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Journal Articles

Discharge suppression for anode modulator in J-PARC linac

Chishiro, Etsuji; Kawamura, Masato*; Hori, Toshihiko; Sato, Fumiaki; Shinozaki, Shinichi

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1224 - 1226, 2013/08

no abstracts in English

Journal Articles

J-PARC operation data archiving using Hadoop and HBase

Yoshii, Akinobu; Kikuzawa, Nobuhiro

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.690 - 693, 2013/08

no abstracts in English

Journal Articles

Calibration of gafchromic dosimetry films for large-area ion-beam distribution measurement

Ishizaka, Tomohisa; Imai, Koji*; Yuri, Yosuke; Yuyama, Takahiro; Ishibori, Ikuo; Okumura, Susumu

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.594 - 596, 2013/08

no abstracts in English

Journal Articles

High power RF test station for RFQII at J-PARC linac

Hori, Toshihiko; Chishiro, Etsuji; Shinozaki, Shinichi; Sato, Fumiaki; Morishita, Takatoshi; Kondo, Yasuhiro; Futatsukawa, Kenta*; Fukui, Yuji*; Kawamura, Masato*; Sugimura, Takashi*; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1240 - 1242, 2013/08

no abstracts in English

Journal Articles

Design of control system for the 2nd and 3rd charge exchange system in J-PARC 3GeV RCS

Kawase, Masato; Yoshimoto, Masahiro; Yamazaki, Yoshio; Takeda, Osamu

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.734 - 737, 2013/08

no abstracts in English

Journal Articles

Development of MLF-inhibit system for J-PARC

Ishiyama, Tatsuya; Ito, Yuichi; Kikuzawa, Nobuhiro; Suzuki, Takahiro; Oi, Motoki; Meigo, Shinichiro; Sakai, Kenji; Kato, Yuko

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.714 - 716, 2013/08

no abstracts in English

Journal Articles

Proposal of an asymmetric optical resonator for the monochromatization of an LCS $$gamma$$ ray source

Nagai, Ryoji; Hajima, Ryoichi

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.980 - 982, 2013/08

Non-destructive measurement systems of nuclear material are under development in our group. The measurement systems are based on monochromatic $$gamma$$-ray generated from laser Compton scattering (LCS) based on energy-recovery linac accelerator technologies. The accuracy improvement of the non-destructive measurement systems and the exploration of the precise excitation state in an atomic nucleus are attained by further developing a pure monochromatic LCS-$$gamma$$-ray source. The energy spread of a mode-locked short pulse laser restricts the monochromaticity of the LCS-$$gamma$$-ray source. Therefore, an ultra-narrow band width laser should be used for instead of the short pulse laser. We propose an asymmetric confocal Fabry-Perot optical resonator as a supercavity of the pure monochromatic LCS-$$gamma$$-ray source. We present R&D status and basic characteristic for such optical resonator.

Journal Articles

Deflecting cavity for a temporal response measurement of a photocathode

Nagai, Ryoji; Sawamura, Masaru; Nishimori, Nobuyuki; Hajima, Ryoichi

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.656 - 658, 2013/08

Technologies for the next generation light sources based on energy-recovery linac (ERL) are under development in our group. Photocathode related technology is a key technology for the ERL based light sources. Temporal shape control of the photocathode gun generated electron beam is indispensable to generate ultra-small emittance electron beam. A 1300 MHz deflecting cavity has been developed for a temporal shape measurement of an electron beam from a 250-kV DC photocathode electron gun. The cavity is a rectangle shaped TM120 mode with the unloaded quality factor $$Q_{0}$$ = 17660. The deflecting angle is $$pm$$9.5 mrad for the electron bunch with $$pm$$50 ps with 134.7 W input RF power.

Journal Articles

Operation status of the J-PARC ion source

Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Koizumi, Isao; Takagi, Akira*; Namekawa, Yuya*; Yamazaki, Saishun; Ueno, Akira

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1081 - 1083, 2013/08

no abstracts in English

Journal Articles

Present status of JAEA-Tokai tandem accelerator and booster

Matsuda, Makoto; Abe, Shinichi; Ishizaki, Nobuhiro; Tayama, Hidekazu; Nakanoya, Takamitsu; Kabumoto, Hiroshi; Nakamura, Masahiko; Kutsukake, Kenichi; Otokawa, Yoshinori; Asozu, Takuhiro; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.362 - 366, 2013/08

no abstracts in English

Journal Articles

Development of a 500-kV photoemission DC gun at JAEA

Nishimori, Nobuyuki; Nagai, Ryoji; Matsuba, Shunya; Hajima, Ryoichi; Yamamoto, Masahiro*; Miyajima, Tsukasa*; Honda, Yosuke*; Iijima, Hokuto*; Kuriki, Masao*; Kuwahara, Makoto*; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.255 - 259, 2013/08

no abstracts in English

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

Precise measurement of the installed cable attenuation

Futatsukawa, Kenta*; Anami, Shozo*; Kobayashi, Tetsuya*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*; Sato, Fumiaki; Shinozaki, Shinichi

