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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:100

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

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

Negative muonium ion production with a C12A7 electride film

Otani, Masashi*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Kawamura, Naritoshi*; Matoba, Shiro*; Mibe, Tsutomu*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Yamazaki, Takayuki*; Hasegawa, Kazuo; et al.

Journal of Physics; Conference Series, 1350, p.012067_1 - 012067_6, 2019/12

 Times Cited Count:0 Percentile:100

Negative muonium atom ($$mu^+$$e$$^-$$e$$^-$$, Mu$$^-$$) has unique features stimulating potential interesting for several scientific fields. Since its discovery in late 1980's in vacuum, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has relatively low-work function (2.9 eV). In this paper, the negative muonium production measurement with several materials including a C12A7 electride film will be presented. Measured production rate of the Mu$$^-$$ were 10$$^{-3}$$/s for all the Al, electride, and SUS target. Significant enhancement on electride target was not observed, thus it is presumed that the surface condition should be more carefully treated. There was no material dependence of the Mu$$^-$$ averaged energy: it was 0.2$$pm$$0.1keV.

Journal Articles

Disk and washer coupled cavity linac design and cold-model for muon linac

Otani, Masashi*; Futatsukawa, Kenta*; Mibe, Tsutomu*; Naito, Fujio*; Hasegawa, Kazuo; Ito, Takashi; Kitamura, Ryo; Kondo, Yasuhiro; Morishita, Takatoshi; Iinuma, Hiromi*; et al.

Journal of Physics; Conference Series, 1350, p.012097_1 - 012097_7, 2019/12

 Times Cited Count:0 Percentile:100

A disk and washer (DAW) coupled cavity linac (CCL) has been developed for a middle velocity part in a muon linac to measure muon anomalous magnetic moment and search for electric dipole moment. I will accelerate muons from $$v/c$$ = $$beta$$ = 0.3 to 0.7 at an operational frequency of 1.3GHz. In this poster, the cavity design, beam dynamics design, and the cold-model measurements will be presented.

Journal Articles

Bunch shape monitor for the high-intensity H$$^{-}$$ beam with 3 MeV using the carbon material

Kitamura, Ryo; Futatsukawa, Kenta*; Hayashi, Naoki; Hirano, Koichiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Moriya, Katsuhiro; Nemoto, Yasuo*; Oguri, Hidetomo

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.51 - 54, 2019/07

The longitudinal measurement and tuning at the beam transport after the RFQ are important to reduce the beam loss and the emittance growth in the J-PARC linac, when the high-intensity H$$^{-}$$ beam of more than 60 mA is supplied. The new bunch shape monitor (BSM) using the carbon-nanotube (CNT) wire is necessary to measure the bunch shape of the high-intensity H$$^{-}$$ beam with 3 MeV, because the CNT wire has a high-temperature tolerance and a small energy deposit. However, when the high voltage was applied to the CNT wire to extract the secondary electron derived, the discharge prevents the power supply from applying the voltage. Therefore, the discharge should be suppressed to measure the bunch shape with stability. Considering the characteristics of the CNT as the emitter, when the length of the CNT wire was short, the high voltage of -10 kV was applied to the CNT wire. The current status and future prospects of the BSM using the CNT wire are reported in this presentation.

Journal Articles

Development of the bunch shape monitor using the carbon-nano tube wire

Kitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Kondo, Yasuhiro; Moriya, Katsuhiro; Oguri, Hidetomo; Futatsukawa, Kenta*; Miyao, Tomoaki*; Otani, Masashi*; Kosaka, Satoshi*; et al.

Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.2543 - 2546, 2019/06

A bunch shape monitor (BSM) is one of the important instruments to measure the longitudinal phase space distribution. For example in the J-PARC linac, three BSMs using the tungsten wire are installed at the ACS section to measure the bunch shapes between the accelerating cavities. However, this conventional BSM is hard to measure the bunch shape of H$$^{-}$$ beam with 3 MeV at the beam transport between the RFQ and DTL sections, because the wire is broken around the center region of the beam. The new BSM using the carbon-nano-tube (CNT) wire is being developed to be able to measure the bunch shape of the H$$^{-}$$ beam with 3 MeV. The careful attention should be paid to apply the high voltage of $$-$$10 kV to the CNT wire. The several measures are taken to suppress the discharge from the wire and operate the CNT-BSM. This presentation reports the current status of the development and future prospective for the CNT-BSM.

Journal Articles

Analysis of interlocked events based on beam instrumentation data at J-PARC Linac and RCS

Hayashi, Naoki; Hatakeyama, Shuichiro; Miura, Akihiko; Yoshimoto, Masahiro; Futatsukawa, Kenta*; Miyao, Tomoaki*

Proceedings of 7th International Beam Instrumentation Conference (IBIC 2018) (Internet), p.219 - 223, 2019/01

J-PARC is a multi-purpose facility. Accelerator stability is the one of important issues for users of this facility. To realize stable operation, we must collect data on interlocked events and analyze these data to determine the reasons for the occurrence of such events. In J-PARC Linac, data of interlocked events have been recorded using several some beam loss monitors and current monitors, and these data have been are analyzed and classified. In J-PARC RCS, new instrumentation is being introduced to obtain beam position. We discuss the present status and future plans related to this subject.

