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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

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

Design and delivery of beam monitors for the energy-upgraded linac in J-PARC

Miura, Akihiko; Ouchi, Nobuo; Oguri, Hidetomo; Hasegawa, Kazuo; Miyao, Tomoaki*; Ikegami, Masanori*

Journal of the Korean Physical Society, 66(3), p.364 - 372, 2015/02

 Times Cited Count:2 Percentile:20.53(Physics, Multidisciplinary)

In J-PARC Linac, an energy upgrade project has started to achieve the design beam power of 1 MW at the exit of downstream synchrotron. To meet with significant upgrades of the beam parameters, beam monitors used for the beam commissioning are modified and fabricated. We discuss how to design and assemble the beam monitors for the upgraded Linac. We delivered them for the new upgraded beam line periodically and newly fabricated monitors for the longitudinal matching are also delivered because of the frequency jump between original RF cavity and newly developed cavity. Finally we suppose the commissioning plans to support the monitor check.

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

Development of RF chopper system at J-PARC Linac

Hirano, Koichiro; Ito, Takashi; Kondo, Yasuhiro; Shinozaki, Shinichi; Chishiro, Etsuji; Miura, Akihiko; Morishita, Takatoshi; Ikegami, Masanori*; Kubota, Chikashi*; Sugimura, Takashi*; et al.

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.858 - 861, 2014/06

Two RF-deflecting cavities as a chopper and a beam scraper have been used in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We plan to increase a peak beam current up to 50 mA by replacing an ion source and a RFQ after the summer shutdown in 2014. Beam loss occurs in the RF chopper for the 50 mA operation. Moreover, the beam scraper cannot fully stand the beam load with 50 mA, 0.5 ms, 3 MeV, and 25 Hz. We have studied the new RF chopper cavity by using HFSS code and the tandem scraper system with two scrapers.

Journal Articles

Bunch shape monitor for J-PARC linac

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

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.705 - 708, 2014/06

In J-PARC linac, a project for energy and intensity upgrade has been progressed since 2009 using Annular-ring Coupled Structure (ACS) cavities. Because the longitudinal matching of the injection beam to the ACS cavities is required as well as the transverse matching, we decided to employ the bunch shape monitors (BSM's) to measure the longitudinal beam profile. We developed three BSM's in collaboration with INR (Institute for Nuclear Research: Russia) for the upstream part of the ACS section. We introduce the structure of BSM and mention the measured results taken during the commissioning of BSM.

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:0(Physics, Multidisciplinary)

Journal Articles

Beam loss occurred at DTL cavity in J-PARC linac

Miura, Akihiko; Miyao, Tomoaki*; Ito, Takashi; Hirano, Koichiro; Nammo, Kesao*; Maruta, Tomofumi; Tamura, Jun; Ikegami, Masanori*; Naito, Fujio*

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.653 - 655, 2013/08

The beam operation of J-PARC linac was suspended until December 2011 due to the damage by the Tohoku earthquake in March 2011. After resumed the operations, we measured the residual radiation along with the beam line during a short interval. Because the higher residual radiation was detected at the surface of drift tube linac (DTL) cavity by radiation survey, we installed the scintillation beam loss monitors (BLM) at the points where the higher radiation was detected to understand the cause of the radiation. Even the DTL section is low energy part of the linac, fine structure of the beam loss was observed by the scintillation BLM. And we measured the beam loss occurred at the DTL with the parameters of beam orbit and cavity settings. Also, the BLM is employed for the linac tuning. In this paper, the result of the radiation measurement and beam loss signals obtained by the scintillation BLMs are presented.

Journal Articles

Simulation study on longitudinal beam profile measurement by using RF chopper at J-PARC linac

Maruta, Tomofumi; Ikegami, Masanori*

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.420 - 423, 2013/08

no abstracts in English

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

Journal Articles

Beam loss reduction by the beam duct realignment in the J-PARC linac beam transport line

Tamura, Jun; Ao, Hiroyuki; Asano, Hiroyuki; Ikegami, Masanori*; Maruta, Tomofumi; Miura, Akihiko; Morishita, Takatoshi; Oguri, Hidetomo; Ouchi, Nobuo; Sawabe, Yuki*; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.377 - 380, 2013/08

In the J-PARC linac, almost all the cavities and magnets have been precisely aligned because the accelerator tunnel has been deformed by the 2011 Tohoku Earthquake. In the beam transport line called MEBT2 and A0BT at the downstream of the drift tube linac, the beam duct has been roughly aligned after the precise alignment of the quadruple doublets. During the first beam operation after the earthquake, remarkable beam loss and residual radiation have been recognized at the MEBT2 and A0BT. As the result of the duct position measurement, the misalignement including over 10 mm shift from the beam axis was found. By conducting the beam duct realignment, the beam loss and the residual radiation were successfully decreased. In this paper, the procedure of the beam duct alignment and the beam loss due to the misalignment are described.

