply system for RF-chopper at J-PARC Linac

Futatsukawa, Kenta*; Ikegami, Masanori*; Ito, Yuichi; Kikuzawa, Nobuhiro; Sato, Fumiaki; Shinozaki, Shinichi; Suzuki, Takahiro*; Chishiro, Etsuji; Hirano, Koichiro; Fang, Z.*; et al.

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1149 - 1153, 2014/06

no abstracts in English

Journal Articles

Progress of beam commissioning and beam loss mitigation in the J-PARC linac after the Tohoku earthquake

Maruta, Tomofumi; Miura, Akihiko; Sako, Hiroyuki; Tamura, Jun; Ikegami, Masanori*; Futatsukawa, Kenta*; Fang, Z.*; Miyao, Tomoaki*; Liu, Y.*

Journal of the Korean Physical Society, 63(7), p.1274 - 1279, 2013/10

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

Journal Articles

Beam commissioning of J-PARC linac after Tohoku Earthquake and its beam loss mitigation

Ikegami, Masanori*; Fang, Z.*; Futatsukawa, Kenta*; Miyao, Tomoaki*; Liu, Y.*; Maruta, Tomofumi; Sako, Hiroyuki; Miura, Akihiko; Tamura, Jun; Wei, G.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.64 - 67, 2013/08

Oral presentation

Frictional properties of Main Fault Gouge of Mont Terri, Switzerland

Aoki, Kazuhiro; Seshimo, Kazuyoshi; Guglielmi, Y.*; Nussbaum, C.*; Shimamoto, Toshihiko*; Ma, S.*; Yao, L.*; Kametaka, Masao*; Sakai, Toru*

no journal, , 

Oral presentation

Fault reactivation experiment and frictional properties of Mont Terri Rock Laboratory, Switzerland

Aoki, Kazuhiro; Seshimo, Kazuyoshi; Nussbaum, C.*; Guglielmi, Y.*; Shimamoto, Toshihiko*; Sakai, Toru*; Kametaka, Masao*; Ma, S.*; Yao, L.*

no journal, , 

In order to contribute to the Fault Slip experiment, JAEA has performed friction experiment of borehole cores of the measured interval using a rotary-shear low to high-velocity friction apparatus at Institute of Geology, China Earthquake Administration. Friction experiments were done either dry with room humidity or with 30wt% of H$$_{2}$$O, at a normal stress of 1.4 and 4.0 MPa and at low to intermediate slip rates ranging 0.21 microns/s to 2.1mm/s. Cylindrical specimens of Ti-Al-V alloy with 40 mm in diameter were used as rotary and stationary pistons and the alloy pistons exhibit similar behaviors as host rock specimens.

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