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.765 - 768, 2013/08

no abstracts in English

Journal Articles

Status of J-PARC linac LLRF after the Tohoku Earthquake

Futatsukawa, Kenta*; Anami, Shozo*; Kobayashi, Tetsuya*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*; Kawamura, Masato*; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.769 - 773, 2013/08

no abstracts in English

Journal Articles

Beam stabilization of the J-PARC ion source by ARC current $$Delta$$$$Sigma$$ feedback control

Okoshi, Kiyonori; Ito, Yuichi; Ueno, Akira; Oguri, Hidetomo

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1105 - 1108, 2013/08

The negative hydrogen ion source driven by an arc discharge with a lanthanum hexaboride (LaB$$_{6}$$) filament is under operation for the J-PARC (Japan Proton Accelerator Research Complex). In order to minimize the beam loss in the J-PARC, especially in the 50 GeV-MR (Main Ring), the allowable beam fluctuation of the ion source is very low ($$pm$$ 0.3 mA). On the other hand, the arc impedance is always changing due to the accumulation of boron on the low temperature surface of the filament and the exhaustion of the filament itself. The rather rapid increase of the arc impedance is produced by the former reason for a few days after the start-up of the overhauled ion source operation. Since the arc voltage is set to a constant value, basically the beam current is stabilized by keeping the arc current, that is arc impedance. Therefore, a control program simply negative-feedbacking the difference between the measured arc current and the setting one to the setting of the filament voltage was used at first. However, the beam current fluctuation by the feedback was not negligible to minimize the beam loss at the MR due to the insufficient setting resolution of the filament voltage (0.01 V). Therefore, the $$Delta$$$$Sigma$$ feedback system was installed into the program, in order to keep the arc current more precisely. The arc current fluctuation was reduced from about $$pm$$ 0.6 % to $$pm$$ 0.2 % by the improved feedback system. Consequently, the beam current fluctuation was successfully reduced to within about $$pm$$0.1 mA.

Journal Articles

Status of J-PARC accelerators

Hasegawa, Kazuo

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.339 - 343, 2013/08

The status and progress of the J-PARC accelerators are reported. After nine-months of beam shutdown by the Great Earthquake, the J-PARC facility resumed beam operation. In December 2011, operations were carried out at low duty such as single-shots or 1 to 2.5 Hz for beam tuning. At the beginning of January 2012, we started beam tuning at the full repetition rate of 25 Hz at the linac and the RCS. After the tuning, user programs of the MLF, NU and HD started. The beam power was increased from 100 to 200 kW to the MLF users, from 3.3 kW to 6 kW to the Hadron users, and from 140 to 200 kW to the Neutrino users. The beam availability, however, went lower to 73% in JFY 2011 due to the trouble of the linac klystron power supply in March, but it has got back to 90-94% as of June in JFY2012. We have also much upgrade work during the shutdown period or in parallel to the operation.

Journal Articles

Design study of J-PARC timing system for nuclear transmutation experimental facility

Ito, Yuichi; Kawase, Masato; Kikuzawa, Nobuhiro; Ouchi, Nobuo

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.738 - 740, 2013/08

A transmutation experimental facility (TEF) is planned in J-PARC 2nd construction phase. 400 MeV/250 kW of negative hydrogen ion beam will be delivered from LINAC to TEF. The LINAC is now operating in repetition of 25 Hz and LINAC should be operated in 50 Hz to keep beam power for existing experimental facilities. The timing system should also be operated in 50 Hz. However, some control subsystems and data acquisition subsystems are strongly optimized for 25 Hz operation especially in RCS. A design for J-PARC timing system to support TEF will be discussed in this report.

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

Development of a Cs-seeded RF-driven H$$^{-}$$ ion source for the J-PARC

Yamazaki, Saishun; Ueno, Akira; Namekawa, Yuya*; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Koizumi, Isao; Oguri, Hidetomo

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.260 - 264, 2013/08

A cesium (Cs) seeded RF-driven H$$^{-}$$ ion source using an internal-antenna developed at the SNS (Spallation Neutron Source) is under development for the J-PARC (Japan Proton Accelerator Research Complex). The axial magnetic field optimization by using an axial magnetic field compensation (AMFC) coil significantly enhances the H$$^{-}$$ ion beam by typically 10%. An H$$^{-}$$ ion beam with a flat top duty factor of 2.5% (1 ms $$times$$ 25 Hz) of 77 mA, whose about 90% (corresponding to about 70 mA) of emittance of each direction is within 1.5 $$pi$$mm$$cdot$$mrad, is successfully extracted. During a demonstration operation over 100-hours, an H$$^{-}$$ ion beam over 66 mA was successfully produced with a relatively low RF power of about 40 kW by seeding Cs for 4-minutes a day.

39 (Records 1-20 displayed on this page)