Journal Articles

Simulation study on the longitudinal bunch shape measurement by RF chopper at J-PARC linac

Maruta, Tomofumi; Ikegami, Masanori*

Proceedings of 26th International Linear Accelerator Conference (LINAC 2012) (Internet), p.395 - 397, 2012/09

no abstracts in English

Journal Articles

Longitudinal beam diagnosis with RF chopper system

Maruta, Tomofumi; Ikegami, Masanori*

Proceedings of 52nd ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2012) (Internet), p.591 - 595, 2012/09

no abstracts in English

Journal Articles

Beam start-up of J-PARC linac after the Tohoku Earthquake

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

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3293 - 3295, 2012/05

no abstracts in English

Journal Articles

Longitudinal beam profile measurement at J-PARC separated drift tube linac

Maruta, Tomofumi; Miura, Akihiko; Sako, Hiroyuki; Wei, G.; Ikegami, Masanori*

Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.1245 - 1247, 2011/09

In J-PARC linac, we have been experiencing beam losses at the beam transport line after the linac exit. There has been an argument that the longitudinal loss could be a cause of the beam loss, which motivated us to conduct an experimental investigation on the margin between the longitudinal acceptance of the linac and the actual beam distribution. In the experiment, we have introduced a "tank level scan" to measure the margin in the energy direction in addition to the conventional phase scan which has been employed to measure the margin for the phase direction. The measurement scheme and experimental results are presented in this paper.

Journal Articles

Longitudinal beam acceptance of J-PARC drift tube linac

Maruta, Tomofumi; Miura, Akihiko; Sako, Hiroyuki; Wei, G.; Ikegami, Masanori*

Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.2592 - 2594, 2011/09

Since we have no tool to measure the longitudinal beam profile at the J-PARC linac, we have tuned operational parameters for the matching of both longitudinal and transverse directions only from the measurement of the transverse beam profile by wire scanners at matching sections. Therefore it is very useful for us if the beam profile on the longitudinal phase space can be measured. It motivated us to measure the longitudinal acceptance of the DTL. In the measurement, we introduced a "tank level scan" to measure the shrinkage of the acceptance when we reduce the tank level of 1st DTL cavity in addition to the conventional phase scan. In this presentation, we will present the measurement scheme and experimental results.

Journal Articles

Beam monitor deformation by Tohoku Earthquake and its recovery project

Miura, Akihiko; Hasegawa, Kazuo; Oguri, Hidetomo; Ouchi, Nobuo; Igarashi, Zenei*; Miyao, Tomoaki*; Ikegami, Masanori*

Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.2328 - 2330, 2011/09

On March 11, 2011, the great earthquake occurred off the Pacific coast of Tohoku. This earthquake and related ones caused the big damage of the J-PARC accelerators. As for the beam monitors in J-PARC linac, some commissioning tools had damage and the vacuum leakage was observed. In the recovery work, we inspected the damage and put the emergency steps for the vacuum equipment. In this paper, detailed inspection results of beam monitors are described and also the recovery work is introduced.

Journal Articles

Beam loss detected by scintillation monitor

Miura, Akihiko; Maruta, Tomofumi; Sako, Hiroyuki; Hasegawa, Kazuo; Ouchi, Nobuo; Igarashi, Zenei*; Miyao, Tomoaki*; Ikegami, Masanori*

Proceedings of 2nd International Particle Accelerator Conference (IPAC 2011) (Internet), p.1257 - 1259, 2011/09

Ar-CO$$_{2}$$ gas proportional beam loss monitors (BLMs) have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. For the future energy upgrade of J-PARC linac, because 21 RF cavities are additionally installed in the beam line, the background noise would be serious problem. We employed the scintillation monitors to measure the beam loss which would bring more accurate beam loss measurements with suppression of X-ray noise. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. In addition, the availability of the scintillation monitor is also confirmed at the low energy part. This paper describes the beam loss measurement system using a scintillation monitor.

97 (Records 1-20 displayed on this page)