Journal Articles

Longitudinal bunch size measurement using an RF deflector

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

Nuclear Instruments and Methods in Physics Research A, 908, p.313 - 317, 2018/11

 Times Cited Count:0 Percentile:100(Instruments & Instrumentation)

It is extremely important to diagnose beams in accelerators to improve accelerator operation. In the low velocity section of a proton or heavy ion linac, the diagnostic method for longitudinal beam properties is less established compared to that for transverse properties. We have developed a new diagnostic method for the longitudinal bunch size by utilizing an RF deflector. We evaluated the uncertainty in bunch size measurement through simulation, and it was obtained as 0.5$$^{circ}$$. In addition, we measured longitudinal beam emittance through bunch size measurements at several RF amplitudes of an upstream buncher. The measured emittance was 0.13$$pm$$0.01$$pi$$ deg$$cdot$$MeV, which was consistent with the simulation result.

Journal Articles

Study of a tuner for a high-accuracy bunch shape monitor

Moriya, Katsuhiro; Kawane, Yusuke*; Miura, Akihiko; Futatsukawa, Kenta*; Miyao, Tomoaki*

Journal of Physics; Conference Series, 1067, p.072009_1 - 072009_3, 2018/09

 Times Cited Count:0 Percentile:100

no abstracts in English

Journal Articles

First muon acceleration using a radio-frequency accelerator

Bae, S.*; Choi, H.*; Choi, S.*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Hasegawa, Kazuo; Iijima, Toru*; Iinuma, Hiromi*; Ishida, Katsuhiko*; Kawamura, Naritoshi*; et al.

Physical Review Accelerators and Beams (Internet), 21(5), p.050101_1 - 050101_6, 2018/05

 Times Cited Count:9 Percentile:15.06(Physics, Nuclear)

Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu$$^{-}$$), which are bound states of positive muons and two electrons, are generated from through the electron capture process in an aluminum degrader. The generated Mu$$^{-}$$'s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu$$^{-}$$'s are accelerated to 89 keV. The accelerated Mu$$^{-}$$'s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

Journal Articles

Interlocked events of beam loss monitors at the J-PARC linac

Hayashi, Naoki; Kikuzawa, Nobuhiro; Miura, Akihiko; Futatsukawa, Kenta*; Miyao, Tomoaki*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.540 - 544, 2017/12

The J-PARC linac operation is stable, however, the numbers of interlocked events due to single beam loss monitor (BLMP) is increasing. Recently, the counts is comparable to the number of RFQ trip, and a measure has been required for improvement of the operation efficiency. Thus, every event data has been analyzed and classified into three categories. It is found that there are characteristic signal or pattern of BLMP for every categories. Although the linac BLMP detector is standard, its setting parameters are differ from those of other two synchrotrons in the J-PARC. To optimize time resolution, the input impedance of its pre-amplifier is selected to be 50 $$Omega$$ and interlock is defined in raw signal height and width not integral signal of BLMP. Some new parameters has been tried to reduce unnecessary interlock.

Journal Articles

Status of the J-PARC Linac LLRF system

Futatsukawa, Kenta*; Fang, Z.*; Fukui, Yuji*; Shinozaki, Shinichi; Mizobata, Satoshi; Sato, Yoshikatsu*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.486 - 489, 2017/12

In the J-PARC linac, the LLRF systems consist of twenty-four 324-MHz systems and twenty-five 972-MHz systems for ACS cavities. The 324-MHz LLRF systems, which were installed in the stations of RFQ, DTLs, and SDTLs, have been used since the beginning of the J-PARC and are more than ten years into the development. Realistically speaking, the incensement of the failure frequency for these systems is expected. Additionally, it is difficult to maintain those for some discontinued boards of a digital feedback (DFB) and a digital feedforward (DFF) at cPCI, and the older OS and developing environment of software. Therefore, we are starting to study the new LLRF system of the next generation. In the present, we are exploring several possibilities of a new way and investigating each advantage and disadvantage. The project and the status of the development for the new system in the J-PARC linac LLRF are introduced.

