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Maebara, Sunao; Antonio, P.*; Ichikawa, Masahiro; Takahashi, Hiroki; Suzuki, Hiromitsu; Sugimoto, Masayoshi
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.561 - 563, 2014/06
no abstracts in English
Nishimori, Nobuyuki; Nagai, Ryoji; Matsuba, Shunya; Hajima, Ryoichi; Yamamoto, Masahiro*; Miyajima, Tsukasa*; Honda, Yosuke*; Uchiyama, Takashi*; Iijima, Hokuto*; Kuriki, Masao*; et al.
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.174 - 178, 2014/06
no abstracts in English
Yuri, Yosuke; Yuyama, Takahiro; Ishizaka, Tomohisa; Yoshida, Kenichi; Ishibori, Ikuo; Okumura, Susumu
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.138 - 142, 2014/06
no abstracts in English
Miyawaki, Nobumasa; Fukuda, Mitsuhiro*; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu; Arakawa, Kazuo*; Kamiya, Tomihiro
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.500 - 502, 2014/06
no abstracts in English
Enami, Kazuhiro*; Furuya, Takaaki*; Sakai, Hiroshi*; Sato, Masato*; Shinoe, Kenji*; Umemori, Kensei*; Sawamura, Masaru; Cenni, E.*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.602 - 604, 2014/06
no abstracts in English
Harada, Hiroyuki; Meigo, Shinichiro; Shirakata, Masashi*; Sato, Yoichi*; Tamura, Fumihiko; Tejima, Masaki*; Hashimoto, Yoshinori*; Igarashi, Susumu*; Koseki, Tadashi
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.39 - 43, 2014/06
The J-PARC 3-50 BT line is the beam transport line of extracted beam from 3-GeV rapid-cycling synchrotron (RCS) to 50-GeV main ring (MR). The RCS is the high-intensity proton accelerator, which designed beam power is 1 MW, and has the complex source of space charge effect, etc. Therefore, the uncontrolled emittance growth and beam halo increase nonlinearly with the increasing the beam power. Additionally, physical aperture of MR with 81 
mm mrad is smaller than that of RCS with 486 mm mrad. Therefore, the 3-50 BT line has the collimators in order to scrape the tail/halo of extracted beam from the RCS. The designed collimator aperture is 54 mm mrad. It is required to measure and optimize the optics parameter in the collimator area for taking full advantage of beam collimation. This paper will introduce the method of optics measurement and report the result of the measurement and optimization based on the simulation.
Hatakeyama, Shuichiro; Yoshimoto, Masahiro
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1082 - 1084, 2014/06
In J-PARC RCS (Rapid Cycling Synchrotron), in order to perform transverse orbit matching of the injection beam, it is used a total of 7 sets of multi-wire profile monitors (MWPMs). It is considered that beam loss around the equipments of injection beam line will be increased significantly because it is planed the beam power from the LINAC will be enforced in this fiscal year. So we will install a new MWPM on the H0 dump line to measure the injection orbit more precicely. In this time, we have developed a new data acquisition system using multi-channel digitizer. As the feature, it is improved the S/N ratio as compared with the present system using a multiplexer. Also the cost of the new system is estimated to be lower than the present system. In this report it is described the performance of the new DAQ system by using real beam with the existing MWPM2.
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.
Tamura, Fumihiko; Yamamoto, Masanobu; Omori, Chihiro*; Yoshii, Masahito*; Schnase, A.*; Nomura, Masahiro; Tomizawa, Masahito*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.125 - 129, 2014/06
For the slow extraction in the J-PARC MR, the rf voltage ins the cavities is turned off after finishing the acceleration to obtain a coasting beam. During the debunching process, the average momentum decrease due to the longitudinal coupling impedances in the MR. The decelatation continues until a well debunchedbeam is foarmed. The deceraration causes a reduction of the extraction efficiency due to the chromatic effects. In the J-PARC MR, a momentum loss has been observed at a relatively low beam power. To achieve higher beam power with keeping the high extraction efficiency, measures against the momentum loss are necessary. In this article, we report the observations and simulation results of the momentum losses. We adopt the rf feedforward method to cancel the wake voltage in the cavity as a measure of the momentum loss. By the feedforward, the momentum loss is significantly reduced. We achieve a high extraction efficiency, 99.5%, at the beam power of 20 kW.
Oguri, Hidetomo
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.313 - 317, 2014/06
no abstracts in English
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.