Journal Articles

Development of the bunch shape monitor in the J-PARC L3BT

Moriya, Katsuhiro; Okabe, Kota; Liu, Y.*; Miura, Akihiko; Futatsukawa, Kenta*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1081 - 1083, 2017/08

no abstracts in English

Journal Articles

Detection of H$$^{0}$$ particles in MEBT2 chicane of J-PARC linac

Tamura, Jun; Miura, Akihiko; Morishita, Takatoshi; Okabe, Kota; Yoshimoto, Masahiro; Ao, Hiroyuki*; Futatsukawa, Kenta*; Maruta, Tomofumi*; Miyao, Tomoaki*; Nemoto, Yasuo*

Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2308 - 2310, 2017/05

In the Japan Proton Accelerator Research Complex (J-PARC), H$$^{0}$$ particles generated by collisions of accelerated H$$^{-}$$ beams with residual gases are considered as one of the key factors of the residual radiation in the high energy accelerating section of the linac. To diagnose the H$$^{0}$$ particles, the new analysis line for the H$$^{0}$$ particles was installed in the matching section from the separated-type drift tube linac (SDTL) to the annular-ring coupled structure linac (ACS). In the analysis line, the accelerated H$$^{-}$$ ions travel in chicane orbit by the four dipole magnets. In the beam commissioning, we directly detected the H$$^{0}$$ particles by using a carbon plated installed to a wire scanner monitor and indirectly detected the H$$^{0}$$ particles by using a scintillation detector. We also confirmed that the signals change with vacuum condition in the SDTL section.

Journal Articles

Beam-loss monitoring signals of interlocked events at the J-PARC Linac

Hayashi, Naoki; Kato, Yuko; Miura, Akihiko; Futatsukawa, Kenta*; Miyao, Tomoaki*

Proceedings of 5th International Beam Instrumentation Conference (IBIC 2016) (Internet), p.368 - 371, 2017/03

It is important to understand why the beam loss occurs during user operation. It is understandable that the beam loss results from RF cavities failure. However, it would be still useful to study the beam loss detailed mechanism and to know which beam loss monitor (BLM) experiences the highest loss or is most sensitive. This may lead a reduction in the number of interlocked events and a more stable accelerator operation. The J-PARC Linac BLM has a simple data recorder that comprises multiple oscilloscopes. Although its functionality is limited, it can record events when an interlock is triggered. Of particular interest here are the events associated with only the BLM Machine Protection System (MPS). These may reveal hidden problems with the accelerator.

Journal Articles

Development of beam scrapers using a 3-Mev linac at J-PARC

Hirano, Koichiro; Asano, Hiroyuki; Ishiyama, Tatsuya; Ito, Takashi; Okoshi, Kiyonori; Oguri, Hidetomo; Kondo, Yasuhiro; Kawane, Yusuke; Kikuzawa, Nobuhiro; Sato, Yoshikatsu; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.310 - 313, 2016/11

We have used a beam scraper with the incident angle of 65deg to reduce the beam power deposition density in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC linac. The 65$$^{circ}$$ scraper was irradiated by the H$$^{-}$$ beam up to particle number of 1.47E22. We observed a lot of surface projections with several hundred micrometers high in the beam irradiation damage on the scraper by using the laser microscope. In order to study the limits of scrapers, we constructed a new 3 MeV linac at J-PARC. We will conduct the scraper irradiation test at the end of this year.

Journal Articles

Beam commissioning of the linac for iBNCT

Naito, Fujio*; Anami, Shozo*; Ikegami, Kiyoshi*; Uota, Masahiko*; Ouchi, Toshikatsu*; Onishi, Takahiro*; Oba, Toshiyuki*; Obina, Takashi*; Kawamura, Masato*; Kumada, Hiroaki*; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1244 - 1246, 2016/11

The proton linac installed in the Ibaraki Neutron Medical Research Center is used for production of the intense neutron flux for the Boron Neutron Capture Therapy (BNCT). The linac consists of the 3-MeV RFQ and the 8-MeV DTL. Design average beam current is 10mA. Target is made of Beryllium. First neutron production from the Beryllium target was observed at the end of 2015 with the low intensity beam as a demonstration. After the observation of neutron production, a lot of improvement s was carried out in order to increase the proton beam intensity for the real beam commissioning. The beam commissioning has been started on May 2016. The status of the commissioning is summarized in this report.

Journal Articles

Development of bunch shape monitor at J-PARC Linac

Futatsukawa, Kenta*; Kawane, Yusuke; Tamura, Jun; Nemoto, Yasuo; Hayashi, Naoki; Fukuoka, Shota*; Mayama, Minoru*; Miura, Akihiko; Miyao, Tomoaki*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1246 - 1250, 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

Development of RF chopper system at J-PARC Linac, 2

Hirano, Koichiro; Kondo, Yasuhiro; Kawane, Yusuke; Shinozaki, Shinichi; Miura, Akihiko; Morishita, Takatoshi; Sawabe, Yuki; Sugimura, Takashi*; Naito, Fujio*; Fang, Z.*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.944 - 947, 2015/09

Two RF-deflecting cavities as a chopper and a beam scraper have been used in the MEBT1 between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We replaced with a newly fabricated RF chopper to decrease beam loss for the operation with 50 mA. We installed two new scrapers to absorb the higher power of the deflected beam by the RF chopper. This paper describes the RF chopper system and beam irradiation test results of the scraper.

46 (Records 1-20 displayed on this page)