Miyao, Tomoaki*; Miura, Akihiko; Kondo, Yasuhiro; Morishita, Takatoshi; Sugimura, Takashi*; Ouchi, Nobuo; Oguri, Hidetomo; Maruta, Tomofumi*; Naito, Fujio
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1049 - 1052, 2014/06
In J-PARC linac, a project for energy and intensity upgrade has been progressed using 50 mA RFQ(Radio-Frequency-Quadrupole) linac cavity. Because the RFQ had already fabricated, test stand for its performance test was newly produced. In the test stand, we designed and fabricated the monitoring system including beam current monitors for the beam transmission measurement and the beam phase monitors for the energy measurement. We will refer the detail of the monitoring system and the data obtained during the performance test. New testing devices are also mentioned.
Hori, Toshihiko; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; Oguri, Hidetomo; Futatsukawa, Kenta*; Fukui, Yuji*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1001 - 1003, 2014/06
no abstracts in English
Watanabe, Yasuhiro; Tani, Norio; Inoue, Keigo*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.628 - 631, 2014/06
no abstracts in English
Kawamura, Masato*; Chishiro, Etsuji; Hori, Toshihiko; Shinozaki, Shinichi; Sato, Fumiaki; Fukui, Yuji*; Futatsukawa, Kenta*; Yamazaki, Masayoshi*; Sagawa, Ryu*; Miyajima, Noriyuki*; et al.
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.605 - 607, 2014/06
This report describes the present status of the klystron power supply systems for the J-PARC linac. The systems for the 181 MeV linac were operated from September to May. A few breakdowns were occurred, and are described in this report. The new systems for the upgrade of the linac from 181MeV to 400 MeV have been installed until now, and the 3 HVDCPSs and the 3 anode modulators of the new systems have been operated. All the systems for 400 MeV linac will be operated in this autumn.
Suganuma, Kazuaki; Togashi, Tomohito; Kinsho, Michikazu
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.870 - 872, 2014/06
We started the initial tests of thyratron CX2004X at the switching test stand of the J-PARC. Deuteron gauss of this model is about 2 times as much as CX1193C one, by employing two reservoir tanks. A log life time more than thyratron CX1193C could be expected.
ray sourceNagai, Ryoji; Hajima, Ryoichi
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.781 - 783, 2014/06
Non-destructive measurement systems of nuclear material are under development in our group. The measurement systems are based on monochromatic -ray generated from laser Compton scattering (LCS) based on energy-recovery linac accelerator technologies. The accuracy improvement of the non-destructive measurement systems is attained by further developing a pure monochromatic LCS--ray source. The energy spread of a mode-locked short pulse laser restricts the monochromaticity of the LCS--ray source. Therefore, an ultra-narrow band width laser should be used for instead of the short pulse laser. We have proposed an asymetric confocal Fabry-Perot optical resonator as a supercavity of the pure monochromatic LCS--ray source. The influences due to the distortion and the misalignment of the mirrors were evaluated by a raytrace method. We present R&D status and the evaluation results for the optical resonator.
Tamura, Jun; Ao, Hiroyuki; Nemoto, Yasuo; Asano, Hiroyuki*; Suzuki, Takahiro*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.437 - 439, 2014/06
no abstracts in English
Sugimura, Takashi*; Hirano, Koichiro; Nammo, Kesao*; Kurihara, Toshikazu*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.862 - 866, 2014/06
By introducing a new ion source and a new RFQ, beam current will increase from 20 mA to 50 mA. According to an increase of the beam current, wasted beam that should not be accelerated in the following accelerator sections also increase. To stop wasted beam, there is a beam scraper in the MEBT region just after the RFQ at the beam energy of 3 MeV. An existing beam scraper is made of carbon composite material and it has a dent caused by merely small beam current of 20 mA in daily operation. A new scraper that endures upgraded beam current of 50 mA is the essential item for the beam power upgrade of J-PARC. Thermal simulations on several materials have been performed with the ANSYS code assuming the upgraded beam power. They revealed that maximum temperatures in a beam cycle are much higher than their melting points in some materials and consequently that lessening of heat load for a scraper by beam operation is an essential factor.
Ito, Takashi; Hirano, Koichiro; Sugimura, Takashi*; Nammo, Kesao*
Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.977 - 981, 2014/06
The Japan Proton Accelerator Research Complex (J-PARC) facilities were extensively damaged by the Great East Japan Earthquake on March 2011. We restarted the beam operation in December 2011 after the recovery works. However, a multipactor problem of SDTL5B cavity was occurred after the beam restoration. To solve this problem, we performed the analysis of the impurities on the inner surface of the cavity, adopted the countermeasure that is the improvement of the vacuum condition of the cavity and performed the conditioning of the cavity carefully in the summer maintenance period of 2012. By adopting the countermeasure and conditioning, the multipactor problem improved just after the beam restoration and the operation power had been decreased. We present the result of the countermeasures and the present operation status of the SDTL5 in this report.
